VCCA Home Forums TECHNICAL - GENERAL Electrical - 6 volt 8 Volt Battery

Ok. I found a document titled Chevrolet Confederate Series BA and Series BB Delco-Remy System. I tried to take a picture of it and upload it here. I couldn't figure out how to do that so I'm typing it out for you guys. I would very much appreciate your comments.

GENERATOR : Model 943-J. Third brush regulation. To adjust generator output, loosen small round headed screw on commutator end plate, take off cover band, shift third brush counter-clockwise to increase or clockwise to decrease charging rate, tighten the locking screw. Rotation counter-clockwise at commutator end. Maximum charging rate 18 amperes (cold) at 8.2 volts reached at 1700 R.P.M.

GENERATOR DATA
Cold Test: Amperes 16-18 - Volts 8.2. - R.P.M. 1700
Hot Test: Amperes 11-13 - Volts 7.55-7.85. - R.P.M. 1750-1850.

These numbers seem to be significantly different from what everyone is telling me.

Please comment.

As stated several times above, since the 943 J generator is unregulated the max. generator output should be 10 amps. The specs. above are used on the generator test bench but on the car the output should be 10 amps max. You can set up your generator to the 18 amps as shown on the spec. sheet but don't expect your generator to last long when the generator armature starts to throw solder and your battery boils because of the constant overcharging. Again, on the 943 J generator 10 amps is max.

The above amps are at the generator proper. If you are going by the ammeter one or two amps are being consumbed by te ignitin so with 10 amps on the ammeter the generator is actually producing 12 amps.Also test is made with generator hot.

Like with any third brush system, you have to adjust the current (via the third brush) in such a way that your battery does not get cooked too bad. What this means in plain English is that you would NEVER set to the maximum rated current. Since there is no voltage regulator you have to pay attention and dial it back, way back.

The goal is to keep the battery full without boiling it. You guess, based on your driving habits. If the battery goes dead or boils,you crank it up or down a little (at the third brush) and try again. No matter what you do it will never be right all the time. Such is life with a third brush.

P.S. If Junkyard Dog says it will overheat and throw solder at something over 10 amps, I believe him, no matter what the book says.

Everything you guys said makes sense. It's one thing to test the generator to make sure it's working properly. It's something else to adjust it so it's doing it's job. I'll set it at 10 amps. I know this topic has been beat to death in dozens of threads. Thanks for the help.

Ok. That was easier than I thought. Third brush set at 10 amps under acceleration. Doesn't seem to matter at what rpm over about 1200 to 1500. It goes to 10 amps and stays there. Drops to about 4-5 at idle. Drops to 0 with parking lights on. Drops to discharge with headlights on. Does that sound right?

Yep, that sounds correct. With the lights on the discharge will vary from -3 to -5 amps at idle depending upon the resistance of the wiring and etc.

Thanks Dog. I feel pretty good about it now. Just one more question and I'll shut up. Doesn't that mean with the headlights on and discharging 4-5 amps the engine is running off the battery and will kill it over time? I do drive the car at night but no more than 10 or 12 miles.

The -3 to -5 amps discharge is with the engine running at idle. At driving speed with the lights on the amp meter should show around -1 amp discharge to 1 or 2 amps charge. On tour guys will drive with their lights on from time to time so that the battery will not get overcharged and boil.

Ok, thanks. And thanks to all.

With a 1-3 amp discharge you can probably drive about three days before the battery is so low the car will not run.

With a much more modern car with 12v, fully charged battery and alternator not charging I have driven for 3 hours at night before the lights were ineffective. I havent been unfortunate enough to need to try this on a 6v system though.
Tony

Teacher: "Children, children, please take your seats. Class will come to order. We're going to have another lesson on Chevy 6-volt generators."

Olsarge: "Teacher, teacher, I have a question. On my 1932 Chevy the tab says 946-C. I know it's not the correct generator. It belongs on a 1936. Is there any appearance or functional difference in the 943-j and the 946-c?"

Teacher: "Very good question. Junkyard Dog, would you please explain the difference between the two generators in both appearance and function? Anyone else can comment too."

Teacher: "Johnny turn around and leave Sally's pigtails alone."

Hey, Teach! Teach!
I can answer that. The original 943J generator was not vented, did not have a fan next to the pulley and only one wire coming out of the case. That wire went to the cut-out. It was the power wire from the generator to the battery. Later generators had vents in the end plates and a fan to move air through the generator. They were capable of higher outputs because the fan and vents kept them cooler than if they were closed. The power output for the 943J was regulated by a "third" brush that was installed between the other two brushes. That brush controlled amount of power to the field coils, therefore the magnetic field and output. If the generator was intended to be externally regulated the wire to the field coils was taken out of the generator to a regulator mounted on a fender, core support, firewall inside the engine compartment or to the light switch. It is the light switch connection that confuses a bunch of people.

Hey, Teach I see the Dog digging up a bone. Nope it is a beer can. Silly dog that can is empty. When he realizes his mistake he will be here shortly. Got to stop at the fire hydrant first.

Hey Teacher!!! Will you get that Dippy Chippy to pay attention in class instead of looking at Laura May's boobs so that he will know what is going on in class? If Chippy would have paid attention like he should he would have noticed that the Mutt was burying the empty beer can and not digging it up because the Pooch drank all of the beer outta the can first! Next the fire hydrant stop to see what is going on there.... that is if the hydrant hasn't been moved since the Dog was there last.

Yep, the description that Dippy Chippy presented above pretty much explains it all. Class dismissed!!

Teacher: "Chipper, you move to the head of the class. Now read all the posts above and tell the class if that changes any of the settings about the amperage output. Should the third brush be readjusted to higher for the 946-c than the 10 amps specified for the 943-j? I'm sure Junkyard Dog will be along soon. I saw him chasing a squirrel up a tree."

Sorry Dog. I guess you came in while I was writing on the black board. For being tardy write "I will not chase squirrels" 100 times.

Teach!
Unless you have an issue with the battery losing charge there is nothing good that comes from upping the output. In most cases 4-6 amp output is far better than higher values. It will keep the battery charged (except for multiple very short trips) and not over charged. Higher outputs will overcharge the battery and reduce its life. Guess the Dog has been "burying" too many cans.

Thanks Chipper. You can skip the test on Friday. You already have an A.

The Pee Dog agrees with the Dipper Chipper........less output is better than more output.

Gotta go bury some more cans.................

Without a doubt we have run the battery down in this thread. The best solution is to use the correct 6-volt battery and correct anything on the car that hinders the correct operation. That will solve most of your problems.

In view of the above I will lock this thread.