S-Class W222 - Problem With Start Stop Function

[Tahushi]

The main battery for my S-Class S350 (2014, Diesel, LWB) was showing low voltage and cranking Amps. The start stop function was also not working (the light wasn't turning green) So I put a new genuine Mercedes battery. The start stop function still does not work (not turning green). I read somewhere there could be an issue with Auxiliary Battery AKA Voltage Converter. There are no warnings or fault sings. Any thoughts

 

[Tonygw]

yup could be the aux battery, you might be better posting in the electronics or engine section of the forum for a better responce ;-)

 

[Tahushi]

thx

 

[219]

You may need to get codes read and possibly a stored fault cleared

 

[John]

It will be a proper battery on a 2014 rather than a voltage converter (which is a capacitor basically).

Not sure if same place on an S350 but on an S500 it is behind the right hand fuse box (you have to remove the boot carpet on the right to get to it).

Chances are it will have a problem also if your main battery was duff.

You usually get a message when it is though so strange you don't having replaced the main.

If you have a decent modern charger you could try charging it (I rigged up some additional wires from mine so I could charge it from the boot).

If not replace but you are supposed to replace aux and main at the same time anyway I understand.

 

[Tahushi]

It will be a proper battery on a 2014 rather than a voltage converter (which is a capacitor basically).

Not sure if same place on an S350 but on an S500 it is behind the right hand fuse box (you have to remove the boot carpet on the right to get to it).

Chances are it will have a problem also if your main battery was duff.

You usually get a message when it is though so strange you don't having replaced the main.

If you have a decent modern charger you could try charging it (I rigged up some additional wires from mine so I could charge it from the boot).

If not replace but you are supposed to replace aux and main at the same time anyway I understand.

I can't find enough info on the secondary battery regarding it's location and whether S350 has it. Last week I drove my car on the motorway for few hours and I noticed that the stop start sign has turned green for a little while but once I started driving in within town, it disappeared and now it doesn't turn green no matter how much car is used with in town. When it was working fine, it would turn green even using my car for a little while. My be I will take it to an indipenetent specialist to find the root cause not that I am missing much as I would turn it off most of the time.

 

[John]

I can't find enough info on the secondary battery regarding it's location and whether S350 has it. Last week I drove my car on the motorway for few hours and I noticed that the stop start sign has turned green for a little while but once I started driving in within town, it disappeared and now it doesn't turn green no matter how much car is used with in town. When it was working fine, it would turn green even using my car for a little while. My be I will take it to an indipenetent specialist to find the root cause not that I am missing much as I would turn it off most of the time.

I turn mine off these days.

It's a nice idea but on an S Class which draws 800 million gigawatts of power a second, when it is off it's whooping both the batteries.

I know it's clever enough to turn itself back on when a number of criteria are no longer met but even so.

Looks like it does have one even though they got the model nomenclature wrong:

My W222 Mercedes S-Class (S350 CDI)

 

[TomF]

I can't find enough info on the secondary battery regarding it's location and whether S350 has it. Last week I drove my car on the motorway for few hours and I noticed that the stop start sign has turned green for a little while but once I started driving in within town, it disappeared and now it doesn't turn green no matter how much car is used with in town. When it was working fine, it would turn green even using my car for a little while. My be I will take it to an indipenetent specialist to find the root cause not that I am missing much as I would turn it off most of the time.

After reading the electronic manual and speaking to a merc specialist I learnt that the indicator will go green only if a number of factors are right, ie outside temp, inside temp, what electrical items are running etc.
I had a new aux batt fitted (which takes care of stop/start) it didn't change the way stop start works. There doesn't seem to be much logic to it, one morning it will be green immediately and the next after a few miles lol

 

[TomF]

Hey tahushi, have you found the electronic function that puts the handbrake on while waiting at traffic lights etc...
When you brake to a standstill give the footbrake a short sharp stab, you'll see a 'hold' icon on the display. Just accelerate to set off again. Brill idea