Hello I am on here today because my 2002 Volvo s60 non turbo had this code coming up while I was on the highway headed home,(battery low voltage) my A/C completely stopped working, threw my throttle body into limp mode, so right away I got off the highway just in time to pull the vehicle over before the car completely died. I tried to turn the car back on but battery was completely dead, I sat for about 15 minites and tried to turn the car on again and it cranked over so I was able to get it home. The next day I was able to pick up a brand new battery and got it on with the vent hose connected and everything proper, I turned the car on and let it run for 20 minutes ,after that I went on a drive , a few miles down the road the low voltage warning was back on. So i got back home turned the car off and turned it back on. My RPMs were having trouble keeping the car on kept having (low battery voltage) on a new battery. I'm thinking it's the alternator or the regulator.

 

No suggestions here but it does occur to me that, given the evident (from postings) fragile nature of Volvo electrics, an ammeter would be far more useful than a blinking display that announces the speed limit. I wonder if those responsible for design decisions ever drive the cars.

 

start by measuring battery voltage with the car off. an 80% charged battery will be in the 12.6V range a drained battery will be below 12.2 If you see something like 9.8, that suggests a dead cell in the battery... Next give it a charge (ie battery charger or jumper cables may need 10 minutes to get enough voltage/energy to start the car.). Start the car up and again measure voltage across the terminals. A normal alternator should push out 14-14.5V to the battery. If you are still at 12.6 you have no charge coming from the alternator. If you see something in between, leave the car running and add an electrical load by turning on the rear defroster, high beams, fan blower on high, AC-DC on the stereo etc. If your car maintains 13.5 or so volts your alternator is doing the job. If that drops the voltage below 12 or 12.5 your back to looking into at a charging system problem. (alternator, cables, battery terminals, voltage regulator etc)

Note that many cars allow you to swap out the voltage regulator vs the whole altnerator/generator assembly (depending on the failure symptoms). Do a quick google search on your make/model to see if a dealer store like Tasca lists a replacement for the voltage regulator.

 

I had the same issue with the same message on my 02 S60. The alternator was not putting out voltage. I replaced the worn out brushes in the alternator with chinese Ebay ones for $12. Quite a job to remove though. Had to pull the PS pump and lines, and 2 of the 4 bolts that secure the AC compressor. Saved a BOATLOAD OF MONEY.