E220d stop start not working and state of battery?




I bought a battery health tester today and the figures for the 80Ah 800A original battery were: CCA 650, SoH 66, SoC 61 and v 12.37. Outside temp is currently about +5c and the car has been driven about 75km today. The battery is the original (week 37/18) and the car has done about 125k km.
Do these figures point to a battery problem, or a charging problem? There are no fault codes being picked up by my fault code reader?
Help!
I always thought the function was fairly useless. If I just barely stop as I'm pulling into a parking space, the car would shut off. If I was stopped at a traffic light for more than a minute, the car would start up again. I really don't think it's saving the planet.




V - 12.13v (was 12.37
CC - 660 (was 650)
SoH - 71% (was 66)
SoC - 13% (was 61)
Very confused - WTAF?









I bought a battery health tester today and the figures for the 80Ah 800A original battery were: CCA 650, SoH 66, SoC 61 and v 12.37. Outside temp is currently about +5c and the car has been driven about 75km today. The battery is the original (week 37/18) and the car has done about 125k km.
Do these figures point to a battery problem, or a charging problem? There are no fault codes being picked up by my fault code reader?
Help!
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Plus I understand it’s best to replace the voltage regulator (aux battery) along with the main battery. I don’t really look forward to replacing the voltage regulator as it’s in an awkward spot in the pass footwell and a lot of stuff needs to be removed. With this issue of auto start/stop not working I’d think it’s more than likely the aux battery (voltage regulator) and not the main.
I do notice though when I charge the main battery with my battery tender everything works fine for a while. I’d think charging the main battery also charges the Aux. must be a capacitor or two is bad in the aux? Kinda seems like under engineering to me I’m surprised I got 4.5 years out of it. Plus for a maintenance item like the aux you’d think it would be in a more accessible location.
Last edited by 2012 merc amg; Feb 7, 2023 at 10:34 PM.
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Spoke to some technical people at work today who know about these things, they are 99% sure that one of the cells is breaking down, hence the random readings and that the Alternator is doing most of the work. Clearly all is not well so I will bite the bullet and get a new battery (about €150 delivered here in Germany but not a “Mercedes” one)… I’ll let you know how I get on.
You don't need to replace the capacitors with a battery change.




Job Done



