I had the low battery voltage light come on, it eventually died and I decided from searching the forum that it could be nothing but the alternator/ voltage regulator. Knowing my luck with cars, I just replaced both, probably didn't need to but what the hey. It was a foregone conclusion that this would solve my problem, but it doesn't seem to have done so.

I drove the car around for about 20 minutes and my Low Battery Voltage light came back on. I have the car home now and measured the voltage at the battery (11.95) which was understandable as we have driven it and it seems to be losing charge. I turned the car on and then the voltage at the battery dropped to 11.4 and went lower when the RPMs increased. This voltage was at the battery and tomorrow I will test it and see what the voltage reads at the alternator itself, in the mean time, assuming a good new alternator, does anyone have any ideas what it may be?


Thanks in advance.

Car is an '02 V70 T5, has 140,000 mi on it, and I don't think it's the battery because the battery is only 2 months old.

 

Check the alt output. Maybe you got a bad new alt.

 

If you have a charger make sure the battery is charged all the way. With your volt meter connected and on start the car. See how low the voltage goes when starting. Anything below like mid 10 volts on starting there is an issue with the battery as well.

 

I will check that in the morning, thank you. Say it's good, is there another aspect between the alternator and battery that it could be. Seems unlikely. What is the best way to check the alternator output?

 

Just checked the alternator output with a charged battery. At the battery it measures 12.7-12.9 when off, and 12.0- 12.2 when on. At the alternator, it measured 12.7 off and 11.9 on.
Seems to me like a bad new alternator.
We got it from Autozone, has anyone heard of/ had a bad experience with their products. I suppose I will just have to swap alternators out again.

It was so much fun the first time, I'm giddy to do it again :P

 

It was a bad new alternator.

Just a word of caution, if you ever have to get a rebuilt alternator from Autozone, etc. have them test it before you leave, as two of the three alternators that the location had failed the test.

Or just buy genuine Volvo and avoid the headache.

I will be posting a DIY for the replacement on my model (the '02 varies slightly from the previous gen, enough to make a new DIY worth it)

 

Glad you figured it out. Sad you had to do the job again.