Originally Posted by SamS
I will surely give a full report for its behavior during a hour's worth of stop-and-go!
Yes, the batteries will age over the years, and ultimately hold less charge. I've seen unofficially where the batteries have a lifetime warranty. I'm checking with BMW NA right now to confirm. I honestly doubt I'll keep the car more than 4 years, which should have minimal impact on battery performance for that age.
Lifetime warranty? My guess is that will be finely worded so decay is considered normal wear and tear. LiOn and LiOn Phosphate cells can decay 10-20% per year, and heat over 100F means decay on the higher end of the scale. Hopefully they gel cooled (chemically cooled) them in addition to the fans BMW put back there.
It looks like the AH batteries are manufactured by A123Systems. The cells BMW uses are cylindrical cells, MADE IN CHINA.
And A123Systems filed for Ch11 bankruptcy. Lovely. Looks like Johnson Controls will take over. Hopefully that's for the better.