Generator questions.

[GComo]

Hello all,
I am the proud new caretaker of an early 30 AA. I have much to learn and look forward to the journey. I have notice that the ammeter in my truck does not seem to show much positive charge. I have tried moving the third brush on the generator and it doesn't seem to change the charge rate. I also tried to excite the generator with no change. Where should I be looking next??

[KimVanOrder]

First; If the battery is fully charged, the amp meter will not show any charge. So, If you have a Volt meter in your tool box, (If not, get one), and check the battery voltage. When a battery is charged with a battery charger / maintainer it gets charged to as much as 7.5 volts. So the truck can run for a long time without any need for the Gen. to 'kick in'. If it is charged, run it down, Lights on, crank engine with ignition off, etc. Once it is down to around 5 volts, start it up and then the Gen. can actually charge the battery. Also when it is running check the voltage at the gen. and see what it is putting out. Should be just over 6 volts.

Let us know how it goes.

KVO

[dhetch]

Hi GComo,
If you have the standard Model A/AA generator, be very careful to not run the engine without the output of the generator connected to the battery. Without a load, a properly working 3rd brush generator will burn itself up.
That said, the standard Model A charging system does not have a voltage sensing control. The third brush is the charging current control. It can adjust from a little output current to a little more. Engine speed is a big factor in generator output; at idle it will put out very little and at cruising RPM it will be a little more.
Through the years many of the Model A's have had the ammeters in the dash replaced by 30-0-30 ammeters and it will be harder to see any small charging rates on one of these. To check your ammeter, with the engine off, turn on your headlights on and see what it indicates. If it does not show a reasonable discharge, the ammeter has either been bypassed or is not working.
If it shows a discharge, still with the lights on, start the engine, run it at about 1000 RPM and the discharge should go to at least a slight charge. If you can't get the starter to turn over the engine with the lights on for a short time, it is probably either the battery or corroded battery terminals. Clean the terminals and charge the battery.
If you still have trouble, get back on the forum.
Good luck!
Dave

[GComo]

Dave,
When I turn the lights on the ammeter shows a discharge of approx10. This is the same wether the engine is running or not. If I rev the engine up to around 2000 rpm the meter gets to around 0 with the lights off. And stays well below 0 with them on.

[dhetch]

GComo,
Have any fuses been added to the circuit? If so, check them first. Do not have the engine running while checking the fuses. If you can't find any blown fuses, again with the engine off, try the horn while you watch the ammeter. If the car is wired correctly, the horn power wire is connected to the generator cutout output connection and you should see a discharge when blowing the horn. If the horn works and you see a discharge while blowing it, you are down to a bad generator cut-out, a bad generator, or both. It is time to take the generator with cutout off and take them to a good auto electric shop for testing and repair if indicated. If the generator needs repair and is original, you might want to ask yourself if you would be better off with a higher output generator or alternator.
If the horn works and you do not see a discharge, you have other wiring issues and need to get more help that I can give you from here. Where are you located? Maybe another forum member is near you and can help you while being able to see the wiring. Stop back on the forum and give us an update.
Good Luck
Dave

[SHELBY MESSER]

To all that is concerned. Lots s s of charging problems can be solved with the fan belt. One thing is belt tight, by tight does not only mean tension around the pulleys, By using the fan blades try to turn engine over(rotate engine with IGN switch OFF) If fan blades rotate, but the crank shaft does not rotate, or if you see any slippage of belt on the crank shaft replace the fan belt. Belts are available at all auto part houses. Bring your old belt and tell you want a (B) belt. I don't know the length, but your old belt will provide the length. Belt problems will cause 95% of the charging problems, battery 2%, relay 2% wiring 1%. This is what I have found in my 56 years of owning and working on A models or Model A s . Shelby, Sacramento.

[GComo]

I removed the cutout and can hear pieces rattling around inside. I will try a new cutout tomorrow and see what happens.

Thanks for the help guys.