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Discussion Starter #1
My Eco Start/Stop stopped stopping back in January, and between then and March (when we were all asked to stay a home), I had been driving it quite regularly.
I just assumed it stopped working because the battery won't hold charges (my console display does not have the yellow/green color change feature). Today, I climbed down the passenger side and checked the aux battery with my multimeter, and to my surprise, it was at > 13V (which I assume is a pretty healthy number).
I guess what I want to find out is: is Eco Start/Stop supposed to work off the aux battery? If so, sounds like I have another problem. Is there any way to "reset" it and try out first before I bring it to the dealer for some expensive surprises? Anybody knows?
 

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What the main batt status - after overnight static?
 

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There is a myriad of conditions for eco to work — many sensor data points and both batteries’ states of charge
Sometimes i wonder how it manages to work at all with so many status requirements
Anyway if the aux seems (?) ok, then a main battery soc check after an overnight sit may be an indicator
The headache is when both batteries are fine
 

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Mine on my 45 didn't work for almost a year... No error message or anything.

That is just fine ;)😅
 

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another lucky one with the correct malfunction :p
 

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Discussion Starter #7
Thanks for all the replies - I let the main battery sit overnight, assuming my $10 multimeter is correct, it seems to be at 12.2V, I assume that's low? does anybody know? - the car starts fine always though...
 

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Thanks for all the replies - I let the main battery sit overnight, assuming my $10 multimeter is correct, it seems to be at 12.2V, I assume that's low? does anybody know? - the car starts fine always though...
Mine hasn’t worked for a year now. I don’t know if it’s the aux battery or the main battery, but I’m afraid to fix it. I don’t need Eco start/stop.
 

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Mine hasn’t worked for a year now. I don’t know if it’s the aux battery or the main battery, but I’m afraid to fix it. I don’t need Eco start/stop.
Leave it like that if you don't have an error message.
 

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Thanks for all the replies - I let the main battery sit overnight, assuming my $10 multimeter is correct, it seems to be at 12.2V, I assume that's low? does anybody know? - the car starts fine always though...
State of charge (soc) is a tad low
Typical moderate condition is 2.1v/cell or 12.6v
Might be cheaper (and functional in the long run) to try a ctek charger for a couple days
Worse case is the battery or something else is dying or faulty but you still have the charger for long term use
I learned the hard way (twice!) about trusting a low soc battery ... then sure enough one day it just drops to less than 10v
Just my 2 cents
 

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ps
Check for blown/frayed fuses
Main box in engine compartment next to battery
Secondary box in passenger footwell behind upper carpet section
 

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Discussion Starter #12
jmc:

Thanks so much for all the advises - I climbed down the passenger side in the first place to check the fuses.. the little fuse diagram was alittle disorienting but to me, all looked ok (showed readings on my little multimeter)... as to a ctek charger.. I have never even heard of such a thing, I guess it is time for me to do some research.
 

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i have migrated to the ctek mxs5.0 for my cars
decent unit with thermal compensation and auto desulphate
cute little gadget
( suggestion: wait for engine compartment to cool down somewhat before charging )
though after a few charge cycles and if no bad fuses ... if the eco still acts up then gonna need to see what benz specific stored codes exist
will be a dealer service visit ... or a good independent benz shop
 

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i have migrated to the ctek mxs5.0 for my cars
decent unit with thermal compensation and auto desulphate
cute little gadget
( suggestion: wait for engine compartment to cool down somewhat before charging )
though after a few charge cycles and if no bad fuses ... if the eco still acts up then gonna need to see what benz specific stored codes exist
will be a dealer service visit ... or a good independent benz shop
CTEK MSX5.0 is a brilliant charger. I do a full Recon every year & then a normal charge after every car clean during the winter months. It does seem to make the Eco start/stop more consistent.
 

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Yes, very finicky. It seems to me that the battery has to be 100% charged for the Eco system to work consistently. Some of the models only seem to charge the battery whilst driving on the overrun, so you need a heck of a long drive to replenish a battery that hasn’t been driven much or has stood or has done short runs.
 

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Correct ... it seems to be an on demand charging algorithm, or when load is low like coasting and down slopes
Not a constant charge like the old days
 

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Correct ... it seems to be an on demand charging algorithm, or when load is low like coasting and down slopes
Not a constant charge like the old days
There is a huge load now on car electrical systems even when parked. If you are doing big mileages you would probably be ok, but I would still recommend a boost from a quality charger.
 

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typically 250~300mA after stabilization though thats still about 3.5wh
 

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Correct ... it seems to be an on demand charging algorithm, or when load is low like coasting and down slopes
Not a constant charge like the old days
There is a huge load now on car electrical systems even when parked. If you are doing big mileages you would probably be ok, but I would still recommend a boost from a quality charger.
typically 250~300mA after stabilization though thats still about 3.5wh
The Ctek msx5.0 is exactly what you would get if you ordered a charger from Mercedes/Bmw/Audi & Porsche in the UK albeit with a slight cosmetic difference look at a vastly inflated price
 
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