I just changed my battery and I wondered the same thing. Two vents and only one used, so I'll try to find a plug (or put duct tape )
Originally Posted by MP3_E46
Verify there is a plug in the vent on the other side if the battery. Autozone gave me one that fits in there when I returned to ask about it. Bit of a pain to push in with an already installed battery though.
I tried to register it myself with my laptop, software and k-line cable but it didn't work. The battery has a replacement warranty of 3 yrs. So I'll leave it unregistered.
2007 E90 AW 323i Step | Lowered 1.25"/1" | BMW Performance Exhaust | PBX | Debadged | Scangauge II | Style 162 18" & 161 17" wheels & rear 15mm spacers