Hello, This winter I've been driving my e34, so the 2003 330i has been sitting in the garage. The 330i starts fine, but the battery indicator remains on and I assume the amperage is low. When my e34 sits for long periods, I attach a Battery Tender trickle charger using alligator clips to the battery terminals and forget about it. I assume that's possible with the 330i, but I'm wondering if there's a simpler connection point than the battery terminals on this trunk mounted battery? Thanks
Indeed there is: Use the jump-start terminals in the engine bay. See this post for details. I was responding to an M Roadster owner but the E46 is the same.
Yup, I plug my Battery Tender into the under-hood terminal on my E46 M3 for winter storage. Works great. I can usually feed the cable up by the windshield edge of the hood so the hood will close even while connected.
My BMW OEM Battery Tender actually has a plug that goes into the cigarette lighter. It (the car) never "powers down" the outlet like I think some of newer cars do after a period of time.