1G voltage fluctuates from 13.7 volts to 12 volts and lower..?

[MarkyGsX]

My cars voltage reading recently started fluctuating, usually my voltage reading is around 13.5 or higher and stays there consistently while driving and at idle. The other day i forgot to disconnect the power to the battery and I accidently arched a wrench on the ground of the alternator and caused a spark which in turn blew my alternator fuse. Ever since then the cars voltage reading reads 13.6 to 13.7 at idle, but when i drive the car the voltage will drop to 12 volts or lower, even when im at idle the voltage reading will be 13.6 and then i hit the brake while still in idle not moving and the voltage will drop to 12.5, I replaced the alternator fuse and still the same symptoms. My car never did this before i arched the ground on the alternator, and i also had the alternator tested several times and passed all 3 tests at autozone....? now im pretty confused....is it possible that it could still be the alternator failing somehow even though it passed the tests at autozone..? any help appreciated....thanks

 

[thiazole]

I don't think Autozone puts it under a load when they test it. As you said, it holds 13.6V at idle. I don't think their conditions are any harder than that. My bet is that something got fried in the alternator. It might be easy to repair the alternator for someone who knows what he is doing - it might save you some money if you could find someone like that. I think these alternators are expensive.

 

[luv2rallye]

Auto stores do a lousy and incomplete job of testing alts. Take it to a REAL place that just repairs alts and starters (see yellow pages).