# Car cell phone charger draining battery? **URL:** \ **Category:** Factual Questions\ **Created:** [December 31, 2002, 4:18pm UTC](https://boards.straightdope.com/t/car-cell-phone-charger-draining-battery/145882 "2002-12-31T16:18:11Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![hajario](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hajario/32/171_2.png) [@hajario](https://boards.straightdope.com/u/hajario)\ **Post date:** [December 31, 2002, 4:18pm UTC](https://boards.straightdope.com/t/car-cell-phone-charger-draining-battery/145882/1 "2002-12-31T16:18:11Z")
The last couple of times that I used my cell phone recharger that plugs into my car’s A/C jack, it seems like there is less charge in my cell phone’s battery based on the indicator reading. The recharger that plugs into the socket in my house works well. Is it possible for a car recharger to go bad and have the opposite of its intended effect? TIA, Haj ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [December 31, 2002, 5:38pm UTC](https://boards.straightdope.com/t/car-cell-phone-charger-draining-battery/145882/2 "2002-12-31T17:38:00Z")
Your car’s A/C jack? You have an AC/DC converter with an A/C outlet in your car? Or you do you really mean that you are plugging in a DC plug into a cigarette lighter? Are you doing this while the car is running, or not running, keys off, or ignition on? My car’s cigarette lighter/accessory outlet is live only when the ignition is on, so the phone will discharge. ---
**Author:** ![Jake](https://avatars.discourse-cdn.com/v4/letter/j/f475e1/32.png) [@Jake](https://boards.straightdope.com/u/Jake)\ **Post date:** [December 31, 2002, 5:43pm UTC](https://boards.straightdope.com/t/car-cell-phone-charger-draining-battery/145882/3 "2002-12-31T17:43:00Z")
I’m not clear on what an A/C jack is. Some kind of inverter? I have one of those portable jumper units, and the manual states that charging it with DC will shorten the life of the battery in the unit. They recommend charging with AC. ---
**Author:** ![Cubsfan](https://avatars.discourse-cdn.com/v4/letter/c/f4b2a3/32.png) [@Cubsfan](https://boards.straightdope.com/u/Cubsfan)\ **Post date:** [December 31, 2002, 5:48pm UTC](https://boards.straightdope.com/t/car-cell-phone-charger-draining-battery/145882/4 "2002-12-31T17:48:34Z")
> [@](#): > > \*Originally posted by CookingWithGas \* > \*\*My car’s cigarette lighter/accessory outlet is live only when the ignition is on, so the phone will discharge. \*\* Not true, most all of those chargers have diodes in them that that will not let the current flow backwards thru the charger. If shouldn’t discharge in that situation. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [December 31, 2002, 5:50pm UTC](https://boards.straightdope.com/t/car-cell-phone-charger-draining-battery/145882/5 "2002-12-31T17:50:23Z")
> [@](#): > > \*Originally posted by Stinkpalm \* > \*\*Not true, most all of those chargers have diodes in them that that will not let the current flow backwards thru the charger. If shouldn’t discharge in that situation. \*\* Sorry, I wasn’t specific enough. It’s not draining back into the car’s system. A cell phone that is unplugged will discharge just sitting there, so that’s what would happen in this case. ---
**Author:** ![hajario](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hajario/32/171_2.png) [@hajario](https://boards.straightdope.com/u/hajario)\ **Post date:** [December 31, 2002, 6:46pm UTC](https://boards.straightdope.com/t/car-cell-phone-charger-draining-battery/145882/6 "2002-12-31T18:46:08Z")
First of all, please excuse this dumbass M.E., I meant the DC power from the cigarette lighter jack. It appears that the battery on the cell is significantly draining from being hooked up to this jack lately, much more so than if it were just sitting by itself. This occurs when the engine is running. Haj ---
**Author:** ![susan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/susan/32/17537_2.png) [@susan](https://boards.straightdope.com/u/susan)\ **Post date:** [December 31, 2002, 6:55pm UTC](https://boards.straightdope.com/t/car-cell-phone-charger-draining-battery/145882/7 "2002-12-31T18:55:26Z")
How do you know it’s draining? I’ve found that I get a shorter charge on the phone if I unplug it from the car charger before its display blanks out. When I charge it as I do at home, i.e., letting it charge all the way, it holds the charge similarly. ---
**Author:** ![hajario](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hajario/32/171_2.png) [@hajario](https://boards.straightdope.com/u/hajario)\ **Post date:** [December 31, 2002, 7:03pm UTC](https://boards.straightdope.com/t/car-cell-phone-charger-draining-battery/145882/8 "2002-12-31T19:03:38Z")
> [@](#): > > \*Originally posted by Shoshana \* > **How do you know it’s draining?** Because it goes from three little bar thingies to one little bar thingie in a five minute car drive. This would usually take a 45 minute phone call. Haj