An electrical question about alternators
 

If an alternator does not have either the two socket plug on it NOR the *B* output wire that feeds the battery, and the engine is running, will the alternator be hurt/destroyed over a long period of time. Say a year or so of running with no electrical connections on it but the belt connected and spinning the alternator.

I know that with no electrical wires connected to it, if you put a meter on the B output terminal you'll see thirty plus volts. Its one of those *if a tree falls in the forest and no one is around, is there a sound* question.

I would not see a problem with this. There would be no load on it so it should run just as long if not a little longer than if it was under load.

May I ask why? I have a thought if it is what I am thinking.

btw, I spent my high school summers rebuilding alt and starters.

-billy

Well, It's a little embarassing. I read a thread on this site a week or so ago about re-locating the alternator and combined that with my need to order a double pulley alternator pulley from Mazdatrix along with the idea that pulley cost forty four bucks.

Well I like to piddle with the car. So why not put one of the four spare series four alternators where the airpump goes to use as sort of an idler pulley to take the place of the airpumps belt that helps run the water pump.

So I piddled yesterday and put the spare alternator on after doing some fabrication, and it works just fine. Then this morning out of curiosity I put a output wire on hte *B*terminal just to see if that was one of the good or bad alternators in the shed, and if the engine was reved up to a couple of grand there was an output in the thirty vdc range.

So wanting to piddle some more I was about to go to PePboys and buy some wire and run the output to the fusebox/battery and a switched source of 12v to the small plug for alternator regulator control voltage.

But then I got lazy and realize I need to do some more serious piddling on the house/yard/laundry/you name it. So I might just leave well enough alone.

Thanks for the response.

Without knowing/looking for a schematic of the inside of the alternator, I would say that you're probably okay. When engineering with motors/coils/inductors in any application, it is standard to see a shunt diode that will pass current that may be harmful to the circuit. This would be seperate from the rectifier - a fifth diode that is probably rather large. Again, I have not been inside the alternator circuitry so I cannot promise anything.

:p:

Monty

If there is no voltage on the input wire, the output of the alt can spike up past 30 volts. The regulator uses the reference for the amount of charge.

Sort of found that out already though huh?

Yeah. No load situation. I also found out that if your smart you won't run a wire from the output to the battery just b ecause your curious about what will happen if two alternators are connnected to the battery at the same time. Never said I was smart. Dummy Dimwit here.

Still, it does make a good idler pulley. I suggest closing this thread ....forever.

Did you lose any eyebrows over that one?

Does anyone actually make a pre-fabbed idler pulley for the air pump replacement?

as per your request... closed