Generator questions...

jjbubaboy

Seems like my electrical system cant keep up at night with the lights on.
I want to check out the output on the Autolite 3 brush generator of my 36T.
It is wired through an Autolite cutout relay versus a regulator.
So, how do I check the output for volts and amps?
I do have an older craftsman analog meter box that I am using as a digital volt meter is picking up too much interference and not
reading correctly.
Do I check across the armature and field posts on the generator?
But that wont tell me the charge to the battery...
Can I check across the terminals of the cut out?
If so, which ones? Bat, field or armature, and which combination?
I believe it is an externally grounded generator, correct? Thats my assumption due to the metal cap on the Field term that
connects the terminal to the body of the generator and it is grounded.
The manual doesnt seem to explain it well enough for an apprentice like me!
If I unbolt the cut out and just ground it with a jumper it would be much easier to get reading off of.
Would that work?
Thanks for any help!
Jeff

PS. I am considering upgrading to a powergen just for the added power and simplicity. And also to keep the appearance of a generator.
But they aint cheap....

DocHornet

I'm no pro on generators, but I believe you should be able to check voltage from the armature post to ground. That will show you what the generator is putting out.

Then you could turn on the lights and rev it up a bit, and check voltage at the battery (i.e. downstream from the cutout relay). If less than 6.5 volts or so at the battery, but armature is putting out more, then it would indicate a relay problem... perhaps just an adjustment in order?

Park_W

Doc is pretty much on target. The voltage is key. Think of the amperage as just a result of the voltage . . . if your wire and connections are good, the battery will be getting charged. Measure the voltage at the "battery side" of the cutout; it should be above 6v at a fast idle, and should be 7v or better at "highway RPMs." Then do the same thing with the headlights on. Should be 6.5 or so at highway RPMs. Remember this is not a fully regulated generator, so voltage is not going to be steady over a wide range of engine speed. If it's OK without a load, and not high enough with the lights on, you can try to adjust the "third brush" in the generator. See the service manual for procedure. Moving the position of the third brush is simply a crude way of adjusting the output power.

Geoff

You can convert these generators to two-brush and use a regulator, or you can simply transplant a later model from preferably a '53-'55 Hudson, Chrysler or Studebaker, with the matching regulator. They just bolt right into place, and you mount the regulator instead of the cut-out. Alternatively there are 6 volt alternators available, but these look obviously non-original. If you prefer to keep the original then you need to temporarily mount a ammeter in series between the B terminal on the cut-out and the starter-mounted connection from the battery, then run the engine at road speed and turn the lights on. If the ammeter is showing a discharge then you have to adjust the third brush to show a 1 or 2 amp charge rate, or else you will drain the battery with prolonged night driving. Be aware though, that this is a fixed-rate charging system, and if you drive extensively during day-time without the lights on for some of the time, you will over-charge the battery resulting in loss of electrolyte.
Geoff

Park_W

And that's why our grandfathers, on long trips, drove with the headlights on. Many of them continued to do so even after well regulated charging systems came along.

jjbubaboy

Ok,
Think I have a little better understanding now.
Thank you, Doc, Park and Geoff!

Jeff

jjbubaboy

One more thing,
How do I determine if my Autolite gen is 'internally' or 'externally' grounded?

Geoff

All generators of that era have separate Field and Armature terminals. Those used with a cut-out have the grounding cap on the field terminal, whereas if you have a regulated system it is grounded through the regulator.

ernie28

What I have done on my Essex is keep the 3rd brush on the original generator and adjusted to have max charge of 22 amps to cover night driving and not overload the generator. Then I also put a regulator in the system so not to cook the battery. Best of both worlds in my view.

Park_W

That's the way the late thirties cars were equipped except for the bottom of the lineup . . . no voltage regulator, but a current limiter to avoid high charging rates that could damage battery or generator.

PAULARGETYPE

PARK MY DAD DID THAT ON HIS 50 FORD ALL THE TIME

jjbubaboy

So Geoff, does the grounding cap make it an externally grounded unit?
Thanks.
Jeff

Geoff

Correct.