Car stereo drains battery: Is 30-50 mA normal?
April 16, 2013 11:30 AM   Subscribe

The circuit that runs my aftermarket Pioneer stereo is draining the car's battery at a rate of 30-50 mA when the car is off. Faceplate on/off doesn't make a difference. Is this within normal range?

It's enough to drain the battery completely if I don't drive every few days, so lately I've gotten into the habit of pulling the fuse. But that sucks.
posted by qxntpqbbbqxl to Travel & Transportation (7 answers total)
Best answer: Does the stereo work when the car is off with the key removed?

It's been awhile, but the stereos I've installed had 2 power leads. One is meant to be hooked into unswitched power, and just draws the tiny bit of current necessary to keep the clock working. The wire that carries power to actually run the stereo as a music-playing device should be hooked to switched power, so that it only works when the ignition switch is on. If yours was installed incorrectly with both wires attached to unswitched power, that could be your problem.
posted by jon1270 at 11:42 AM on April 16, 2013 [1 favorite]

Best answer: 30-50mA is about half a's high for a well-designed circuit on standby (depending, of course, on how much the circuit has to do, how many lights it has to run, etc.). Certainly higher than I'd be willing to put on the battery of one of my vehicles, if I wanted to be sure of still being able to start it after a few days.

Is it possible that you left a signal wire unconnected? Perhaps the stereo can't tell when the vehicle is turned off, so it's actually running but just not playing anything. In that case, half a watt for on but idle is not that bad!

If you can't solve it any other way, you could put a relay in the power line, and have it activated by something that really is switched with the rest of the car.
posted by spacewrench at 11:43 AM on April 16, 2013

Came to say what jon1270 said: you probably have the "power" and "display" +12v connections flipped or shorted.
posted by AzraelBrown at 11:47 AM on April 16, 2013 [1 favorite]

Here's an article that might help with troubleshooting. It could be another component in your car that's draining the battery - but the linked article implies that a reasonable drain from a stereo in standby is 1-3 mA.
posted by gorbichov at 11:48 AM on April 16, 2013

Best answer: 50mA for a week is 50mA × 24h/day × 7days/week, which comes to 8.4Ah. A fully charged car battery in good condition should be good for at least 50Ah.

So even if your stereo is indeed wired wrong, if your car won't start after your stereo's been drawing 50mA from its battery for a couple of weeks then it's time you bought a new battery.
posted by flabdablet at 11:58 AM on April 16, 2013 [3 favorites]

Response by poster: The stereo does not work when the car is off.
posted by qxntpqbbbqxl at 12:07 PM on April 16, 2013

Check the orange wire.
posted by rhizome at 1:06 PM on April 16, 2013

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