12v system service required?
 

Latest warning / error to present itself to me. Have found scant reference to this in this forum, other than battery needs charging or take car for a long drive. I trickle charged the battery last night and is showing full, it was low.

I get the warning every 5 mins or so.

Any ideas?

This may be the final straw for me.

Edit 2021 XC90 T8 w/ polestar for reference.

Online manual also no use in giving any info. I’m lucky to be able to speak to my local Volvo service dept, even to book a service, so not confident they will be able to help me all that much.

Correct me if I am wrong, but your car should be still on warranty, just book in warranty repair and they should take care of it. I also 2021 T8 with Polestar, but XC60 version, and I don't intend to worry myself much if such problem arises, a warning light of any kind on the dashboard is their job to take care of and do the repair under warranty.

You are right. However with all of these things it is the inconvenience of having to take time off of work and away from family to deal with these things. Through previous bad experiences my confidence in the car service world is unfortunately low.

I’m conscious I’m posting similar info on my issue which is touched upon in a number of threads. By posting I always hope that it might be useful for someone in the future who has a similar problem.

To summarise and update on some findings:

- post 12v system service message I connected my CTEK trickle charger via front terminal points under bonnet of my 21 XC90 T8. Indicated state of charge was low and overnight my CTEK was showing a full charge.

- that day I drove ~30 miles mostly in AWF and PE modes and received constant 12v system service requirement messages every few minutes.

- on getting home I plugged my CTEK charger directly to the rear battery and to my surprise was showing as low. Again I left it charging overnight and was showing fully charged by this morning.

- I’ve not received any more error messages all day since directly charging the rear 12v unit. I have purchased an eyelet adapter for my charger with the traffic light system to show state of charge. Curiously after fitting it was showing as amber “in need of a charge”. I got my multimeter out and measured the voltage on the rear battery at 12.54v. 10 mins later it was 12.24v and registering as red on the adapter (in desperate need of charge) which seems really weird, given the car was off, only the boot was open.

- after driving the car in PE mode (deliberately to engage the ICE) for another 20 miles or so the adapter shows green and the multimeter is reading 13.40v across the battery.

I’ve no clue what is going on here, I’ll need to speak to Volvo about it I guess. On the face of it it appears I’m suffering huge battery drain for some unknown reason, enough to go from fully charged via CTEK to ~12.2v in the same day.

If anyone has any ideas I’m all ears.

Thanks

Further update for anyone who has interest.

Car booked in for service and investigative work on 4 weeks time, as soon as Marshall could fit me in.

Gent on the service desk advised trickle charging from the main battery and not from the terminals under the bonnet(!), contrary to advice in other threads.

Voltage of my battery continues to be all over the shop. Was 12.5v before a short run in Pure mode, and 13.5v after, so battery is clearly receiving charge whilst driving, but then seems to drop quite rapidly whilst not in use.

Starting to question the state of my 12v battery…

To my understanding, you will be provided with a replacement loan vehicle while your car is in the repairs. So, technically, the entire thing is only two occurrences when you have to drive to the dealer - once to give them the car, and once to get the car back. In between, you will drive a loan car. That's how I understand it, although I have not had a warranty repair as of yet, so correct me if I am wrong.

Sure. The largest car the dealer has to loan is an S60, though they have 3 XC40s so I guess naturally more likely.

I couldn’t care except I’ve got 3 kids to cart around and with a newborn all the clobber that needs to go in the boot, so as our main family car an extended stay with Volvo would be an inconvenience to put it mildly.

12v battery reading 12.24v and CTEK says in desperate need of charging.

Is it not worth trying someone other than Marshalls? I put them in the same category as Stoneacre.....

Sadly I have a service package with Marshall’s so somewhat loathed to now take it elsewhere. My time is something of a scarce commodity and realistically I don’t have time to yo-yo to Bedford and back unfortunately.

If Marshall’s can’t sort it I think I will move it on.

Further update. Having been showing 12.24v last night (car not used), I used the car to commute to the station this morning and I preheated it. I took a measurement before I left; 13.96v.

Philip, you clearly do many, many more miles than I do and I’m wondering if that has a bearing. Clearly my 12v battery gets charged during use / preheating, which as far as malfunction issues goes, has to be a good thing. I try to do most of my driving in Pure and my car has been slowly installing a nav map upgrade a few percent at a time, so maybe that has been taking its toll?

I will save all of you my adhoc battery level reading updates and see what Volvo say in a months time and will continue to charge the 12v battery, if needed, directly from the battery per advice I received from Volvo service (given charging from the terminals in the front bonnet appeared not to work as anticipated).

Thanks for the help.

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
==================================================
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

I have had to replace the 12v battery on my 2020 Focus with fewer than 20,000 miles. I have had the vehicle from new.
I had to replace the 12v battery on my EV, also owned from new, in December after it completely died at a similar mileage.
Testing my 13 year old Volvo, no modem, no connectivity it pulls 20mA 2 hours after switching off. That car can sit for weeks with no issues. Both the connected 2020 cars pull 0.23 - 0.25mA (as tested though this can change if the modem is activated) when asleep and can drain the 12v battery in less than three weeks to the point the central locking will not work. If I leave anything plugged in (accessories such as dashcam, phone charge cable or wireless android adapter) the EV is dead overnight. It appears the ports do not shutdown if they detect something is plugged in.

As an aside, I checked my Volvo this morning while out and about, the alternator output is 13.6v when driving, this increases to 14.5v on overrun. Confirms the AGM battery headroom overboost.