When I installed a generator with a Fun Projects voltage regulator, I went with their voltmeter since I have always felt voltage gives me a better indicator of the over-all charging situation. I make a point to drive the car fairly often so I wasn't terribly concerned about the tiny load from the voltmeter running the battery dead. However, it does sound like a good idea to have a switch, so I wired it with a grounding switch mounted to the back of one of the dash plate screws.
This method met several of my goals:
1. Do Not Drill More Holes In This Car.
2. Avoid nylon zip-ties at all cost.
3. Tell me what I want to know.
4. Keep it as 'period-correct' looking as possible while meeting goal No.3.
Since the car does not have an ammeter, I used an analog DC ammeter in series with the generator wire to set the third brush properly, following Mr. Regan's detailed instructions provided with the voltage regulator. Don't want to burn up that generator!
Best regards. BE
"I went with their voltmeter since I have always felt voltage gives me a better indicator of the over-all charging situation."
Why do you feel that the voltmeter is better than an ammeter?
A voltmeter will give direct reading of the condition of the battery and also tell if the battery is being over or under charged.
An ammeter will only show the charge or discharge rate but does not really tell the condition of the battery.
What the voltmeter won't tell you is that you have a current drain in your system, that is until your battery runs down somewhat.
I can see the battery voltage before I start the car and with all lights and other electrical loads off. Even if there is a very small load on the battery that isn't noticed with an ammeter, I expect I will see a low voltage if it has effected the state of charge as shown in the chart Jim posted (or if the battery itself is no longer holding a charge between drives). Once the engine is running, if I see voltage above 6.5, I know it's charging, and the generator is putting out more than the electrical load from lights, etc.. To be perfectly honest, I'm not sure that 6.5 volts is the magic number, mainly I'm looking for a voltage a bit higher than before the engine was started. Please don't ask me to quantify that 'bit', it's kind of like smut; I may not be able to define it, but I know it when I see it.
Best regards. BE
Thanks for the observations.
Talk slow, think fast.