Stop/start

[TomF]

Hello MB fans,
Anyone with more experience of the stop start advise me? I'm trying to work out the logic behind my stop start but there's no pattern so far. Some days the on screen icon is green on start up and others it stays yellow for up to 10 miles or so..
I'm trying to make sense of the manual which mentions battery charge, temp inside car, temp outside car??
I have a new aux battery.
Cheers all..

 

[markjay]

The performance of the ECO Start/Stop function is affected also by the condition of the main battery, not just the auxiliary battery. The logic behind it is that if the main battery isn't in top condition, the additional load of having to restart the engine more often could prove detrimental to the battery, hence why the Start/Stop function would not be allowed to work if the main battery isn't at top performance. The main battery may be perfectly serviceable otherwise, and continue to work fine for a number of months or even years, but it is no longer good enough for Start/Stop.

That said... as you correctly pointed-out, Start/Stop is affected by many variables, and MB are a bit vague on what's what. There is no hard rule here, or a metric you can use to measure the performance of the Start/Stop function, but I would say that if the ECO light is green more often than not, then it's probably OK and it's the best you can expect from the system.

You can scan the Stop/Start ECU for fault codes using STAR (or iCarsoft), just to be sure, though it is worth noting that not all Stop/Start faults register a fault code in the ECU - weak batteries, for one, do not show up on the scan, but will still stop Start/Stop from working.

On another note, Stop/Start puts additional load on the batteries (though the main battery is AGM so should in theory last just as long as a non-AGM battery would last in a non-Start/Stop car), and also the frequent starting places additional load on the timing chain so could lead to premature stretching (though unless the car covers very high mileage, this is unlikely to cause an issue), and for the reasons above many owners just switch it off.

 

[TomF]

Hmm I'm thinking switch it off. Its novel at the moment as I've never had it before. I'm already switching it off in heavy traffic where I move a few feet at a time continuously..
Thanks for your advice

 

[esscee]

Like many that have this function on their vehicle, I don't use it. As soon as engine is running I turn Comand on and stop/start off.

 

[Sweetooth]

My stop start doesn't work anymore the battery is 4+ yrs old. I don't miss it . I don't think it does much to improve the mpg.

 

[Dodipops]

Thing is nonsense, works when you don’t want it to and doesn’t work when you think it should.
I’ve got a Merc, Audi and a Kia and they’re all the same.

 

[OneForTheRoad]

Best thing to do if its there in the boot where the aux battery is , pull the 7.5 amp fuse from its holder . No more stop start ..

 

[markjay]

I have no issue with switching-off or disabling Stop/Start, but I wouldn't be happy if there was a feature in my that's faulty. If it failed... I'd repair it, and then switch it off.

 

[wongl]

According to the MB ECO Start/Stop documentation (posted on MBClub in another thread, it depends on several factors - too many to summarise here. However, I have found that in everyday use really only three factors affects the operations of the ECO Start/Stop in my R172 (which I have found is similar in my daugther's W246).

1. Engine coolant temperature - the temp gauge needs to be >60 degrees
2. The main and aux batteries need to be in good order and charged
3. The cabin temp must have reached the selected temp at least once after the car has been started

Assuming the batteries are in good order and charged, I often need to trigger ECO Start/Stop at the first set of traffic lights from my apartment by turning off the Air Con momentarily after the coolant temp has reached 60 degrees. This method always successfully trigger the ECO symbol to be lit on my dash with the ECO Start/Stop kicking in the next time I stop. If I don't disable the Air Con, I could drive all the way to work without the ECO symbol lighting up on my dash as the Air Con continues to work hard to lower the temp in my from an outside temp of circa 33 degrees to my selected cabin temp of 22 degrees.

 

[wongl]

1. Engine coolant temperature - the temp gauge needs to be >60 degrees
2. The main and aux batteries need to be in good order and charged
3. The cabin temp must have reached the selected temp at least once after the car has been started

P/S on my car, turning off the air con and back on before the coolant temp has reached 60 degrees will not trigger the ECO start/stop when the coolant temp reaches 60 degrees. I have to turn off the air con after the coolant temp reached 60 degrees to force trigger ECO start/stop.

So perhaps the logic programmed in my car appears to be 'cabin temp is reached AFTER coolant has reached 60 degrees'. But the official MB documentation on ECO start/stop simply state that 'cabin temp has been reached once' and did not state it has to be reached after coolant temp has reached operating temp. You may need to experiment in your car to figure out what logic has been programmed in your car.

 

[wongl]

I have no issue with switching-off or disabling Stop/Start, but I wouldn't be happy if there was a feature in my that's faulty. If it failed... I'd repair it, and then switch it off.

I think most people on this forum (although I understand it is not for everyone) are enthusiasts who like to maintain their cars working as the factory intended. Certainly it bothers me a lot when something in my car is not functioning as it should, even when it is something I may never use (the auto parking function for example).

It annoyed me that ECO start/stop didn't on the R172 when I purchased it, and budgeted £2000 to have it fixed during my decision to buy the R172. (The seller simply reported that the ECO Start/Stop never worked as expected and stopped working altogether months before he decided to sell.) Luckily for me it turned out to be the Aux Battery which cost only £120 from the one and only MB dealership chain in HK. With money left over from my budget, to ensure a trouble free motoring experience I also replaced the main battery with the largest Varta battery that would fit a R172. I now know exactly when the two batteries were replaced and the quality of these batteries (which I maintain by recharging then with a CTEK at least once a month).

It is my pride and joy and I enjoy tinkering with it to make sure every feature on the car is as it should be. Well, with the exception of the Smartop box - but since this integrates so brilliantly into the car and enhances the the car, I had to break a rule or two!

 

[ToeKnee]

The smart top box on the R231 SL has a function to turn off stop start, of course you can use the console switch to turn it back on again if you want it on for the trip!

 

[wongl]

The smart top box on the R231 SL has a function to turn off stop start, of course you can use the console switch to turn it back on again if you want it on for the trip!

The Smartop for the R172 'remembers' the last setting for ECO Start/Stop whenever the engine is started. As such it does not disable ECO Start/Stop but if the driver switches off ECO, the Smartop module will set ECO to off when the engine is restarted.