Originally posted by Ray:
Except for the fact that there is a mega-fuse inline with the alternator to prevent that from happening. SHOULD not be any reason to burn up the alternator..

At any rate.. 20 minutes, possibly to check the fuse and replace.. or 1-6 hours depending on severity of bolts, etc, on the ALT to replace, simply on a whim?

the smarter choice would be to at least CHECK the fuse before ripping in to a repair such as this..



Oh.. and a Bridge rectifier (you are referring to) to create AC would have TWO placed in a REVERSE-biased manner, and two in a forward-biased manner..
Normal operation would pass the positive portion of each AC waveform through to the battery and car as positive voltage, and the negative portion to either ground or a discharge cap.

reverse hookup would then send the negative waveforms to the same exact setup, and would be reverse-biased, allowing NO CURRENT flow to the battery (but MAX flow through the now forward biased other pair to the discharge cap/ground. causing the fuse to blow.

OR to paraphrase: your megafuse is likely STILL the culprit.


Ray



I really hope there is a fuse in the +12V link between the alternator and the battery that protects. But at least the schematic of the charging system in my repair manual shows none.

I'm not understanding your description about the way a rectifier bridge works and how that would prevent a backward-connected battery from frying up the diodes. Below is a link to a simple schematic of the rectifier circuit I sketched. If you reverse the battery connection you should expecting a huge current. I wish I'm wrong though.

The smoothing capacitor alone at the alternator output is too small in capacity to blow any fuse in our cars, even the lowest rating ones (3A), on a 12V battery.
charging

1997 Contour Sport Duratec MTX 2000 Olds Intrigue GLS Sterling Edition