My 2005 S Cabrio has been just maddening w a current drain killing the battery. It was at the dealer to replace a seat cover they tore replacing a warranted airbag sensor but REFUSED to troubleshoot the issue as it didn’t have a genuine Mini battery in it. I don’t think either battery that’s been in it is the problem. They did claim the alternator was weak so I replaced it, same dead battery two days later.

Got around to checking draw while pulling fuses. Started out with a 2,120mA draw (!), but pulling the F14 interior light fuse in footwell box dropped this to 1,200mA, still a lot. Kept pulling fuses and found removing the F4 fuse dropped it to 100mA. Still seems high but, hey, computers.

So now checking draw from dead with F4 fuse out shows 930mA, then 700 and finally 100mA after maybe a minute or two...

What the heck is F4? The symbol is Greek to me and searches only yield results for later models.

All help deeply appreciated!!!

 

According to Bentley, it's the fuse for the General Module BC1. One of the problem I see with that is that by pulling that fuse, you're disabling a lot of things, central locking, alarm, etc. So you can't really pin it on the module alone unless you're disconnecting every systems connected to it one by one until you find the faulty one.

However, it's the infamous module that kicks the bucket, usually from a leaky sunroof tube. It's in the kick panel on the right side. One thing you could do fairly easily would be to remove the connectors and see if you there's any corrosion in there. Could be corrosion grounding or activating something you're not noticing and drains the battery. If it's fine, you'll have to check all systems it's controlling one by one.

 

Somehow this doesn't surprise me. Have experienced similar trace levels of helpful empathy from the local dealership's repair greeter staffing, the common hiring qualification for whom appears to be confirmed lifetime idiocy.
Watching this thread if you happen to find the source of the leak. Have a similar drain here. Park it for a few days to a week and a half, the battery drains. Two weeks and and it's completely dead. Battery born-on date September 2017. Mystifying.