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I have a 2018 C Class 220d AMG Line Estate and owned it for approx 8 weeks. The Start/Stop facility has never worked. In at the dealer today they say the battery is low causing the malfunction. I have covered 1600 miles with the car and total mileage is 6500. Many of my trips have been distant and on M/way I would have thought that would have been sufficient to fully charge. My guess is that the battery is not accepting full charge or alternator is not delivering sufficient charge. Vehicle starts immediately with no issues. Anyone had a similar issue?
Hi, from what I have read in the thread below the start/stop function is powered by the auxiliary battery (located under the dash) which is actually voltage capacitors that are separate from the main battery. The thread describes the system and others with the "auxiliary battery malfunction" issue list the dealership's solutions:
Hi Plutoe, Thanks for your advice - The issue is that the workshop is concentrating on charging the main battery and not mentioned the auxiliary. I am more than happy to offer them suggestions. I already proved that my trips were more than enough to fully charge the main battery. Thanks again for your info. Cheers
Thanks for the information Ron. That is very helpful, I am better equipped to talk to the service dept at the dealership. They are taking the car back in 11 November
That's weird, even when it's cold the eco start will kick in after only a few miles
its all controlled by a harness connected to the negative battery terminal, if that is unplugged it won't work and the Green "A" on the dash won't come on
Very rare that it works on mine, sometimes if I turn the a/c off it will work. Works more often in summer, sometimes I've got to do 60 miles for it to work.
I had the intermittent start/stop pb with my C200. It’s a 2105 and has done 4000 miles/yr average. The car is still under warranty as I only recently bought it under Approved Used programme. It just went for its service. Merc originally told me they would not replace the main battery even thought they found it defective, citing under usage. I complained and they then (fortunately) changed it under Warranty. It’s now all working fine. However even the battery manufacturer VARTA who I called say cars have to do 10k miles/yr to keep a battery in good order. Low mileage they say causes sulphurication of the plates and over a short time the battery will degrade. VARTA will not replace it under manufacturers warranty in such conditions. Net if you are a low mileage user, then a monthly check/connecting it to an external battery charger is required. They say when not in use the battery should be 12.6v. Anything less it needs a charge either by regular driving or a manual charge with an external charger. As start stop does drain batteries, I will charge mine externally every month. Either that or pay £350 for a new one!! Hope this helps.
I had the intermittent start/stop pb with my C200. It’s a 2105 and has done 4000 miles/yr average. The car is still under warranty as I only recently bought it under Approved Used programme. It just went for its service. Merc originally told me they would not replace the main battery even thought they found it defective, citing under usage. I complained and they then (fortunately) changed it under Warranty. It’s now all working fine. However even the battery manufacturer VARTA who I called say cars have to do 10k miles/yr to keep a battery in good order. Low mileage they say causes sulphurication of the plates and over a short time the battery will degrade. VARTA will not replace it under manufacturers warranty in such conditions. Net if you are a low mileage user, then a monthly check/connecting it to an external battery charger is required. They say when not in use the battery should be 12.6v. Anything less it needs a charge either by regular driving or a manual charge with an external charger. As start stop does drain batteries, I will charge mine externally every month. Either that or pay £350 for a new one!! Hope this helps.
Start/stop does not drain the main battery since the system does not use the main battery.
If you read my post above and the thread link in that post the start/stop system uses a separate power source which is called "auxiliary battery" and does not affect the main battery. The "auxiliary battery" is actually voltage regulator/capacitor (pictured above) which are charged when you drive through kinetic energy. You can see the "auxiliary battery" being charged when your display is set to: Range, Consumption, and Max Charge (Max Charge goes green when you are braking and is an indicator of the auxiliary battery getting charged.)
The start/stop system is disabled to protect the main battery when the voltage regulator/capacitor is malfunctioning and an "Auxiliary Battery Malfunction" warning is appears in the display. Other conditions will disable the system that are not related to a malfunction.
There seems to be quite a few defective voltage regulator/capacitors installed and I have read of a recall that was issued on some of them.
Last edited by Ron P Baker; Nov 4, 2019 at 10:30 AM.
Reason: clarity
If you read my note carefully I did not say the Start/Stop system drains the battery. But thank you for the clarification that its the kinetic energy that supplies the charge to the aux battery ie the capacitors. That's comforting to know all those school runs, constantly starting the car shouldn't be an issue. That said my point is that the start/stop green light coming on is a function of the main battery condition (correct me if I am wrong) ie if the battery has deteriorated, even though its ok to normally start the car, the start/stop green light will not turn green. Hence my comments about keeping the battery in tip/top condition if you are a low mileage user. Now that I have a new battery, the start/stop green light come on after a few miles....never did that before..which proves to me my point.
You could be correct Woodstore. Though there is scant detailed information about the system available there does seem to be some cases where the condition of the main battery will affect the start/stop system's availability. Mercedes has released only vague descriptions about how the system works and it leads to confusion on a system that owners have a lot of questions about, particularly when the system is leading owners to require service.
I've research it but I'm still unsure of a lot. I suppose the only ones who definitively know are Mercedes tech's with access to the internal information. Cheers.
My Start/Stop stopped working like 6 months ago, my C class is from 2016.
Dealer told me the main battery need replacement. I didn't replaced at that moment, and few month later a warning message started to show up in the main cluster gauges, was something like "stop car, don't turn engine off"
After checking the "engineering mode" the battery level was like 60 or 70 max, and in one night will go from 70 to 60.
I replaced the main battery and Start/stop started working as usual, and battery level is now more than 80.
Bought my 2015 C300 with 43K mi in February this year the auto start/stop never worked and my auto wipers never worked either. In July my battery gave up the ghost got the stop the car message. Bought a new battery and Bam Auto stop/start worked and so did the auto wipers. But honestly I hate the Auto Start/Stop and turn it off every time I drive! Wish it would stay off!
I had my main battery warrantied last week because eco stop/start stopped working a month ago.
They said main battery needs to be 80%+ charged for eco function to work. Asked them to check the aux battery for eco but they said it's working fine.
Thanks for this. None of the Mercedes information I found or owner posts that I read mentioned that the start/stop would be disabled if main battery falls below 80% charge. Very interesting.
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ECO Start/Stop
