12 volt battery charging problem on 48 volt mild hybrid EQ Boost car

[cclass200]

Hello all,

I’ve an ongoing problem with a 2021 model C-Class - so I thought I’d ask if anybody else has seen or heard of anything similar.

A couple of months after taking delivery my car showed a red “12 volt battery not charging error” message. I ignored it, but did stop when various electrical things (like COMAND) started shutting down. But, having turned the car off and on again, the problem disappeared. To be safe, it was checked in to the dealer who installed a replacement battery and upgraded the software.

A couple of months later I get the same error message. This time the dealer changed the starter/alternator (ISA).

Two more months pass and the same error message - this time I’ve had more software upgrades.

Apart from the failures being around every two months, there is no logic to them (in terms of usage, journey length etc).

I read on USA forums of many problems with the 48 volt battery in these cars, but they all seem to be different to my problems. However, my dealer did let slip that I’m not the only one. I’m getting the distinct impression there is a flaw, whether mechanical or software, that MB don’t know how to fix, and it doesn’t just apply to C Class.

So, has anybody else experienced, or heard of, something similar? Sure, this is all warranty work, but I’m starting to get fed up with 2 monthly visits to the dealer - it’s time consuming and requires somebody else to ferry me backwards and forwards. I’m also losing faith in the car.

Any thoughts?

 

[Tony Dyson]

I'm afraid the only advice I can give you is to insist that he dealership either picks up and returns your car from your home/place of work or leaves a courtesy car in place for your use while they have the car! Very few people know or fully understand how these things work and as long as the dealership continues to attempt to fix it your options are limited, I think I would be talking to MB Head Office by now about the return of the vehicle for a full refund as it is not fit-for-purpose and have a look at the Consumer rights act 2015 for support, Good luck!

 

[ayu]

Hello all,

I’ve an ongoing problem with a 2021 model C-Class - so I thought I’d ask if anybody else has seen or heard of anything similar.

A couple of months after taking delivery my car showed a red “12 volt battery not charging error” message. I ignored it, but did stop when various electrical things (like COMAND) started shutting down. But, having turned the car off and on again, the problem disappeared. To be safe, it was checked in to the dealer who installed a replacement battery and upgraded the software.

A couple of months later I get the same error message. This time the dealer changed the starter/alternator (ISA).

Two more months pass and the same error message - this time I’ve had more software upgrades.

Apart from the failures being around every two months, there is no logic to them (in terms of usage, journey length etc).

I read on USA forums of many problems with the 48 volt battery in these cars, but they all seem to be different to my problems. However, my dealer did let slip that I’m not the only one. I’m getting the distinct impression there is a flaw, whether mechanical or software, that MB don’t know how to fix, and it doesn’t just apply to C Class.

So, has anybody else experienced, or heard of, something similar? Sure, this is all warranty work, but I’m starting to get fed up with 2 monthly visits to the dealer - it’s time consuming and requires somebody else to ferry me backwards and forwards. I’m also losing faith in the car.

Any thoughts?

I have the same problem, “12V battery not charging”. But when I see the error message, even I step the gas pedal, it move really slow.
I went to service 3 times. At first one, they checked for error message, and did nothing. Then, they upgraded the software and charge the battery. At last one, they changed same part ISA.
After two months, the error came back yesterday.
Have you solved the problem?