6volt alt with a 8 volt battery

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Schweck1914
Posts: 15
Joined: Mon Jan 07, 2019 5:25 pm
First Name: Richard
Last Name: Schwechler
* REQUIRED* Type and Year of Model Ts owned: 1914 touring,1914 speedster
Location: Waukesha Wisconsin

6volt alt with a 8 volt battery

Post by Schweck1914 » Thu Jan 08, 2026 10:24 am

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


TXGOAT2
Posts: 8335
Joined: Sun Feb 14, 2021 10:08 pm
First Name: Pat
Last Name: McNallen
* REQUIRED* Type and Year of Model Ts owned: 1926-7 roadster
Location: Graham, Texas
Board Member Since: 2021

Re: 6volt alt with a 8 volt battery

Post by TXGOAT2 » Thu Jan 08, 2026 10:38 am

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.

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