Electrical problem, intermittent load killing alternators?

[roamer]

Okay, need some help. About a month ago my turbo died on the highway, typical alternator death - slowly lost power, then died altogether. I replaced both the alternator and the battery.

A few weeks after that, I started seeing an issue where after the car had been running a while the same lights that were on when the alternator bit it were coming on intermittently (ABS, battery, e-brake). Very intermittently. They would stop seemingly based on random events - turning sharply, reducing the engine load, reducing the electrical load. Nothing logical in the pattern. Problem got worse over time, taking less time to start happening.

Pulled the new alternator and took it back to the auto parts place, which tested it - was totally blown. So they replaced it, we tossed it in and did a short drive. No problems. They also tested the new one, which was fine.

So I start driving home, and the problem recurs. Much faster than before, still intermittent. I stop and catch a movie while I think about it and plan the next steps. (Avengers movie is awesome, BTW.)

Leave the theater and start up, and the lights come on immediately. They stay on for most of the trip home. Still seem to be coming on/off without any logical sense. I'm not running ANY electrical loads I don't have to - no climate control, no lights, no stereo. Only change I do not is once, when I'm sitting at a light, the engine rpm at idle drops and the lights go out. If we assume the RPM load was for charging, then whatever load was on there that stopped is the cause. It was a pretty hot day out, I'm suspecting the radiator fans.

Go home and check the fans. They both turn when pushed, but stop fairly quickly. They don't slow down, just stop. Neither has any play or wobble. I need to get some sleep so I can work tonight, so I can't mess with it any longer.

Only mod on the car that might be important for this is an MSD ignition, but that's a constant load, not intermittent - and if that were screwed the cat just wouldn't start, I think.

Has anyone seen this before? Is the fan going bad and forcing the electrical system to work harder to push it? Are there some other loads I'm not aware of? Anyone have any other suggestions? This is my daily driver and I want it to stay that way, but I need it to be reliable, and I know that electrical problems can be very tough to diagnose. Thanks in advance for any help people can give.

[Legacy777]

Have you had this "new" "new" radiator tested again after the lights came on?

The radiator fans should spin fairly freely when they are off.

Due to how the alternator and ebrake, battery lights are wired, they designed to come on if there is a short in the alternator. So either there is a short/ground in the wiring or the alternator. Which is why I suggest getting that new alternator tested.

Maybe the autoparts store got a bad batch of alternators. They are poorly rebuilt most of the time.