Usual Battery Drain

[SteelPriest]

Hey guys, I wonder if you could help me out with a problem I'm trying to fix.

The battery in my 52 reg Mini One has been going flat a lot quicker than i reckon it should (after a week or so without use), and I'm trying to work out why.

I've had 2 new batteries in as many years, and the most recent one is like 6 months old. A fair amount of this time it was sitting unused while I moved house a lot. I still only use the car for a couple of short journeys every week.

I bought a multimeter in order to see if the car is draining it. I fully charged the battery (it went to about 12.8v), then disconnected it and connected the multimeter between the negative connector and battery post.

For the first 5 mins or so the car seems to draw 500mA or so, which then goes down to 180mA. At about the 20 minute mark this goes down to 120mA. After about 40 minutes this goes down to 20mA, although this flickers briefly up to 120mA again about every 30 seconds.

Does this sound normal? Could this very brief (less than a second) draw of 120mA be causing my battery to drain quicker than it should?

I took out every (!) fuse one by one to try to stop this happening, but none made a difference :|

any ideas?

*edit* PS The car does seem to be charging the battery when it's on - the voltage across it with the engine running is 13.8v or so.

[mab01uk]

This similar thread may have info which will help you:
http://www.mini2.com/forum/maintenan...ery-drain.html

[SteelPriest]

Thanks for the link to that thread - I'm pretty sure it's not the radio, as although i have a 3.5mm jack adapter installed on the cd changer socket, i took the whole damn thing out yesterday and the 120mA draw was still there.

I suppose it looks like it might be corrosion somewhere. The One doesn't have an immobiliser does it? Mine is pretty low spec - I don't even have a glove compartment.

On a slightly different note - how hard is it to rewire a 12v socket to be live all the time? I was thinking I might be able to deal with this by getting a solar trickle charger...

[danieledd]

I had a 2009 clubman that would drain down in less than a week being idle. Had to keep a 2amp charger connected when not in use. Too much normal drain, I was told by MINI DEALER. Now it is O K as long as I disconnect charger before getting under way!!!!!!

[The Nun]

Could be something simple like a stuck on boot light?
I heard of that draining a battery before now.

[SteelPriest]

Yeah I initially thought it was the boot light, as the latch had broken (again!). But I got this fixed and it's still happening.

Also, the boot light uses a lot more than 120mA.

I had found some people who reckoned the cd changer connection in the boot can sometimes short and cause a drain, but i can't find a cd changer connection in the boot :S

[mab01uk]

Quote: Originally Posted by SteelPriest (original)

The One doesn't have an immobiliser does it? Mine is pretty low spec - I don't even have a glove compartment.

All modern cars including your One have an engine immobiliser 'by law' I believe but the alarm was optional in 2002 on Mini One.......if you have the optional alarm fitted there will be a red flashing led on the end of the RH steering column stalk when it is armed.

[SteelPriest]

Yeah I definitely don't have an alarm (good choice so far, 10 years of not being stolen...), but that other thread seems to suggest it could be the immobiliser?

I wish I could just leave it plugged in, but it's parked on the street :l