So, will charging the cell phone in a car drain the battery if the car is not running? My husband and my brother-in-law both agree that my sister and I are totally off on this one. Please tell us because right now we are arguing about this too often.

Letsseehere… the battery in my cell phone is 3.4w. A 500 CCA car battery stores about 6000 watts. So you could completely recharge your cell phone at least 1000 times before you actually drain the battery to a point that the car wouldn’t start. The amount of energy small electronics is pretty insig…

No, charging a cell phone in a car with the engine off will not drain the battery noticeably faster than not charging a cell phone in a car. You can leave it connected and charging for over a week with no problems.

I wouldn’t worry about it either. Carry an aux jumper battery in the trunk with a DC jack and use it regularly out of the car too if necessary, esp camping…and don’t worry about it.

In some cars you have to have the key in the ignition and set to ACC (accessory) to get power to the 12V DC outlets. This means more stuff is on in the vehicle while the phone is charging and the key is in the car, a security hazard. My cars are like this so charging the phone when off is a rare, …

I would bet that the electric wind spring driven clocks we had back in the old days from the 1930’s through the 1960’s consumed more power than the power required to charge a cell phone battery. These clocks would rewind about every 2 minutes. We certainly didn’t leave the engines running so that …

This is interesting. I would not think that the converter (dc to ac) would draw power unless you had something plugged into the converter. In the case of the cell phone, the car battery is already supplying direct current and the cell phone battery needs to receive direct current to be recharged.

Cigarette lighter charger, assuming a cigarette lighter.

the car battery is already supplying direct current and the cell phone battery needs to receive direct current to be recharged. But unless that cell phone is 12 volts (maybe less), it will need to adjust the voltage and that is usually done by converting to AC and then back to DC.

No, car phone chargers use a DC to DC converter, mainly because that’s cheaper and smaller. It has the added benefit of being much more efficient than a DC to AC to DC scheme would be. Also, they cut down to a few milliamps or even micro-amps once the phone battery is full. Typical cell phone bat…

Draining the car battery

Maintenance/Repairs

papapb August 28, 2010, 2:58am 7

I had a ac/dc converter in my cigarette lighter adapter that caused my battery to drain. I couldn’t figure out the problem, and ended up being referred by my car mechanic to an electric specialist. Cost me a couple hundred bucks to find out the converter will drain my battery. Something to know - the specialist hadn’t seen that one before. gl.

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Draining the car battery

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