Testing 12v batteries

The engine management light has illuminated on my DS4 E tense.
Theres no faults showing on the cars diagnostic tool.

A quick Google search has indicated this warning light could come on if one or both of the 12v batteries is or faulty.
As some of you may already know I’ve had battery issues since buying the car.

I’ve just checked the batteries and heres the results.

Engine running:
Main 14.8v
Auxiliary 14.8v

Engine off, car settled for half hour:
Main 12.44v ???
Auxiliary 13.07v

Is the main one a bit low ?
I havent done a trickle charge for a little while either.
Plus I do low mileage, and mostly running in either hybrid or full electric mode.

The car has had 4 main battery replacements already under warranty, but the dealership are saying they cant find a fault or reason why they are going faulty.
Also, in all the time they have been replaced the engine management light has never come on.
This is the first time I’ve seen it.
Another thing to perhaps mention is that the car is due a service in 5 weeks according to the messages on the car, could this be why the light has come on ?
I would expect to see the spanner icon though !

Any advice appreciated.

@Jactac - those voltages are (running and engine off) at both batteries are almost identical to what I see on my DS4 E-tense - and everything seems fine. When I was close to a service interval recently it was definitely only an orange spanner symbol that came up in the dashboard. Looking at the manual - the engine management light is only orange and either flashing or steady - both with contact service centre as action needed. I’d get the error codes checked and see what the car thinks is wrong.

Thanks for your advice Andy.

Its good to know the battery readings are similar to yours.

The engine management light is still on this morning, it’s orange and static.

I read online that sometimes this can appear if any of the 12v batteries are low or failing, but over the last 2 years when I’ve had issues with the batteries, I’ve never had this light appear.
I only knew there was issues with the batteries when the dealership service department was testing them when there was an issue with the Welcome lights & locks.
The car is going in Friday for its service, so they can check it out at the same time.