[schaff]

Just hooked up my 20amp alternator to my fan. I hooked a multimeter up to the positive wire and to ground but it said ~0.1v then I got to thinking maybe that's because it's not pulling a load like when its hooked to a batt. Any simple ideas for checking these things?

 

[Kajun]

You have to "excite" it before it will start charging. Ground it to a batt, crank the engine, then momentarily touch the positive to the small alt post. Doesn't have to be a big wire. Then test it with a voltmeter.

 

[water snake 2]

we always touch a screwdriver or wrench to the back of the chevy alts. the very center of the alt .if its magnetized it is a good sign on some of the tractors we have have to rev them off of idle before it starts charging.

 

[schaff]

Good deal. I'll try that.

 

[mudfish]

Go to auto zone, they got a good tester

 

[schaff]

I put the multimeter to the batt without the alternator grounded and it read 12.8 and when I grounded the alt it read 13.5. Looks like it works

 

[CPrice]

just crank the fan, apply 12 volts from the battery to the alternator to excite it, then disconnect the alternator wire, u should have 12v then. do not kill during this process.

 

[cocoloco]

It has to be connected to a battery. If it is a one wire alternator it won't start charging till you rev it. Check battery voltage before the start up. The alternator should charge a volt and a half above battery voltage.

 

[whiteriverrambo]

sounds like you got it schaff. are you talking auto alt? I thought I remember you saying something about adding the Honda rectifier style alternator.???? I think there's a little confusion on witch you meant. yes a automotive alt won't start charging until a certain rpm. usually12-1700. but by changing the pulley configuration you can tune like I did to make sure your automotive alt is excited even while your engine is at idol.

 

[schaff]

Yah rambo, its the Honda alt that came with the motor. I just never hooked it up. But yes it seems I got it working. Thanks for the help everyone!