>I performed my first engine run in my RV-4 the other day,, and all went
>very well, except for a problem with excessive (excessive to me anyway)
>voltage. I have a standard, "Vans-issue 35amp alternator with a sealed,
>solid state voltage regulater,,, again, from Vans. I am using your crowbar
>OV protection module and I have a standard setup of a split-type master,
>with a field circuit protected with a 5amp breaker.
>
>The voltage ranged from 15.1 to as high as 15.8v. Now, I only ran it twice
>for five minutes per run so I didn't allow myself to much time for
>troubleshooting.
>I am fairly confident in the reliability of the voltmeter, curtesy of a
>VM1000 which shows a "normal" bus voltage of 12.3 with the engine not
>running. Correct me if I am wrong, but I believe your OV module triggers at
>16v?? In any case, the field breaker did not trip but this still seems very
>odd to me as the regulator is pre-set at the factory at 13.8v,, or so I
>have been told.
A regulator can be confused into believing that the bus voltage
is too low and causing the system voltage to run too high. This
happens when there is excessive voltage drop between the alternator's
output terminals and the regulator. The problem is generally caused
by undersized wiring.
You're correct that our OV modules are set for 16.0 to 16.5 volts
with 16.2 being the room temperaure nominal. The readings you were
getting are too low to cause the ovm to trip . . . but getting close.
Do you have a voltmeter with some long leads? There are a couple of
measurements that would be good to know:
While the engine is running and the VM1000 is reporting a high
bus voltage, what is:
(1) voltage at the regulator's input and ground terminals?
(2) voltage across the battery posts?
(3) voltage from alternator b-lead and alternator case?
If all these voltages are within a few hundred millivolts
of the VM1000 reading, then the regulator is bad. If the
regulator input voltage (1) is 13.8 and other voltages
high, then we need to diagnose some excessive wiring or
ground voltage drops.
Bob . . .
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