Battery Drain When Locked and Completely off

Clasomato · 07-06-2024, 11:22 PM

Hi all,

First time posting here so please let me know if you need anymore info.

So I just brought this car off my mate has about 100kms on it and I brought it knowing or more accurately thinking that the battery would need to be changed.

I had my mechanic family friend have a look at the battery before getting a new one and the negative terminal was sparking indicating something is drawing current when the car is off and a good chunk of it.

Would be great if anyone could lend me a hand here. Said mechanic friend is really only clued up on Jap cars and is a bit of a geezer so finds it hard to get to the fusebox (terrible spot aye).

Cheers

Grease23 · 07-07-2024, 08:33 AM

The "spark test" your friend is using to suggest a problem probably doesn't mean anything at all. Lots of cars (I'll go so far as to say most newish ones) will have a small spark when the terminal is connected or taken off. A healthy electrical system often has some slight current drain that won't be a problem unless the vehicle sits for a long, long time.

I'm guessing the trunk is open when he/she sees the spark? The trunk light will do that. Sparks around batteries are never a good idea. Measure the current draw, something that can be done with a very inexpensive multimeter. My car (2013 E93) and probably yours draw more current for a brief time after everything is off, then that cuts down to a very low draw. Mine has an orange light near the shifter; when that goes out after a few minutes the current draw is down to practically nothing.

If the hood is open, try pulling up on the switch for the warning light. That seems to cut current draw even more on mine.

07-06-2024, 11:22 PM	#1
Clasomato Registered 0 Rep 2 Posts Drives: 320i E90 Join Date: Jul 2024 Location: New Zealand iTrader: (0)	Battery Drain When Locked and Completely off Hi all, First time posting here so please let me know if you need anymore info. So I just brought this car off my mate has about 100kms on it and I brought it knowing or more accurately thinking that the battery would need to be changed. I had my mechanic family friend have a look at the battery before getting a new one and the negative terminal was sparking indicating something is drawing current when the car is off and a good chunk of it. Would be great if anyone could lend me a hand here. Said mechanic friend is really only clued up on Jap cars and is a bit of a geezer so finds it hard to get to the fusebox (terrible spot aye). Cheers
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07-07-2024, 08:33 AM	#2
Grease23 Private 60 Rep 62 Posts Drives: BMW 328i Join Date: Jan 2024 Location: Seattle iTrader: (0)	The "spark test" your friend is using to suggest a problem probably doesn't mean anything at all. Lots of cars (I'll go so far as to say most newish ones) will have a small spark when the terminal is connected or taken off. A healthy electrical system often has some slight current drain that won't be a problem unless the vehicle sits for a long, long time. I'm guessing the trunk is open when he/she sees the spark? The trunk light will do that. Sparks around batteries are never a good idea. Measure the current draw, something that can be done with a very inexpensive multimeter. My car (2013 E93) and probably yours draw more current for a brief time after everything is off, then that cuts down to a very low draw. Mine has an orange light near the shifter; when that goes out after a few minutes the current draw is down to practically nothing. If the hood is open, try pulling up on the switch for the warning light. That seems to cut current draw even more on mine.
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