E350 Coupé 2010 red battery light

[Nicoace]

Hi all, I have a 2010 E350 diesel coupe.
The red battery light comes on intermittently and sometimes shuts down command/radio.
I have looked at my onboard computerthat tells me the following:
Engine off-
Supply voltage of HU 12.3v
Battery voltage via CAN 12.3v
Engine running-
Supply voltage of HU 11.6v
Battery voltage via CAN 11.8v

Is this a battery issue? Main or auxiliary?
Is this an alternator issue possibly?
The car drives perfect and at this time the red battery light is intermittent. THANKS

 

[BlackC55]

Probably an alternator issue. It should be 14.4V running directly off the battery or the back of the alternator. It has smart charging so give it a minute or so running to check the alternator output.

Get a genuine alternator and you may need a new battery too. My advice is to buy genuine batteries, they are better.

We have had so many issues with aftermarket alternators on these engines.

 

[Nicoace]

Thank you.

 

[David404]

I had the red battery light come on on my old E320 (W211 series so no stop/start) but otherwise same engine.

Local Indie diagnosed as alternator failure (££ Ouch) which I had replaced. If that is the problem after replacing the alternator I'd recommend charging both batteries to 100% with a good quality smart charger. That way you start from a known position.