My Mini battery died last week and i took the car to the miniofdallas dealership for getting it checked. There was an external light system failure also on this car before the battery died.

I got a call from service today saying, that battery has a bad cell and the computer on the mini has logged a message saying the battery died because the key was left on and since it was my fault, mini refuses to pay for the battery replacement, even though i have maintenance and warranty on the car till 2011. I even have extended maintenance on this vehicle.

I have told them there is no way the car can be left on, since it shuts down after a while if its left on and the key is not inside. I mean how hard is it to turn off the mini.

I don't know what to do now. Did any of you had similar experience???.

 

A bad cell is a bad cell. Period! It has nothing to do whatsoever with the key being left on, off, in the car or on the moon. The battery is bad now. Cells degrade over time due to age, use,insufficient maintenance, or low charging voltage and insufficient current. It's a chronic failure, not an acute failure.
You may be able to drain the battery to the point of having insufficient starting voltage, but not kill a cell.
This is the second instance of a Mini battery dying because the key was left in that I've heard of, which kind of perplexes me. Having close to thirty years of experience in the electronics industry, and a lot of experience with batteries, battery banks and charging circuits, I have to wonder just what is being powered with the key in, but the car off. If the CPU is staying powered up, which I suspect, this could explain the static demand on battery in the form of current draw. However most process CPU's have a low voltage threshold setpoint that turns off the processor to protect it from a low voltage/ over current condition.

Short answer is that they're blowing smoke. I'd call Mini.