S204 Replace main battery

[Ted]

Yes. My stop/start Jeep had one from new. Stopped stop/starting after about 18 months and I replaced it with a newish ‘normal’ lead acid battery I had knocking around (same size, slightly increased capacity) after about three years when the voltage in the morning was getting too low for comfort.
This served me well including the stop/start until I sold the car at 7 1/2 years

 

[BlackC55]

Get a genuine one. They are not too expensive, fit first time and last.

 

[XFJagman]

If you have stop start/eco button the auxiliary battery may be faulty too if its the original one.
That would explain why the eco light isn't green.

In a 2017 E Class, is the auxiliary battery really a battery or just a voltage convertor? See ebay advert:

Pardon our interruption...

My E Class stop/start light has been amber since just after I took ownership of it, at 4 years old with its original battery. Funny thing is, it worked on its test drive but not once I bought it! The dealer told me it could be due to the number of things I am running, such as Sat Nav and Aircon. I think they sold me a car with a duff battery.

 

[OneForTheRoad]

In a 2017 E Class, is the auxiliary battery really a battery or just a voltage convertor? See ebay advert:

Pardon our interruption...

My E Class stop/start light has been amber since just after I took ownership of it, at 4 years old with its original battery. Funny thing is, it worked on its test drive but not once I bought it! The dealer told me it could be due to the number of things I am running, such as Sat Nav and Aircon. I think they sold me a car with a duff battery.

My 17 reg coupe was a battery in the boot.