Join Date: Nov 2013
Location: Jacksonville, FL
Many people, including myself, avoid this issue and purchase the relatively inexpensive Deltran Battery Tender charger. Deltran includes the necessary direct to battery 'pigtail' to plug in the charger with the standard SAE plug.
And, while the BMW manual states disconnecting the battery terminals, that is pure phooey as I, among others, of course have used these chargers on all BMW's with no concern for many years, and more likely the prohibition based upon the notion that there are some pretty 'dirty' chargers out there.
I currently have three Deltran Batter Tender chargers, charging three BMW cycles with CAN-bus technology with these chargers. I hedge my bets a bit by putting them on an inexpensive light timer so that they charge for only one hour per day.