Is this alternator good or bad?
- Thread starter dogememe
- Start date
I may be missing something there, but I don’t see the output amps. It appears to be functional at what ever load is being applied
I guess my thought is whatever that one measurement it failed was because it’s a different alternator than the part number I put in to test it?
Probably not, the stator voltage is probably the AC voltage from the stator and before it goes the rectifiers that convert it to a DC voltage. 10.64 VAC would convert to about 15.0 volts DC.
I think you have a bad stator or it's shorted to ground (possibly a shorted diode). I'm not familiar with this tester so I might be wrong but that's my best guess.
I'm not at all sure anything is wrong.
X2. I wondered the same thing, but the OP is having it tested for some (unspecified) reason so I'm sort of guessing that it is.
Frankly if that reading is of the stator AC voltage I'm wondering how they accessed it since AFIK those connections are always made inside the alternator and aren't accessible without taking them apart. But since it's a custom HO alternator it might be built differently.
A customer left it as a core return so I bought it for core value of $25. It was a completely different alternator than the one they purchased so I have no idea what the backstory is on it. But since it’s not the same as the one they bought I think it might be OK was just not the right one for their project… I want to see if I can install it on my Yukon
Yeah, I was just trying to avoid actually going through the effort of installing it just to find out it’s dead. Then again my belt squeaks so guess I gotta replace the belt anyway so that’s half the work. I’m not worried about the $25, a risk worth taking IMO. Been wanting to do an e-fan conversion but last time I did it on a different truck the stock alternator was not good enough at idle. So if this one works that would let me do that upgrade in the future.
I agree, but in this situation one also has to ask how difficult it is to install in this vehicle.
It will probably take less than half an hour total to install and if it doesn’t work out put my original back. So not a big deal. And like I mentioned I need to replace the belt anyway so not too big of a problem. I’m just lazy. Haha.
The last time that I had an alternator tested the Advanced Discount AP store near me used a machine that actually spun up the alternator and measured the output voltage and current with meters (digital ones IIRC). No computer screen involved. You might try taking it to a different store or to an old time auto electric shop that still has an early style tester. Sometimes simpler is better.
A few years ago I found generator/battery/starter tester driven by a big AC motor that was build, probably in the 1950s, for the US Army in a surplus store. I STILL regret not buying it!
A few years ago I found generator/battery/starter tester driven by a big AC motor that was build, probably in the 1950s, for the US Army in a surplus store. I STILL regret not buying it!
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I always bench test alternators myself.
Figure out a way to hold it securely, and use a decent drill to spin it. Connect it to a battery and wire up the idiot light. I put a voltmeter on the battery and see what it goes up to when the excitation RPM has been reached (when the idiot light goes out).
You can also test diode leakage with a multimeter.
That is all I do. No real load test unless the battery is significantly discharged.
Figure out a way to hold it securely, and use a decent drill to spin it. Connect it to a battery and wire up the idiot light. I put a voltmeter on the battery and see what it goes up to when the excitation RPM has been reached (when the idiot light goes out).
You can also test diode leakage with a multimeter.
That is all I do. No real load test unless the battery is significantly discharged.