Auxiliary battery

[keith of kent]

Car is E350 Bluetech S212 estate 2015. The aux battery was replaced under MB warranty just inside the 3 years from new. The is now 7 years old, I replaced the main battery earlier this year, I now wonder how heathy the aux one is.
More to the point; where is it?The Adblue tank fills the space where by rights, a spare wheel ought to live.
If it's one of those small alarm/motorcycle type ones and not too expensive, I'd rather replace it than have the inconvienience of faliure

 

[geoffus]

If it fails then your stop start will not work, so more of a convenience I would say.

 

[keith of kent]

geoffus, I agree, I always turn it off straght away.
But where is the aux battery, or is this a secret only know to MB?!!!!!!!!!!!

 

[geoffus]

Yours may be a capacitor under the glove box if it’s not a motorcycle type battery in the boot,
Mines in the boot and it’s always been flat, doesn’t worry me at all.