Big red battery!

[idlerider]

When the weather's cold, my E350 shows the large red battery light on start-up. I use a smart trickle charger but that seems to make no difference. The car starts and runs OK although when this happens some things (seat heaters, rear screen heater, tailgate motor, etc.) don't work for the first mile or two. It's been doing this - but only in v cold weather - for a couple of years. I'm suspecting the auxiliary battery but before I pod out about £90, does anyone have better knowledge/experience about the likely cause?

 

[Wighty]

Are they original batteries , if so change both

 

[idlerider]

Are they original batteries , if so change both

Auxillary looks like - main isn't.

 

[Tony Dyson]

Test them, disconnect one of the Neg battery chassis links to ensure you don't gat any cross-battery influence and test the batteries first thing in the morning after they have rested overnight then reconnect the disconnected link, start the engine and test again, see what voltages you get then go from there!

 

[LostKiwi]

Put a meter on the batteries (engine off). If either are under 12.4v replace it.

 

[idlerider]

I'll be investigating all this once the wind and rain abates! Many thanks to all who responded.

 

[idlerider]

Put a meter on the batteries (engine off). If either are under 12.4v replace it.

You were right! Auxillary battery would only manage 11.1v after charge and dropped fast. Now changed - problem fixed.

 

[brandwooddixon]

Auxiliary batteries are a pain. It would be good if we could just replace them with a decent battery rather than a pocket sized thing that obviously isn't up to the job intended. Either that or the charging system that MB put in isn't up to it.