davidtan9955

Hi ,
Do we need to reprogram after replacing the auxillary battery on our W212?

S-Prihadi

Nope. AFAIK only BMW need programming when new battery in place. BMW got some sort of battery aging algorithm, related to its charging profile, which one need to reset if new battery in place.

davidtan9955

S-Prihadi

Okey David, you are welcome. Just make sure you do not leave the positive battery cable dangling and naked, do use plastic bag ( insulator ) of some sort to protect it from shorting to vehicle chassis/body.
Regardless that the aux battery relay is not engaged to starting battery...yet, such pre-caution is a must when changing battery on a car with 2 batteries.

dbldpr

If you ask the dealer he says they keep a charge on the cables to keep the info. They lie. It is only to make more money to justify what they charge for labor. I disconnect mine brought it into pep boys and drove back home and installed and nothing was lost. The warranty is longer than what the dealer offers and I saved $150 on labor. Took about 10 minutes total time to take out and put in.

happyeds

If you haven't made the change here's another tip. Use an empty plastic coke or water bottle cut off an inch or more of the top and when you disconnect the battery cables put the bottles over the cables. No chance of shorting anything out.

thefisch

Thanks for the tip. I normally just wrap a rag around it.