[Joe K]

Unrestrained by a battery, a Model A generator will put out up to 32 volts.

Of course many who have issues with the battery connection and find it goes "open circuit" frequently find their headlights and a whole bunch of other bulbs suddenly "burned out." That 32v will do a number.

8V batteries will work just fine if everything else around it is designed for 8 volts. Last I checked, 8 volt light bulbs were pretty much restricted to 9 volt lantern battery spotlights. With the new world of LED headlight bulbs which work fine on 6V or 12V, they'll probably work fine on 8 volts too.

And your starter motor compared to operation on 6V will sound quite "perky" on 8 volts since it is 25 percent higher voltage. If that is your goal, you can use 12V battery with a stock Model A generator and your stock starter will sound REALLY perky at 12v. And you can consider your 12V incandescents bulbs even brighter than 6v 32cp bulbs - which they may be being a modern bulb.

Its all a matter of what you want to do. 8V cell batteries can still be found. NOT like 6V batteries though and you may have to settle for a case size somewhat different than the Model A. 8V Batteries probably more plentiful than 8V bulbs. Might make for a short 6V bulb life unless you have some sort of "dropping resistor" planned.

I myself have stuck pretty much with 6V. Except for that one time I "jumped" the Model A from my regular car - Model A headlights OFF.

Joe K