@99sh, Thanks for following up and sharing the solution to the issue. That is why these forums are so useful!
I sell an Electronic Voltage Regulator for Model A Generators. So, my bias here is therefore declared ��.
Like ndnchf, I have tested a bunch of generators and found that they typically put out over 9V until the load matches the output setting of the third brush. After that, as load increases, generator output voltage drops.
The maximum charge voltage for a 6V battery is 7.1volts. Above 7.1V the battery electrolyte starts to gas off. If the electrolyte drops below the level of the battery plates, the battery life will be compromised. The gassing off can also cause battery terminal corrosion. Minimum 6V battery charge voltage is 6.45V so if the generator is putting out less than that, the battery is being drained.
This is why the owner’s manual said to adjust the third brush depending on day or night driving conditions = headlamps on or off. The owners manual also said to regularly check the battery electrolyte.
As electrical loads increased in the mid to late '30s Ford caught up to other manufactures and introduced a voltage regulator. The electromechanical voltage regulator at the time adjusted the current to the field coils to maintain the generator output below 7.2V. It also restricted the maximum current output of the generator to protect wiring and the battery.
Tom Wesenberg designed an electronic voltage regulator (EVR) for the Model A generators (Long-style and Powerhouse) that fit within the generator case. James Petersen also had a similar circuit design that attached to the cover band. James passed a couple years ago. The EVR does the same thing as the electromechanical voltage regulator – regulates current to the field coils to limit voltage output to 7.1V. It works up to the maximum output of the stock Model generator which is around 10 to 12 amps. Tom sold his EVRs for over 20 years until he sadly passed.
I had an alternator on my car and I didn’t like the fact that it required a high RPM to kick in (that is why it has such a small pulley for the Model A). I didn’t like the look of a modern device on my car which I went out of the way to try and keep authentic (but not to be judged (;-). …and I didn’t need over 60A of output as I don’t have a fridge, cigarette lighter, flood lights or run Christmas decorations. I tracked down Tom in 2008, got one of his EVRs, and as everybody that owns one will attest, it has worked flawlessly since. So… I don’t agree that the answer to everybody’s generator problems is an alternator. The Model A generator is dependable, easy to maintain and fix, and as the above conversation testifies, there are a lot of people on the Forums willing to help and gentlemen like Steve (ndnchf) and others who can fix’m for you.
I now sell an EVR based on the same design as Tom’s, with some improvements. I am retired and do this to help the hobby so sometimes I have them available and sometimes I don’t until I build another batch. The EVR circuit design is well known, however, I spent over a year figuring out the components Tom used – which were obsolete anyway. I had a lot of great help from the Model A community along the way – thank you.
Additional details are on the recent “voltage regulator” post on this Forum if you are interested.
Thanks for reading. And as we say in Canada – “sorry”... particularly if I offended anybody.
