Generator / Charging issue

[JOES31]

Background info is: 6 volt generator with a New Rex diode
cut out. Battery is 3 years old seems good.... 3rd brush
all the way up, (lowest charging possible). Grounds are clean.

Problem: When daytime driving (high idle +) the voltmeter I have on the battery will keep going up all the way to 8.3. Come to a stop, and it goes
to around anywhere from 6.5 to 7.2. Back on the gas and she starts climbing up again.

Night time driving is good. Tops out around 7.4. ( I use LED headlight's)

Amp gauge is around 6-9 amps driving in the daytime. Thought that
was what we strived for. Car has sat for 3 hours, volts at the battery shows 6.56.

Can a tired battery cause this?

It' s like I said, 3 years old, car is started once a month. Sorry for so much info, just trying to present this with as much info to help this.

 

[David R.]

I’m new to model As. Working on AA project. I rebuilt my generator and with 3rd brush about halfway it would peg 20 amp meter. Not sure how accurate these amp meters are, but I moved brush almost all way up and get about 7-8 amps at fast idle. Had to adjust cut out so it cut in at lower rpm. Is your battery overcharging?

 

[JOES31]

I’m new to model As. Working on AA project. I rebuilt my generator and with 3rd brush about halfway it would peg 20 amp meter. Not sure how accurate these amp meters are, but I moved brush almost all way up and get about 7-8 amps at fast idle. Had to adjust cut out so it cut in at lower rpm. Is your battery overcharging?

That's what I'm trying to figure out. The question really is can a weak/bad battery cause this situation?

 

[eagle]

At 6 amps of charging that is too high of voltage. Are you using an analog voltmeter? Have you checked it against a known good voltmeter? Is the electrolyte level up where it belongs in the battery? If all above is good, you could have a bad battery, but if so you should noticed reduced cranking ability. Try cranking it with the ignition off, does it seem to hold up OK?

 

[nkaminar]

You can take the battery to an automotive store to have it load tested. As others have stated, check the electrolyte level if the battery has removable caps. If the LED head lights provide 7.4 volts, then you could drive with the headlights on. This will provide another layer of safety too.

 

[Dino's A]

Last night I took that New Rex cutout off & put back the older
diode cut out. No more high voltage problems. Old one runs
a bit low and thats reason why I changed it out in the first place.

Daytime running tops out at 6.9. Night time around 6.4.

Battery is still good & strong.

This whole thing started when I installed the logo lites LED headlights and at idle
one of the lights would flicker a bit. Both bulbs did it when swapping them out to the other side, so not a defective bulb. All connections are good, tight, clean.

I'm most probably going to install a Powermaster alternator, and that should
power & regulate the car much better. nkaninar-you are right, I could of just run the
car with the lights on all the time, safer of course, but I want to solve the problem
first and then I have the option of lights on or off.

Thanks to you and all that helped me-
Dino Falabrino
I appreciate all the help folks!

 

[Badpuppy]

I don't see much of a problem. 8.3V should be ok for a short time after starting. (Battery hydrates above 7.8V.) If coil is connected to the battery side at the firewall (28-29) then ammeter will show generator "charging" the coil as well as battery. If connected on generator side (30-31) then it should show only battery charge of 1-3 amps.

Nominal battery resting voltage is 6.3V. I would say 6.56 after only 3 hours indicates a healthy battery.

The older diode c/o may have some internal resistance causing the difference.

 

[rotorwrench]

The three brush generator was not the best unit for all situations. When adjusted for mostly day time operation, 6-amps was about as high an output needed. Any more than that will be detrimental to the battery over long drives. The night time adjustment could be as much as 12-amps but the lights have to be on to run it long distance.

The battery sets the overall voltage since it is unregulated. Ohms law takes affect on voltage at high amp output. The higher the amp output the higher the voltage can get. The battery is happy at 7.1 to 7.3 volts but more than that gets the battery in the red zone.

Most owners back in the day either didn't know how to adjust the generator or they just didn't want to. They would wonder why the headlights would start dimming out during a long drive after dark. There was an aftermarket output relay available that would kick in higher amp output for running lights. It would consume the excess amperage during daylight operation. I've heard that these relays would function OK for a while and then the resistor would burn out.

The little voltage regulators made by John Regan, Tom Wessenberg, and others were the best thing for any three brush generator. If any of the suppliers of these are still cranking them out then that's the best way to go. I don't know if James Peterson is still making them or not. The others are out of production.

 

[JOES31]

I don't see much of a problem. 8.3V should be ok for a short time after starting. (Battery hydrates above 7.8V.) If coil is connected to the battery side at the firewall (28-29) then ammeter will show generator "charging" the coil as well as battery. If connected on generator side (30-31) then it should show only battery charge of 1-3 amps.

Nominal battery resting voltage is 6.3V. I would say 6.56 after only 3 hours indicates a healthy battery.

The older diode c/o may have some internal resistance causing the difference.

My complaint was that the more and longer I drove, the voltage kept getting higher.

 

[Badpuppy]

My complaint was that the more and longer I drove, the voltage kept getting higher.

Odd. Generator output power increases with higher rpm. P=EI, so both voltage and current increase, given a constant load resistance. Your readings should follow generator rpm, not time in use. Unless something else is going on - generator heating?