I've seen this question asked and answered several times, but never the correct answer. I have stop/start, so have the larger aux battery. The QR code on the B pillar shows it to be located in the right rear of the luggage area (That's where my friends E350 wagon aux batt is). I'm pretty much down to sheet metal and no joy. Hope someone can help

Look under....that is where ours is in the GLS550. On my C it is in the dash, never need to replace it on either of my E's. But, if that was the GLS it would be under the stuff you see over there, and it is a wonky attachment thing with the nuts being removed towards the outside of the car.

Then I'll dig deeper, Thanks!

Nope. Not under or anywhere near those components. Hopefully someone with an E63 wagon will check in.

As i remember, it depends to your E63 spec.,
some of E63 wagons located on passenger side under carpet, and some located on the Right side of the spare wheel well..

(-;-ZAYED-;-)

Now I want to know - being as I have the E63 Wagon......

It's in the trunk, next to the subwoofer if I recall correctly. I can take a picture tonight.

Yup - like that!

Thanks, but please look at the pic I posted of the "trunk" area of my E63 S wagon (not sedan, not GLS). No battery there.

That is the image of a 2014 E63S...taken today. The GLS is further outboard to the exterior of the car and under the fuse and SAM.

My 2016 wagon had no battery there either!
I never had to service the auxiliary battery, I have no idea where it was :/

Could be here....

Nope - that's a 2019 - 213 chassis?

The picture shown is of a E63S wagon, I'm 95% sure.
Do you have "Eco" button up front? Start / Stop functionality? If not - maybe that's why?

Here is my 2016 wagon, it's under the felt cover (in the blue circle):


Here is Youtube video that may be helpful:

Try look under driver side underdash. There is where aux battety is on our 2016 e63s wagon.

For ref
https://mbworld.org/how-tos/a/merced...battery-389645

We dont know that, all we know is it is not where we expect it. It very well could be there because it is not where the rest of us have ours....for all we know it is on the moon and uses some mystic waves to charge your car.

Eeehm, I bet my left nut that is a 213 chassis.....

Look at the other YouTube video - for wagons with start/stop and the larger battery - it should be in the trunk. Some cars (I thought mainly without star/stop and the smaller aux battery) have it under the dash. The bigger battery doesn't fit there.
Assuming the OP has a S212, and it's a US spec car, and he has stop/start, I have no idea why there is no aux battery there. Weird.

My 2016 E63 wagon had stop/start and no extra battery in the trunk.

[QUOTE=Yakatak;8930559]I've seen this question asked and answered several times, but never the correct answer. I have stop/start, so have the larger aux battery. The QR code on the B pillar shows it to be located in the right rear of the luggage area (That's where my friends E350 wagon aux batt is). I'm pretty much down to sheet metal and no joy.
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Try look under driver side underdash. There is where aux battety is on our 2016 e63s wagon.

For ref
https://mbworld.org/how-tos/a/merced...battery-389645

Easiest repair I have done.

???\

Thanks to everyone for their suggestions. I still haven't looked under stuff on the passenger (right) side cockpit. I have start/stop so likely have the larger battery, (I got the battery from a MB dealer and they sent the large one). So...I doubt it will be under the dash, but will have to look. The only other variable I failed to mention originally is that this is a Canadian import. The search goes on. If I ever find it, I will post it here.