My wife and I went on vacation for a long weekend, and our 2003 Mini Cooper S manual sat idle from Friday night through Wednesday morning. My wife drove in to work (about a 30 minute drive on the freeway) with no issues, nice warm day.

She took a late lunch and the Mini was 100% dead. Other than being able to open the door with the remote, it appeared there were no electrics. Tried to start it and there were no lights, no cranking, no nothing.

I came out and had the same problem, but I couldn't even get the electric door locks to work. After discovering that my manual cable to unlock the rear hatch under the rear seat was missing (it's a used car for us), I tried to unlock the doors again in desperation, and unlocked, although I would swear the unlocking sounded a bit "weak".

Took a look at the battery and saw no obvious connection or corrosion issues. There was a small bit of white corrosion on the bolt for the negative terminal connecting to the body of the car (not on the battery). Removed the battery, cleaned the connections a little, and ran the battery down to AutoZone. It passed their battery test with flying colors. (Unsure of the exact age of the battery, as I've only had the car since March, but it's not OEM and looks fairly new.)

Came back, popped the battery back in, tried again, and the car started up without an issue. Have stopped and started it at least 6 times since yesterday and haven't had a problem. Drove it in today without issue.

Any thoughts? Maybe it was just that bit of corrosion on the negative terminal? Maybe something was more loose than I thought? Any other tests I should do?

 

Two ways to go,

1) You fixed the problem and clear sailings are in your future.

2) Go to your local garage, I'd give Mini Dealer a pass on this one, and have
both battery and alternator charging specs tested. I'd go this route for
peace of mind.

Good luck...

 

Check the grounds...both on the battery and in the engine compartment by the motor mount.
next if those are all fine, i might suspect the +battery cable that runs under the car may be damaged....a few folks have had them replaced....but i would try a battery first if the age is unknow.unknown...cheap enough...might have an internal isssue and moving it fixed it for a bit...not sure if it is possible, but it is a cheap and eay thing to eliminate from the mix before spending a few $$$ on troubleshooting....and its gonna need one someday....