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Old 03-27-2017, 03:31 PM   #26
ShinyC10
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Re: Alternator

....if I remember correctly, the volt reading on the alt stud should be the same as the reading on the battery correct? I'm getting .4 volts lower at he battery at idle
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Old 03-27-2017, 08:25 PM   #27
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Re: Alternator

You could see a slight voltage drop depending on how many things are using power at idle speed. If you raise the rpm to 1500-2000 and check it your alternator output should keep up with all loads and be about 14 volts at the battery.
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Old 03-29-2017, 03:28 PM   #28
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Re: Alternator

Somebody please correct me if I'm wrong, but I think that the only thing that can cause voltage drop between the alt and battery, at any rpm and load, is resistance in the wiring (including connectors) between the two. To me, a drop of 0.4 volts sounds a little high, but instead of worrying about the difference, I would first measure voltage from the battery + post -- NOT the connector on the cable -- to ground at starterman99's 1500-2000 rpm. If that voltage is at least 14.1 (some might say 14.2 or 14.3), then everything in the charging system is working: alt, voltage regulator, wiring, connectors and terminals, even the belts. It would be nice, but not necessary, to see that much voltage at idle. It's necessary to see that much voltage with everything turned on and at above-idle rpm, if your alternator output is enough to run all the loads at once. Which it should be.
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Old 03-29-2017, 03:37 PM   #29
ShinyC10
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Re: Alternator

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Originally Posted by lsversaw View Post
Somebody please correct me if I'm wrong, but I think that the only thing that can cause voltage drop between the alt and battery, at any rpm and load, is resistance in the wiring (including connectors) between the two. To me, a drop of 0.4 volts sounds a little high, but instead of worrying about the difference, I would first measure voltage from the battery + post -- NOT the connector on the cable -- to ground at starterman99's 1500-2000 rpm. If that voltage is at least 14.1 (some might say 14.2 or 14.3), then everything in the charging system is working: alt, voltage regulator, wiring, connectors and terminals, even the belts. It would be nice, but not necessary, to see that much voltage at idle. It's necessary to see that much voltage with everything turned on and at above-idle rpm, if your alternator output is enough to run all the loads at once. Which it should be.

I guess I forgot to include the voltage numbers I got from multimeter. The battery at idle was reading 14.22 but at the alt stud was reading 14.62. Again, this was at idle
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Old 03-30-2017, 03:21 PM   #30
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Re: Alternator

Given you.r reading of 14.22 volts at idle, I'd say your entire charging system is working great. The only thing I would worry about, IF you have high-amp add-ons like electric fans and mega-watt stereo amplifiers, is whether the alt is putting out enough amps to cover worst-case everything-on amperage requirements.
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Old 03-30-2017, 06:20 PM   #31
ShinyC10
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Re: Alternator

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Originally Posted by lsversaw View Post
Given you.r reading of 14.22 volts at idle, I'd say your entire charging system is working great. The only thing I would worry about, IF you have high-amp add-ons like electric fans and mega-watt stereo amplifiers, is whether the alt is putting out enough amps to cover worst-case everything-on amperage requirements.
No electric fans here but I have a couple amps but nothing crazy. One is a 600 watt and the other is a 200 watt
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