So, I bought my 2008 about 3 weeks ago. Less than a week after I got it the battery was dead. Pretty sure it was the original battery with 65k miles on it. I bought a new battery and then this morning it was dead...again. The doors were all closed, no lights on...I can't figure out why it could die in one day like that. I drove it yesterday and it didn't do anything weird...any ideas?

 

does it crank? interior lights come on when you open the door? would guess the alternator is your issue.

 

You can take the car to your local auto parts store to have the battery and charging system checked out, usually for free. Sometimes even new batteries fail or are sold with not quite a complete charge. While unlikely, if you did not drive much after replacing the battery and the battery did not have a great charge on it, the battery may not have charged enough since you replaced it. I would also check for cable tightness on the posts. It would not be the first time a mechanic was distracted and did not tighten things properly. Make sure you let us know the solution. We all love to find out the solution to a mystery.

I would also contact the seller. If it was a dealer the car could have been on the lot for awhile before selling. MINI's will slowly lose their battery charge when not driven regularly or driven often only short distances, two common occurrences with cars that are for sale.

 

When I got in the car this am, it was dead...dead. Nothing, no lights, no nothing, key fob would not lock the doors, the lock button on the inside didn't work...no dome light...nothing.

It did jump off, right away, as soon as the terminals were connected it powered on...then started no trouble. My guess is alternator...and I couldn't even locate that...looked up removal...HA! I am handy, but that I am not doing...what an odd design and location of an alternator.

 

I didn't worry about the battery in the car when I bought it...it looked like OEM. More concerned about the new battery...going to get a Battery Tender tomorrow and let it charge up good.

 

A bad alternator will usually result in a warning light....
Bet you have either a bad battery or a "phantom" load aka a parastic drain/draw....

 

I wondered about phantom leaks....I have no radar detector, no phone plugged in...if it was phantom it would have to be from the car itself.

 

Even a load leak or phantom load will let you switch the door locks or some map light. This sounds either dead dead or a loose connection IMO.

 

I double checked the terminal leads at the battery, both were tight, snug and well seated. I was the one who put the battery in...it cranked right up today...still going to get a Battery Tender charger today and let it sit on it all night.