mellonc

My automatic stop/start decided to stop working. I tried to turn the eco button on/off. but nothing works. (10 minute drive or 1 hour drive - don't seem to make a difference). Is there something in the setting that I'm missing?

LILBENZ230

You probably have a weak main battery. When the battery is weak the start/stop not functioning is one of the first signs. Happened to me and many others here.

DFWdude

Discussed a million times here. ECO Stop/Start is among the first features to be dropped as priority when your main battery is low on charge. Recharge your battery and it should come back. And do a search for other threads on this topic.

cetialpha5

I thought it was a dying aux battery that did that. Check that also and charge it up although many end up getting replaced as they go bad faster than the main battery.

DFWdude

In my experience, nope. My dealer replaced my main battery under warranty, and ECO Stop/Start returned instantly. I even asked the service tech which battery, and he said the main battery.

ygmn

Consider yourself LUCKY... I think majority hate that feature of ECO STOP/START at red lights etc.

DFWdude

But it is proving helpful at predicting the state of charge in the battery.

kajtek1

I love the feature since we spend quite some time at red lights.
System has about 6 parameters that need to be meet for it to work.
When battery low charge is mostly the case, your guess is as good as mine. Hook up the scanner.

mellonc

You people are super helpful. I’ll check the battery.

BTW. I Like this feature on my car cuz I don’t have to listen to the diesel clatter when stopped. On a gasoline car, I can imagine it being annoying...

mellonc

Replaced the battery today. And, yes. The feature is working again. I don’t have to listen to the diesel drone at traffic lights anymore.

JamalD

I called the parts department at my local Benz dealership and they said the $290 aux battery (voltage converter) was the culprit for my auto start/stop not working. I bought the part and it didn’t solve the issue

I went to my local PartSource and they tested my battery for free and out of 800 CCA I was getting 468 CCA, voltage was around 12.6 V. Clearly the battery was not the strongest although I’ve never had problems with cold starts.

I changed the battery to the Interstate 760 CCA H6 AGM (48 series). It was a little smaller than the stock battery which had me worried, but worked perfectly. Auto start/stop was working within minutes.

KEY08

Weak Main battery is always the reason for ESS not working. That tech was wrong

Macawlover70

are you guys talking about the car battery itself or is there a separate battery for the start stop function. New Benz owner and completely ignorant do excuse stupid questions.

kajtek1

ECO stop has mid-sized aux battery in the trunk to help during engine stops. It started in 2014 for US models.
Previous models without ECO have small battery in dash for emergency gear shifting.

DFWdude

So, let's not confuse anyone. The Aux battery "helps" to maintain electrical continuity to ACCESSORIES during ECO Stop when the car is off. It is not responsible for executing ECO Stop/Start. The main battery is used for ECO Stop/Start.

See post 11 (below) for confirmation of this. It appears that dealers misunderstand AUX battery function as much as we owners.

kajtek1

I have never seen MB publication explaining clearly what aux battery in ECO system does. ECO restart is done by ignition and starter is only directional help.
Forum experience says aux keeps the the voltage for lights, when main battery cranks the engine, so you don't have dimming lights,
One of the batteries also powers electric pump that keeps pressure in ATF system.
Frankly I am not eager to investigate. Why would I?
Point is that like I posted above, there are several parameters that need to be meet for ECO to do the stop.
Both batteries are on the list.

Macawlover70

Is there a min outside temp?

Left Coast Geek

the aux battery also powers the electronics when the engine is starting. starter motors can drag the system voltage down to like 9 or 10 volts, and stereos, computers don't like that at all, so they are switched over to the aux battery when the main battery is running the starter motor. older cars would just shut the stereo and lights and stuff off when you cranked the motor, but that would be ugly with the COMAND system, having it have to boot back up, relink to your media, figure out what it was doing and resume, meanwhile reload the navigation, etc etc.

Macawlover70

When replacing main battery Must or should it be a Mercedes brand or is an equivalent battery of another brand adequate ? Say Die Hard etc with same specifications?

Left Coast Geek

any decent brand AGM battery with adequate CCA (I think its 760 CCA) and size H6 for gas cars or H8 for diesel . I like Deka/East Penn's Intimidator AGM batteries, 9A48.

kajtek1

MB doesn't manufacture batteries.....
Mostly they put Varta batteries, who can be manufactured in several countries.
If you are in US, I found Costco the best for the batteries.
Just few months ago bought H8 battery for my GLE, what is common battery from E class to Sprinters.
Took my Solar tester with me.
The 1000 CA rated battery delivered 1600 CA, so it is very good start.
Costco also offers no-hassle warranty.
I tend to abuse it from time to time. When I see my replacement warranty is about to expire, I test my battery and when it it on the edge of parameters, I take it back to Costco for full refund. Nobody ever tested if the battery is really bad.

Macawlover70

Well shoot. Tested the batteries and they said the main was good and aux bad. Replaced aux and still doesn't work. Shows yellow in the dash. I read somewhere in the conditions for it to operate temp was one. I'm in Montana. Very cold. Any opinions or information about minimum/maximum outside temp conditions?

kajtek1

I don't think outside temp affect ECO, but my car clearly waits till engine reaches 60C before it will start working.
Than cabin comfort is a factor here, so maybe computer keeps the engine running till your cabin gets warm?
If you don't have scanner to read the values, you might try to set your cabin thermostat to low and see is ECO will start working.

Macawlover70

Eco started working after every warmed up. Yay. Thanks for all the replies. 😎

Left Coast Geek

yeah, eco also won't shut off the engine if the cabin is hot and the AC is working to bring it down. once the cabin is near the set temperature, then eco can do its thing.