Intermittent start/stop issue

Paul555

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Hello, looking for some technical advice.
I've a 2015 E250 Diesel and I began to have a "aux battery malfunction" show up, so I replaced it with a new battery the shop recommended (not a genuine MB type but same spec). Now all the options work ie. Hold brake, parking available indicator, including the start/stop function. But the start/stop function doesn't always work and when it does it goes back to yellow from green after one time but it never shows malfunction, WHY?
The battery was fully charged after buying it, could it be a loose connection??

Thanks in advance
 

AMGeed

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Welcome to the forum Paul :)
The car has to meet many variables before the stop/start function works.

Off the top of my head, the oil and water have to be at optimum temperature (at least a 4 mile drive in my car), the a/c off and the car in Comfort mode. If you have a Sport mode setting on the transmission, stop start won't work if its selected. A slight drop in voltage in the aux battery will disable the stop/start until recharged by driving.
 

sonic

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As above keep driving it & the battery charged, I am sure that will restore it.
 

MBDevotee

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Dreaming of a CL55k - one day maybe....
Do you use a lot?

If it’s getting a lot of daily use fine, but occasional use means it takes a while to get battery back up to 95% + charge or whatever Mercs threshold is.....
 

Tony Dyson

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It also needs BOTH batteries to be in peak condition to work well, target voltages are 12.6v without the engine running and a max of around 14.8v with.
 

TheBlimp75

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As above and I’m pretty sure external temperature has a factor aswell so with the low temperatures we are experiencing at the moment that may well be affecting it aswell.


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Paul555

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Welcome to the forum Paul :)
The car has to meet many variables before the stop/start function works.

Off the top of my head, the oil and water have to be at optimum temperature (at least a 4 mile drive in my car), the a/c off and the car in Comfort mode. If you have a Sport mode setting on the transmission, stop start won't work if its selected. A slight drop in voltage in the aux battery will disable the stop/start until recharged by driving.
Thanks for your quick response AMGeed, it used to work for the old battery after 5 mins or so and that was with AC on, but I'll try again with AC off hopefully it'll help. It can take 30+ mins before the eco symbol turns green now but may go off after one stop.
 
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Paul555

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Do you use a lot?

If it’s getting a lot of daily use fine, but occasional use means it takes a while to get battery back up to 95% + charge or whatever Mercs threshold is.....
Hey MBDevotee thanks for your help, no I don't use it much really but I did charge the battery all night then drove 30ish km before going healthy and then unhealthy after one stop
 
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Paul555

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It also needs BOTH batteries to be in peak condition to work well, target voltages are 12.6v without the engine running and a max of around 14.8v with.
Thanks Tony, I know the aux is fully charged but I may give the main a quick spruce tomorrow see if it makes a difference. I almost never use the stop start( I don't think it's good for an engine) just don't want something that's not quite right
 
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Paul555

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As above and I’m pretty sure external temperature has a factor aswell so with the low temperatures we are experiencing at the moment that may well be affecting it aswell.


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Thanks blimp, I'll look into this, I don't want to be wasting my time trying to fix something not broke
 

Srdl

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Mine works with Aircon on. But, for the last few weeks it hasn’t turned green - cold weather and very limited “essential” short trips. Batteries are only two years old.
 

MBDevotee

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Dreaming of a CL55k - one day maybe....
I think it won’t work as much when the weather is this cold.

Also, stop start doesn’t hurt engines - the starter generators are totally different to the old style pre-engaged starters, and it on,y does it once hot and oil up round engine.

But yes, if you have 2 batteries they will both need to be full, and in this weather I think 30km (20 miles) would be needed to get it hot enough to start working.

So it may not be broke at all....
 

Tony Dyson

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Thanks Tony, I know the aux is fully charged but I may give the main a quick spruce tomorrow see if it makes a difference. I almost never use the stop start( I don't think it's good for an engine) just don't want something that's not quite right
I know exactly what you mean there, I find SS more annoying than not and usually disable it when I remember, but I do like to see the indicator turn green when first used from cold as it serves to me as an indicator of healthy battery conditions, I replaced both my batteries from original in Oct '19 and this winter from a cold start it takes only a few minutes 5-6 before the indicator turns green.
I think it won’t work as much when the weather is this cold.
Also, stop start doesn’t hurt engines - the starter generators are totally different to the old style pre-engaged starters, and it on,y does it once hot and oil up round engine.
But yes, if you have 2 batteries they will both need to be full, and in this weather I think 30km (20 miles) would be needed to get it hot enough to start working.
So it may not be broke at all....
I find that a very interesting statement @MBDevotee, I am of the understanding a potential weakness in an engine such as the OM651 was the simplex timing chain and associated guides/sprockets, so how does starting/restarting an engine, whether hot or cold, by the different methods have any changed impact on the simplex timing chain and associated gear?
 

ajlsl600

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I think it won’t work as much when the weather is this cold.

Also, stop start doesn’t hurt engines - the starter generators are totally different to the old style pre-engaged starters, and it on,y does it once hot and oil up round engine.

But yes, if you have 2 batteries they will both need to be full, and in this weather I think 30km (20 miles) would be needed to get it hot enough to start working.

So it may not be broke at all....

I dont share ur view on stop start not hurting engines. I disable mine at every start. Sure it stretches chains .damages chocolate cam sprockets premature wear of ring gear and starter.
 

brandwooddixon

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I'll admit that I turn mine off every chance that I get, but as mentioned I too like to see the light go green before I disable it.

Admittedly the start-stop feature places no strain on the starter motor and gear, but I'd still stand that the timing gear and other ancillaries get more wear. The timing chains and gear due to the initial impulse strain on start-up and any turbo-chargers on the lack of cooling oil flow at the first junction after a high speed motorway run.

I also can't help but wonder if the lack of flowing oil might contribute to emulsion forming in the rocker covers due to condensation if the car is used primarily for town journeys.

Oh and trying to manoeuvre whilst parking with it working really sets my teeth on edge.
 

ajlsl600

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A bit vocal but I think its generally correct.just stop start is xullshxx to baffle emissions guys.that costs makers dimes and us dollars..
 


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