jansa

I disassembled most of the cabin filter area, can't find the aux battery. Even- though I bought the part from the dealer, and I assume I have one, but where it is located then??? Checked also under air filter under the hood. Any input is welcomed.

Figuero

I have never heard of an Aux battery in the W210.

jansa

I thought when you get red error message - battery icon + charge it meant aux battery. Part department just sold it to me knowing my car year and model?

ejsheltra

The only battery you have is under the right side passenger rear seat. It is black gel for heavy duty or standard if not many options. They last 4-7 years for standard and 5-9 for the gel. The gel is around $200 US from the dealer. Batteries must carry full charge for motor to turn over AND start.