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Discussion Starter #1
What are the correct steps in testing your Alt.

My battery (that I just bought 1 month ago) is not charging or the Alt is bad. A 3 wire powermaster.
 

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Put a voltmeter at the Altenator output. Bring your RPM up to abot 1500 - 2000 and turn everything on. You should have 14 - 14.5 volts. Is it internally regulated?
 

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Just did the test and it just stays at 10 must be bad alternator. Internally regulated.
 

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are all three wires hooked up? I had the problem last week where I was only getting 12.5 volts. turned out I had neglected to hook up the "gen" light wire. hooked it up and Im seeing 14 volts.
 

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Just did the test and it just stays at 10 must be bad alternator. Internally regulated.
If it is hooked up correctly, take it to a rebuild shop and have them fix it. It could be something really minor.
 

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have auto zone test it first.

if you are getting 10 volts doesnt that mean you are running off battery power?

also, you should charge your battery :D
 

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have auto zone test it first.

if you are getting 10 volts doesnt that mean you are running off battery power?

also, you should charge your battery :D
He is probably running off the battery. I'm surprised he got it started without a jump.
 

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Discussion Starter #8
The alt. is toast when I took it off to get it tested I noticed a bunch of little parts falling out of it. So I opened it up and the brushes are toast and one I cant even find. The springs for the brushes are wrapped around the wires. What could have caused this am I running the Alt to fast? This was a powermaster 100 amp alt 4 yrs old. Whats next?
 

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Yea, no warrenty left, My wife is going to take it today and see if I can get it rebuilt. Do you think that it was spinning too fast?
 

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Yea, no warrenty left, My wife is going to take it today and see if I can get it rebuilt. Do you think that it was spinning too fast?
They can go to 20K RPM for short periods, 18K continuous. What is your pully ratio? that is what determins the altenator speed.
 

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the links are not working. You just need to know the circumferance of your crank and alt pulleys. If the crank pulley is 12 inches in circumferenc and the alt pully is 4 inch in circumference then your ratio is 3:1 Multiply your RPM * 3 and you will have your altenator speed. you can use a tape measure to measure the circumference.
 

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Discussion Starter #16 (Edited)
tnblkc230wz the links are not working. You just need to know the circumferance of your crank and alt pulleys. If the crank pulley is 12 inches in circumferenc and the alt pully is 4 inch in circumference then your ratio is 3:1 Multiply your RPM * 3 and you will have your altenator speed. you can use a tape measure to measure the circumference.
5"= crank 8,500 rpm is that right? I not to good at math.
1.75"=alt

Sorry about the links i will see if I can get them to work!
 
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