Are 2.1 and 1.0-amp sockets really different on a USB charger?

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Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by nisiprius » Thu Feb 06, 2020 12:56 pm

Many USB wall chargers have a pair of USB type-A sockets labeled "2.1A" and "1.0A."

Are they really different--is the 2.1A socket really capable of supplying more current? Or was this just a clearer way to label them then saying "3.1A max total?"

Yeah, I know I could figure this out myself with sufficient experimentation, but discharging a device twice to the same exact charge level, and setting a timer to remember to check back in four hours is a lot of work.
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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by dukeblue219 » Thu Feb 06, 2020 1:04 pm

Yes, they are usually different. You could test with a phone and a battery charge monitoring app (like Ampere) that will show you the charge rate after a few seconds plugged in.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by whodidntante » Thu Feb 06, 2020 1:38 pm

Another consideration for charging rate is the cable

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by sailaway » Thu Feb 06, 2020 1:44 pm

I can't charge my iPad (gen 2) on a 1A charger.

If the cable and the battery allow, you will likely see faster charging times with the 2.1A.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by nisiprius » Thu Feb 06, 2020 2:53 pm

dukeblue219 wrote:
Thu Feb 06, 2020 1:04 pm
Yes, they are usually different. You could test with a phone and a battery charge monitoring app (like Ampere) that will show you the charge rate after a few seconds plugged in.
Thanks! Amazing. An app. Who knew? Everyone but me, I guess.

OK, thanks to all who answered, I have my answer.
Annual income twenty pounds, annual expenditure nineteen nineteen and six, result happiness; Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by dukeblue219 » Thu Feb 06, 2020 3:10 pm

nisiprius wrote:
Thu Feb 06, 2020 2:53 pm
dukeblue219 wrote:
Thu Feb 06, 2020 1:04 pm
Yes, they are usually different. You could test with a phone and a battery charge monitoring app (like Ampere) that will show you the charge rate after a few seconds plugged in.
Thanks! Amazing. An app. Who knew? Everyone but me, I guess.

OK, thanks to all who answered, I have my answer.
Suppose I should have left a caveat that not all phones will support this out of the box and I'm only on Android. No clue if iPhones have similar metrics available.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by jebmke » Thu Feb 06, 2020 3:20 pm

whodidntante wrote:
Thu Feb 06, 2020 1:38 pm
Another consideration for charging rate is the cable
Cables can make a big difference. I replace all my OEM cables with the heavy Anker cables.
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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by RootSki » Thu Feb 06, 2020 8:20 pm


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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by tooluser » Thu Feb 06, 2020 9:48 pm

nisiprius wrote:
Thu Feb 06, 2020 2:53 pm
dukeblue219 wrote:
Thu Feb 06, 2020 1:04 pm
Yes, they are usually different. You could test with a phone and a battery charge monitoring app (like Ampere) that will show you the charge rate after a few seconds plugged in.
Thanks! Amazing. An app. Who knew? Everyone but me, I guess.

OK, thanks to all who answered, I have my answer.
Please report back on what you find out.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by nisiprius » Thu Feb 06, 2020 9:54 pm

tooluser wrote:
Thu Feb 06, 2020 9:48 pm
nisiprius wrote:
Thu Feb 06, 2020 2:53 pm
dukeblue219 wrote:
Thu Feb 06, 2020 1:04 pm
Yes, they are usually different. You could test with a phone and a battery charge monitoring app (like Ampere) that will show you the charge rate after a few seconds plugged in.
Thanks! Amazing. An app. Who knew? Everyone but me, I guess.

OK, thanks to all who answered, I have my answer.
Please report back on what you find out.
For right now, what I found out is that when a device is close to fully charged, the charging speed is apparently intentionally limited and is much less than 1 amp regardless of which socket I use... so I don't know yet.
Annual income twenty pounds, annual expenditure nineteen nineteen and six, result happiness; Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by 02nz » Thu Feb 06, 2020 10:01 pm

sailaway wrote:
Thu Feb 06, 2020 1:44 pm
I can't charge my iPad (gen 2) on a 1A charger.
You can absolutely charge an iPad (any generation) on a 1A charger. I did just that with an iPad 2. It may say "Not charging." But actually that means "charging slowly."

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by shess » Thu Feb 06, 2020 10:06 pm

02nz wrote:
Thu Feb 06, 2020 10:01 pm
sailaway wrote:
Thu Feb 06, 2020 1:44 pm
I can't charge my iPad (gen 2) on a 1A charger.
You can absolutely charge an iPad (any generation) on a 1A charger. I did just that with an iPad 2. It may say "Not charging." But actually that means "charging slowly."
Some chargers cannot charge an iPad while it is in use. Such chargers charge the device slowly when you put it to sleep.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by brianH » Thu Feb 06, 2020 10:06 pm

RootSki wrote:
Thu Feb 06, 2020 8:20 pm
USB testers are pretty cheap too
https://www.amazon.com/Eversame-Multime ... 45&sr=8-90
I have one of these USB volt/amp meters and a load device that can apply up to a 4 amp simulated load. It's pretty interesting to play around with it on various charging bricks and cables. I've found most charging devices are pretty good about providing what they're rated for, and not a single bit more. The voltage drops sharply above the rated amps.

I'm not looking to destroy my chargers, but it would be fun to set up an experiment to see what happens if I applied the rated load for 6+ hours. I think I'd want to do that test outside, away from anything flammable.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by JonnyB » Thu Feb 06, 2020 11:06 pm

Yes, the ports are different. The device plugged into the port doesn't know the capability of the port, so it gradually turns up its current while monitoring the bus voltage. Bus voltage is nominally 5V but as you draw more current from a port than it is designed for, the voltage begins to drop. Your device senses this input voltage drop and in response, reduces the amount of current it is drawing.

The charger also monitors its output voltage and if the voltage gets below 2V, it is supposed to shutdown. But typically, your device will reduce its current draw well before 2V because there's no point in drawing lots of current if your voltage is only 2V. As you know Power = Current * Voltage.

So your device will throttle itself to drawing something around 1A from the 1A port and 2A from the 2A port because that is the best the charger can put out before its voltage begins to droop.

So you should always use the higher rated port if available, even if your device only is capable of using 1A. That is because the voltage will be closer 5V. The device itself will make sure that it never draws any more current than it can handle, even on a high current port.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by marcwd » Thu Feb 06, 2020 11:14 pm

jebmke wrote:
Thu Feb 06, 2020 3:20 pm
whodidntante wrote:
Thu Feb 06, 2020 1:38 pm
Another consideration for charging rate is the cable
Cables can make a big difference. I replace all my OEM cables with the heavy Anker cables.
Come on... Make a big difference how? This reads like audiophile tweako stuff.
Last edited by marcwd on Thu Feb 06, 2020 11:55 pm, edited 2 times in total.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by 02nz » Thu Feb 06, 2020 11:28 pm

marcwd wrote:
Thu Feb 06, 2020 11:14 pm
jebmke wrote:
Thu Feb 06, 2020 3:20 pm
whodidntante wrote:
Thu Feb 06, 2020 1:38 pm
Another consideration for charging rate is the cable
Cables can make a big difference. I replace all my OEM cables with the heavy Anker cables.
Come on... Make a big difference how? This reads like audiophile tweako stuff.
I agree, cables do NOT make a difference in charging speed unless the cable is defective or out of spec (e.g., some USB-C cables do not support the Power Delivery standard).

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by shess » Fri Feb 07, 2020 12:43 am

02nz wrote:
Thu Feb 06, 2020 11:28 pm
marcwd wrote:
Thu Feb 06, 2020 11:14 pm
jebmke wrote:
Thu Feb 06, 2020 3:20 pm
whodidntante wrote:
Thu Feb 06, 2020 1:38 pm
Another consideration for charging rate is the cable
Cables can make a big difference. I replace all my OEM cables with the heavy Anker cables.
Come on... Make a big difference how? This reads like audiophile tweako stuff.
I agree, cables do NOT make a difference in charging speed unless the cable is defective or out of spec (e.g., some USB-C cables do not support the Power Delivery standard).
My experience with Raspberry Pi devices is that when you notice something being flaky, nine times out of ten it's either the cable or the charger. Admittedly, it's usually the charger, though I've had my share of MicroUSB cables which got tossed for being unreliable after a few months of use. So far only one USB-C cable got tossed, but that one was for lack of proper connection (I'd often find my device uncharged because the cable had slipped out - Monoprice braided cable, which surprised me, usually they're adequate on these things).

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by kevinf » Fri Feb 07, 2020 10:18 am

marcwd wrote:
Thu Feb 06, 2020 11:14 pm
jebmke wrote:
Thu Feb 06, 2020 3:20 pm
whodidntante wrote:
Thu Feb 06, 2020 1:38 pm
Another consideration for charging rate is the cable
Cables can make a big difference. I replace all my OEM cables with the heavy Anker cables.
Come on... Make a big difference how? This reads like audiophile tweako stuff.
There are A LOT of out-of-spec cables out there. If you're using what came with your phone you are likely ok, but 3rd party cables are a risk. Sticking with the name brands is vital. There is an engineer that tests USB cables he buys and three-quarters of them do not meet the published spec. This isn't even considering build quality/longevity.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by Luke Duke » Fri Feb 07, 2020 4:07 pm

02nz wrote:
Thu Feb 06, 2020 11:28 pm
I agree, cables do NOT make a difference in charging speed unless the cable is defective or out of spec (e.g., some USB-C cables do not support the Power Delivery standard).
So, in other words, cables can make a difference.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by Chuck » Fri Feb 07, 2020 4:29 pm

You only need to look at a voltage drop calculator (search for one online) to see the effects a cable can have.

Start with 5V, then try 3, 4, 5, 6, 10ft cable lengths. Try 22 to 28 AWG. See what you get. If you don't end up with 4.2V, your battery will probably not fully charge. If you don't get 3.7V, it won't charge at all.

For example, a 6ft 24AWG cable will drop 0.62V at 2A.

If you think a 15ft cable would be more convenient (I tried this once) the end result is 1.5V of drop, and the phone saying "charging error."

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by wander » Fri Feb 07, 2020 4:35 pm

2.4 A charger is the fastest per port output. I use 1.0 amp port when I leave the phone plugged in all day as a hot spot so I won't damage the phone battery and use 2.1 port to shorten charging time when in hurry.
Last edited by wander on Fri Feb 07, 2020 4:46 pm, edited 1 time in total.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by dukeblue219 » Fri Feb 07, 2020 4:40 pm

nisiprius wrote:
Thu Feb 06, 2020 9:54 pm
For right now, what I found out is that when a device is close to fully charged, the charging speed is apparently intentionally limited and is much less than 1 amp regardless of which socket I use... so I don't know yet.
Batteries don't charge linearly. An empty battery charges MUCH faster than a nearly full battery. That's why you can get from 0 to 50% on some phones in half an hour but the next 50% takes forever.

That said, lithium ion and lithium polymer batteries have complex charging needs and phones DO use a lot of "intelligence" to optimize their lifetimes,so it's probably a little of both.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by marcwd » Fri Feb 07, 2020 6:16 pm

Chuck wrote:
Fri Feb 07, 2020 4:29 pm
You only need to look at a voltage drop calculator (search for one online) to see the effects a cable can have.

Start with 5V, then try 3, 4, 5, 6, 10ft cable lengths. Try 22 to 28 AWG. See what you get. If you don't end up with 4.2V, your battery will probably not fully charge. If you don't get 3.7V, it won't charge at all.

For example, a 6ft 24AWG cable will drop 0.62V at 2A.

If you think a 15ft cable would be more convenient (I tried this once) the end result is 1.5V of drop, and the phone saying "charging error."
Yes, you can create scenarios that result in problems. The point is that the OEM cables that come with the product are fine. You needn’t discard them and replace with “heavy duty Anker cables” for example. And OEM cables are closer to 3ft, not 6ft, and certainly not 15ft.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by 02nz » Fri Feb 07, 2020 8:52 pm

Luke Duke wrote:
Fri Feb 07, 2020 4:07 pm
02nz wrote:
Thu Feb 06, 2020 11:28 pm
I agree, cables do NOT make a difference in charging speed unless the cable is defective or out of spec (e.g., some USB-C cables do not support the Power Delivery standard).
So, in other words, cables can make a difference.
Well, of course if something is defective or doesn't support the functionality you need, it makes a difference. My point - in response to a post about changing from OEM to thicker Anker cables - was that changing to a thicker cable doesn't get you faster charging. (Of course there may be other advantages, perhaps the thicker cable holds up better to abuse. And I've had good experiences with Anker products, which are definitely more reliable than off-brand products.)

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by mnsportsgeek » Fri Feb 07, 2020 9:52 pm

Today I learned there are people that replace their perfectly fine OEM charging cables with 3rd party alternatives. Amazing.

Better get those $120 HDMI cables to improve that digital signal too.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by willthrill81 » Sat Feb 08, 2020 12:33 am

nisiprius wrote:
Thu Feb 06, 2020 9:54 pm
tooluser wrote:
Thu Feb 06, 2020 9:48 pm
nisiprius wrote:
Thu Feb 06, 2020 2:53 pm
dukeblue219 wrote:
Thu Feb 06, 2020 1:04 pm
Yes, they are usually different. You could test with a phone and a battery charge monitoring app (like Ampere) that will show you the charge rate after a few seconds plugged in.
Thanks! Amazing. An app. Who knew? Everyone but me, I guess.

OK, thanks to all who answered, I have my answer.
Please report back on what you find out.
For right now, what I found out is that when a device is close to fully charged, the charging speed is apparently intentionally limited and is much less than 1 amp regardless of which socket I use... so I don't know yet.
It depends on the device. I use a USB ammeter on our primary home charger, and my phone charges at a steady .71 amps until it's nearly full. But we have a li-ion battery pack that charges at about 1.4 amps. And there are other USB devices that will use up to 2.4 amps.

A USB charger is a bit like the outlet in your house. The potential for a standard outlet in the U.S. is 15 amps at 120 volts of AC current (i.e. 1,800 watts), but very few devices that can be plugged into such an outlet will use that much power. Most use far less. The same is true of a USB charger. It might have the potential to provide 1.0, 2.1, or 3.0 amps of current, but each device will only consume what it needs.
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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by willthrill81 » Sat Feb 08, 2020 12:38 am

02nz wrote:
Thu Feb 06, 2020 11:28 pm
marcwd wrote:
Thu Feb 06, 2020 11:14 pm
jebmke wrote:
Thu Feb 06, 2020 3:20 pm
whodidntante wrote:
Thu Feb 06, 2020 1:38 pm
Another consideration for charging rate is the cable
Cables can make a big difference. I replace all my OEM cables with the heavy Anker cables.
Come on... Make a big difference how? This reads like audiophile tweako stuff.
I agree, cables do NOT make a difference in charging speed unless the cable is defective or out of spec (e.g., some USB-C cables do not support the Power Delivery standard).
Cable length and gauge definitely impact charging speed. That being said, I don't know what the specs are for specific devices with cables of varying lengths.
02nz wrote:
Fri Feb 07, 2020 8:52 pm
Of course there may be other advantages, perhaps the thicker cable holds up better to abuse. And I've had good experiences with Anker products, which are definitely more reliable than off-brand products.
Anker usually makes good products, but I had two different 6' Anker cables fail within the span of a couple of months. The little 'hooks' on the bottom side of a micro-USB male end were what failed specifically.
“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: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by boomer_techie » Sat Feb 08, 2020 4:47 am

nisiprius wrote:
Thu Feb 06, 2020 12:56 pm
Many USB wall chargers have a pair of USB type-A sockets labeled "2.1A" and "1.0A."

Are they really different--is the 2.1A socket really capable of supplying more current?
Some USB devices can control their battery charging current. To do this, they need to know the current capability of the charger. An ad-hoc standard has evolved to indicate this via resistors connected to the USB data wires. The 2.1A socket likely indicates to the device that it is able to supply a higher current.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by Dude2 » Sat Feb 08, 2020 5:30 am

There is no reason not to plug your device into the higher rated amp source. The lower rated source probably has smaller (higher gauge) wires that can't handle the juice. On the other hand, don't plug in to the lower rated amp source if your device requires more than 1 A.

If you have a true power supply (a piece of test equipment), you set the voltage, and then you crank the amp dial all the way up. The device will draw what it needs, and since you typically will be plugging and unplugging different devices to your power supply, you don't want to accidentally not provide enough current. Thus, "crank it to 11" on the amp dial.

Similarly, if you find plugs laying around for your router, switch, etc. and the block specifies 12 V 1 A for one and another says 12 V 2.1 A, assuming the device says it needs 12 V 1 A (or less), then feel free to use either one for your device (assuming the plug into the device is the correct one).

What I've said above is a general truth that will apply in all circumstances, but what you're talking about here is charging a battery. At some point they discovered that they could get charge into the battery faster if they did a bunch of fancy pulse modulation, so the 1 A and 2.1 A plugs probably correspond to a standard that correspond to a battery charging scheme. Mentioned above, resistors probably do clue in the circuitry for which circuit you are using. From that perspective, it's all going to come down to the particular battery and the associated charging scheme. You have to research what is required and what results you should expect. Basically, whatever your phone manual said to do, that's what you should do, but if these are true standards, hopefully they have made it such that you won't hurt the phone or the battery by plugging into the lower amp USB plug.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by LifeIsGood » Sun Feb 09, 2020 6:06 am

Not to hijack this thread but several times in the past I've attempted to charge my iPad on an airplane using their USB outlets. The iPad initially shows it is charging and then stops. This has occurred on different planes at different times. Any ideas about what is happening?

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by Dude2 » Sun Feb 09, 2020 7:46 am

LifeIsGood wrote:
Sun Feb 09, 2020 6:06 am
Not to hijack this thread but several times in the past I've attempted to charge my iPad on an airplane using their USB outlets. The iPad initially shows it is charging and then stops. This has occurred on different planes at different times. Any ideas about what is happening?
The plane just can't deliver the amps. Hopefully there are smarts on the device that can detect this and not allow itself to be hurt by it. Many devices are known to blow when they are in a brown out situation.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by lazydavid » Sun Feb 09, 2020 7:56 am

LifeIsGood wrote:
Sun Feb 09, 2020 6:06 am
Not to hijack this thread but several times in the past I've attempted to charge my iPad on an airplane using their USB outlets. The iPad initially shows it is charging and then stops. This has occurred on different planes at different times. Any ideas about what is happening?
Does the lightning bolt go away completely, or does it just say "Not Charging"? The latter just means that the power source is not sufficient to operate the device and charge it at the same time. I haven't kept up with the specs on the more recent ones, but early iPads consumed about 460-480 milliwatts when the screen was on and the device was in basic use (web browsing, email, etc). So a standard 1.0A, 500 mw charger could keep the battery from discharging, but couldn't actually charge it unless the screen was off.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by rkhusky » Sun Feb 09, 2020 8:07 am

Regarding cables, our daughter used a cheap charger on her iPod and part of the tip came off and wedged into the charging port, blocking other chargers from working. Apple store guy said that was common.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by Chip » Sun Feb 09, 2020 8:18 am

LifeIsGood wrote:
Sun Feb 09, 2020 6:06 am
Not to hijack this thread but several times in the past I've attempted to charge my iPad on an airplane using their USB outlets. The iPad initially shows it is charging and then stops. This has occurred on different planes at different times. Any ideas about what is happening?
As others have said, just not enough juice on the airplane. I have an old iPad that will usually show that it is charging on the airplane (lightning bolt shown), but the battery charge indicator slowly declines as I'm using it. But it will decline much faster if not plugged in.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by LifeIsGood » Mon Feb 10, 2020 5:54 am

I can't remember if if the lightning bolt is present or not. I'll check next time I fly. Thanks for the tip.
lazydavid wrote:
Sun Feb 09, 2020 7:56 am
LifeIsGood wrote:
Sun Feb 09, 2020 6:06 am
Not to hijack this thread but several times in the past I've attempted to charge my iPad on an airplane using their USB outlets. The iPad initially shows it is charging and then stops. This has occurred on different planes at different times. Any ideas about what is happening?
Does the lightning bolt go away completely, or does it just say "Not Charging"? The latter just means that the power source is not sufficient to operate the device and charge it at the same time. I haven't kept up with the specs on the more recent ones, but early iPads consumed about 460-480 milliwatts when the screen was on and the device was in basic use (web browsing, email, etc). So a standard 1.0A, 500 mw charger could keep the battery from discharging, but couldn't actually charge it unless the screen was off.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by Momus » Mon Feb 10, 2020 7:11 am

Yes, 2.1a slot is faster. But, that's only 1 equation. Power (watt) = A (current) X Voltage

It depends on your device. The electronics pulls power they need. When you charge, you always want to use the highest watt charger availabe, plug it in into the highest rated A slot to get the fastest charging speed. The tech is also different on each electronic.

Oneplus/Huaweii phone with VOOC charger (30-50 watts). Blazing speed 20 mins for 60% .
Android phones with QC 4.0 charger (27 watts).
iPhone 11 pro with any 18-20 watts charger. iPhone is the slowest out of the above because it doesn't support QC or VOOC, it does support PD charger about 20 watts, not the fastest but not too bad.

Cable makes a big different. Crappy cable can deliver 0.5A only, while VOOC cable can deliver 4A. So, you need to buy the right cable for your device. The easiest way to test it is by using Ampere app to see which charger + cable combo gives you the fastest charging rate.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by Psyayeayeduck » Mon Feb 10, 2020 7:42 am

nisiprius wrote:
Thu Feb 06, 2020 9:54 pm
tooluser wrote:
Thu Feb 06, 2020 9:48 pm
nisiprius wrote:
Thu Feb 06, 2020 2:53 pm
dukeblue219 wrote:
Thu Feb 06, 2020 1:04 pm
Yes, they are usually different. You could test with a phone and a battery charge monitoring app (like Ampere) that will show you the charge rate after a few seconds plugged in.
Thanks! Amazing. An app. Who knew? Everyone but me, I guess.

OK, thanks to all who answered, I have my answer.
Please report back on what you find out.
For right now, what I found out is that when a device is close to fully charged, the charging speed is apparently intentionally limited and is much less than 1 amp regardless of which socket I use... so I don't know yet.
So think of charging your phone like a giant spring attached to a wall. When you initially push that spring, it is easy to compress the spring with little resistance. Around the 50% compression state of the spring, the spring starts pushing back giving you resistance so it takes more of an effort from you to continue compressing the spring. As you get closer to the 100% compression state of the spring, the spring starts resisting ever more which then takes more of an effort from you until you reach 100% compression state of the spring.


Charging a phone behaves similarly. When a phone is low battery (uncompressed state of the spring), charging a phone is very easy. As your battery life increases, charging the phone takes a bit more effort (more amperage). When a phone battery starts reaching 100%, it takes more of an effort to charge a phone to that 100% battery state. Since your phone is limiting you to <1 amperes, it takes a relatively long time to reach full battery status. Using the spring on the wall example, it's like pushing on the spring with a sprained wrist. It will eventually charge but it will be slow as molasses.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by nisiprius » Thu Feb 13, 2020 9:40 am

I have another question. Can someone point me at a technical description at the "right" level of just how USB charging works... what the spec is? In particular, does it turn out that virtually all chargers that has a pair of ports labeled "2.1" and "1.0" are using the same popular chip (or identical chips made by different vendors?

With regard to results, regrettably I have concluded that the Android application named "Ampere" is flaky and even worrisome. On a sample size of three Android devices... current phone, old phone, and tablet... plugged into "1.0A" and "2.1A" ports and a "2.4A" charger, with 30% charge, I never saw a charging rate higher than 600-700 ma. An indication that this might just be inaccurate, rather than correctly reporting something about the charging regime, is that when running Ampere and not plugged into a charger, two of the device give negative readings like -200 ma, but the third gives an exact zero and nothing else.

What is worrisome is that on the tablet, when I plugged it in, after a few minutes the tablet began sounding a repeated alert saying that there was moisture detected, and quit charging. There was no obvious reason. Unplugging and replugging the cable did nothing, doing a forced stop of the Ampere app in the Settings app did nothing, applying a vacuum cleaner for a minute around the charging port did nothing, the tablet apparently lost the ability to charge. After shutting power off and on again, it then behaved and charged normally. That's scary. It led me to uninstall Ampere, and I'm not going to try installing it again.
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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by brianH » Thu Feb 13, 2020 11:58 am

nisiprius wrote:
Thu Feb 13, 2020 9:40 am
I have another question. Can someone point me at a technical description at the "right" level of just how USB charging works... what the spec is? In particular, does it turn out that virtually all chargers that has a pair of ports labeled "2.1" and "1.0" are using the same popular chip (or identical chips made by different vendors?
The whole USB power delivery spec is a huge mess. This may provide some explanation: https://www.androidauthority.com/usb-po ... ry-806266/

My understanding that the standardization around 2.1A is due to that being the max draw of older iPads, so manufacturers of chips/chargers just kind of standardized the max around that. Typically, depending on the device, charger, and cables, it can pull anywhere from 500mA to 2A.

I would recommend one of the USB multimeters recommended earlier to get a true reading. Apps like Ampere are just able to report back what the internal charging controller says, which may not actually be accurate.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by willthrill81 » Thu Feb 13, 2020 7:53 pm

nisiprius wrote:
Thu Feb 13, 2020 9:40 am
I have another question. Can someone point me at a technical description at the "right" level of just how USB charging works... what the spec is? In particular, does it turn out that virtually all chargers that has a pair of ports labeled "2.1" and "1.0" are using the same popular chip (or identical chips made by different vendors?

With regard to results, regrettably I have concluded that the Android application named "Ampere" is flaky and even worrisome. On a sample size of three Android devices... current phone, old phone, and tablet... plugged into "1.0A" and "2.1A" ports and a "2.4A" charger, with 30% charge, I never saw a charging rate higher than 600-700 ma. An indication that this might just be inaccurate, rather than correctly reporting something about the charging regime, is that when running Ampere and not plugged into a charger, two of the device give negative readings like -200 ma, but the third gives an exact zero and nothing else.

What is worrisome is that on the tablet, when I plugged it in, after a few minutes the tablet began sounding a repeated alert saying that there was moisture detected, and quit charging. There was no obvious reason. Unplugging and replugging the cable did nothing, doing a forced stop of the Ampere app in the Settings app did nothing, applying a vacuum cleaner for a minute around the charging port did nothing, the tablet apparently lost the ability to charge. After shutting power off and on again, it then behaved and charged normally. That's scary. It led me to uninstall Ampere, and I'm not going to try installing it again.
It sounds like the app is junk. I agree that using it again would be a bad idea.

You really need a good USB ammeter, something like this one that's only $11. It will tell you the exact voltage coming out of the USB outlet (should be 5.1, but I've seen it go down as low as 4.9; much lower than that and you probably have a bad charger) and the amperage flowing into the device. As you've seen, apps have limitations and are not dependable. A quality, separate meter is.

Phones are all over the place with the amps that they consume. Our old phones would need up to 1,300 milliamps to charge at top speed, but our new ones (DW and I have the same model) will not go above 740, despite having larger batteries. An ammeter will tell the real tale. It's also a good idea to travel with one of these so that you know that your device is charging properly. It can also be very useful to help you identify if a cable/charger/device has gone bad.
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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by 02nz » Thu Feb 13, 2020 8:16 pm

nisiprius wrote:
Thu Feb 13, 2020 9:40 am
I have another question. Can someone point me at a technical description at the "right" level of just how USB charging works... what the spec is?
As I understand it there are broadly four different kinds of USB charging:

1. Slowest but most universally supported: 5V at 500 mA (2.5W), almost any USB port can supply this, but not enough to power many modern devices

2. Still 5V, but higher amperage up to about 2.4A (12W). All recent iPhones and iPads support this. Most after-market chargers support something close to 2-2.4A (10-12W). The small print at the bottom of the charger usually has the specs.

3. Qualcomm's proprietary Quick Charge (QC), supported on many Android smartphones. This technically out of spec for USB and is not supported by iOS devices, and it gets confusing because there are different iterations of it, with weird voltages and amperages. But at a minimum you should still be able to plug in a non-QC device like the iPhone and still charge, just more slowly. Generally USB ports supporting QC are green, sometimes orange.

4. Power Delivery (USB-PD), up to 100W. This only works over a type-C connection. Voltages and amperages vary a lot for this, and not all chargers support all the combinations in the spec (higher-powered ones are generally bulkier). For example, the newer iPhones support USB-PD when used with a Lighting-to-USB-C cable, but only up to 18W. Generally you can use higher-powered charger for a lower-rated device (e.g., my 45W ZMI charger, which can power most laptops supporting USB-PD, also works fine with my iPhone, but only up to 18W), but you'll run into issues (slow charging, no charging at all, or even crashes) if you try to power a higher-powered device with a lower-rated charger.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by Momus » Thu Feb 13, 2020 9:01 pm

A couple basic ports you have to know the difference. On your computer/laptop, it normally support either of these. USB 2.0 ports can only output 500mA max. It's best not to charge your phone plugging it directly from your laptop or computer. Use a stand alone charger.
USB 3.1 5V 900mA (4.5 watt) via USB-A port
USB 2.0 5V 500mA (2.5 watt) via USB-A port

My phone, Oneplus 7 pro pulls as much as 6A at 5V (30 watts). It has VOOC tech built in (this is not a common tech). I use a VOOC charger.

Android phones normally uses Quick Charge tech. Quick Charge 3.0 goes up to 6.5V at 3A, creating 19.5 watts. QC 1.0 which allowed devices to charge at 5V/2A (10 watts). QC 2.0 allows to charge at 5V/1.6A, 9V/1.67A, or 12V/1.2A (14.4 watts max) and QC 3.0 allows to charge at 3.6V-6.5V/3A (19.5 watt max), 6.5V-9V/2A, or 9V-12V/1.5A.

IPhone does not use any of the above proprietary fast charging tech. iPhone 8 or later does support USB-PD power delivery. You can only get the fast charging rate if plug it in into a USB PD port. This port/slot looks like USB C (smaller; plug at any orientation). This is NOT a USB A port - old school looking port where you have to get to right orientation to plug it in. The device will be able to pull around 18-20 watts using the correct charger.

Most phone will throttle down on taking power immediately after reaching 80% to prevent battery damage. So, if you need to measure using Ampere app, do it when you are at low 0-50% charge. If you measure it at 80-100%, you won't see it pull any noticeable current, you will get a wrong reading. Software doesn't break your device. There are a lot of other apps to try. The problem with 1 particular app, sometimes the developer does not include/test your phone, and the software fails to detect what you have and you get the wrong reading. And, some cables limits your current delivery to 500mA (0.5A), so try to use an OEM cable at the minimum.

At this point, I don't even know what you are using. If you want the fastest charging rate, buy the right chargers. Android, buy an QC rated charger. An iPhone? Buy a USB PD charger. Own Both? Just get a USB PD charger (if your device support QC 4.0, it will also support USB PD).

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by 02nz » Thu Feb 13, 2020 10:14 pm

Momus wrote:
Thu Feb 13, 2020 9:01 pm
IPhone does not use any of the above proprietary fast charging tech. iPhone 8 or later does support USB-PD power delivery. You can only get the fast charging rate if plug it in into a USB PD port. This port/slot looks like USB C (smaller; plug at any orientation). This is NOT a USB A port - old school looking port where you have to get to right orientation to plug it in. The device will be able to pull around 18-20 watts using the correct charger.
The bolded part is not quite right - USB Power Delivery and USB Type-C are not two kinds of ports. Type-C is the type of physical connector, which can support data, power, and/or video output, depending on the device's capabilities. Power Delivery is the relatively new protocol for, well, delivering power (up to about 100W) through the USB-C connection. On Apple devices you need a USB-C to Lightning cable. On every other type of device I've seen (smartphone, tablet, laptop) you need a cable with USB-C connectors on both ends for Power Delivery to work (and of course both charger and the device must support Power Delivery - some devices with USB-C ports do not).

So USB Type C doesn't really live up to its first name of "Universal." :wink:

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by Momus » Thu Feb 13, 2020 11:28 pm

02nz wrote:
Thu Feb 13, 2020 10:14 pm
Momus wrote:
Thu Feb 13, 2020 9:01 pm
IPhone does not use any of the above proprietary fast charging tech. iPhone 8 or later does support USB-PD power delivery. You can only get the fast charging rate if plug it in into a USB PD port. This port/slot looks like USB C (smaller; plug at any orientation). This is NOT a USB A port - old school looking port where you have to get to right orientation to plug it in. The device will be able to pull around 18-20 watts using the correct charger.
The bolded part is not quite right - USB Power Delivery and USB Type-C are not two kinds of ports. Type-C is the type of physical connector, which can support data, power, and/or video output, depending on the device's capabilities. Power Delivery is the relatively new protocol for, well, delivering power (up to about 100W) through the USB-C connection. On Apple devices you need a USB-C to Lightning cable. On every other type of device I've seen (smartphone, tablet, laptop) you need a cable with USB-C connectors on both ends for Power Delivery to work (and of course both charger and the device must support Power Delivery - some devices with USB-C ports do not).

So USB Type C doesn't really live up to its first name of "Universal." :wink:
I'm just pointing out the distinction, most people don't even know what USB-C PD port looks like, and think it will look like USB-A port. It's exactly the same USB-C port (most newer androids) you have at the bottom of your phone. It will be labeled "PD".

Some recommendations for the chargers
https://www.google.com/amp/s/www.cnet.c ... -for-2020/

Don't buy this if you phone/device only supports QC 3.0, it's NOT gonna give you fast charging.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by Momus » Fri Feb 14, 2020 5:49 pm

Here is the interpretation of the results when I use a charger not meant for my phone. https://imgur.com/a/lixqCJm
The ampere app is a hit or miss depending on your device, but usually you can make sense what happens with the reading. There are other apps to try.

Taken with Quick Charge 3.0 capable charger, notice the OUTPUT description on the charger.
1st slot = 2.4A slot with a description of 5V=2.4A (12 watts) - I get a reading of 1300 mA
2nd slot = QC 3.0 slot with a description of 3.6-6.5V=2.4A/6.5-9V=2A/9-12V=1.5A (18 watts) - I get a reading of 1300 mA

Unplugged under max brightness, it has a discharge rate of -630 mA. When unplugged under normal brightness, my phone has a discharge rate of -290 mA (about 40% brightness). This gives a true reading of 1300 + ~200 mA = 1500 mA while I am using the phone = 1.5A, I will get 1.5A current using any one of the slot no matter what the slot description is. This is because my phone does NOT support QC tech and the default max of my phone negotiates 1.5A from 2.4A slot or QC slot. If I have a correct tablet or QC 3.0 capable phone I will draw 2.4A from this charger. I am maxed out at 1500 mA = 1.5A with any random charger that says 2A slot and above. If I plug this into 1A slot charger, I will have a reading of around 700-800 mA (1000mA - 290 mA); I have none in my house because I throw that garbage away. I know I am using the wrong charger for my phone since the phone is capable for so much more.

The last picture is when I plugged it into a VOOC charger (Warp Charge 30 watt = 5V-6A charger). I get 5800 mA (5.8A) reading under normal brightness while the phone is on. My phone supports VOOC tech, not Quick Charge. :beer

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by BuddyJet » Sun Feb 16, 2020 2:42 pm

Small warning about using a high amp outlet on all devices. When I connected my Samsung watch wireless charger to a high amp outlet, the wireless unit started to smoke. After a quick disconnect, the plastic around where the cable plugged in had melted.

I’m more careful about the power supplies now.
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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by willthrill81 » Sun Feb 16, 2020 3:45 pm

BuddyJet wrote:
Sun Feb 16, 2020 2:42 pm
Small warning about using a high amp outlet on all devices. When I connected my Samsung watch wireless charger to a high amp outlet, the wireless unit started to smoke. After a quick disconnect, the plastic around where the cable plugged in had melted.

I’m more careful about the power supplies now.
That didn't happen because the outlet was 'high amp'. Certain chargers only work with certain types of outlets, which is probably why you encountered that problem.
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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by lazydavid » Sun Feb 16, 2020 3:52 pm

BuddyJet wrote:
Sun Feb 16, 2020 2:42 pm
Small warning about using a high amp outlet on all devices. When I connected my Samsung watch wireless charger to a high amp outlet, the wireless unit started to smoke. After a quick disconnect, the plastic around where the cable plugged in had melted.

I’m more careful about the power supplies now.
This is almost certainly a fault in one of the components, and not actually related to the Amperage rating of the charger. Electronics only draw as much power as they need. I regularly charge my phone with a 95w laptop charger, which does not cause it to melt or explode. :) Similarly, many of the outlets in your home are capable of supplying 20A at 115V, or 2,300 watts. But if you plug in a little LED night light like this one, it only draws half a watt.

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Re: Are 2.1 and 1.0-amp sockets really different on a USB charger?

Post by Dude2 » Mon Feb 17, 2020 3:53 am

BuddyJet wrote:
Sun Feb 16, 2020 2:42 pm
Small warning about using a high amp outlet on all devices. When I connected my Samsung watch wireless charger to a high amp outlet, the wireless unit started to smoke. After a quick disconnect, the plastic around where the cable plugged in had melted.

I’m more careful about the power supplies now.
It's actually the opposite. If you try to plug a device that needs more amps than the outlet is able to provide, it will brown out and destroy itself. (At least it has the potential to do that if there isn't any self-protection built in.)

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