Okay...I made a dumb mistake. I almost always leave the key in the ignition (in the garage of course). Well, for the first time ever I accidentally left the key in the on position. The next morning I got in, and it wouldn't start. I haven't had much of a chance to mess with it. Today I went out and tried to jump it with my wife's Mustang...it didn't do anything. I know it takes a lot of juice to turn a MINI's engine over, so what can I do to get my MCS going again? Any advice would be greatly appreciated.

Thanks

 

generally if a battery is totally dead...you must leave the cable connected to the car jumping it for a bit.
So leave them connected for 10-15 minutes, then try to crank. (the dead battry is acting like a sponge, asorbing all the power comming through the cable...the guage and length on the cable ((thicker and shorter better, cheap , long cables bought on sale are pretty poor)), and health of the other cars battery also comes into play here..)
One tip...when a battery has been depleted to 100%, the sometimes fail much faster as it is very demanding physically on the battery...sometimes they never do recover.

 

I have left my key on as well as my lights and the battery on my 29 d.00did not go dead because after a short while the computer will shut stuff down to avoid the battery going dea

 

The info is good for ANY car...
some cars have various save power tricks for when a light is left on, etc, but in the end, mistakes happen, and folks have found ways to kill most every car battery...

 

I'll try letting it charge for awhile. My wife and I have our anniversary tomorrow, and we're planning to take the MINI on a little trip. So, I really hope the battery survives. It's fairly new. (November 2011) I'll see what happens once I get it started. Thank you for all the help!

 

draining it completely is bad for the batteries life. I would get a trickle charger and completely charge it (like a battery tender) and try not to do this agin

 

I've also found it impossible to jump a COMPLETELY dead battery recently
due to the "dead battery sponge effect" mentioned above.

Try jumping it from the Mustang (running) with one of the terminals to the
MINI's battery disconnected. You need a standard guage jumper cable, not a
thin, wimpy one. After it starts, you can put the terminal back on the MINI's
battery but don't disrupt the connection from the Mustang to ground and the
positive cable when you do this. Leave the Mustang hooked up for at least a
few minutes more before taking it off and don't turn the MINI off until it has
run or driven a while to give the alternator half a chance to try to recharge
the battery (this may or may not work, it the battery is really gone, it may not hold
a charge no matter how long you try to charge it up).

 

Ground to the block, not to the battery.