mini cooper key off power draw

Curious if anyone's had any occasion to measure the standby current draw on a stock Mini Cooper S, circa 2010.

I measured 260mA on it on shutdown, and it didn't drop further for the 10 minutes or so that I was monitoring.
Initially it was about 2.7A, and dropped in steps to about 450mA after about 40 secons. At the 1 min 12 second mark it went to 260 mA.

I'd expect this level of draw to be a problem, so I'm thinking it must drop to a sub 20mA level at some point, maybe after some extended period that I didn't have the patience to wait for.. Or, there's a problem with this car, although it's sat for a week and restarted before.

I measured the current with a ammeter through the negative battery cable, maintaining connection on hookup by holding the terminal on the post as I inserted the ammeter inline.

260mA would be enough to kill the battery in a few days. 10 minutes should be more then enough time for the electronics to go to sleep.

General rule of thumb is no more then 50mA at idle after all computers have gone in to sleep mode. It may not be a bad idea to give it 30 minutes and see what the draw is after that.

Are you having issues with the car or just playing around?

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Kevin Pierson

It's something I saw in the course of investigating a dead battery/no start, except that was due to installation of a OBD-II monitoring gauge that was keeping the ECM awake, and drawing a constant 2.7A. That took down the battery after a day of sitting.

Afterwards, I was trying to get a baseline on the key off current draw, and that's when I measured it stabilizing to this quarter amp draw after about 70 seconds. Watched it for a while after that but I never saw it drop, but I wasn't in a position to just leave my Fluke 88 connected up on the street to go back inside, so I had to call it quits.
I've started looking into it on some forums and there appear to be some frequent reports of batteries failing prematurely that may or may not be related to this, if in fact it doesn't shut down further. Some people said they were told the car has to be driven a certain minimum number of miles yearly, which seems to me a roundabout way of saying it can't sit for extended periods.
However, this particular car once sat for a week and had no issues with not starting, so it either will shut down after allowing some more time, or something went bad on the car causing this key off drain. Or the newish battery was able to bridge that gap of discharging 42Amp-hours.
I'll check further next chance I get...

I'm with Kevin on 30 mins for all the sleeper circuits to shut down, 50mA would be be my guess as well. wonder if there's a relay sticking somewhere.
The wiring on this vehicle is similar to the BMW 3/5 Series, we don't get that problem with them.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

I think you guys are right, it seems this particular car happens to take longer to shut down fully, it's been reported to be 15 to 30 min depending on options. Why this is necessary isn't clear, but as long as it eventually does it, no worries.