Here something for you tree hungers,,,lol,,,that mean me too since I drive a I3,,,,the new wave of battery’s,,,,this is a picture of PHEV X5 battery pack,,,,problem was one of the battery cells are inop,,,,there are 6 battery cell packs,,,you can see they are stacked on top of each other,,,2 row of 3 battery cells,,,,what happened the a/c compressor failed causing the battery cells to overheat and cause damage. You can see the a/c lines and expansion valve located inside the battery box,,,,the a/c free on is pumped inside the battery box and between the battery’s to keep them cool. This is one of the a/c tray that is sandwiched between the 2 stacks of battery’s,,,,,,cooling all the battery.