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Alternator Voltage Problem

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Ty

07-15-2003 18:44:56




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I just bought a new alternator for my JD1010. The guy set it up for 14.65 Volts. After I installed it I checked the voltage and it read about 35 volts. I took it back and told the guy about it and he checked it out on his test stand and it read 14.65 volts. I put it back on my tractor and again read 35 volts. I borrowed a better volt meter the next day and am reading about 45 volts with it. The only thing I can think of is that he tested the alternator with it rotating one direction, and it goes the opposite direction when installed on the tractor. Would this make a difference on the output? Am I missing something else here? I measured the discharge voltage at the lug with nothing else hooked up to it, similar to what was done on the test stand.

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Ty

07-17-2003 02:57:46




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 Re: Alternator Voltage Problem in reply to Ty, 07-15-2003 18:44:56  
I hooked the alternator up to the battery, started the tractor and then checked the alternator voltage under load and it works fine as you all expected. Thank you! Ty



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John T

07-16-2003 07:06:48




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 Re: Alternator Voltage Problem in reply to Ty, 07-15-2003 18:44:56  
Ty, Definitely YES. That alternator needs the battery load hooked to it to operate and accurately regulate its output voltage. Hook her up and try and post back, but my guess is it will regulate properly once you do that. Good Luck John T



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Bus Driver

07-16-2003 04:22:59




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 Re: Alternator Voltage Problem in reply to Ty, 07-15-2003 18:44:56  
I make it a practice never to run an alternator without a battery connected. Many alternators will suffer damage to the diodes with an uncontrolled open.



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Lee

07-16-2003 02:02:13




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 Re: Alternator Voltage Problem in reply to Ty, 07-15-2003 18:44:56  
What Clooney said. Test stand may not have spun it up as fast and/or two wire connection may have been wired differently. Feild coil will act as a load somewhat so for a range of RPM, voltage will stick at 14 for a while. Exceed that critical range and voltage will rise execessively without a real world load such as a lead/acid battery to charge. I'm betting that he had a load somewhere and you just didn't notice it right off? Rotation direction should not make a bit of difference.

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Clooney

07-15-2003 19:00:11




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 Re: Alternator Voltage Problem in reply to Ty, 07-15-2003 18:44:56  
Ty, open circuit voltage is not a good measure of an alternators output. It really needs to charge into a load to settle down & achieve a constant regulated output. Hook the battery(s) into the system & re-check the output [hot & at fast idle].
~Rotation direction isn't usually a factor with an alternator.



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