Originally Posted by shadowx360
It came with a BMW AGM battery, though it died on me a week after buying the car and I had it replaced even though the dealer thought it was fine. I figured out later that the issue was that the IBS module was not hooked up so it wasn't sending the message to the DME to kill off drainage when power got low. After I hooked it up, I checked for any battery resets/recodings and found none. I tried to message him yesterday and he never replied, probably meaning he was having battery problems.
Anyways, I'm missing parts 2-8 so I'll go place an order with realOEM, the stuff like the elbows you can't get elsewhere.
I'm not sure the lineage of your battery, but the OEM battery in the 330i was a white regular, flooded-cell, lead-acid battery, not an AGM. Whoever installed the replacement battery after the original one that came with the car from the factory, seems to not know what they were doing. I'd suspect the IBS is damaged (it is easily damaged) and that is what is causing your battery problems.
Attached is the TIS battery replacement procedure.
Hope all this helps. You can't order from real OEM.com but you can find all the part numbers and then order the parts on line. I use getBMWparts.com because they are a large stocking dealer and usually have most everything in stock or two-days shipment from BMW USA. Just get all the parts from them, or at least use all BMW OEM parts, the prices or not unreasonable.