Further to previous posts, I drove a total of 160 miles today, almost exclusively on petrol and by the end of the day my battery was not fully charged (CTEK light thingy flashing orange). This evening I took my son to football training, 6 mile round trip on electric only and battery seemingly fully charged (flashing green). So appears 12v charged more on a short electric trip than a longer one on petrol….

12V System Service required light (yellow and red battery)
 

I am having the same issues with the 12V System Service required light displaying randomly on some trips but not on others. Car has now been in the Volvo Dealers 3 times. 1st time the engineers said give it a long trip and it should go away (did not work). 2nd time they replaced the battery monitor and the alternator (did not work). 3rd time they replaced the alternator again saying the previous alternator showed a fault (did not work). I will be contacting the dealer again to inform them to try again to fix this. It is my belief this is a known problem but they do not know how to fix it. I will update this site with my updates as time goes by. Any thoughts from your good selves will be appreciated.

Hmm. That doesn’t inspire me with confidence. I can say that trickle charging the battery directly on my T8 makes the issue go away for a period of time. Connecting under the bonnet does not resolve it. I did a 120 mile trip recently when it reared its head again, so I agree the long trip thing is tripe.

I’m wondering if it’s the 12v battery itself. I’ve been monitoring the voltage across it and it has the ability to drop rather quickly.

Update: I called dealer to inform them that above problem reappeared yesterday on trip to Llanelli (47 miles). The 12V light did not appear on the trip back home. Dealer has booked car in for Monday 18 April 2024 for the whole week to do investigations including contact with Volvo themselves. A loan will be provided to me while the investigations take place. They stated they had not seen this problem very much before hand. I stated it is a problem in other parts of the UK on various models of Volvo but root cause unknown. Again I will update this site when I know more.

I assume this is the normal car dealer nonsense where they've done everything other than the obvious - i.e. replace the battery.

Even from the same batch one battery might last 5 years and another fail in 6 months.

I've got a car (not a Volvo) that needs a new battery every autumn without fail for example, the batteries are an odd size/shape and spec and are just not very good quality - or I can pay 4x the price for the maker's own battery, which was replaced under warranty at 18 months and failed 19 months later - so I just buy the cheap ones each autumn. When they start to fail they show as fully charged after a run yet are down to sub 12v the next morning. I put a new one on and it's fine for 12 months or so, then it happens again. Just bad batteries.

My first move would be to replace the battery in the car. Dealer of course won't do that if it's in warranty but I would bet if it was out of warranty and you were paying it would be the first thing suggested...

Update: Today (27 March 2024) I received my Volvo XC60 2018 back from the Volvo dealers after 7 working days being investigated for the root cause for the 12V System Service Required light coming on in the dashboard display. The Dealer had been in contact with Volvo via a formal request to seek a solution to the problem. Volvo suggested they change the rear bumper harness, which they did but this did not fix the problem. The Dealer continued to submit requests for a solution but there were no replies from Volvo either yesterday or today. As Easter was approaching I requested to have my car returned to me today as I had family commitments including a trip to Sheffield. The Dealer was surprised that Volvo themselves were not forthcoming in replying to their requests. I have booked the car into the Dealers for Monday 15 April to again investigate the root cause for this issue. Again I will update this site when I know more.

Update: Today (Monday15 April 2024) I left my Volvo XC60 2018 at the dealers to further investigate the root cause for the 12V System Service Required light coming on in the dashboard display. It is now Friday 19 April 2024 and the dealer called me on Tuesday to ask if I had a GPS Tracker installed in the ODBII port. I stated yes - for the last 2 years I had an AA Genie ODB tracker installed but recently the AA have discontinued this tracker for a new service called "AAx". I evaluated this new service which I found to be a poorer service compared to the Genie service so I cancelled the Genie service. I have now fitted a ScorpionTrack FMB020 GPS tracker in the ODBII port. I gave this information to the dealer and also asked them to perform tests to check for ground shorts and parasitic draws. I await their responses to this. As before I will update this site when I know more.

Final Update:
Volvo 12V System Service Required Issue on my Volvo XC60 D4 Momentum PRO
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Received my car back from Volvo Dealer on 25/04/2024 finally. Invoice details:
Inv 12v system failure.
Cable Harness - FMDM - Cost £78 / Labor £250
Notes:
Checked battery, test OK.
Sent report to Volvo requesting support.
Carried out investigation as per instructions.
Cable harness rear bumper replaced as break in wire found.
Carried out road test fault still present.
Liaised with Volvo - Issue found in wiring on loom between ECM and ACM. Break in wire found.
Repaired and road tested. Car OK.
My thanks to the Volvo Dealer for getting to the root cause for the 12V System Service Required light coming on. Well done Volvo.

Does your charger (MrM83) have a recondition option ? It looks like your main battery has/is sulphated.

The 13+v reading is when your engine is running or 400v traction battery is driving the car, not the 12v battery.

When you connect the battery to the charger connect the negative lead from the charger to the body, not the -'ve terminal of the battery or the end of the -'ve battery lead where it connects to the body this can give a false reading in the BMS.

My 2020 Ford Focus is doing the same thing, I have ordered a replacement AGM battery with a higher CCA value though same Ah number. When I switch off, the battery is showing 12.7v which drops to 12.4v within an hour, overnight this drops to 12.19v before I start the car. Anything lower and I am risking being stranded. My car is throwing ABS, steering angle and front camera errors, active cruise control is dropping out with the camera issue.

Interesting thanks.

Keith, I am pleased your issue seems to be sorted. I would have thought a break in a wire would cause a more permanent error though?

I’ve not driven my XC90 as much of late as I’ve got a new little electric car I run around in. I also took the OBD power unit I was using for a dashcam from my XC90 and put it in my electric car. It’s the Garmin unit and has the option to run for 10 mins, 24 hours or permanent. I’m wondering if this unit was causing sufficient drain to give this 12v error as whilst I haven’t driven the car as much, I’ve not had the error since.

With regards to your question GMcL, I do have the recon option on my CTEK. I also have the charger connected to the terminals and not negative to the body. If there is a convenient place that I can attach the negative lead of the charger to (loop fitting) I could do that. Does anyone know of somewhere suitable?

Many thanks