Overcharging Alternator?

[CatGuy]

Now that I have the lack of charging behind me....hopefully....it now seems to be overcharging.....maybe. I was able to get it out for a brief drive Saturday. The car lives in the corner of the garage on dollies with two other old cars so it's an unwelcome chore. I drove it for around 20 minutes and it always showed near 15amps charge and never varied much. Turning on the lights will drop it some and with the spark and throttle fully retarded it will go back to '0'. I felt the battery and it was only very slightly warm. The battery is an Optimum. Maybe it takes awhile to charge the battery? The 6v alternator I have came from Snyders.

[TXGOAT2]

If the battery is not in good condition and fully charged, it will take a while for it to reach full charge. Starting the car, if it starts quickly, will not discharge the battery much. Extended cranking will deplete the battery, and require more time to recharge. I would try putting a slow charge on the battery for at least 24 hours or more with a charger-maintainer at about 2 amps or so. Then start the car and run it down the road for half an hour or so. The charge rate on the ammeter may be 15-20 amps for a few minutes, but it should begin to go down after 5 to ten minutes of driving at road speeds. Normal voltage for a typical 12 volt alternator system is around 14.3 volts with the battery well charged and the engine running above idle speed. A 6 volt alternator would probably show about 6.7 to 7.3 volts or close to it. The charge rate and indicated voltage on an alternator on a Model T might be lower than typical, due to the low engine speeds of the T. On an extended drive, the ammeter should indicate a low charge rate, usually under 2 amps. Dashboard ammeters are not known for being accurate or reliable.

[TRDxB2]

The function of the ammeter is confusing you. If you look at a battery maintainer is set for either 6v or 12v and outputs 2 amps for example. It is volts that charge the battery not amps. Amps regulate how long it would take to charge the battery. The Model T ammeter is measuring the load on the system to power things. It indicates the flow of the electricity in the system. So a + reading says that its outputting and a - indicates more is needed. We look to the ammeter as an indication of the flow to or from the battery, but it is the amount of voltage that charges the battery, the amps are what it needs to do that. So you should be okay if the voltage is within spec. Note the system has nothing to disconnect the battery when its fully charged. Optima recomened a maximum of a 10 amp battery charge so the 15amps maybe to much, but with the headlights on and the battery getting charged 15 amps would be the load on the system
https://thebatterybase.com.au/how-to-re ... y-charger/

[TXGOAT2]

The Optima may be be gel type battery. They don't like high charge rates. In this case, I'd try a long charge at low amps, like 2 amps or less, (*use a battery charger/maintainer that can accomodate a 6 volt battery) to be sure the battery is fully charged, then hand crank start the car and observe how the ammeter behaves as you drive it at least several miles. The ammeter should drop back to 3 amps or less in a few miles of driving, even if you use the starter to crank the car, assuming it starts easily. I have a 6 volt Optima battery and a stock generator, which has no regulator. It will overcharge the battery if precautions are not taken. I assume your 6 volt alternator has an internal regulator. If that's the case, it should prevent overcharging, at least with a standard 6 volt wet cell battery. I'm not sure if an alternator regulator designed for a regular wet cell battery will work properly with an Optima type battery, but I think it would. Many alternator rebuilders caution against using the car's alternator to charge dead or deeply discharged batteries. They recommend fully charging the battery before using a newly installed alternator. All connections in the charging circuit need to be clean and tight, and all wiring needs to be of the proper gauge. High resistance connections or loose connections may prevent the alternator regulator from working properly.

[TRDxB2]

From the this web site https://thebatterybase.com.au/how-to-re ... y-charger/
Will my high-output alternator damage the OPTIMA battery?
No, as long as the voltage is properly regulated. Because the Optima battery has a very low internal resistance, it will accept high current more efficiently than conventional batteries.
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Form the optima site https://www.optimabatteries.com/charging

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Again it is the voltage, not the amperage, that is used to charge the battery. So the ammeter is reading the load on the system, the battery being charged is one load and the headlights being on is another. Say 10amps for the battery & 5amps for the headlights = 15amps. Then when you turn the headlamps off it should drop Note the 10 & 5 are assumed values.