How much does a phone charging drain a car battery?

[Deleted User]

Hi,

I'm going camping and wondered how much a phone charging would drain a car battery? Specifically a HTC Desire and a Honda Jazz.

I'm planning to buy a power pack but wondered about this anyway

Thanks

Avoriaz

A small 12 volt car battery will have a capacity of about 45 amp hours.

That will charge a lot of phones.

Have a look at the capacity of your phone battery and do the sums.

A typical phone battery might be 3.7 volts and one amp hour so a few charges won't make much inroads into your car battery.

Make sure that other things such as the alarm or sat nav don't drain the car battery if the car isn't used for a while.

Maybe start it up and take it for a short run to top up the battery every week or so.

iamcornholio

It wont drain anything if the socket only works when the engine runs or ignition is on - and if the ignition is on there will be other things draining the battery too

The charger will use more current than it outputs or the phone/phone battery inputs

grizzly1911

Using the Avoriaz example theoretically about up to 80 times. with a 20% inefficiency.

In practice less as 1.) the charge rate would slow down and 2.) there must be a minimum charge at which the battery would actually turn over the engine, more for a diesel too.

Many car batteries are bigger these days especially with the number of diesels.

When we have been camping we have often charged 2-3 phones, run a fluorescent camp light, charged cameras each night. even with only short journeys on some days <5m never had a problem.

Cars these days often have a secondary power take off socket in the back that isn't ignition dependant.