W207 - 2012 E250cdi Eco Start Stop not working

Botus

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Chap at work says his start stop stopped a while back. He only does long journeys and 6 months ago replaced the main start stop battery. Merc dealer now says the "motorcycle battery" in the back is US and a new one will fix the eco stuck on yellow (not green)

a small receipt type thing on the 100 quid invoice for diagnosis, shows a print out saying the battery should be 170EN. It is in current state low on volts, at 12.3 and the battery's only putting out 71EN

so what is an EN?
why would the baby battery be any part of stop start, and does anyone have any experience of this cure or usual suspect for the fault?

I was a bit disappointed at the XENTRY diagnosis / software print out. Looks to have every module listed but isn't as clear or informative as the one I got. It lists many modules, I'd guess over 35 with hardware and software versions, but the dates are unfathomable listing nearly every module as having 3 hardware versions and 3 or 4 software versions.. I thought it might mean its listing each software variant its had on the car, but I don't think so. Its seems to me more like a random list of junk. All it really shows is a big tick on all the modules with the exception of an air vent "mechanical issue" one side on the AC.
 
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Uncle Benz

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The small battery is the usual reason for stop/start to stop working. I replace hundreds of them. Very occasionally the little black box next to it, split charge relay thing, is dodgy, but I think I've only changed three of those.
 

John Laidlaw

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My stop start battery in the boot went us when the car was 3 years old, not unsurprised at all
 
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Botus

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thanks guys
 
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Botus

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thought I'd give an update, owner was quoted 300 to diagnose and replace bike battery in the boot.

he bought one from euro carparts for 65, fitted himself, couldn't be bothered to charge it up, did one 30 mile journey, switched AC on off Car on off.... stop start works as it used to
 


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