Millsy2.0

Good day folks. I am at a loss for this problem with my 2012 R350 Bluetec...
On December 28th I had an oil change done and they washed the car
It was super cold approx -20C
On December 29th I went out in the morning. Keyless didn't work, opened the car with the metal key, went to start and nothing.
On December 31st I bought jumper cables, followed the jump procedure from the manual and wahoo all was great drove around, did errands, with multiple stops that involved turning off the engine and restarting.
On January 1st - dead again in the morning. Frustrated I left it and searched for a replacement battery
Left car in the driveway for the week (still super cold -20 to -30) and on Friday the 5th bought new battery
Replaced the battery (super easy) and boom car started like a dream, ran around all day again, no problems
Next morning Dead again - jump start, drive around, good highway run and left in a heated garage for about 6 hours - car restarted no problem
Next morning dead again
Would really appreciate some help here. I have heard there may be a 2nd battery somewhere but Google isn't very helpful for the 2012 model year.
Any insight you can provide would be great!
Thanks

slawek

check if one of the memory buttons on your front seat is not stock or push and see if your seat move in all directions.You have a power drainage somewhere in system ,usually is your amplifier, radio, automatic lack or front driver seat.

efzauner

Sam module draining the battery..... go to dealer. to fix. have to connect to Star to check it out. Had same problem on my 2008. Died in our garage over xmas holidays just a few days. Dealer replaced battery. Then I could not start at airport parking 1 am. -30C Dealer then changed a rear SAM module.. problem fixed. Luckily all under extended warranty...

testknight

id consider alternator as well. most auto parts stores will check it free although they may need to charge up your battery first.

R350NYC

I read there were some people who had this issue on an M class and it was the result of the satellite module going bad and failing to turn off. Try removing the fuses associated with this in the trunk (search for the R350 fuse map and disconnect anything relating to the radio/dvd/satellite for the night). If in the morning, your battery is still dead, then its another issue.

r320

I had a rear hatch door the latch was sticking when it got really cold and would put the rear interior lights on and off. It would occasionally trigger the alarm which is how I figured it out. Some contact cleaner and spray oil fixed the problem.

Easy way to figure out the draw with a test light. remove the postive cable from the battery put the test light in line with the battery if the test light is on there is a draw, remove fuses until the light turns off to figure out which circuit is causing the problem.