Battery/Altenator Voltage regulator. Could it be an issue?

[CitROeNALD]

Just musing if there is a fault on my C4 Grand MK2 (2018 plate) that is not showing up with a code. Or if it would show up if there was a fault.

This car's first battery seemed to go bad only 3 years after owning. The Eco Mode would go on very quickly, and eventually the garage replaced it. I think lack of use during covid killed it.....or rather, I assumed that was the cause.

It has an EFB battery.

Sadly there was still an period of covid after this where the car got little use, and this battery has not seemed to fair much better.

It never has an issue cranking, and I see no other issues other than Eco Mode coming on very aggressively. This time the garage tested it and they said it all came back fine.

However, even with a long charge with a smart charger or long runs, even though it might be fine for a day or so, Eco Mode comes back very quickly. It shuts power off only a min or so after turning off the car.

But, like I said, no other presentations of a bad battery. Cranking was fine in the coldest winter temps we had too.

So.....my question is......what could be the cause? Just a battery that is slowly going bad?

Or, could there be an issue with something like the battery voltage regulator or something.

I think the alternator is fine, no codes get thrown up.

If the voltage regulator was, say, over volting the battery and slowly damaging it or something, would that throw up some kind of code?

The last time I tested the voltage across the battery with the engine running, I thought the voltage seemed to be slightly high, but I would have to do another test to confirm.

[merlin667]

Which engine do you have?
The voltage should be around 14.2 to 14.4 or 14.5V.

What i noticed on my 2.0 BlueHDI: as long as i drive short distances (less than 40km daily) the charging level of the battery drops down to 70 or 65% even though the battery is less than 2 years. and bringing it back up to 80% or more needs like 500km more or less without stopping. and a few days later its back to 70% or even less during winter time with shortened "ECO Mode".
I stopped caring about it as long as it cranks and starts up beautifully.