Orange battery symbol

[S500 Pete]

Hi all, I hope everybody on here is well.

I have a yellow battery symbol with the wording "Start Engine refer to user manual" coming up when I get in the car (W222 S500). When I start up it goes away.

I can't find anymore detail in the owners manual or searching on line

The car has only had very occasional use for a few months because I have been away and my son just took it out every couple of weeks to keep it going. Even before that the stop start didn't work so I am thinking that the battery may be below a recommended level. However, in the last couple of days it has had a few short runs (5 miles or so) and the message is still coming up.

I have put it on charge using the underbonnet terminals to see if that helps.

Any ideas?

 

[Chrishazle]

Give it a full overnight charge of the main battery if a twin battery system, your battery is low and needs a good maintenance charge.

 

[S500 Pete]

Give it a full overnight charge of the main battery if a twin battery system, your battery is low and needs a good maintenance charge.

Thanks, Trying a charge using a CTEC set to AGM and restore. Only problem is the car is outside and I can't shut the bonnet properly with the charger clips on the terminals. I will leave it on till later and then decide whether to chance leaving it with the bonnet open overnight.

 

[Tony Dyson]

DON'T USE RESTORE WITH THE BATTERY CONNECTED TO THE CAR!

DID YOU READ THE OM WHICH CAME WITH YOUR CHARGER?

 

[S500 Pete]

DON'T USE RESTORE WITH THE BATTERY CONNECTED TO THE CAR!

DID YOU READ THE OM WHICH CAME WITH YOUR CHARGER?

Nope, I will go and check now.

 

[S500 Pete]

Hi,

Just checked again (I only read the manual once when I bought the charger) it doesn't mention not using recond with the battery connected. What would be the problem?

At the moment it is still on stage 3 "Bulk" so a while to go until it gets to stage 6 "Recond" This puts it on to 15.8V for 2-6 hours. It has already pushed 15.8V in stage 1"Desulphation".

 

[Tony Dyson]

It's the high voltages you need to avoid as if the charger is car connected you will be applying the excess voltage directly onto the car's Control Modules SAM's,

and other sensitive equipment, disconnect the -ve link from the battery to the car body, this will interrupt the supply to the car's electronic components. there will be a statement in the OM somewhere.
​

 

[S500 Pete]

It's the high voltages you need to avoid as if the charger is car connected you will be applying the excess voltage directly onto the car's Control Modules SAM's,

and other sensitive equipment, disconnect the -ve link from the battery to the car body, this will interrupt the supply to the car's electronic components. there will be a statement in the OM somewhere.
​

Thanks Tony, Looking at the sequence it has already been at 15.8V in the start stage so I am thinking that if it is going to hurt anything it has already done it. I have used this charger on my wifes GL250 while it was in the garage for 2 months but rather than let it run continuously I had it on a timer for 30 minutes a day which would have been doing the start up 15.8V each time. It didn't seem to do it any harm so I am going to chance letting it carry on.

I am connected to the terminals under the bonnet to make sure I do both batteries so cant really disconnect.

I think it might actually be the aux battery because the stop start hasn't worked for quite a while. Problem at the moment is getting it checked. My OBD reader just sees 3 codes that I can't find on any lists.

 

[S500 Pete]

Going to reset it not to do Recond, just in case. Wishing I had a good old fashioned charger that just showed how many amps it was taking.

 

[malcolm E53 AMG]

Does sound as if the battery is goosed the battery should read 12.6V engine off, first signs of a failing battery is generally no Stop/Start availability. I replaced mine last year and used the Tanya website they generally have the best price on Varta/Bosch with next day delivery and I always give the battery a few hours top-up before fitting. Since fitted the new battery Stop/Start availability is within 2 miles of start-up not that I use it but it is a good battery condition indicator lol

 

[alexanderfoti]

It just means that the main battery needs a charge or the batt voltage will be too low to start the car. Wack it on charge, as you have done, or take it for a long drive

 

[Tony Dyson]

Going to reset it not to do Recond, just in case. Wishing I had a good old fashioned charger that just showed how many amps it was taking.

Best plan, never put anything more than 14.8v onto a car connected battery, with a bit of luck there will be no damage, here's hoping.

 

[alexanderfoti]

Best plan, never put anything more than 14.8v onto a car connected battery, with a bit of luck there will be no damage, here's hoping.

I'm sure it will be fine. We have had cars with faulty alt regulators pumping 18v into the system. A lot them shutdown with an overvoltage code.

 

[S500 Pete]

Thanks Alex

 

[S500 Pete]

Been on since yesterday morning and not got beyond stage 3 which is the bulk charge so I reckon the battery is on its way out. I am going to start looking for one at a sensible price that I can get delivered. Will look at the Tanya site and tomorrow will phone Mercedes at Grangemouth. I just hope that it is the main battery not the little pack behind the dashboard.

 

[alexanderfoti]

Been on since yesterday morning and not got beyond stage 3 which is the bulk charge so I reckon the battery is on its way out. I am going to start looking for one at a sensible price that I can get delivered. Will look at the Tanya site and tomorrow will phone Mercedes at Grangemouth. I just hope that it is the main battery not the little pack behind the dashboard.

It's a 100+ah battery, so a small charger with loosses will take 15+ hours to fully charge. I wouldn't write it off just yet

 

[S500 Pete]

Thanks Alex,
I have left it on charge for now so see how it goes, not going anywhere at the moment anyway and have my wife's car if I do need to.

 

[Tony Dyson]

After your charger has completed it's current charge cycle, then run a de-sulph and repair cycle making sure you have disconnected the -ve link from the battery to the car body and see what battery charge you end up with then.

 

[Blobcat]

Is it an AGM battery? I had a 2018 Mercedes AGM battery that wouldn’t hold a charge. Took the cell caps off (bit difficult as under stickers and need to use a hammer and punch to get them to turn to un-do) and all were low on electrolyte.
Topped up and charge came back almost instantaneously

 

[S500 Pete]

Thanks for all the tips and ideas. Checking the battery it is the original 2014 Mercedes one. I have decided to replace it regardless as I hate the idea of it letting me down when I know it is probably past it's best.
Interesting that most suppliers suggested an 019 battery which is 90 Ah and 353mm long The one in the car is an 020, 105Ah and £60 dearer.
I have gone for the 020 from Tanya at just under £200, ouch.

Be well everybody.