Charging woes

37 Cab

37 Cab

Well-known member
My 37 has a 2 brush generator and a voltage regulator. Generator mounted fan. It will only charge 6.7 volts with the battery connected but charges 7.2 with the battery disconnected. Having trouble starting hot. I called Whitney`s about an alternator conversion. Talked to Tom. Apparently His dad has passed and now Tom has been diagnosed with ALS. He said he has two to do then he is most likely done. He said the shaft diameter is different between the 2 and 3 brush generators so i am not sure what I have since it is a 2 brush but has the fan mounted to it. I feel like my generator is not putting out enough amps to keep up. Any help would be appreciated..
 
It would help if you explain how and where you are testing this voltage. You should not test anything with the battery disconnected. A fully charged 6 volt battery at rest should read about 6.3 volts. Generators do not charge at engine idle speed. To test generator remove the regulator field wire from its terminal and connect it over to the armature terminal on the regulator. Connect test voltmeter between a good ground and regulator armature terminal. Rev engine up to 2000 rpm plus and hold for one minute. A good reading should be 7.3 to 7.5 volts DC.. If it is under 7 volts then the generator is faulty and needs repair. Please report back. Regards, Kevin.
 
Original 1937 Fords had a three brush generator with a round cut out on top of gen. No voltage regulator. Your car has been modified to a later two brush gen and a voltage reg. Regards, Kevin.
 
Thank you. I know it has been modified. I was testing with my volt meter connected to the regulator battery terminal and ground at 2000 rpm. I will test it as you recommended and report back. Thanks again.
 
37Cab
Contact Steve Blancard here on the barn NDNCHF. He is "THE" man on generators, send it to him and he will fix it up right, generator and cut out. When you get it back from him its better than new!!!! AND If you don't have the correct generator and cutout for your 37, he most likely does!!
 
With the field connected to the armature it charges 7.5 volts. Checking at the battery with wires connected normally it only shows 6.6 volts. If I drive it until up to temp it will not start. Starter is new 2 years ago and has a heat blanket on it because my Fenton cast iron header is close. I’ve checked all my grounds and added an engine to frame ground. Thanks for the help guys.
 
What is the battery voltage when you are trying to start it
when it is up to temperature as you crank?
 
I can 2nd what was said above about Steve Blancard. He just rebuilt 3 generators for me. He does a thorough video explanation; tear down diagnosis on each one and then sends more info when he’s done. I learned a lot about them, and frankly he redefines the term “Rebuilt” for me. His level of service and workmanship is on the next level. Here His email address is, as he communicates by email; splitdorf@cox.net
 
Sounds like there resistance somewhere in between the generator regulator and battery. Or it could be the regulator. There’s good tests we used out of the ford supplement service forum booklets that helped us to track a similar situation I had. Turns out it was the backside of a brass bus bar between the two circuit breakers under the dash that was badly corroded.
 
I haven’t checked but if it’s only charging 6.6 I can’t imagine it would be fully charged. I can charge the battery and a week later it cranks fast.
 
I would suggest that the battery may be tired and it should be load tested by a good auto electrician. A faulty battery can hold the voltage down. At 7.5 volts on your test with the regulator bypassed the voltage should have got over 8 volts. Otherwise a high resistance in the wiring somewhere. Check your ammeter connections and the starter solenoid terminals. Regards, Kevin.
 
Thanks Kevin. The voltage was climbing so maybe I should test it again. You may be right on the battery. Charge volts at 2000 rpm go to 7.2-7.3 if I pull the cable off and read voltage at the cable.
 
52flthed said:
Sounds like there resistance somewhere in between the generator regulator and battery. Or it could be the regulator. There’s good tests we used out of the ford supplement service forum booklets that helped us to track a similar situation I had. Turns out it was the backside of a brass bus bar between the two circuit breakers under the dash that was badly corroded.
Click to expand...

I ran a 12 gauge wire from the regulator battery terminal to the battery with no change.
 
It sounds like the generator is charging. A fully charged battery should resd about 6.3 - 6.35 volts. You are getting 6.6 to 7.2 volts at various locations.l, which indicates the generator is working. I suspect either high resistance in ground connections or a tired battery. As suggested, have your battery load tested at a FLAPS.

Steve
 
ndnchf said:
It sounds like the generator is charging. A fully charged battery should resd about 6.3 - 6.35 volts. You are getting 6.6 to 7.2 volts at various locations.l, which indicates the generator is working. I suspect either high resistance in ground connections or a tired battery. As suggested, have your battery load tested at a FLAPS.

Steve
Click to expand...

I agree with this, and will add one more thing. If it proves out bad, buy the new battery from them; don't just say "Thanks" and drive away to the nearest discount outlet. These people provide a lot of service to the community and we should support them or they will disappear. Prices are usually right in line as well. I am considering a new 6 volt Optima for my '51; not because of any problem, but because it's 13 years old. To my surprise, the best price I could find anywhere was my local NAPA.
 
It was the battery. 6.2 volts fully charged but failed the load test. I know new cars but the old stuff is a learning curve for me. I’m grateful for this forum and all the help I get here! Thanks guys!!
 
Ive been waiting for that question to be answered. I might add that I would not think that every auto parts store was the best place to have a battery load tested. An auto electrician would be best, they have the training and experience. Regards, Kevin.
 
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