Hey Guys I’m not sure which way to turn here, my dash keeps coming up with a low battery warning. I get that, as the stop start has stopped working so I guess the battery will need replacing. All the places I have googled tell me there are two batteries (like my wife’s E220). I cannot find an auxiliary battery anywhere on the car so do I only have one battery with the stop/start facility?
TIA

I think 2016-17 on moved to a capacitor instead of second battery. Easy way to know is remove the boot right side panel. If you see a battery then you have a second battery. If not you will see some large cabling going into the capacitor.

The second battery does not power the stop start system anyway, it is the main battery.

I fitted this about a year ago and really happy with it. Stop / Start works just fine and was the cheapest one Tayna sell and comes with a 4 year warranty.

https://www.tayna.co.uk/car-batteries/powerline/019agm/

Nick