Starter battery and split charge

[LimaHotel]

My friend has a 2016 T6 from a conversion company. It has a 80ah AGM starter battery and the converter installed a ‘smart battery isolator’ split charge instead of a b2b charger.
The alternator was replaced a couple of months ago.
The van has been throwing up a stop start error for a while and now the radio is playing up. I checked the battery voltage yesterday with Carista which read 12.1v

To cut a long and possibly rambling story short (apologies, I’m writing this when I should be working!) is it possible for a split charge to end up damaging the battery? Or is the low battery voltage more likely to be an alternator fault?
The van is driven nearly every day and covers decent mileage.

Thanks!

 

[t0mb0]

The first, obvious, question is one of timing - did the starter battery issues start when the split charge was installed or was it already an issue?

A mis-configured split charge could possibly be the cause of the issue, for example if it was activating when it shouldn't and draining the starter when the alternator wasn't available.

There are plenty of other things it could be too though that are maybe more likely - to start with first check what starter battery it is, if it's a Moll these are known to have issues, hopefully this isn't the case though as Moll's I think are EFB rather than AGM and I think they appeared later than 2016. Secondly, check the negative terminal of the starter, if it's got anything on it that isn't the factory connection that could be an issue because it'll be bypassing the shunt the system uses to know how much charge is in the starter and so may not turn the alternator on when it should do.

 

[t0mb0]

Also, get the starter battery checked, if it's the original 2016 battery then it could be approaching the end of its natural life. Having said that, I have a 2016 T6 with the original starter and that's fine, although it's spent its life being trickle charged by solar so it's probably had it relatively easy.

 

[LimaHotel]

The first, obvious, question is one of timing - did the starter battery issues start when the split charge was installed or was it already an issue?

A mis-configured split charge could possibly be the cause of the issue, for example if it was activating when it shouldn't and draining the starter when the alternator wasn't available.

There are plenty of other things it could be too though that are maybe more likely - to start with first check what starter battery it is, if it's a Moll these are known to have issues, hopefully this isn't the case though as Moll's I think are EFB rather than AGM and I think they appeared later than 2016. Secondly, check the negative terminal of the starter, if it's got anything on it that isn't the factory connection that could be an issue because it'll be bypassing the shunt the system uses to know how much charge is in the starter and so may not turn the alternator on when it should do.

She bought it converted so unfortunately no way of knowing whether the issue was there prior to the split charge being installed

The battery is an Exide EK800. I’ve not checked the date on it so unsure if it’s the original at the minute - I’ll check though
Thanks!