Voltage Overcharging Issue
 

Hi Yall,
I'm working on an issue in my 1941 Super Deluxe. Its a 6V positive ground and the battery is Overcharging to 8.3V+. I opened the voltage regulator and it looked sort of burnt and was not adjustable, So I opted to get a new one.
The generator is also the 2brush non adjustable one.
I got the blue cover one (part #51A-10505) and installed it today, but I am having the same overcharging issue. The regulator is very very hot while running and still charging the battery to well over 8V
I tried turning out the screw on the bottom of the FLD relay, but no change.
I can push on the plate and disconnect the relay and the voltage goes down, so I dont think its stuck, but i'm stumped
I followed the instructions the reg came with to polarize the reg by touching the FLD to the BAT briefly and saw a small spark

Not sure where to go from here.

1st pic the old reg 2nd pic the new reg

Re: Voltage Overcharging Issue
 

1st pic the - old reg
https://www.fordbarn.com/forum/attac...8&d=1747780016

2nd pic the-new reg
https://www.fordbarn.com/forum/attac...9&d=1747780016

https://www.fordbarn.com/forum/attac...0&d=1747780016

https://www.fordbarn.com/forum/attac...1&d=1747780016

Re: Voltage Overcharging Issue
 

What condition is your battery in ? What is its voltage fully charged ? Are all cell the same when using the hydrometer ? A weak cell could cause a constant charge , if I remember correctly.
Has anything been done to the generator, like someone converting it to 12 volts ? Where do you live ? I’ve got many good generators if you lived close, we could change it out to eliminate that as a cause .

Re: Voltage Overcharging Issue
 

The battery is brand new. I bought it 2 days ago and the voltage is in the last pic. It was sitting at 6.43 when I turned the car off

Re: Voltage Overcharging Issue
 

it's my understanding (and the reader(s) may well be aware of it) that the OEM voltage regulator in a 1941 ford is essentially a low-pass filter that is designed to dispense with voltages above the safe limit for charging a 6v battery. how it dispenses with voltages above the safe/useable limit varies with the voltage regulator AFAIK, as the methods have evolved through the years. some of them convert the excess voltage and amerage to heat. hence some older style voltage regulators run very warm...by design.

i would think that if the a voltage regulator in a 1941 ford with a flathead engine in it that was letting more than say, 7 volts through was one that may have modified by an owner that invested in the hack of putting an 8v battery in the car and wanted an 8v voltage regulator to match.

Re: Voltage Overcharging Issue
 

I don't fool with 6V much, but in a 12V system, you want 13 +/- volts going to the battery to charge it. This isn't the same principle in a 6V system?

Re: Voltage Overcharging Issue
 

My understanding of recommended charge setting is the nominal system voltage plus 20%. So 6 volts X 1.2 = 7.2 volts. 12 volts X 1.2 = 14.4 volts.

Re: Voltage Overcharging Issue
 

yes as Alan noted, charging voltage is 10-20% (it varies depending on a number of battery characteristics, as i understand it) higher than the nominal voltage of most batteries.

for those that are interested...it is quite common for a generator to supply (unless some action is taken) less than the required charging voltage, while at idle for instance, to the voltage regulator. in that event, so my research has shown, the voltage regulator uses its "field" terminal connection to the generator to raise the generator's output voltage to the proper charging voltage for the battery.

IOW, the voltage regulator is constantly tweaking the generator to emit the proper charging voltage if the voltage is too low, and removes voltage that is too high by either converting it to heat or shunting it, it some cases, to ground. some more modern voltage regulators (usually connected to alternators rather than generators) actually convert excessive voltage to the proper charging voltage so as not to waste power.

the voltage regulator also monitors the battery's charge (for the google tells me so :)) and will sense when full and stop current flow to the battery altogether.

Re: Voltage Overcharging Issue
 

This definitely seems correct based on what i have read as well, but It seems like the generator is always running and the field terminal is always "on" and therefore always charging the battery at max which is how we get the ~9V at the generator and ~8.4V at the battery... now how do we fix that

Re: Voltage Overcharging Issue
 

I did consider this, but the voltage regulator I put in is a new 6v regulator and the battery is also a new 6v battery. Not sure if there is anything else that would cause it to run closer to 8V

Re: Voltage Overcharging Issue
 

A digital voltmeter may not read correctly due to the amount of static the early flatheads put out. Suggest using an analog voltmeter.

Re: Voltage Overcharging Issue
 

i might suspect that it doesn't work properly, or double and triple check the voltage necessary to charge a 6v battery. and verify, as mentioned, that the measuring apparatus and methodology is correct.

might not be a bad idea, to measure someone else's similar car (assuming one is available) using the same methodology and apparatus and compare.

BTW, Google's AI response to the output of an OEM 1941 Ford voltage regulator is all over the place, depending on how one phrases the question. in some instances it clearly states that it is 6v and in other queries where the word "charging voltage" is used, for instance, it makes it clear that a charging voltage needs to be closer to 7v.

i've learned to beware of Google AI responses. WRT verity they should probably be viewed as Sir Winston said, "...not the end, nor the beginning of the end, but rather the end of the beginning..." ha

Re: Voltage Overcharging Issue
 

Not sure if this has been mentioned above but you don't adjust anything by turning screws. You have to bend the tabs where the springs attach. Now I must state that my experience of success has been very poor. If anyone has specific instructions of which tab should be bent, in which direction and how to test it I would be all ears.
Mart.