John T, someone, explain this electrical

I was born farming. I must be fairly good at it - I'm still at it. I tackle most repairs myself unless my back dictates I can't lift it, etc. There is one thing I need explained, because I just don't get them (I'm a little embarrassed to say). Charging cutouts.

I know old tractors had them and in some cases (my old red machines which are now 12 volt) they were integral with the lighting so you got everything charged. That's not really my area of question. All of my big machines are way too new for a cutout. I'm talking about old cars.

So I use the old 35 Chevy 1.5 ton for chores and stuff. It has a cutout on the original generator. When I start it the amp gauge goes over to maybe 10 amps (12 amp generator) - depending on RPM. The truck does about 50/50 driving and idling, so when it is just idling, I pull the throttle enough so that it shows at least some charge at all times this time of year. There's no heater in it, but the lights are on a lot and starting that big engine in zero degree weather isn't easy.

I get that the cut "in" is at a high enough voltage and cut "out" at a low voltage to keep from having a short to ground when the truck is shut down. I think I have that the right way. Anyway, here are my questions:

Should the truck always charge full tilt at a rate determined by rpm or does it sense that the six volt battery is topped off like a regulator? Should the rate vary with all of the lights on? When I turn them all on I see it charge about the same rate (the amp gauge is hooked and working correctly as far as load side, etc). With the old tires I'm running it only does chores around the farms, but with new tires I might run it to the coop on a nice day for grinding base. Should it charge the same rate the whole time? If this were the case I guess I need to be watching the cells in the six volt battery for water needs. How would an Optima-style handle a cutout if this is the way they are to work?

I get it was different technology but how does it really work (other than acting like a switch to disconnect the battery wire once the generator isn't spinning anymore)? It clearly works fine as the old truck always starts and has never needed a charge. I'm just wondering what that amp gauge should be doing when the truck runs for an hour or something.

The way I understand it works, though a little before my time...

The cutout is only there to prevent the generator from drawing the battery down when stopped or turning too slow to make power.

The voltage is regulated inside the generator by a 3rd brush that limits the output. Some are adjustable by moving the brush slightly.

So when the battery voltage reaches the preset voltage of the generator, it will drop back on the output amps. But since there is always some draw from the ignition and any accessories, and chances are it gets started a lot being used off road, it will always show some level of positive charge.

And yes, they did tend to need the battery level checked. But again, being driven off road, you don't want to keep so much water in the battery that is wets the top from splashing. Just keep the plates covered.

In most simple voltage regulators you will see two sets of coils/contacts. One is the cut out, just like your cut out. Before staring, these points will be open, preventing the generator from drawing on the battery. Power from the generator should pull these points closed upon start up. The other set is the regulator, and these points will be closed, under spring pressure. As you start up and get some charging, the coil vs the spring do a delicate dance to "regulate" voltage. So delicate, your eyes can't work fast enough to see it.
Any simple cut out systems I'm familiar with on older tractors have a low/high switch, along with the adjustable third brush generator, giving you some choice based on how you use the machine.

Good thoughtful questions, not sure I can give any exact answer not knowing the cutout or voltage regulation circuitry (to whatever if much of any extent) your old chevy has.

The very early systems used ONLY a cutout relay that works basically as you suspected which closed when the genny reached a pre set voltage (to charge battery) then opened at lower voltage (so battery didn't reverse discharge thru genny). It has in and out voltage settings and the contacts can become resistive or burned which affects charging LOT OF VARIABLES

On those early systems many were three brush gennys which had an adjustable third brush so you could regulate the max charge at high RPM so the battery didn't overcharge and boil out the acid (That may be what you have???????????) IN addition some tractors used a manual LOw/HIgh switch (maybe part of the light switch) for low or high charging settings. Low maybe for day use at high RPM and High for night use when lights are on and/or a lot of low RPM use

Later systems had a more sophisticated and better regulation using a full fledged Voltage Regulator which in addition to a cutout also regulated field current flow for more precise charging. The early ones had one additional relay which was a combination Voltage and Current sensing regulator while others had TWO extra coils, one for voltage regulation and a separate for current regulation.

NOW FOR HOW YOURS IS WORKING it sounds like its doing all it can based on its early simple basic operation method. Charging depends on RPM,,,,,,,,,,Belt Tension,,,,,,,,,Battery condition,,,,,,,,,,Genny condition including BRUSHES and tension and commutator. I don't think I can give any exact answer as to HOW IT SHOULD WORK since it depends on battery voltage and third brush location and the cutout relay contacts and the voltage in/out settings

Stabilization is improved if the brushes are long enough with sufficient down tension and especially a clean smooth non oiled non carboned commutator and a good tight belt and a good battery. If shes not charging enough adjust the third brush if it has one and its adjustable

Theres more but I'm headed to a bluegrass festival and need to get going, I will check back tonight

John T

Just a thought,does your gen. have a 3rd brush to adjust the charge like the early fords?

Hi, if you want more charge, do you move the third brush closer to the other brush or farther away? I have that system on my Farmall Cub. Ed Will Oliver BC wine capital

The generator will always be putting out it's full ability whether the battery needs it or not. A cutout is just a mechanical diode stopping current from flowing backward to the generator making it a motor. You can buy new cutouts that look original but do use a diode inside. A generator may be able to be adjusted for output. There also is a design max output for a RPM. Going over that RPM the output will retard some. Good battery connections are a must or the generator will burn up.

In my really younger days I asked my Dad why he turned on headlights in daytime on his 35 & 36 model cars. He said generator was set to keep full charge for short trips, but run lights if over 30 miles to keep battery from overcharging. Said he didn't have to do that anymore when he got modern & bought a 39 model car.

HTH
Willie

You move the 3rd brush closer to increase the charge.

"Should the rate vary with all of the lights on? When I turn them all on I see it charge about the same rate (the amp gauge is hooked and working correctly as far as load side, etc)"

If the system is wired correctly the ammeter will only show charge_discharge current in and out of the battery. The ignition and light source is connected at the generator input to the ammeter so as long as the generator can maintain both the battery charge and ignition_light demand the ammeter reading should read the same with lights on or off.

You are on track about the cut out.

The box we call a "regulator" is really a limiter and not a regulator. A true regulator maintains either constant voltage with varying current, or constant current with varying voltage.

Do an internet search for "1952 Battery Side of Voltage Regulation". it is a Delco Remy manual that explains the interaction of the battery, cutout, and "regulator" as a limiter. You should find a downloadable version listed.

Hi, if you want more charge, do you move the third brush closer to the other brush or farther away? I have that system on my Farmall Cub. Ed Will Oliver BC wine capital

Sounds to me like you already have it figured out. Yes the cut out is just an on/off switch. No it doesn't monitor the battery. Charge rate varies by rpm's & nothing else. If my memory is correct(CRS) the engine ignition system is using about 5 & 1/2 amps while running. That leaves you with 4 & 1/2 amps charging the battery when the genny is maxed out. Pull the lights on and you're using all 10 amps at least. Don't have a clue how you gauge is hooked up but it isn't giving you an accurate reading on what's going back to the battery. It's just telling you how much the genny is putting out. That may be the way all cars were wired in the thirties. If it were wired like a tractor you would be showing a slight discharge any time you weren't at full throttle with the lights on. Yes I would keep a close watch on the water level and I woulden't consider an Optima. It might work but I woulden't trust it to not go BOOM.

You asked the same question earlier and I said move it closer.