Looking for some insight. My 49 merc is still running the 6 volt charging system. I had the generator tested by the local old timers and said it charges just fine. What I’m running into is that with the headlights on the car isn’t charging, after about a 20 minute drive home with the lights on the car has to be jumped the next time I try to start it. Without the load of the lights the generator will keep the battery charged. My initial thought was the dimmer switch but I haven’t had a chance to investigate. Any insight? Also! The lights stay bright the entire drive
Do you have a voltmeter? If not, you need to get one or a friend with one. With the car running at a fast idle, say 1000 rpm, measure the voltage at the battery. It should be about 7.5 volts. Now, turn on the lights and see what it does to the voltage. It should stay around 7.0 volts or at least 6.8. In order to tell you what to do next, I need to know those voltages. My guess is that the initial reading is barely above 6.6 volts and drops below that when the light are on. However, that may not be the case.
I've had cheap multimeters around here that won't hardly work with a running flathead. Long leads help.
That has always been the rub with a generator, they often don't put out enough amps to recharge the battery when you have a draw on the system when running. That is especially true if you have a lot of slow going or stop and going and don't get much speed with the headlights on. You need a constant 1500 or more rpm for it to charge efficiently with the lights on.
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