Last night I finally got around to replacing (upgrading) my supercharger serpentine belt with a new Fleetrunner Gates K080505HD V-Belt belt. It's about 1/2" shorter than the stock belt to better match up with the smaller supercharger pulley. Took all of 5 minutes by using the 17mm wrench, loosening the belt tensioner, and swapping the belt. I can't believe the garage charges $120 to do this!
Here's a quick little video of my new HULK colored belt ;)
If you get this belt on Amazon - it's over 1/2 price of what most stores sell it locally for. Unbelievable!
Several models of Mercedes have a 2nd battery - often referred to as the Auxiliary Battery. It's hidden in the E55 under the cabin air filter in the engine bay.
FYI - The primary battery is in the trunk :)
I was informed of a fantastic deal on the aux battery on Amazon - 50% off!
Installation was a total breeze, the bolt/washer setup is different from the OEM setup, but now there are no issues with my electronic brakes and/or other 12V items in the car :) Highly recommend this battery - save yourself about $200 in the process!