KSWitwer

I am installing a hitch on my 2013 GLK 350 and need to connect the power wire for the power module (protects the vehicle wiring from a bad or incorrectly wired trailer) to the battery. I was looking for a good way to route this wire up to the front batter and in the process discovered the auxiliary battery in the back, near the spare tire. Also noticed the small battery is fed from a relay of some sort that appears to have a connection from the front battery as well as the connection to the rear battery. The relay seems to act like a switch allowing the alternator to feed the aux battery, as needed.
My two questions are 1) is it okay to use this small battery for my trailer lighting module power, and 2) recommend connecting to the battery connection on the relay or on the front battery/alternator connection?

Thanks everyone.
KSWitwer

dbldpr

Welcome hopefully someone will know

Rocman8

that auxiliary battery is a buffer battery for the stop/start function. i would try to hook up somewhere else. there are plenty of empty slots in the rear sam fuse box right there.

KSWitwer

Thanks for the feedback Rocman8 and for the Welcome note dbldpr.

MJ50

moved to X204 forum...

fabbrisd1

Yes - proper power connection is to the front/main battery - frankly that is the labor intensie part of the install - once done, you are "goog".

bradsh

I cannot imagine why this would matter. My understanding is that the aux battery is connected to the main battery whenever the vehicle is running. I actually wonder if you could get away with hooking up a subwoofer amp to it as well. Of course, there is that handy relay electrical hub nearby as well.