Battery size

[jimbosxl]

Hi , just wondering what the recommended battery size (power) for a 2007 E280 (3.0L)
I can't find any mention of it in the manual.
A new 74Ah mercedes battery was installed by my local merc dealer 14 months ago
but its not holding the charge overnight and I have to run it every day to keep it up.
It was rested for a month recently and went as low as 3V. Nothing I can see is left on
to drain it. The garage is closed due to Virus. Thinking maybe the battery is faulty
and needs to be replaced, so would a more powerful one be better?
Thanks

 

[cheddar]

I would expect a bigger battery to be fitted as standard, I've not seen a V6 diesel model with anything less than an a 110 (80Ah), more normal is the 019 (90+Ah).
It does sound more like you have a battery drain though, best get that tested at auto electrics or mercedes specialist.
If there is an excessive battery drain, replacing the battery will only mask the symptoms for a while.

 

[Will]

74Ah does sound a little on the small side, but it shouldn’t be going flat overnight - certainly not at this time of year.

You say it’s been fitted for 14 months so I guess was working okay until recently sitting for a month?

Maybe give it a decent charge first of all (off the car if need be) and see how you get on, if it was specced snd supplied/fitted by MB it will be under warranty anyway

 

[Major774]

74Ah sounds a bit low for the W211 (2007 model) but it could be right based on the options ticked for your car, the parts department would have checked this.

Losing charge overnight points towards a battery drain matter.

 

[BlackC55]

Id buy a genuine MB one from your dealer. They are better and it will be exactly what your car should have. Ask for discount as the mark up is huge.