2000 Volvo V70XC - Christmas day battery light came on and car just died while driving down the interstate...Bad Alternator. Replaced alternator. Checked alternator with battery charger that has alternator check and everything was cool. Car ran superb up until last week. Intermittent dummy lights coming on and off (ABS/TRACS), engine lacks power, RPM's surge between 800 and 1000. Checked alternator with battery charger and it read fault for the alternator. Replaced the alternator (thankfully under warranty). Subsequent alternator check with new alternator shows alternator fault again. If I leave the car running I can hear it slowly begin to die due to lack of battery voltage. I had Victor fix the ABS a couple of years ago.

I know that the alternator test from the battery charger is not an end all be all of testing, but I can't really believe that I got 2 bad alternators in a row. Bought a new battery when I changed the alternator, so I don't really think that is it. The battery checks out fine. Should replace the battery cables? Could I not be tightening the lead from battery to alternator enough? Is there a fuse, fusible link or relay that I should check? Nothing looks burnt in either fuse box, but I know that I can't see inside the relays.

Something else that I might include is ignition issues. Key spins in ignition sometimes. It will eventually catch. Took the electrical part of the ignition apart and found one of the 4 U shaped plastic pieces was broken...glued it back together as a stop gap measure until I order new part. I can't really see how the ignition would not allow the alternator to charge while the car is running.

Sorry about the long post, but I have changed many alternators in many cars and have never run into this issue before.

Thank you in advance for your help.

Loose Moose

I'm am beginning to think that it is the voltage regulator. I found some breakage in the positive cable at the terminal. Just for a little troubleshooting, I clipped of the terminal and replaced it. No change in charging. I did find something interesting this evening though. I put the battery charger on with the battery still connected. After about 6 hours of charging at 2 amps, the alternator was hot. I can see how this could happen, but I thought it was strange. I put a multimeter on the battery and got 13.3V, 13.1V at the relay box and 12.9 at the alternator. I started the car and got 18.1 at the battery and the realy connection. Would this indicate voltage regulator or bad positive battery cable?

Thank in advance for you help.

Voltage regulator. You will destroy the electrics and the battery at 18V!
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My name is Klaus and I am a Volvoholic.

The ignition switch is not the problem, but still needs to be replaced.

Let your car run for a bit and check the red wires running to the battery. Stories abound with one of the wires going bad, gets very hot to the touch, and an expensive part to replace.

I also doubt that the alternator is at fault, but is being overworked.
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My name is Klaus and I am a Volvoholic.

It sould like a possible bad ground wire. Ck all conections and then see if charging problem is still there. Let us know.