2011 S550 4MATIC CONSTANT DRAIN ON BATTERY

Thanks I'll give it a try

The S-Class is so loaded with electronics and safety features that are active 24/7.....its always a big drain on the battery. Get a 12V battery tender (you get it in all auto stores for 20-30 bucks), and hook it up to the terminals if the car will sit longer than a week or two. If you let the battery get drained below a certain charge too many times, you will kill it eventually. Take care.

In 2009 MB S550 eliminated trunk battery. Following years there is one large 12v starter battery under hood against passenger firewall. There is another small auxiliary 12v battery under driver side dash which assists in electronic gear shifting and transmission operation. MB sophisticated electronics require healthy batteries, alternator, sensors, fuses and SAM (single acquisition module). They all must be working properly and SAM must be programmed to vehicle. This will allow functionality buttons to work prevent premature battery draw. You would think MB would have these related problems solved. They do not.