Generator charging revisited

V

vern hodgson

Well-known member
Ok, using a digital voltmeter, set on 20v dc. Wiring disconnected output side of cut out reads 8+ volts. Connecting wiring to cut out to check voltage the volt meter goes bannanas. What is going on
 
The generator can put out 20v and yours goes nutz probably because of the 'dirty' signal. An old analog meter will probably work.
 
Another option is to add a capacitor across the DVM leads. A condensor normally used for the ignition can be used. If you use another capacitor make sure it is installed correctly. An electronic capacitor will have a negative and positive side. You can just leave it installed if you want because it will eliminate most electrical noise coming out of your generator. You may be able to hide it inside the cutout or you can just install it anywhere, like inside the instrument panel. Just connect the capacitor between the lead coming from the generator to ground.
 
I have to assume this is a 3-brush model A type generator. This type of generator gets it's voltage sense from the battery since there is no voltage regulator. It may be easier to check voltage at the battery terminals when using a digital unit. The system connections all have to be tight to get a good reading. Any loose connections and it will be intermittent in operational indications.
 
Do not run a generator with output connections open. With no load it tries to produce infinite voltage. (And burns out.)
 
The DMM will also pick up RFI from the ignition system causing it to go nuts.
 
Last edited:
vern hodgson said:
Oops, hope didn’t damage it, ran less than a thirty seconds or so.
Click to expand...

Should take longer than 30 sec for damage. But the field coil wasn't happy about it nonetheless.

If you're trying to check generator voltage out, probe as close to the battery as you can get. It's a great noise filter.
 
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