[bensanford]

I was thinking about proactively replacing the AGM original battery in my 230i. The battery is approaching 7 years but seems fine. I was looking at the battery in the floor of the trunk and it is certainly a lot cleaner that batteries in my previous cars which were usually in the hot engine compartment. (maybe that's why it is lasting longer?)

The battery in my 230i appears to be Group size 49 (or DIN size H8). It's almost 14" long, and rated at 90 Ah. Then I looked in my wife's 330, and the battery installed in it is considerably smaller, Group 49 (or DIN size H5), and it's considerably smaller, being just under 10" in length, and rated at 70 Ah. There is plenty of room in the 330 for the larger battery, and there are already threaded mounting holds in the floor of the trunk to accommodate a larger battery - but of course that one doesn't need replacement yet.

For now, I just need to find the right H8 sized battery for by 230i, and fortunately I have time to figure that out. I think I will stay with the largest size, which won't add that much weight.