Battery Warning Display

[johned]

Evening all,
Jumped in my regularly used 2013 E Class S212 today and after about 30 seconds the warning below popped up.


I was on a bit of a mercy mission so had to ignore it and drive for about 8 miles. Car ran fine but message stayed up on display. When I've arrived at my destination I turned the car off, gave it a few minutes to totally shut down, started up again and checked for messages which came up blank, and 10 seconds later same warning came up. I checked the owners manual (print version and in-car version) both of which were about as much use as a chocolate fire guard. Main battery is only 2 years old. I'm going to throw a voltmeter over the battery in the morning to check the cold battery voltage then start the car to check it's charging but in the meantime does anyone know if this may be a main or auxilliary battery problem? If auxilliary can I still drive it until until I can get it to a garage on Monday? Cheers.

 

[mioba]

you are doing the right thing and yes.

 

[mattkh]

,,,,,,, I'm going to throw a voltmeter over the battery in the morning to check the cold battery voltage

Keep looking at the voltmeter as you crank. If it goes below 10v, charge the battery.
The alternator is 9 yrs old. Mileage...?

 

[johned]

Keep looking at the voltmeter as you crank. If it goes below 10v, charge the battery.
The alternator is 9 yrs old. Mileage...?

I've put a volt meter across both batteries cold this cold morning. Both are showing a healthy 12 to 12.5v so they are obviously charging. I noticed that as soon as the error message comes up on the dash the stop start function switches off and can't be switched on again so I'm assuming the problem, if it is a real problem, as with the auxilliary battery?

 

[EmilysDad]

I've put a volt meter across both batteries cold this cold morning. Both are showing a healthy 12 to 12.5v so they are obviously charging. I noticed that as soon as the error message comes up on the dash the stop start function switches off and can't be switched on again so I'm assuming the problem, if it is a real problem, as with the auxilliary battery?

A healthy battery should be around 12.7 ...

Google Image Result for https://i.sstatic.net/clBVt.gif

 

[mioba]

seems low tbf....and the voltage with car running.

 

[johned]

seems low tbf....and the voltage with car running.

I'll check later.

 

[Tony Dyson]

12.5v is fine and the 12v reading battery I assume is your Aux SS battery I would replace.

 

[johned]

Ok engine running and I'm getting around 14-14.5v across both batteries. I'm going to take it for a run and measure again when I get back.

 

[Tony Dyson]

Ok engine running and I'm getting around 14-14.5v across both batteries. I'm going to take it for a run and measure again when I get back.

This indicates you have a healthy charging circuit, your battery measurements will be more accurate from this morning after sitting all night doing nothing, immediately after a charge you will read a false high known as a surface charge which will dissipate over time or the first 10 mins or so of use.

 

[johned]

Ok went for a 30 mile left the car 1/2 an hour then measured again and both batteries were around 12.5v. Looks like a trip to the garage on Monday and throw a diagnostic at it.
Thanks for the interest, advice and suggestions everyone.

 

[alexanderfoti]

I would hazard a guess you have a "battery internal resistance too high" code on one of the batteries.