M5 Expert (>4000)
Join Date: Jun 2003
Location: Rancho Palos Verdes, CA
Thanked 602 Times in 389 Posts
I have two BMWs on trickle chargers all the time ... used them for years. NO problems ... my M5 battery is 7 years old, and still strong. My 323is battery is old and good, as well.
Hook up the batteries to the under hood teminals. Then you can carefully run the power cable, and close the hood and lock it ... Under the hood is much easier than in the trunk.
If you have a LOW battery, charge it slowly for 12 hours, before trying to start. BMWs have a circuit that shuts OFF sensitive electronics (computer modules, for example) when the battery gets TOO LOW.
"The greatest obstacle to discovery is not ignorance; it is the illusion of knowledge."
- Daniel Boorstin