js.larocque

I've got an alternator from an 81 and I would like to see if it works, I've plugged my voltmeter on the positive B terminal and the ground on the body and I don't see any voltage change 0.00V very solid so I guess there is someting I'm doing wrong!
There is a "L" terminal and an unidentified terminal on the back of it, is one of them somekind of trigger to activate the charging?
Do I need to put a load on the alternator to see a voltage change?

I'm not expecting to get 12V just by turning it by hand, I just want to see if it's "fonctionnal"

gsl-se addict

iTrader: (3)

In the US at least, most autoparts stores will test the alt for free. Really, you cannot test them by spinning by hand.

jgrewe

iTrader: (1)

Put it back on the car,hook it up and run the car. If the alt is making power the center of the back of it will be magnetic. Touch a screwdriver to the bearing cover and it should stick.

djessence

Or if you are gonna go through the effort of hooking it up, see if you are getting the right voltage on the voltage guage..... but i would just go get it tested at an autoparts store or localish mechanic type. they often will do it wor free to

js.larocque

Thanx for the replies , going to an autopart and have it tested is a good idea , I will do so when ever I get some time. My car is in storage right now so I can't try it on the car! The other thing is that this is for a project and the purpose will not be to recharge a battery, lets say it's going to be use as a power supply.

I need to find out how to wire it correctly. I pretty sure there is something to do with those 2 terminals in the back, else I guess I would have got a couple mV out of it by turning it by hand....

any ideas?

rxtasy3

iTrader: (2)

hmmmm....didn't know that. but then again, i'm not in the habbit of poking around the alt with a screw driver while the engine's running. no offense.

as for checking the voltage urself, hook ur volt meter to the bat and note the voltage. start the engine and watch it rise.....voltage that is.

gsl-se addict

iTrader: (3)

R and B should be connected to 12v. The L is just for your alt warning light. The way you are testing might work for a generator, but not an alternator. There needs to be power at the back of the alt to create the magnetic field. It is not like a DC generator, which has permanent magnets.

Also, the alts require a minimum RPM before really outputting anything. For instance, the output test for this alt is supposed to be performed at 2500 RPM.

There is info here about testing, rebuilding, etc. of our alts:
http://foxed.ca/rx7manual/manuals/19...Electrical.pdf

Just take it to be tested. It would be a lot of work to set up your own tester at home. It can be done, but just is not worth it when you can get it tested properly for no cost at nearly any autoparts place.

Jeff20B

iTrader: (13)

I once got an alt to charge outside of an engine bay. I electrically hooked it up, then spun the front nut with a hand drill. As soon as the circuit closed and the alt began to charge, it put a serious load on the drill motor - so much that it nearly torqued out of my hand, and the alt itself, which I was pressing down against the floor, tried to rotate on me. I guess that's what 55 amps feels like. lol