Will an attached iphone drain a car's battery?

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RooseveltG
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Will an attached iphone drain a car's battery?

Post by RooseveltG » Fri Dec 06, 2013 6:51 am

My car has an ipod connector in the glove compartment that remains powered on even when the car is turned off. I recently attached an old iphone 3 to use as an ipod and I want to leave it in the glovebox. Does anyone know if this will drain the car's battery?

Thanks in advance.

Roosevelt.

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meowcat
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Re: Will an attached iphone drain a car's battery?

Post by meowcat » Fri Dec 06, 2013 7:46 am

Not for a very, very, long time. If the car is started/driven regularly, there shouldn't be any issues.
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RDB
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Re: Will an attached iphone drain a car's battery?

Post by RDB » Fri Dec 06, 2013 8:49 am

We have done this in my wifes car for a while and it has never caused any issue.

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Toons
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Re: Will an attached iphone drain a car's battery?

Post by Toons » Fri Dec 06, 2013 8:52 am

meowcat wrote:Not for a very, very, long time. If the car is started/driven regularly, there shouldn't be any issues.

Agree, I have 2 IPod touches, one for each car that I leave in both cars all the time along with charging both phones when we are using either car,no problems :happy

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nisiprius
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Re: Will an attached iphone drain a car's battery?

Post by nisiprius » Fri Dec 06, 2013 9:13 am

Car batteries are in the ballpark of 60 ampere-hours, at 12 volts = 720 watt-hours.

I have a "Kill A Watt" gadget that measures power consumption. It says that my AC iPod charger draws 1 watt when not connected to an iPod; 4 watts when charging an iPod. So, conservatively, it would take 180 hours, or a week, for a charging iPod to drain a car battery. It's probably better when the iPod is charging directly from a car battery, but anyway, it would be on the order of 4 watts / 12 volts = 300 or so milliamps while the iPod is charging. It would be unlikely that it doesn't drop at all once the iPod is fully charged, but unlikely that it drops to zero.

Even if it's only 1 watt once the iPod is fully charged, that does seem to be high compared to the "parasitic drain" of modern automotive electronics (which are always on even when the car isn't running), which Googling suggests is 30-50 milliamps. So I guess it's a consideration.

An iPhone probably draws more.

It's not going to drain your battery overnight, and if you're driving your car once or twice a week it couldn't matter. It sounds like it would be good practice to disconnect it though, like if it's going to be parked a couple of weeks at an airport garage...
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RooseveltG
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Re: Will an attached iphone drain a car's battery?

Post by RooseveltG » Fri Dec 06, 2013 9:49 am

Great responses. Thank you.

Roosevelt.

retiredjg
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Re: Will an attached iphone drain a car's battery?

Post by retiredjg » Fri Dec 06, 2013 9:56 am

This is my experience also. I'm on the road full time and leave something charging in my truck almost 24 hours a day. Could be the GPS, an iPod, cell phone, or an inverter (which charges my computer and hot spot). Have not had any problems.

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Drain
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Re: Will an attached iphone drain a car's battery?

Post by Drain » Fri Dec 06, 2013 10:06 am

I thought that when the car is off, the lighter is unpowered, so an iPod or iPhone won't charge at all. That seems to be how it is in our car, anyway.
Darin

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wander
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Re: Will an attached iphone drain a car's battery?

Post by wander » Fri Dec 06, 2013 10:14 am

Will an attached Iphone drain a car's battery? Yes, of course.
Last edited by wander on Wed Dec 11, 2013 4:48 am, edited 1 time in total.

ieee488
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Re: Will an attached iphone drain a car's battery?

Post by ieee488 » Fri Dec 06, 2013 10:25 am

Drain wrote:I thought that when the car is off, the lighter is unpowered, so an iPod or iPhone won't charge at all. That seems to be how it is in our car, anyway.
I have two 12V outlet connectors in my Honda. One on the front console is off when the car is off.
The other which is inside the armrest console, according to the owner's manual, is on even when the car is off.
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Re: Will an attached iphone drain a car's battery?

Post by retiredjg » Fri Dec 06, 2013 11:00 am

I also have 2 outlets. One is hot all the time.

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Epsilon Delta
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Re: Will an attached iphone drain a car's battery?

Post by Epsilon Delta » Fri Dec 06, 2013 12:20 pm

nisiprius wrote:It's probably better when the iPod is charging directly from a car battery, but anyway, it would be on the order of 4 watts / 12 volts = 300 or so milliamps while the iPod is charging. It would be unlikely that it doesn't drop at all once the iPod is fully charged, but unlikely that it drops to zero.

...

It's not going to drain your battery overnight, and if you're driving your car once or twice a week it couldn't matter. It sounds like it would be good practice to disconnect it though, like if it's going to be parked a couple of weeks at an airport garage...
The conclusion is reasonable, but ...

At least some car adapters use a linear voltage regulator. If the output is 4W @ 5V it draws 800mA. On the input side it would draw 800mA at 12V for 9.6W. The missing 5.6W is dissipated as heat in the adapter (That's not a lot of heat, you may or may not feel the adapter is warm to the touch)

Another issue is the no-load current drawn by the adapter. Some draw more than others. Some car adapters are much worse than AC adapters, since there are US and EU programs to reduce the standby losses for AC (mains) adapters which don't apply to car adapters.

One take away from this is that the design and quality of implementation of an adapter can matter. If you leave the adapter operating in an parked vehicle and are worried about the vehicle battery you want one that is designed with efficiency in mind. I'm not sure how you would select such a device without extensive testing, you might be able to find one that advertises high efficiency, but that might be puffery.

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Epsilon Delta
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Re: Will an attached iphone drain a car's battery?

Post by Epsilon Delta » Fri Dec 06, 2013 12:26 pm

retiredjg wrote:I also have 2 outlets. One is hot all the time.
It's worth reading the owners manual. In some cars you can configure various outlets to be either on or off when the car is off by moving fuses. These days it might be a matter of configuring software.

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Re: Will an attached iphone drain a car's battery?

Post by allsop » Fri Dec 06, 2013 1:07 pm

RooseveltG wrote:My car has an ipod connector in the glove compartment that remains powered on even when the car is turned off. I recently attached an old iphone 3 to use as an ipod and I want to leave it in the glovebox. Does anyone know if this will drain the car's battery?

Thanks in advance.

Roosevelt.
You did not write in which temperature conditions you do this, and in a cold climate I would not recharge.

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