Alternator Keeps burning Up
 

Just purchased a 2000 Mazda Protégé for my daughter. It keeps burning up alternators. I drove it to O'Reilly’s they check it and said the voltage regulator was bad. I purchased one last Saturday and it was toast by the next day. I got a warranty replacement and put it in last night. Started the car and checked the voltage at the battery. It was 13.8 to 14.2. I proceeded to turn the heater on with the fan on full, everything was fine. Then I turned the lights on and the alternator started to squeak and make noise. I checked the voltage at the battery and it was back down the 12.8. I think when the lights are turned on, it somehow cooks the alternator.

I did add ground wires to the battery in case they were corroded. One to the engine and another to the body.

Please help.

Are you getting a new one or a rebuilt. They carry Ultima and the part number will start with N or R but I'm guessing rebuilt. It could just be bad luck because there could be a few in the pipeline that weren't rebuilt properly. If that's the case you might try the other type but it'll be more expensive. Before I did this though I'd run my positive lead back to the starter and harness and be sure it's not shorted anywhere as well as charging the battery completely up, let it rest a few hours to cool off then load test it to see if it's ok.

BTW we've had a 2001 since new, it has over 220,000 miles on it and going strong. They are awesome little cars but if you can find one buy it a new dash unit for the heat and air controls. If you don't need it now you will as the fan speeds will start going away and the a/c compressor switch will stop working. Only weakness I know of.

Someplace in the system is a VERY BAD ground, creating high resistance. Things like that are a PITA to track down.