Overcharging?

If you have a poor connection in the charging circuit, then the generator voltage can be too high, even though it won't reach the battery. Where did you measure 8.5 volts?
 
Ok, just sort of an update. The voltage is being measured directly at the battery terminals. I let the battery trickle charge for the last day or so. Checked the battery voltage just as it sat, before starting, and showed 6.6v. This was done with both an analog meter and a digital fluke meter. Both meters showed the same voltage. I then started the car and set the rpms at a fast idle (prob around 1200 rpm). The charging system looked to be working good for the 1st minute. The battery voltage then started to spike. It increased rapidly up to 8+ volts. I removed the cutout and removed the cover to watch what was happening. The points closed when the car was started and never opened until I shut the car off. The cutout I have does not look like anything (internally) like I have seen in anything I've read. It looks cheap and I think I've just got a Chinese cutout. If I adjust the 3rd brush I can peg my amp gauge needle in either direction, charge or discharge. Thanks for all the replies and the help!
 
I read what I just posted and need to correct some things. It's the contacts on the cutout that I watched close and not re-open. The cutout will "cut in" (contacts close) and the gen will charge. It does not "cut out" (contacts open) and stop charging. If I understand this correctly, "cut in" is when it charges the battery and "cut out" is when it stops or when the engine is shut off.
 
The cutout is just an on off switch. When you start the engine the points close
and the generator charges the battery, when you shut the engine off the points
open. The generator is charging the battery any time the engine is running with
the stock system. It does not regulate the charge rate.

Bob
 
Don S. said:
I removed the cutout and removed the cover to watch what was happening. The points closed when the car was started and never opened until I shut the car off. The cutout I have does not look like anything (internally) like I have seen in anything I've read.
Click to expand...

That's exactly how a Model A generator cut out is supposed to work. It is not a regulator. Its only mission is to close the points when the car is running and open the points when the car is shut off. This prevents battery drain when the car is shut off.

In essence, YOU are the regulator by moving the third brush when necessary. When doing a lot of night driving (winter) you move the brush for greater charging (10 amps or so at speed). When mostly day time driving, you move the brush to reduce charging (5 amps or so at speed).
 
You need to move the adjustable brush UP to LOWER the output. So, looking at the generator from the rear, you move the adjustable brush clockwise.
 
QUOTE: When you start the engine the points close and the generator charges the battery, when you shut the engine off the points
open

My understanding is that the generator doesn't actually begin charging until it reaches a certain RPM, usually > 500RPMs. So the Model A cut-out actually cuts in as soon as the ignition is on?
 
ursus said:
QUOTE: When you start the engine the points close and the generator charges the battery, when you shut the engine off the points
open

My understanding is that the generator doesn't actually begin charging until it reaches a certain RPM, usually > 500RPMs. So the Model A cut-out actually cuts in as soon as the ignition is on?
Click to expand...

Once the generator is spinning fast enough to generate enough voltage/current to energize the coil of the cutout, the cutout contacts will close, sending current to the rest of the vehicle's electrical system.
 
Thanks for all the responses to this. My last battery was about 10 years old and I only replaced it because it just didn't have it to crank the engine anymore. I only put water in my battery maybe 1x per year. I understand that the cutout is just that, an on/off switch with no regulation. My amp meter was always at 0 when off, and around 4 when running. Now I'm starting to think the amp gauge is off and I'm putting out more amps than needed. I'm going to try lowering the amps (output) and see how it behaves. Thanks again all!
 
To add to above, there is a very thin shunt wire that sends the current from the generator to ground to prevent the generator from going into melt down when the points are open. The wire is thin enough to do the job but when the points are closed is bypassed and the current to flow through the bigger wire to the battery.
 
A DC clamp-on amp meter is a great tool to have on hand. You don't have to interrupt any of the wiring to get an accurate reading on what is really going on.
 
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