I have a problem. This is what I have. I am running a Powermaster 100 amp alternator, 65 amps @ idle, 1 wire alt. I have been using this alt for 6 months, of which the last 3 the car has not been running or such short distance not noticed....

My battery is in the trunk - 4 gauge wire to the starter. 8 gauge wire from alt to batt. All seemed to work fine. I am changing to larger wires just to make sure.

I recently put in a TKO-600 and drove it around over 20 miles and I noticed my voltmeter gauge was at approx 10 volts!!! I drove it home and when I got to the house it died on me, and gauge read 9 volts!!! Needless to cay I had to charge the new Optima Battery up to get the car into the garage. I double checked that the power wire to the batt from the alt. was not cut, and it was not. I check batt and alt with voltmeter and read same level after charge 12.0 when I started the car. Had my buddy kick the RPM's up to 2500 and the alt did not kick it 100 amps. It used to, but not anymore. I replaced the alternator today after talking to Powermaster and they swapped it out for me. The new one is doing the same thing. Any suggestions on what to check next?

FYI - The wires are all solid 1 peice wires, not several wires soldered together,and are multistrand Monster Cable wire..... The ground runs from the battery to the frame, then I piggybacked another ground terminal from that ground to the motor - starter bolt, underside of motor......

Please help