2011 E550 Auxiliary battery location
 

Looking for the location of the Auxiliary Battery in a 2011 E550 sedan.

Don't know about this particular model but some newer Mercedes cars have it behind back seat, accessible by pulling out front-most trunk panel

It's mounted to the body on the left side of the dashboard behind the light switch. If I remember right, it's a pain in the butt to replace it.

I have a 2010 E550 4Matic and I can not find the auxiliary battery. Big battery is in front of the cab filter. Nothing in trunk and backseat does not come out.

I have both 2007 (soon for sale) and 2010. 2007 has a starting battery under the hood and a big accessories battery in the trunk on the right behind the seats (I believe it's like that for 2007-2009). The 2010 (and newer) has only one large battery under the hood for both starting and accessories, nothing in the trunk.

Auxiliary may mean different things to different people, if it powers the accessories, it's as above. If it is a small battery for configurations backup it could be behind the dash as described in another post above, but I have not looked for it.