6volt alt with a 8 volt battery

[Schweck1914]

Will a 6 volt alternator putting out 40 amps charge a 8 volt battery...

[TXGOAT2]

Probably not, or not very well. The regulator on a modern 6 volt alternator would probably sense the 8.5 volts at the battery and assume the battery was fully charged whether it was or not. A Model T generator will charge an 8 volt battery, since the T generator has no automatic voltage regulation, though it's not a very good idea. A modern 6 volt system will provide about 7.5 volts, and a modern system designed for an 8 volt battery will provide up to 9.5 to 10 volts. (If one exists) The best solution is to use a good 6 volt battery and a stock T generator with a modern voltage regulator added. If your starter is bad, fix it.

[Jeff]

Everything Pat said is accurate. Its not the current that matters - its the battery voltage the alternator "thinks" its trying to charge, in your case 6v. Alternators are not adjustable.

FYI, my 6v Model T Voltage Regulator can be adjusted to charge an 8V battery to 100% full- I've done the mod for half a dozen folks with great success. But you need to use a Model T generator for it to work.

Jeff