Stop start not workingf
 

I’ve got a 2017 V90 and for nearly a year now the stop start hasn’t been working. It went in last year to be fixed and they said they had fixed it under warranty, it worked for 3 or 4 days and then stopped working again. ( I suspect all they did was put the battery on a charger) It’s just gone in for it’s 3rd service and again I asked them to fix the stop start system. They said that the stop start battery ( not the main battery) is ok but only 50% charged, it needs to be at least 75% for the stop start to work. I cover 12,000 miles a year and can see no reason why the battery should not be charging properly with that mileage. I’ve said to the dealer that there must be a fault somewhere for the battery to not be properly charged. They are taking the car back in for 3 days to see if they can get to the bottom of the problem. The dealer says that if their service guys deem the battery to be ok they can’t replace it under warranty... seem to be going round in circles!

I have a s90 same age, and have had no problems. It should last longer than 3 years, but it is an up hill struggle getting the dealers on side with anything that might be deemed consumable.
I’d write to the dealer principal, outlining the issues, and if that doesn’t work, track down the Volvo MD and write to him afterwards.

I had exactly that with my 2017 S90. Eventually, the dealer replaced the battery just recently (don't know if they got a fault code, hadn't done so before). It now works perfectly (which it never did from new). I understand they want to get paid for warranty work so can't just replace things haphazardly, so you might need to be persistent ..

Has the stop started or the start stopped?
(I know it sounds silly, but it's a serious question.)

Get the battery health checked. The systems are really, really fussy about voltages and the AFB/EFB or AGM batteries used to provide the consistent voltage are in fact pretty flaky and no where near as reliable as a conventional SLA unit.