Hello, my 2013 CLS550 has the auxiliary battery malfunction, but it seems like there are 2 different types of auxiliary batteries. How do I know which is the one I have to change?
https://mbparts.mbusa.com/oem-parts/...Y4LWdhcw%3D%3D
https://mbparts.mbusa.com/oem-parts/...Y4LWdhcw%3D%3D
These are the 2 options on Mercedes parts website. Thanks
https://mbparts.mbusa.com/v-2013-mer...rical--battery

Your battery should be located under the driver side dash. Look it up on YouTube for instructions. You can replace it with a motorcycle battery, so take it out and go to a Battery's Plus if there is one near you. You're talking under $30 instead of the insane numbers wanted by MB. It needs to be AGM, Sealed, and have the correct amp hour ratings and you can use the extra money for other goodies on your car.

You can buy it on Amazon as well. It's a tight fit, I still haven't been able to get mine in, I'll probably have to go to the stealer to have it installed.