Battery, Alternator, or Electrical Problems:

[seflovescmh]

Help. I have a 2002 Volvo S60, and the other day my indicator said "Battery Low Voltage." I turned around, went home, parked the car and got our spare car. When I got back home the Volvo would not crank. I took the battery to Auto Zone, and it was dead. I bought a new battery and installed it in the car. Now the car just does not act right. Sometimes I stall when coming to a stop, I occasionally get the "Battery Low Voltage" indicator when driving down the road. (It does go off after a little while.) Although I haven't seen it but one time, the indicator told me to "Check Electrical System."

I have taken the car back to Auto Zone, and they hooked it up and said that the battery and alternator are performing as they should.

Any idea what is going on? Do I need to go ahead and take it in to the shop? Does this sound like the alternator? Any chance this is the ECM learning the new battery?

I have seen some slight improvement. For example, the car always stalled when slowing down before, and the RPM’s dropped real low. Now the RPM’s drop low, but the car does not stall when stopping. Any ideas?

[regent]

Start with checking the B+ stud at the fusebox located on the driver side in the Engine Compartment. That point is a known source of trouble. Look for loose connections, discoloration, oxidation, etc. (Before you begin, disconnect the battery negative.)

The 'relearn' following battery disconnect-reconnect usually lasts a couple of minutes, if that.
Since you have eliminated the battery and generator, it appears that poor electrical connections are the source to your problems.

[packetfire]

You may want to check the alternator output when the car is fully warmed up.
I had an intermittent voltage regulator, and it would look fine at first, but randomly fail when the car had been running for a bit.
There is a Volvo TSB about this, the bad voltage regulators were supposed to only appear in 2001 Volvos.

The key point here is that "low battery voltage" means that the battery is not getting charged.
if the condition is not constant, then the only part that could be intermittent would be the diodes in the alternator (overheat/fail), the voltage regulator (overheat/fail) or the wires (bump or heat disconnects bad connection).

[coflynn]

If it helps, I recently replaced the voltage regulator on my alternator. See www.matthewsvolvosite.com/forums/viewtopic.php?f=9&t=51058. Based on that you might be able to troubleshoot it at least...