A primer on backup battery systems for power outages

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linuxizer
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Re: A primer on backup battery systems for power outages

Post by linuxizer »

ballons wrote: Fri Aug 21, 2020 12:32 amBuy a chest freezer
If only it were possible!
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Re: A primer on backup battery systems for power outages

Post by inbox788 »

hudson wrote: Fri Aug 21, 2020 10:50 amBottom Line: Standard UPSs are probably fine for home use.
I just looked into this and there is a wide variability between cost and function, and no "standard UPS". TrippLite differentiates between "Standby UPS Systems" and "Line-Interactive UPS Systems", yet yours isn't either. It's a "Smart UPS Battery Back Up". I guess Smart (=Line Interactive) vs Standby? Anyway, the key specification to look for is "AVR", automatic voltage regulation.
AVR allows the UPS system to adjust voltage to safe levels during brownouts without switching to battery power, reducing battery wear and preserving charge levels for blackout protection.
https://www.tripplite.com/support/common-power-problems

My dumb UPS seems to regulate sufficiently and transfer fast enough for the devices I've got plugged in most of the time for me not to notice. Adding AVR is better, but not double conversion (which pretty much decouples you from line power) .

BTW, I plugged my microwave into the UPS (dumb; 350VA /200W?) bypass plugs and it worked fine (don't ask why; Covid). I thought about using a backup plug, but didn't get around to testing it. I figure it would work fine while plugged in, but wouldn't work on batteries. Same reason not to plug in laser printers. Inkjet printers might work on battery.

I can just imagine a mission critical server plugged into a double conversion UPS and the new intern uses a spare plug for a microwave to heat up his lunch.
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Re: A primer on backup battery systems for power outages

Post by smitcat »

sport wrote: Fri Aug 21, 2020 11:20 am
willthrill81 wrote: Thu Aug 20, 2020 11:15 pm
Think about this. There are tens of millions of vehicles on the road in the U.S. alone, virtually all of which have lead acid batteries stored right next to large internal combustion engines that get quite hot, and yet battery accidents in even this situation of any kind are extraordinarily rare. Even when accidents do occur, about the worst thing that happens is some battery acid splashes on to someone. For that reason, you should wear eye protection and gloves when working with lead acid batteries.
When the hydrogen in a car battery is ignited, splashing battery acid, while hazardous, is not the "worst thing that can happen". When a battery explodes, jagged pieces of the battery cover become projectiles. This can put out an eye. Battery acid in the eyes is bad, but survivable. Battery acid will not cause meaningful damage to your hands, so gloves are not necessary. However, as you say, eye protection is a must. My knowledge of this comes from years of working in a battery test lab, and developing devices to minimize the chance of battery explosions.
This is why the large battery banks in boats and RV's are installed in common battery boxes - easily used in any location.
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Re: A primer on backup battery systems for power outages

Post by LadyGeek »

It's important to mention that anyone using a UPS in their home must have a properly grounded 3-prong outlet.

There are a lot of reasons. Not only for your safety, but to protect the equipment it's powering.

Adapter plugs (3-prong to 2-prong) are not to be used.
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Re: A primer on backup battery systems for power outages

Post by hudson »

inbox788 wrote: Fri Aug 21, 2020 12:50 pm
hudson wrote: Fri Aug 21, 2020 10:50 amBottom Line: Standard UPSs are probably fine for home use.
I just looked into this and there is a wide variability between cost and function, and no "standard UPS". TrippLite differentiates between "Standby UPS Systems" and "Line-Interactive UPS Systems", yet yours isn't either. It's a "Smart UPS Battery Back Up". I guess Smart (=Line Interactive) vs Standby? Anyway, the key specification to look for is "AVR", automatic voltage regulation.
AVR allows the UPS system to adjust voltage to safe levels during brownouts without switching to battery power, reducing battery wear and preserving charge levels for blackout protection.
https://www.tripplite.com/support/common-power-problems

My dumb UPS seems to regulate sufficiently and transfer fast enough for the devices I've got plugged in most of the time for me not to notice. Adding AVR is better, but not double conversion (which pretty much decouples you from line power) .

BTW, I plugged my microwave into the UPS (dumb; 350VA /200W?) bypass plugs and it worked fine (don't ask why; Covid). I thought about using a backup plug, but didn't get around to testing it. I figure it would work fine while plugged in, but wouldn't work on batteries. Same reason not to plug in laser printers. Inkjet printers might work on battery.

I can just imagine a mission critical server plugged into a double conversion UPS and the new intern uses a spare plug for a microwave to heat up his lunch.
Thanks inbox788!

You powered your microwave with a 350VA UPS....wow! I've tested UPSs with a 12" house fan and let it run until it stopped, but I've never tried a microwave...or hair dryer.

The washing machine sized double conversion UPS with 25-30 batteries in it was hard wired; it was also in a separate and fairly secure area. The intern could probably get into the well marked electrical panel and turn it off and shutdown all the servers. For that eventuality, I had an emergency plan: an updated resume. :)
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Re: A primer on backup battery systems for power outages

Post by inbox788 »

hudson wrote: Fri Aug 21, 2020 1:42 pmYou powered your microwave with a 350VA UPS....wow! I've tested UPSs with a 12" house fan and let it run until it stopped, but I've never tried a microwave...or hair dryer.

The washing machine sized double conversion UPS with 25-30 batteries in it was hard wired; it was also in a separate and fairly secure area. The intern could probably get into the well marked electrical panel and turn it off and shutdown all the servers. For that eventuality, I had an emergency plan: an updated resume. :)
No, not on battery. I think the bypass plug is rated at 10A, enough for a 1000 watt device. [not sure where I got that from and just checked my other UPS and it's only 8 amps across all the plugs]

Just went and did the test. With the battery backed up plugs and while UPS is plugged into wall, line power is being passed thru, and microwave works (same as bypass plug). As soon as I unplug the UPS, everything went out (all the lights on the ups went dark and required a long power button hold reset; on battery, the clock/display does work and goes out as soon as I hit the start button). A longer test (heating up lunch 2-3 minutes) wound up triggering the circuit breaker. It's a 900 watt microwave (output rating), but the input is rated 1350 watts, so pulling more than 11 amps...that's borderline over so that's probably why it's working a short time.

I don't know what AVR limits on devices like yours would do under similar maximum and overload conditions, but they might work similarly. I would think the double converted devices would fail when overloaded, plugged in or not. [you'd have to unplug your server and other equipment to use the microwave if it was within rating or really upsize the UPS]

Tripp Lite 1500VA 1200W UPS Smart Online Tower 100V-120V USB (SU1500XL)
https://www.amazon.com/Tripp-Lite-SU150 ... B000RW5GQY
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Re: A primer on backup battery systems for power outages

Post by mrb09 »

This was an excellent primer on batteries.

For a real-world example, I have a solar system normally grid tied but with batter backup. The batteries are 24 6V T-145 golf cart batteries arranged in two parallel series (2x12), giving me ~450 AH's at 48 volts. That goes into the same inverter as my solar panels for 240 volts.

If the power goes off during the winter, this is usually the result of a snow that covers my solar panels. If we turn the well pump and the heater off and just use the wood stove, we can make it about 3 days on batteries. Longer if I shovel the snow off :)

One thing that may not have have come through in the OP's primer is the diligence needed to check the water levels in the flooded batteries. I wasn't very good about this and toasted my original larger solar specific batteries (~700 AH's worth). I had to pack up and haul 2000 pounds worth of toasted solar batteries and exchange them for the cheaper golf cart batteries. Gives us less run time than we originally had, but we also switched our water system to pump up to storage tanks above our house for gravity feed when the power's out, so we don't have to worry about the well pump now, which was by far the biggest power hog.
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Re: A primer on backup battery systems for power outages

Post by willthrill81 »

LadyGeek wrote: Fri Aug 21, 2020 8:05 am A chest freezer is a good suggestion if anything happens to the one I'm using now.
We had a chest freezer for several years, but last year I agreed with my wife to swap it for an upright. It's less efficient since the cold air pours out every time you open it, but since we only open it about once a day, that's not a big deal at all. The reason for the swap was that my wife much preferred the access to the freezer's contents that an upright provides over a chest freezer. But there's no disputing that chest freezers are superior in pretty much every way.
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.” J.R.R. Tolkien,The Lord of the Rings
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Re: A primer on backup battery systems for power outages

Post by willthrill81 »

mrc wrote: Fri Aug 21, 2020 11:19 am I owned a ~3500w inverter generator that wasn't large enough to run essentials during prolonged power outages. I replaced it with an 8000w Genrac and found out after the fact that my APC UPS won't run on the Genrac power. Something I wish I had considered before the switch.
Wow, that's surprising. Either the Generac is creating some 'dirty' power or that APC UPS is very finicky. My suspicions fall more toward the former, but they Generac really tries to emphasize that the power they produce is clean.

If you know someone with electrical testing equipment, I'd suggest having them test the output of the Generac. If the power is that bad, it might eventually lead to problems for other devices.
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.” J.R.R. Tolkien,The Lord of the Rings
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Re: A primer on backup battery systems for power outages

Post by willthrill81 »

sport wrote: Fri Aug 21, 2020 11:20 am
willthrill81 wrote: Thu Aug 20, 2020 11:15 pm
Think about this. There are tens of millions of vehicles on the road in the U.S. alone, virtually all of which have lead acid batteries stored right next to large internal combustion engines that get quite hot, and yet battery accidents in even this situation of any kind are extraordinarily rare. Even when accidents do occur, about the worst thing that happens is some battery acid splashes on to someone. For that reason, you should wear eye protection and gloves when working with lead acid batteries.
When the hydrogen in a car battery is ignited, splashing battery acid, while hazardous, is not the "worst thing that can happen". When a battery explodes, jagged pieces of the battery cover become projectiles. This can put out an eye. Battery acid in the eyes is bad, but survivable. Battery acid will not cause meaningful damage to your hands, so gloves are not necessary. However, as you say, eye protection is a must. My knowledge of this comes from years of working in a battery test lab, and developing devices to minimize the chance of battery explosions.
Yes, of course, a real battery explosion can happen, but it's a bit like being struck by lightning in terms of the frequency of its occurrence. While we take common sense precautions against lightning strikes, we don't let it keep us from ever going outside. The same should be true here. Many novices to this topic are given all kinds of warnings about lead acid batteries being dangerous, and they never even stop to think that they've been sitting a few feet from one for years in a vehicle. The danger, IMHO, is not remotely high enough to warrant the concern that many have, who may opt for no backup power at all due to hyped up fear of their battery exploding.
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.” J.R.R. Tolkien,The Lord of the Rings
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Re: A primer on backup battery systems for power outages

Post by willthrill81 »

mrb09 wrote: Fri Aug 21, 2020 3:07 pm One thing that may not have have come through in the OP's primer is the diligence needed to check the water levels in the flooded batteries. I wasn't very good about this and toasted my original larger solar specific batteries (~700 AH's worth). I had to pack up and haul 2000 pounds worth of toasted solar batteries and exchange them for the cheaper golf cart batteries. Gives us less run time than we originally had, but we also switched our water system to pump up to storage tanks above our house for gravity feed when the power's out, so we don't have to worry about the well pump now, which was by far the biggest power hog.
Ouch! Thanks for clarifying that.

I've used a Battery Minder #1500 to keep my backup battery charged for years, and since it's monitors the temperature and adjusts the charging voltage accordingly, it results in very little water loss. Over the last two years, I've only had to put a couple of ounces of distilled water in one cell; all of the others are unchanged. Batteries being used more often definitely need more maintenance.

Do you have a generator for backup as well?
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.” J.R.R. Tolkien,The Lord of the Rings
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Re: A primer on backup battery systems for power outages

Post by mrc »

willthrill81 wrote: Fri Aug 21, 2020 3:44 pm
mrc wrote: Fri Aug 21, 2020 11:19 am I owned a ~3500w inverter generator that wasn't large enough to run essentials during prolonged power outages. I replaced it with an 8000w Genrac and found out after the fact that my APC UPS won't run on the Genrac power. Something I wish I had considered before the switch.
Wow, that's surprising. Either the Generac is creating some 'dirty' power or that APC UPS is very finicky. My suspicions fall more toward the former, but they Generac really tries to emphasize that the power they produce is clean.

If you know someone with electrical testing equipment, I'd suggest having them test the output of the Generac. If the power is that bad, it might eventually lead to problems for other devices.
Thanks. I might try plugging the UPS directly into the generator. I don't have access to any test equipment, but I do note the UPS momentarily trips a couple times a week. Sometimes without any storms or wind nearby. More often than a routine self test. The good news is after I upgraded the generator size, and along with a regional tree trimming effort, we haven't had nearly the outages we used to.
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Re: A primer on backup battery systems for power outages

Post by mrb09 »

willthrill81 wrote: Fri Aug 21, 2020 3:52 pm
mrb09 wrote: Fri Aug 21, 2020 3:07 pm One thing that may not have have come through in the OP's primer is the diligence needed to check the water levels in the flooded batteries. I wasn't very good about this and toasted my original larger solar specific batteries (~700 AH's worth). I had to pack up and haul 2000 pounds worth of toasted solar batteries and exchange them for the cheaper golf cart batteries. Gives us less run time than we originally had, but we also switched our water system to pump up to storage tanks above our house for gravity feed when the power's out, so we don't have to worry about the well pump now, which was by far the biggest power hog.
Ouch! Thanks for clarifying that.

I've used a Battery Minder #1500 to keep my backup battery charged for years, and since it's monitors the temperature and adjusts the charging voltage accordingly, it results in very little water loss. Over the last two years, I've only had to put a couple of ounces of distilled water in one cell; all of the others are unchanged. Batteries being used more often definitely need more maintenance.

Do you have a generator for backup as well?
I have a small Honda 2500 Watt Generator, I can plug that into an outside outlet that goes to a dedicated outlet in the kitchen. So if we're off for more than three days and I can't get the panels clear, I can plug the fridge and freezer into the dedicated outlet and run the generator. That was actually our system before we get the solar and batteries. Haven't had to do that since we got the solar though, so far even with the batteries out, I can clear the panels after a storm to at least give us enough power to run the fridge for a few hours a day.
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Re: A primer on backup battery systems for power outages

Post by hudson »

mrc wrote: Fri Aug 21, 2020 4:11 pm
willthrill81 wrote: Fri Aug 21, 2020 3:44 pm
mrc wrote: Fri Aug 21, 2020 11:19 am I owned a ~3500w inverter generator that wasn't large enough to run essentials during prolonged power outages. I replaced it with an 8000w Genrac and found out after the fact that my APC UPS won't run on the Genrac power. Something I wish I had considered before the switch.
Wow, that's surprising. Either the Generac is creating some 'dirty' power or that APC UPS is very finicky. My suspicions fall more toward the former, but they Generac really tries to emphasize that the power they produce is clean.

If you know someone with electrical testing equipment, I'd suggest having them test the output of the Generac. If the power is that bad, it might eventually lead to problems for other devices.
Thanks. I might try plugging the UPS directly into the generator. I don't have access to any test equipment, but I do note the UPS momentarily trips a couple times a week. Sometimes without any storms or wind nearby. More often than a routine self test. The good news is after I upgraded the generator size, and along with a regional tree trimming effort, we haven't had nearly the outages we used to.
You've likely already seen this stuff:

From the APC FAQs: The UPS won't operate online when powered by generator.
https://www.apc.com/us/en/faqs/FA158891/

From Tripp-Lite: Which Type of UPS System Works Best with a Generator?
https://blog.tripplite.com/which-type-o ... -generator
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Re: A primer on backup battery systems for power outages

Post by mrc »

hudson wrote: Fri Aug 21, 2020 5:09 pm
mrc wrote: Fri Aug 21, 2020 4:11 pm

Thanks. I might try plugging the UPS directly into the generator. I don't have access to any test equipment, but I do note the UPS momentarily trips a couple times a week. Sometimes without any storms or wind nearby. More often than a routine self test. The good news is after I upgraded the generator size, and along with a regional tree trimming effort, we haven't had nearly the outages we used to.
You've likely already seen this stuff:

From the APC FAQs: The UPS won't operate online when powered by generator.
https://www.apc.com/us/en/faqs/FA158891/

From Tripp-Lite: Which Type of UPS System Works Best with a Generator?
https://blog.tripplite.com/which-type-o ... -generator
Thanks. Yes, the UPS is controllable via software (Power Chute) that was never written for a Mac :annoyed so I can't adjust the settings.
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Re: A primer on backup battery systems for power outages

Post by inbox788 »

mrb09 wrote: Fri Aug 21, 2020 4:29 pmHaven't had to do that since we got the solar though, so far even with the batteries out, I can clear the panels after a storm to at least give us enough power to run the fridge for a few hours a day.
I've been reading about new ideas and vertical panels as well as wall mounted panels may be good solutions to keeping the fridge running without having to rush to clear off rooftop panels. Still, you probably want to clear them off to get more power for other uses.
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Re: A primer on backup battery systems for power outages

Post by hudson »

mrc,
I'm sure also that you already ruled out borrowing a windows laptop or whatever it takes to run Powerchute to change the settings.
I don't know if that would fix the problem...but it might be the next step before buying a different UPS. It sounds like you might be ok with things like they are?
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Re: A primer on backup battery systems for power outages

Post by ballons »

linuxizer wrote: Fri Aug 21, 2020 11:29 am
ballons wrote: Fri Aug 21, 2020 12:32 amBuy a chest freezer
If only it were possible!
Even pre-covid, it took about 1-2 months to get one so waiting is nothing new. I'm seeing lowes delivering in November for GE's.
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Re: A primer on backup battery systems for power outages

Post by mrc »

hudson wrote: Fri Aug 21, 2020 5:30 pm mrc,
I'm sure also that you already ruled out borrowing a windows laptop or whatever it takes to run Powerchute to change the settings.
I don't know if that would fix the problem...but it might be the next step before buying a different UPS. It sounds like you might be ok with things like they are?
Pretty much. If we have an extended outage, I can only use the desktop for as long as the FiOS modem lasts anyway.
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Re: A primer on backup battery systems for power outages

Post by hudson »

mrc wrote: Sat Aug 22, 2020 10:52 am
hudson wrote: Fri Aug 21, 2020 5:30 pm mrc,
I'm sure also that you already ruled out borrowing a windows laptop or whatever it takes to run Powerchute to change the settings.
I don't know if that would fix the problem...but it might be the next step before buying a different UPS. It sounds like you might be ok with things like they are?
Pretty much. If we have an extended outage, I can only use the desktop for as long as the FiOS modem lasts anyway.
I wonder what kind of power backups the cable companies and the cellular service companies have?
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Re: A primer on backup battery systems for power outages

Post by LadyGeek »

^^^ Backup power is a key part of the facility / cellphone tower design. You can't afford to drop even a single power cycle. Here's one example: Cell Phone Towers Use Standby Power Generators | Telecom Industry
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Re: A primer on backup battery systems for power outages

Post by RetiredAL »

LadyGeek wrote: Sat Aug 22, 2020 11:55 am ^^^ Backup power is a key part of the facility / cellphone tower design. You can't afford to drop even a single power cycle. Here's one example: Cell Phone Towers Use Standby Power Generators | Telecom Industry
LadyG

The Cell People do not have to meet the same availability requirements the Phone Companies have to meet.

Here in Calif with the so-called "multi-day public-safety power shutdowns", the cell system dies after a few hours when their batteries die, as they generally have no onsite backup generator. CA has mandated they add generators, but it's moving slowly.

Up at our mountain cabin, the phone company's local switch box 2 blocks away has a backup propane generator. Thus our POTS telephone works but the nearby cell site dies after a few hours.

Same goes on the Cable TV and Internet. Their equipment has batteries, not generators, so it only works for a few hours without commercial power.

Rural cell towers used to be mostly microwave linked, now they are going with Fiber. When a fire burns down the telephone poles, the fiber connection is lost, so no cell service. This communication loss has been a big factor in several CA fires with densely populated rural clusters.
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Re: A primer on backup battery systems for power outages

Post by telemark »

mrc wrote: Fri Aug 21, 2020 5:18 pm Thanks. Yes, the UPS is controllable via software (Power Chute) that was never written for a Mac :annoyed so I can't adjust the settings.
Some Windows software can run on a Mac using Wine. I don't know if Power Chute is one of them. It depends on how much time you want to spend on it.

https://www.howtogeek.com/263211/how-to ... with-wine/
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Re: A primer on backup battery systems for power outages

Post by mrc »

telemark wrote: Sat Aug 22, 2020 1:05 pm
mrc wrote: Fri Aug 21, 2020 5:18 pm Thanks. Yes, the UPS is controllable via software (Power Chute) that was never written for a Mac :annoyed so I can't adjust the settings.
Some Windows software can run on a Mac using Wine. I don't know if Power Chute is one of them. It depends on how much time you want to spend on it.

https://www.howtogeek.com/263211/how-to ... with-wine/
I have Parallels, and I really don't think I'll fool with it. Thanks though.
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Re: A primer on backup battery systems for power outages

Post by RetiredAL »

mrc wrote: Fri Aug 21, 2020 4:11 pm
I owned a ~3500w inverter generator that wasn't large enough to run essentials during prolonged power outages. I replaced it with an 8000w Genrac and found out after the fact that my APC UPS won't run on the Genrac power. Something I wish I had considered before the switch.
MRC - Some UPSs are very frequency sensitive, like switch to backup at 1hz deviation. Others want a near sinewave, considering anything else a voltage spike. A real PIA! If it's not settable, get a different UPS. We had one at work that was that ( Corp bought ) that switched that way. I tossed it and got one not sensitive.

I can't imagine anything you have at home would care at +- 5 hz, and most modern electronic power supplies wouldn't even blink at +- 20 hz. Motors and transformers don't do well long term with way a lower power frequency.
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Re: A primer on backup battery systems for power outages

Post by ballons »

silverlitegs wrote: Wed Aug 19, 2020 4:49 pm This is an interesting topic. This past weekend I was looking for plans to setup a temporary system of solar panels and batteries to serve a fridge ,freezer and random electronics during an extended outage . Figuring the draw would be 2k Watts a day. I haven’t been able to find a definitive article.
Look up the energy star label for your models, use a Kill-A-Watt device, or use a calc to estimate:
https://www.wholesalesolar.com/solar-in ... calculator

Unless you've purposely bought lower powered appliances (top freezer and manual defrost chest freezer), be prepared to be shocked how much energy they use.
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Re: A primer on backup battery systems for power outages

Post by willthrill81 »

RetiredAL wrote: Sat Aug 22, 2020 1:50 pm I can't imagine anything you have at home would care at +- 5 hz, and most modern electronic power supplies wouldn't even blink at +- 20 hz. Motors and transformers don't do well long term with way a lower power frequency.
In my experience, most items seem to operate just fine with voltage at least somewhat lower than what I've seen recommended, at least for the short-term. For instance, 105 volts at the point of use doesn't seem to bother any devices I've seen, even though that's more than a 12.5% drop from 120 volts. Maybe running them long-term with that voltage would damage them, but I'm not an electrical engineer.
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Re: A primer on backup battery systems for power outages

Post by LadyGeek »

RetiredAL wrote: Sat Aug 22, 2020 1:02 pm
LadyGeek wrote: Sat Aug 22, 2020 11:55 am ^^^ Backup power is a key part of the facility / cellphone tower design. You can't afford to drop even a single power cycle. Here's one example: Cell Phone Towers Use Standby Power Generators | Telecom Industry
LadyG

The Cell People do not have to meet the same availability requirements the Phone Companies have to meet.

Here in Calif with the so-called "multi-day public-safety power shutdowns", the cell system dies after a few hours when their batteries die, as they generally have no onsite backup generator. CA has mandated they add generators, but it's moving slowly.

Up at our mountain cabin, the phone company's local switch box 2 blocks away has a backup propane generator. Thus our POTS telephone works but the nearby cell site dies after a few hours.

Same goes on the Cable TV and Internet. Their equipment has batteries, not generators, so it only works for a few hours without commercial power.

Rural cell towers used to be mostly microwave linked, now they are going with Fiber. When a fire burns down the telephone poles, the fiber connection is lost, so no cell service. This communication loss has been a big factor in several CA fires with densely populated rural clusters.
Thank you for the correction. I understand availability from a communications perspective, but didn't know what the standards were. What you say makes sense.
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Re: A primer on backup battery systems for power outages

Post by willthrill81 »

silverlitegs wrote: Wed Aug 19, 2020 4:49 pm This is an interesting topic. This past weekend I was looking for plans to setup a temporary system of solar panels and batteries to serve a fridge ,freezer and random electronics during an extended outage . Figuring the draw would be 2k Watts a day. I haven’t been able to find a definitive article.
There isn't anything 'definitive' because it depends on many factors, including the power draw of the devices, your latitude, your local weather, and how much reserve power you want in the battery system, among others.

A modern refrigerator kept closed most of the time will run at least 50% of the time, which generally translates into about 2 kWh all by itself. You can figure about the same for most chest freezers. I don't know what 'random electronics' you're referring to, but devices that are recharged or powered from USB outlets are generally very low draw.

Let's work through an example and assume that you need 5 kWh per day. You would want to have a battery system with at least that much capacity, and one cloudy or rainy day would mean that your batteries would be drained and you'd have to rely on something else like a generator. Using something like golf cart batteries, you would need six GC2 batteries with a total capacity of about 5.4 kWh at a cost of about $600.

When charging lead acid batteries, roughly 25% of the power that goes into them is lost due to the heat created in the process, so to recharge a 5.4 kWh battery system, you would need at least 7.2 kWh of daily output from solar panels, maybe closer to 8 kWh. If your area would have about 5 mean solar hours per day (i.e. you would get about 5 times the output of what your solar panels are rated for, so 500 watt hours from a 100 watt solar panel), keeping in mind that this changes with the seasons, then you would need 16 panels at 100 watts each, at a total cost of about $1,280.

You need a charge controller to manage the power flow from the solar panels to the battery system, which will cost about $450 for an MPPT (you definitely don't want a PWM charge controller in this instance). Mounting brackets for the solar panels, wire, connectors, and a 1 kWh pure sine wave inverter would total maybe $500.

So altogether, you're talking about $2,400 for a combined solar panel and battery backup system capable of giving you 5 kWh of power per sunny day. Days without sun would need power from an alternative means, or else you would need to increase the capacity of the whole system accordingly.

Even though I have much more of a 'be prepared' mindset than most, there's no way that I would go for all that unless I was specifically trying to go off-grid. The cost of the system compared to the benefit just isn't there. A small inverter generator and filled gas cans could be purchased for well under $1k and would work day or night, rain or shine, and not require installing panels on your roof, running wire, etc. Yes, the fuel would eventually run out, but by that time, you should have cleaned out your refrigerator and freezer at least.
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.” J.R.R. Tolkien,The Lord of the Rings
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Re: A primer on backup battery systems for power outages

Post by RetiredAL »

LadyGeek wrote: Sat Aug 22, 2020 2:52 pm
RetiredAL wrote: Sat Aug 22, 2020 1:02 pm
LadyGeek wrote: Sat Aug 22, 2020 11:55 am ^^^ Backup power is a key part of the facility / cellphone tower design. You can't afford to drop even a single power cycle. Here's one example: Cell Phone Towers Use Standby Power Generators | Telecom Industry
LadyG

The Cell People do not have to meet the same availability requirements the Phone Companies have to meet.

Here in Calif with the so-called "multi-day public-safety power shutdowns", the cell system dies after a few hours when their batteries die, as they generally have no onsite backup generator. CA has mandated they add generators, but it's moving slowly.

Up at our mountain cabin, the phone company's local switch box 2 blocks away has a backup propane generator. Thus our POTS telephone works but the nearby cell site dies after a few hours.

Same goes on the Cable TV and Internet. Their equipment has batteries, not generators, so it only works for a few hours without commercial power.

Rural cell towers used to be mostly microwave linked, now they are going with Fiber. When a fire burns down the telephone poles, the fiber connection is lost, so no cell service. This communication loss has been a big factor in several CA fires with densely populated rural clusters.
Thank you for the correction. I understand availability from a communications perspective, but didn't know what the standards were. What you say makes sense.
Lady-G

One thing I thought of later, is this cell power issue is usually related to cell only sites. If the site is a commercial tower site (think American Tower) they generally have backup generators.

In the 1989 Bay Area Loma Prieta earthquake, a mountain top radio site on Loma Prieta that I was affiliated with ran for 5+ days on the backup generator. The owner is the site was not able talk to his control equipment as the telephone lines had failed. We had already confirmed via our radio link that our equipment indicated AC power was on. If we were on our batteries, we would have commanded the transmitters to low power, which would extend the batteries to 2 to 3 days. As a piece of trivia, the elevation of Mt Loma Prieta increased 30" from the earthquake.
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Re: A primer on backup battery systems for power outages

Post by RetiredAL »

willthrill81 wrote: Sat Aug 22, 2020 3:13 pm
silverlitegs wrote: Wed Aug 19, 2020 4:49 pm This is an interesting topic. This past weekend I was looking for plans to setup a temporary system of solar panels and batteries to serve a fridge ,freezer and random electronics during an extended outage . Figuring the draw would be 2k Watts a day. I haven’t been able to find a definitive article.
There isn't anything 'definitive' because it depends on many factors, including the power draw of the devices, your latitude, your local weather, and how much reserve power you want in the battery system, among others.

A modern refrigerator kept closed most of the time will run at least 50% of the time, which generally translates into about 2 kWh all by itself. You can figure about the same for most chest freezers. I don't know what 'random electronics' you're referring to, but devices that are recharged or powered from USB outlets are generally very low draw.

Let's work through an example and assume that you need 5 kWh per day. You would want to have a battery system with at least that much capacity, and one cloudy or rainy day would mean that your batteries would be drained and you'd have to rely on something else like a generator. Using something like golf cart batteries, you would need six GC2 batteries with a total capacity of about 5.4 kWh at a cost of about $600.

When charging lead acid batteries, roughly 25% of the power that goes into them is lost due to the heat created in the process, so to recharge a 5.4 kWh battery system, you would need at least 7.2 kWh of daily output from solar panels, maybe closer to 8 kWh. If your area would have about 5 mean solar hours per day (i.e. you would get about 5 times the output of what your solar panels are rated for, so 500 watt hours from a 100 watt solar panel), keeping in mind that this changes with the seasons, then you would need 16 panels at 100 watts each, at a total cost of about $1,280.

You need a charge controller to manage the power flow from the solar panels to the battery system, which will cost about $450 for an MPPT (you definitely don't want a PWM charge controller in this instance). Mounting brackets for the solar panels, wire, connectors, and a 1 kWh pure sine wave inverter would total maybe $500.

So altogether, you're talking about $2,400 for a combined solar panel and battery backup system capable of giving you 5 kWh of power per sunny day. Days without sun would need power from an alternative means, or else you would need to increase the capacity of the whole system accordingly.

Even though I have much more of a 'be prepared' mindset than most, there's no way that I would go for all that unless I was specifically trying to go off-grid. The cost of the system compared to the benefit just isn't there. A small inverter generator and filled gas cans could be purchased for well under $1k and would work day or night, rain or shine, and not require installing panels on your roof, running wire, etc. Yes, the fuel would eventually run out, but by that time, you should have cleaned out your refrigerator and freezer at least.
+1

Good dialog WT.
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Re: A primer on backup battery systems for power outages

Post by smitcat »

willthrill81 wrote: Sat Aug 22, 2020 3:13 pm
silverlitegs wrote: Wed Aug 19, 2020 4:49 pm This is an interesting topic. This past weekend I was looking for plans to setup a temporary system of solar panels and batteries to serve a fridge ,freezer and random electronics during an extended outage . Figuring the draw would be 2k Watts a day. I haven’t been able to find a definitive article.
There isn't anything 'definitive' because it depends on many factors, including the power draw of the devices, your latitude, your local weather, and how much reserve power you want in the battery system, among others.

A modern refrigerator kept closed most of the time will run at least 50% of the time, which generally translates into about 2 kWh all by itself. You can figure about the same for most chest freezers. I don't know what 'random electronics' you're referring to, but devices that are recharged or powered from USB outlets are generally very low draw.

Let's work through an example and assume that you need 5 kWh per day. You would want to have a battery system with at least that much capacity, and one cloudy or rainy day would mean that your batteries would be drained and you'd have to rely on something else like a generator. Using something like golf cart batteries, you would need six GC2 batteries with a total capacity of about 5.4 kWh at a cost of about $600.

When charging lead acid batteries, roughly 25% of the power that goes into them is lost due to the heat created in the process, so to recharge a 5.4 kWh battery system, you would need at least 7.2 kWh of daily output from solar panels, maybe closer to 8 kWh. If your area would have about 5 mean solar hours per day (i.e. you would get about 5 times the output of what your solar panels are rated for, so 500 watt hours from a 100 watt solar panel), keeping in mind that this changes with the seasons, then you would need 16 panels at 100 watts each, at a total cost of about $1,280.

You need a charge controller to manage the power flow from the solar panels to the battery system, which will cost about $450 for an MPPT (you definitely don't want a PWM charge controller in this instance). Mounting brackets for the solar panels, wire, connectors, and a 1 kWh pure sine wave inverter would total maybe $500.

So altogether, you're talking about $2,400 for a combined solar panel and battery backup system capable of giving you 5 kWh of power per sunny day. Days without sun would need power from an alternative means, or else you would need to increase the capacity of the whole system accordingly.

Even though I have much more of a 'be prepared' mindset than most, there's no way that I would go for all that unless I was specifically trying to go off-grid. The cost of the system compared to the benefit just isn't there. A small inverter generator and filled gas cans could be purchased for well under $1k and would work day or night, rain or shine, and not require installing panels on your roof, running wire, etc. Yes, the fuel would eventually run out, but by that time, you should have cleaned out your refrigerator and freezer at least.
Excellent summary - I have not kept up with the latest options here since most of our experience with larger batteries and inverters are with boats.
Some other questions on the newer tech if you are more up on this than us - are the newer inverters more efficient?, the older ones had a loss rate their as well. Do you no longer need a large fuse or circuit breaker in the heavy 12 volts lines? They were expensive.
Batteries, inverters , monitoring ,chargers, wiring, fuses, lugs etc would all really add building a system like this about 8 years back.
And the loss rates both in and out added up as well.
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Re: A primer on backup battery systems for power outages

Post by willthrill81 »

smitcat wrote: Sun Aug 23, 2020 7:00 am Excellent summary - I have not kept up with the latest options here since most of our experience with larger batteries and inverters are with boats.
Some other questions on the newer tech if you are more up on this than us - are the newer inverters more efficient?, the older ones had a loss rate their as well. Do you no longer need a large fuse or circuit breaker in the heavy 12 volts lines? They were expensive.
Batteries, inverters , monitoring ,chargers, wiring, fuses, lugs etc would all really add building a system like this about 8 years back.
And the loss rates both in and out added up as well.
I'm not sure, but I believe that today's inverters are more efficient than the old ones were, though there is still some power loss. There is voltage drop from the panels to the charge controller, from the charge controller to the batteries, etc. Fuses and fuse holders aren't that pricey, but I was merely trying to do a rough estimate for the total cost. Many who aren't familiar at all with this technology might believe it's cheaper than it actually is. Solar with battery backup is anything but inexpensive.
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.” J.R.R. Tolkien,The Lord of the Rings
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Re: A primer on backup battery systems for power outages

Post by smitcat »

willthrill81 wrote: Sun Aug 23, 2020 9:50 am
smitcat wrote: Sun Aug 23, 2020 7:00 am Excellent summary - I have not kept up with the latest options here since most of our experience with larger batteries and inverters are with boats.
Some other questions on the newer tech if you are more up on this than us - are the newer inverters more efficient?, the older ones had a loss rate their as well. Do you no longer need a large fuse or circuit breaker in the heavy 12 volts lines? They were expensive.
Batteries, inverters , monitoring ,chargers, wiring, fuses, lugs etc would all really add building a system like this about 8 years back.
And the loss rates both in and out added up as well.
I'm not sure, but I believe that today's inverters are more efficient than the old ones were, though there is still some power loss. There is voltage drop from the panels to the charge controller, from the charge controller to the batteries, etc. Fuses and fuse holders aren't that pricey, but I was merely trying to do a rough estimate for the total cost. Many who aren't familiar at all with this technology might believe it's cheaper than it actually is. Solar with battery backup is anything but inexpensive.
"Solar with battery backup is anything but inexpensive."
Yes - the list is long and pricey even before adding labor. Thank you
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Re: A primer on backup battery systems for power outages

Post by inbox788 »

telemark wrote: Sat Aug 22, 2020 1:05 pm
mrc wrote: Fri Aug 21, 2020 5:18 pm Thanks. Yes, the UPS is controllable via software (Power Chute) that was never written for a Mac :annoyed so I can't adjust the settings.
Some Windows software can run on a Mac using Wine. I don't know if Power Chute is one of them. It depends on how much time you want to spend on it.

https://www.howtogeek.com/263211/how-to ... with-wine/
Good suggestion, and although I struck out, there is a good chance it will work if you have the right pieces.

I was already testing my UPS, so I thought I had what was needed, and it didn't take too long for me to:

1) Install XQuartz 2.7.11 (needs > 2.7.7)
2) Install WineHQ 5 (note documentation mentions NOT compatible with Catalina; fortunately, I've been too busy to make the move and still on Mojave)
3) Install Powerchute 3.1.0

At step 3), I had to Install Wine mono and Wine Gecko before Powerchute installation would start. Everything happened automatically and with defaults.

Halfway through installing Powerchute, it require connection to the UPS. That's when I discovered that none of the UPS units I had would work. First UPS was a Belkin with USB port, but that wasn't recognized. I did get a error message wrongly reporting that my Powerbook was now running on UPS power; it was running on batteries and only connected by UBS cable to UPS. Unfortunately, the APC software did not recognize the Belkin UPS. Strike 1. So I headed to my old APC UPS and discovered that it didn't have USB port; it did have surge protection for phone/fax line. Strike 2. Next came a newer APC UPS, and it too didn't have a USB port. Strike 3. And finally, and ancient APC UPS I had did have a DB9 port, but no USB; it might work with the right adapter cable.

As you can tell, I have pretty old entry level UPS units, and since I wasn't using the software, it wasn't a feature I sought out, but I did think it was present in more units, like the service ports on many television. Anyway, even without the APC software, there are instructions on how to use the USB connection to shutdown the Macs using built-in powersaver settings. What I was trying to get at was reporting and configuration of the UPS itself provided by the APC software.

https://www.apc.com/us/en/faqs/FA405780/
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Re: A primer on backup battery systems for power outages

Post by inbox788 »

willthrill81 wrote: Sun Aug 23, 2020 9:50 amI'm not sure, but I believe that today's inverters are more efficient than the old ones were, though there is still some power loss. There is voltage drop from the panels to the charge controller, from the charge controller to the batteries, etc. Fuses and fuse holders aren't that pricey, but I was merely trying to do a rough estimate for the total cost. Many who aren't familiar at all with this technology might believe it's cheaper than it actually is. Solar with battery backup is anything but inexpensive.
I didn't think they were that inefficient to begin with. Isn't crossing the 80% mark good enough and marginal benefits inching towards 100%? Sure, you waste somewhat less power and generate less heat, but I'm guessing there's lower fruit to pick.

Pure Sine Wave Power Inverter 3000Watt DC 12 Volt to 120Volt with LCD Display and Remote Control 2X 2.4A USB and 4X AC Outlets with Brand GIANDEL
"Max efficiency 91%"
https://www.amazon.com/Inverter-3000Wat ... B07NZN4K48

BESTEK Power Inverter 1000 Watt DC 12 Volt, Power Converter 1000w DC to AC Converter for Car
This gives an efficiency of 89% which is reasonable. The only issue I noticed was that the unit consumed about 10 watts when powered on with no load connected. Seems a little high, but not a problem if you switch the inverter input instead of the output.
https://www.amazon.com/gp/customer-revi ... 8XJ0KJ9UN/

For me, one of the biggest problems is care and feeding costs (maintenance and replacement of batteries), not just dollars but time and attention. With somewhat reliable grid power, it's even harder to justify the costs for rarely used benefits.

Using something like golf cart batteries, you would need six GC2 batteries with a total capacity of about 5.4 kWh at a cost of about $600.
If I'm reading this correctly, a Tesla Powerwall 1 has 6.4 kWh and can provide 2kW continuous power (3 hours at that rate) for $3000 list 5000 cycles.
https://en.wikipedia.org/wiki/Tesla_Pow ... ifications

One might consider the long term cost effectiveness of various solutions. Used Powerwall units and recycled Tesla car batteries might provide a large supply of cost effective 2nd use batteries for these types of applications.

You would balance efficiency in the solar generation side vs. storage and usage inefficiencies. An extra panel is a fixed cost, say $200. Compare to cost difference going from 88% to 92% efficiency on a inverter, which may be more or less and inefficiency in the battery (lead acid vs lithium) and adding an extra GC2 battery every few years to the system. Usage patterns and frequency of use will help determine where to make tradeoffs.
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Re: A primer on backup battery systems for power outages

Post by willthrill81 »

inbox788 wrote: Sun Aug 23, 2020 1:59 pm
willthrill81 wrote: Sun Aug 23, 2020 9:50 amI'm not sure, but I believe that today's inverters are more efficient than the old ones were, though there is still some power loss. There is voltage drop from the panels to the charge controller, from the charge controller to the batteries, etc. Fuses and fuse holders aren't that pricey, but I was merely trying to do a rough estimate for the total cost. Many who aren't familiar at all with this technology might believe it's cheaper than it actually is. Solar with battery backup is anything but inexpensive.
I didn't think they were that inefficient to begin with. Isn't crossing the 80% mark good enough and marginal benefits inching towards 100%? Sure, you waste somewhat less power and generate less heat, but I'm guessing there's lower fruit to pick.

Pure Sine Wave Power Inverter 3000Watt DC 12 Volt to 120Volt with LCD Display and Remote Control 2X 2.4A USB and 4X AC Outlets with Brand GIANDEL
"Max efficiency 91%"
https://www.amazon.com/Inverter-3000Wat ... B07NZN4K48

BESTEK Power Inverter 1000 Watt DC 12 Volt, Power Converter 1000w DC to AC Converter for Car
This gives an efficiency of 89% which is reasonable. The only issue I noticed was that the unit consumed about 10 watts when powered on with no load connected. Seems a little high, but not a problem if you switch the inverter input instead of the output.
https://www.amazon.com/gp/customer-revi ... 8XJ0KJ9UN/
Yes, efficiency of around 90% sounds about right. That's good, but it means that if you need 5.4 kWh of output power from the inverter, you need about 6 kWh of output power from the batteries.
inbox788 wrote: Sun Aug 23, 2020 1:59 pmFor me, one of the biggest problems is care and feeding costs (maintenance and replacement of batteries), not just dollars but time and attention. With somewhat reliable grid power, it's even harder to justify the costs for rarely used benefits.
A set of golf cart batteries left on an intelligent charger don't need more than a few of minutes of attention once or twice per year to check the fluid level of each cell and replenish them with distilled water if needed. They will last at least ten years if seldom used. I've got a marine battery that's still in great shape after seven years, and they're definitely not as durable as golf cart batteries.
Using something like golf cart batteries, you would need six GC2 batteries with a total capacity of about 5.4 kWh at a cost of about $600.
inbox788 wrote: Sun Aug 23, 2020 1:59 pmIf I'm reading this correctly, a Tesla Powerwall 1 has 6.4 kWh and can provide 2kW continuous power (3 hours at that rate) for $3000 list 5000 cycles.
https://en.wikipedia.org/wiki/Tesla_Pow ... ifications

One might consider the long term cost effectiveness of various solutions. Used Powerwall units and recycled Tesla car batteries might provide a large supply of cost effective 2nd use batteries for these types of applications.

You would balance efficiency in the solar generation side vs. storage and usage inefficiencies. An extra panel is a fixed cost, say $200. Compare to cost difference going from 88% to 92% efficiency on a inverter, which may be more or less and inefficiency in the battery (lead acid vs lithium) and adding an extra GC2 battery every few years to the system. Usage patterns and frequency of use will help determine where to make tradeoffs.
If you're using the batteries regularly, there's no doubt that lithium-ion batteries of some type, like the Powerwall units, are a better option. But for backup batteries that are seldom used, the financial side of it tilts heavily toward lead acid batteries.
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.” J.R.R. Tolkien,The Lord of the Rings
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Re: A primer on backup battery systems for power outages

Post by linuxizer »

An example just popped up of how the big corporate UPS systems become available for cheap if you're willing to refurb them:
https://www.reddit.com/r/homelabsales/c ... d_runtime/

That's a massive amount of power in an online UPS that doesn't require homebrewing an inverter and batteries and wires and a case. Combined with the APC automatic transfer switch that handles battery/generator switching, if your needs are modest this might be a great solution to keep WiFi and maybe even fridge up in between runnings of a small generator.
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Re: A primer on backup battery systems for power outages

Post by dknightd »

mrc wrote: Fri Aug 21, 2020 4:11 pm
Thanks. I might try plugging the UPS directly into the generator. I don't have access to any test equipment, but I do note the UPS momentarily trips a couple times a week. Sometimes without any storms or wind nearby. More often than a routine self test. The good news is after I upgraded the generator size, and along with a regional tree trimming effort, we haven't had nearly the outages we used to.
If your UPS trips when connected to a wall outlet, it might be that outlet is worn out. I had that problem. It took awhile to figure it out. A new wall outlet solved the problem ;) Most builder grade wall outlets are not very good. And if they used the easy stick the wire in the back connection, they are even more likely to get flaky. At least that was my experience.
If you value a bird in the hand, pay off the loan. If you are willing to risk getting two birds (or none) from the market, invest the funds.
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Re: A primer on backup battery systems for power outages

Post by willthrill81 »

dknightd wrote: Mon Aug 24, 2020 8:21 am
mrc wrote: Fri Aug 21, 2020 4:11 pm
Thanks. I might try plugging the UPS directly into the generator. I don't have access to any test equipment, but I do note the UPS momentarily trips a couple times a week. Sometimes without any storms or wind nearby. More often than a routine self test. The good news is after I upgraded the generator size, and along with a regional tree trimming effort, we haven't had nearly the outages we used to.
If your UPS trips when connected to a wall outlet, it might be that outlet is worn out. I had that problem. It took awhile to figure it out. A new wall outlet solved the problem ;) Most builder grade wall outlets are not very good. And if they used the easy stick the wire in the back connection, they are even more likely to get flaky. At least that was my experience.
I'm surprised that NEC allows for those tension connectors to be used. They seem quite prone to failure. When I've had to rewire or change an outlet, I've always used the screws on the side, being careful to curl the lines clockwise (i.e. in the direction that the screws tighten).
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.” J.R.R. Tolkien,The Lord of the Rings
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Re: A primer on backup battery systems for power outages

Post by RetiredAL »

willthrill81 wrote: Mon Aug 24, 2020 9:00 pm
dknightd wrote: Mon Aug 24, 2020 8:21 am
mrc wrote: Fri Aug 21, 2020 4:11 pm
Thanks. I might try plugging the UPS directly into the generator. I don't have access to any test equipment, but I do note the UPS momentarily trips a couple times a week. Sometimes without any storms or wind nearby. More often than a routine self test. The good news is after I upgraded the generator size, and along with a regional tree trimming effort, we haven't had nearly the outages we used to.
If your UPS trips when connected to a wall outlet, it might be that outlet is worn out. I had that problem. It took awhile to figure it out. A new wall outlet solved the problem ;) Most builder grade wall outlets are not very good. And if they used the easy stick the wire in the back connection, they are even more likely to get flaky. At least that was my experience.
I'm surprised that NEC allows for those tension connectors to be used. They seem quite prone to failure. When I've had to rewire or change an outlet, I've always used the screws on the side, being careful to curl the lines clockwise (i.e. in the direction that the screws tighten).
+1 about not using the push-in connectors.

Also note to everyone that neither the screw nor the push-in terminals on outlets are -not- to be used for splicing wires. Use a wire nut. Why, those std outlets are only rate for 15 amps even though it's a 20 amp circuit. Having several high amp loads downstream could be unhealthy to the upstream outlets in a string when those outlets have been used for splicing.

edit to remove a mental opps.
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Re: A primer on backup battery systems for power outages

Post by mrc »

RetiredAL wrote: Mon Aug 24, 2020 9:40 pm
willthrill81 wrote: Mon Aug 24, 2020 9:00 pm
dknightd wrote: Mon Aug 24, 2020 8:21 am
mrc wrote: Fri Aug 21, 2020 4:11 pm
Thanks. I might try plugging the UPS directly into the generator. I don't have access to any test equipment, but I do note the UPS momentarily trips a couple times a week. Sometimes without any storms or wind nearby. More often than a routine self test. The good news is after I upgraded the generator size, and along with a regional tree trimming effort, we haven't had nearly the outages we used to.
If your UPS trips when connected to a wall outlet, it might be that outlet is worn out. I had that problem. It took awhile to figure it out. A new wall outlet solved the problem ;) Most builder grade wall outlets are not very good. And if they used the easy stick the wire in the back connection, they are even more likely to get flaky. At least that was my experience.
I'm surprised that NEC allows for those tension connectors to be used. They seem quite prone to failure. When I've had to rewire or change an outlet, I've always used the screws on the side, being careful to curl the lines clockwise (i.e. in the direction that the screws tighten).
+1 about not using the push-in connectors.

Also note to everyone that neither the screw nor the push-in terminals on outlets are -not- to be used for splicing wires. Use a wire nut. Why, those std outlets are only rate for 15 amps even though it's a 20 amp circuit. Having several high amp loads downstream could be unhealthy to the upstream outlets in a string when those outlets have been used for splicing.

edit to remove a mental opps.
Great info. I only use the screw terminals as well. I've upgraded several receptacles and installed new ones, and I'm always amazed at the difference between the builder grade and the higher end quality (and price, but what does a fire cost?). If I recall, some quality receptacles I bought didn't even have the push-in sockets, just screw terminals. The unit weighed about twice as much as the replaced unit.
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iamlucky13
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Re: A primer on backup battery systems for power outages

Post by iamlucky13 »

inbox788 wrote: Sun Aug 23, 2020 1:59 pm
Using something like golf cart batteries, you would need six GC2 batteries with a total capacity of about 5.4 kWh at a cost of about $600.
If I'm reading this correctly, a Tesla Powerwall 1 has 6.4 kWh and can provide 2kW continuous power (3 hours at that rate) for $3000 list 5000 cycles.
https://en.wikipedia.org/wiki/Tesla_Pow ... ifications
I don't think Powerwall 1 is offered anymore. Powerwall 2 is 13.5kWh capacity, 5 kW continuous/7 kW peak output per unit.

Cost is $6500 per Powerwall, plus $4500 for the Gateway and installation. The Gateway is an automatic disconnect, plus a monitoring and control system. It does not appear they let you buy Powerwall only and use another type of automatic disconnect or a 3rd party installer. You only need one Gateway though, and they discount it by $500 for each additional Powerwall you buy.

Tesla also does not officially rate either version of the Powerwall for cycle life. The 5,000 cycles comes from Musk spitballing in an earnings call, and reading between the lines, it's clear that's based on typical use, which should almost never result in a full discharge. Full discharge cycle life is typically 300-500 cycles for lithium ion batteries, but partial discharge cycles improve cycle life in a better than linear fashion (eg - 50% discharges result in roughly a tripling of cycle life)

What they do specify is a 10 year warranty. Assuming they can protect for that 10 years with 50% average depth of discharge, which I think is still being moderately generous, then the cost of a Powerwall is your energy cost plus $0.193 / kWh for each Powerwall unit, plus $0.133 / kWh divided by the number of Powerwalls for the Gateway.

I'm not sure that cost information is useful for much, though, unless you're planning to use a Powerwall to manage your exposure to a very aggressively priced time-of-use billing plan. You won't accrue very many cycles if you're only using Powerwall for backup purposes, so you might as well focus on total system cost.
silverlitegs
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Re: A primer on backup battery systems for power outages

Post by silverlitegs »

willthrill81 wrote: Sat Aug 22, 2020 3:13 pm
silverlitegs wrote: Wed Aug 19, 2020 4:49 pm This is an interesting topic. This past weekend I was looking for plans to setup a temporary system of solar panels and batteries to serve a fridge ,freezer and random electronics during an extended outage . Figuring the draw would be 2k Watts a day. I haven’t been able to find a definitive article.
There isn't anything 'definitive' because it depends on many factors, including the power draw of the devices, your latitude, your local weather, and how much reserve power you want in the battery system, among others.

A modern refrigerator kept closed most of the time will run at least 50% of the time, which generally translates into about 2 kWh all by itself. You can figure about the same for most chest freezers. I don't know what 'random electronics' you're referring to, but devices that are recharged or powered from USB outlets are generally very low draw.

Let's work through an example and assume that you need 5 kWh per day. You would want to have a battery system with at least that much capacity, and one cloudy or rainy day would mean that your batteries would be drained and you'd have to rely on something else like a generator. Using something like golf cart batteries, you would need six GC2 batteries with a total capacity of about 5.4 kWh at a cost of about $600.

When charging lead acid batteries, roughly 25% of the power that goes into them is lost due to the heat created in the process, so to recharge a 5.4 kWh battery system, you would need at least 7.2 kWh of daily output from solar panels, maybe closer to 8 kWh. If your area would have about 5 mean solar hours per day (i.e. you would get about 5 times the output of what your solar panels are rated for, so 500 watt hours from a 100 watt solar panel), keeping in mind that this changes with the seasons, then you would need 16 panels at 100 watts each, at a total cost of about $1,280.

You need a charge controller to manage the power flow from the solar panels to the battery system, which will cost about $450 for an MPPT (you definitely don't want a PWM charge controller in this instance). Mounting brackets for the solar panels, wire, connectors, and a 1 kWh pure sine wave inverter would total maybe $500.

So altogether, you're talking about $2,400 for a combined solar panel and battery backup system capable of giving you 5 kWh of power per sunny day. Days without sun would need power from an alternative means, or else you would need to increase the capacity of the whole system accordingly.

Even though I have much more of a 'be prepared' mindset than most, there's no way that I would go for all that unless I was specifically trying to go off-grid. The cost of the system compared to the benefit just isn't there. A small inverter generator and filled gas cans could be purchased for well under $1k and would work day or night, rain or shine, and not require installing panels on your roof, running wire, etc. Yes, the fuel would eventually run out, but by that time, you should have cleaned out your refrigerator and freezer at least.
Thank you for the great explanation and write up.

This idea was coming from the be prepared mindset. I was thinking of actually using 300 watt panels and just setting this up on the whim when needed. With the power draw I would need, roughly 5-6 panels and envisioned temporarily setting them on my driveway. This likely wouldn't work.

What If I was to have a battery bank that I charged from utility power. In an emergency, at night, I would switch to battery. I would drain it to 50% and use the excess power of my portable generator to recharge it during the day.
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Re: A primer on backup battery systems for power outages

Post by willthrill81 »

silverlitegs wrote: Thu Sep 03, 2020 9:32 pm
willthrill81 wrote: Sat Aug 22, 2020 3:13 pm
silverlitegs wrote: Wed Aug 19, 2020 4:49 pm This is an interesting topic. This past weekend I was looking for plans to setup a temporary system of solar panels and batteries to serve a fridge ,freezer and random electronics during an extended outage . Figuring the draw would be 2k Watts a day. I haven’t been able to find a definitive article.
There isn't anything 'definitive' because it depends on many factors, including the power draw of the devices, your latitude, your local weather, and how much reserve power you want in the battery system, among others.

A modern refrigerator kept closed most of the time will run at least 50% of the time, which generally translates into about 2 kWh all by itself. You can figure about the same for most chest freezers. I don't know what 'random electronics' you're referring to, but devices that are recharged or powered from USB outlets are generally very low draw.

Let's work through an example and assume that you need 5 kWh per day. You would want to have a battery system with at least that much capacity, and one cloudy or rainy day would mean that your batteries would be drained and you'd have to rely on something else like a generator. Using something like golf cart batteries, you would need six GC2 batteries with a total capacity of about 5.4 kWh at a cost of about $600.

When charging lead acid batteries, roughly 25% of the power that goes into them is lost due to the heat created in the process, so to recharge a 5.4 kWh battery system, you would need at least 7.2 kWh of daily output from solar panels, maybe closer to 8 kWh. If your area would have about 5 mean solar hours per day (i.e. you would get about 5 times the output of what your solar panels are rated for, so 500 watt hours from a 100 watt solar panel), keeping in mind that this changes with the seasons, then you would need 16 panels at 100 watts each, at a total cost of about $1,280.

You need a charge controller to manage the power flow from the solar panels to the battery system, which will cost about $450 for an MPPT (you definitely don't want a PWM charge controller in this instance). Mounting brackets for the solar panels, wire, connectors, and a 1 kWh pure sine wave inverter would total maybe $500.

So altogether, you're talking about $2,400 for a combined solar panel and battery backup system capable of giving you 5 kWh of power per sunny day. Days without sun would need power from an alternative means, or else you would need to increase the capacity of the whole system accordingly.

Even though I have much more of a 'be prepared' mindset than most, there's no way that I would go for all that unless I was specifically trying to go off-grid. The cost of the system compared to the benefit just isn't there. A small inverter generator and filled gas cans could be purchased for well under $1k and would work day or night, rain or shine, and not require installing panels on your roof, running wire, etc. Yes, the fuel would eventually run out, but by that time, you should have cleaned out your refrigerator and freezer at least.
Thank you for the great explanation and write up.

This idea was coming from the be prepared mindset. I was thinking of actually using 300 watt panels and just setting this up on the whim when needed. With the power draw I would need, roughly 5-6 panels and envisioned temporarily setting them on my driveway. This likely wouldn't work.

What If I was to have a battery bank that I charged from utility power. In an emergency, at night, I would switch to battery. I would drain it to 50% and use the excess power of my portable generator to recharge it during the day.
Yes, using a generator in conjunction with a battery bank is the 'best practice', as I noted in the OP.
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.” J.R.R. Tolkien,The Lord of the Rings
silverlitegs
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Re: A primer on backup battery systems for power outages

Post by silverlitegs »

willthrill81 wrote: Thu Sep 03, 2020 10:06 pm
silverlitegs wrote: Thu Sep 03, 2020 9:32 pm
willthrill81 wrote: Sat Aug 22, 2020 3:13 pm
silverlitegs wrote: Wed Aug 19, 2020 4:49 pm This is an interesting topic. This past weekend I was looking for plans to setup a temporary system of solar panels and batteries to serve a fridge ,freezer and random electronics during an extended outage . Figuring the draw would be 2k Watts a day. I haven’t been able to find a definitive article.
There isn't anything 'definitive' because it depends on many factors, including the power draw of the devices, your latitude, your local weather, and how much reserve power you want in the battery system, among others.

A modern refrigerator kept closed most of the time will run at least 50% of the time, which generally translates into about 2 kWh all by itself. You can figure about the same for most chest freezers. I don't know what 'random electronics' you're referring to, but devices that are recharged or powered from USB outlets are generally very low draw.

Let's work through an example and assume that you need 5 kWh per day. You would want to have a battery system with at least that much capacity, and one cloudy or rainy day would mean that your batteries would be drained and you'd have to rely on something else like a generator. Using something like golf cart batteries, you would need six GC2 batteries with a total capacity of about 5.4 kWh at a cost of about $600.

When charging lead acid batteries, roughly 25% of the power that goes into them is lost due to the heat created in the process, so to recharge a 5.4 kWh battery system, you would need at least 7.2 kWh of daily output from solar panels, maybe closer to 8 kWh. If your area would have about 5 mean solar hours per day (i.e. you would get about 5 times the output of what your solar panels are rated for, so 500 watt hours from a 100 watt solar panel), keeping in mind that this changes with the seasons, then you would need 16 panels at 100 watts each, at a total cost of about $1,280.

You need a charge controller to manage the power flow from the solar panels to the battery system, which will cost about $450 for an MPPT (you definitely don't want a PWM charge controller in this instance). Mounting brackets for the solar panels, wire, connectors, and a 1 kWh pure sine wave inverter would total maybe $500.

So altogether, you're talking about $2,400 for a combined solar panel and battery backup system capable of giving you 5 kWh of power per sunny day. Days without sun would need power from an alternative means, or else you would need to increase the capacity of the whole system accordingly.

Even though I have much more of a 'be prepared' mindset than most, there's no way that I would go for all that unless I was specifically trying to go off-grid. The cost of the system compared to the benefit just isn't there. A small inverter generator and filled gas cans could be purchased for well under $1k and would work day or night, rain or shine, and not require installing panels on your roof, running wire, etc. Yes, the fuel would eventually run out, but by that time, you should have cleaned out your refrigerator and freezer at least.
Thank you for the great explanation and write up.

This idea was coming from the be prepared mindset. I was thinking of actually using 300 watt panels and just setting this up on the whim when needed. With the power draw I would need, roughly 5-6 panels and envisioned temporarily setting them on my driveway. This likely wouldn't work.

What If I was to have a battery bank that I charged from utility power. In an emergency, at night, I would switch to battery. I would drain it to 50% and use the excess power of my portable generator to recharge it during the day.
Yes, using a generator in conjunction with a battery bank is the 'best practice', as I noted in the OP.
To accomplish a battery bank as a backup to my portable generator, would this be the way to go for the inverter/charger? https://www.thepowerstore.com/marine-au ... arger.html
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Re: A primer on backup battery systems for power outages

Post by willthrill81 »

silverlitegs wrote: Fri Sep 04, 2020 3:44 pm
willthrill81 wrote: Thu Sep 03, 2020 10:06 pm
silverlitegs wrote: Thu Sep 03, 2020 9:32 pm
willthrill81 wrote: Sat Aug 22, 2020 3:13 pm
silverlitegs wrote: Wed Aug 19, 2020 4:49 pm This is an interesting topic. This past weekend I was looking for plans to setup a temporary system of solar panels and batteries to serve a fridge ,freezer and random electronics during an extended outage . Figuring the draw would be 2k Watts a day. I haven’t been able to find a definitive article.
There isn't anything 'definitive' because it depends on many factors, including the power draw of the devices, your latitude, your local weather, and how much reserve power you want in the battery system, among others.

A modern refrigerator kept closed most of the time will run at least 50% of the time, which generally translates into about 2 kWh all by itself. You can figure about the same for most chest freezers. I don't know what 'random electronics' you're referring to, but devices that are recharged or powered from USB outlets are generally very low draw.

Let's work through an example and assume that you need 5 kWh per day. You would want to have a battery system with at least that much capacity, and one cloudy or rainy day would mean that your batteries would be drained and you'd have to rely on something else like a generator. Using something like golf cart batteries, you would need six GC2 batteries with a total capacity of about 5.4 kWh at a cost of about $600.

When charging lead acid batteries, roughly 25% of the power that goes into them is lost due to the heat created in the process, so to recharge a 5.4 kWh battery system, you would need at least 7.2 kWh of daily output from solar panels, maybe closer to 8 kWh. If your area would have about 5 mean solar hours per day (i.e. you would get about 5 times the output of what your solar panels are rated for, so 500 watt hours from a 100 watt solar panel), keeping in mind that this changes with the seasons, then you would need 16 panels at 100 watts each, at a total cost of about $1,280.

You need a charge controller to manage the power flow from the solar panels to the battery system, which will cost about $450 for an MPPT (you definitely don't want a PWM charge controller in this instance). Mounting brackets for the solar panels, wire, connectors, and a 1 kWh pure sine wave inverter would total maybe $500.

So altogether, you're talking about $2,400 for a combined solar panel and battery backup system capable of giving you 5 kWh of power per sunny day. Days without sun would need power from an alternative means, or else you would need to increase the capacity of the whole system accordingly.

Even though I have much more of a 'be prepared' mindset than most, there's no way that I would go for all that unless I was specifically trying to go off-grid. The cost of the system compared to the benefit just isn't there. A small inverter generator and filled gas cans could be purchased for well under $1k and would work day or night, rain or shine, and not require installing panels on your roof, running wire, etc. Yes, the fuel would eventually run out, but by that time, you should have cleaned out your refrigerator and freezer at least.
Thank you for the great explanation and write up.

This idea was coming from the be prepared mindset. I was thinking of actually using 300 watt panels and just setting this up on the whim when needed. With the power draw I would need, roughly 5-6 panels and envisioned temporarily setting them on my driveway. This likely wouldn't work.

What If I was to have a battery bank that I charged from utility power. In an emergency, at night, I would switch to battery. I would drain it to 50% and use the excess power of my portable generator to recharge it during the day.
Yes, using a generator in conjunction with a battery bank is the 'best practice', as I noted in the OP.
To accomplish a battery bank as a backup to my portable generator, would this be the way to go for the inverter/charger? https://www.thepowerstore.com/marine-au ... arger.html
That's far more expensive than what you'll need, and it works on 48 volts and supplies 230 volts AC. If you're in the U.S., you need 120 volt AC power, and 12 volt battery systems are far more common.

I would recommend buying a separate charger and inverter.

For the charger, it depends on how large of a battery bank you get. If you get something like 6 GC2 batteries, I'd recommend at least a 30 amp charger, and a 55 amp charger like the one below is much better. That one is designed for RVs but will work perfectly for charging a home battery bank.
https://smile.amazon.com/Powermax-Suppl ... ics&sr=1-3

For the inverter, I've had good success using this Bestek 1,000 watt pure sine wave inverter.
https://smile.amazon.com/gp/product/B07 ... UTF8&psc=1

Both of those combined would be under $300.

I would also recommend that you get a 12 volt outlet splitter and a voltmeter that can be plugged into one of the outlets. This will let you check the status of the batteries at a glance.
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.” J.R.R. Tolkien,The Lord of the Rings
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Re: A primer on backup battery systems for power outages

Post by willthrill81 »

linuxizer wrote: Tue Aug 18, 2020 9:08 pm Here's the link to the generator thread, for posterity:
viewtopic.php?f=11&t=322105&newpost=5441323

Some more thoughts:
- RefurbUPS and similar sites offer new batteries in used UPS's. APC makes an extended run line of UPS's. Think beefy fan for cooling, designed for continuous use on rated loads, with large battery capacities compared to their rated loads, and the ability to daisy chain additional battery packs for truly huge run times.
- Whatever battery solution you have, make sure it's a few feet off the ground in case of flooding.
- The best battery is the one that is charged, especially if not using a generator. So I have favored buying inverters for the 60V lawn tools we have (huge capacity; 5++ charges of a laptop), and USB adapters for our 18V drill batteries (powers quite a few cell phone charges off a single battery, and we have 4 or 5 sitting around).
- If you buy a AA/AAA charger, it's worth the extra for a true smart charger and for one that charges each battery separately. I have an older one that only charges the pairs, and it's a giant pain (and likely hurts batteries) because I can never manage to keep them paired off.
Great tips.

Regarding the AA/AAA chargers, I've been using the LaCrosse BC-700 for several years and really like it. It's the Swiss Army knife of chargers and charges each battery independently, can charge at varying rates, and can measure the capacity of a battery. If I were to replace it, I would probably get the BC-1000 since it can charge at a higher rate, although my understanding is that it's not a good idea to recharge a nickel metal hydride battery like the popular Eneloops in faster than about five hours as doing so reduces their lifespan.
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.” J.R.R. Tolkien,The Lord of the Rings
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Re: A primer on backup battery systems for power outages

Post by whomever »

"my understanding is that it's not a good idea to recharge a nickel metal hydride battery like the popular Eneloops in faster than about five hours as doing so reduces their lifespan."

I recently got interested in eneloop charging efficiency, because we sometimes take long (as in a few months) car/backpacking trips, and use one of the UV water purifiers.

With the disclaimer that this is just my best guesses based on a few watt hour measurements I could take, and my reading of the internet's collective wisdom:

-for maximum battery life, yes, charge slowly
-for storing the most electrons in a short time from e.g. a solar panel (which was what I was trying to optimize), charge at high rates - 0.5 to 1C - and only charge to 75% or so. Putting in the last quarter of the charge takes a lot of time and electrons relative to the first 3/4.

Again, what to do depends on whether you have lotsa time and the grid available and want to make your batteries last as long as you can, or whether you have a small solar panel and 4 hours of sunlight this afternoon to capture as many electrons as possible for the week long trip you start tomorrow.

Also FWIW, the rated number of charges for eneloops is 2000 or so. That's a lot of charges. If you charged/discharged it every single day, that's 6 years. My sense is that I'm pretty unlikely to ever hit that limit, or even the reduced number of charges resulting from high charge rates. And eneloops are what, $2 a pop? That's 0.1 cents a charge. If I halve the life, that's 0.2 cents a charge.
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Re: A primer on backup battery systems for power outages

Post by willthrill81 »

whomever wrote: Thu Sep 17, 2020 3:24 pm "my understanding is that it's not a good idea to recharge a nickel metal hydride battery like the popular Eneloops in faster than about five hours as doing so reduces their lifespan."

I recently got interested in eneloop charging efficiency, because we sometimes take long (as in a few months) car/backpacking trips, and use one of the UV water purifiers.

With the disclaimer that this is just my best guesses based on a few watt hour measurements I could take, and my reading of the internet's collective wisdom:

-for maximum battery life, yes, charge slowly
-for storing the most electrons in a short time from e.g. a solar panel (which was what I was trying to optimize), charge at high rates - 0.5 to 1C - and only charge to 75% or so. Putting in the last quarter of the charge takes a lot of time and electrons relative to the first 3/4.

Again, what to do depends on whether you have lotsa time and the grid available and want to make your batteries last as long as you can, or whether you have a small solar panel and 4 hours of sunlight this afternoon to capture as many electrons as possible for the week long trip you start tomorrow.

Also FWIW, the rated number of charges for eneloops is 2000 or so. That's a lot of charges. If you charged/discharged it every single day, that's 6 years. My sense is that I'm pretty unlikely to ever hit that limit, or even the reduced number of charges resulting from high charge rates. And eneloops are what, $2 a pop? That's 0.1 cents a charge. If I halve the life, that's 0.2 cents a charge.
Yes, if your time is limited, charging at a higher rate makes perfect sense, and I agree that even halving the lifespan of an Eneloop battery isn't a big deal.
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.” J.R.R. Tolkien,The Lord of the Rings
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