e220d Cabriolet (2015) Auxiliary Battery Malfunction

[peterould]

Hi all,

I get the above message appearing sporadically on my vehicle (once a fortnight if that). When it appears the normal start / stop battery on braking doesn't work. I understand the auxiliary battery to be a second capacitor in the boot and this is probably due to a lower charge than normal and it usually happens when I've been doing a lot of town driving.

As the garage has just agreed that both batteries are fine charging normally and that the terminals are all fine, is there anything else I should check? Can I ignore this if it's just occasional?

 

[malcolm E53 AMG]

I would buy a CTEK charger if you are doing a lot of short runs and if you get the warning sign plug it in and top the main battery up - if the main battery is the original it’s probably stating to fail at 7/8 years old. If you have a multimeter you can check the health of battery it should be 12.6V fully charged. I do a lot of short runs nowadays and probably top up the battery every three months or so with a CTEK

 

[peterould]

I would buy a CTEK charger if you are doing a lot of short runs and if you get the warning sign plug it in and top the main battery up - if the main battery is the original it’s probably stating to fail at 7/8 years old. If you have a multimeter you can check the health of battery it should be 12.6V fully charged. I do a lot of short runs nowadays and probably top up the battery every three months or so with a CTEK

Apologies for not replying earlier - the email went to spam

The main battery is only around 18 months old and healthy. I think a separate battery charger is a great idea.