Re: check voltage regulator

Karl Townsend wrote:
I've just purchased a 30 year old gasoline engine forklift...

I note that the machine never seems to go off fast charge, by the machine's A-meter. This is the old style voltage regulator style unit. I know nothing about them. Are there any easy checks to know if the regulator is working correctly?




If it's a 6 or 12 volt battery and a "real" DC generator, not an alternator, then:

Put a good voltmeter directly across the battery while the engine is running and you are seeing the ammeter showing a high charge rate.

If you read less than about 7.2 on a 6 volt system or 14.8 volts on a 12 volt one then the battery isn't yet fully charged and the high charging current is just trying to charge it.

How olde is the battery? It may be a junker and never really reach it's full charge voltage. You can test that by charging it for a good long time with a line powered charger.

I don't recall any "easy" way to "prove" an old style voltage regulator is OK and adjusted properly. Many of them had screwdriver adjustments inside which changed the tension on springs. If someone who didn't know his ass from his elbow got inside and F'd those adjustments up they'd have to be reset. You'd need a high current variable voltage source, a variable high current load resistor and decent voltmeters and ammeters to be able to do a thorough "bench test" of one of those beasts.

Most of those old regulators had three relay like devices in them. One was a "cutout" which opened the charge path to the battery when the engine was stopped, so the battery didn't try and motor the generator, burning something up. It could be replaced by a hefty solid state diode nowadays and accomplish the same thing.

The second was a voltage operated relay with normally closed contacts which opened the field supply to the genny when the output voltage got high enough to mean the battery was fully charged.

The third was a current operated relay with normally closed contacts which sensed the genny's output current and opened the field supply to the genny if that current got higher than the sytstem's design limit.

I recall seeing some "Two relay" voltage regulators where the functions of the voltage sensing and current sensing relays were combined into one relay with two coils on it.

Thas' about all I recall about them.

If it's an alternator system with a separate voltage regulator ask a youngster. <G>

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
"Rudeness is the weak man's imitation of strength."
.

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