What was the voltage of the Model T's electrical system?

The Ford Model T’s standard battery-based electrical system was 6 volts.

The Model T’s electrical arrangement was unusual because its ignition relied primarily on a flywheel-mounted low-voltage magneto rather than a conventional modern battery-and-distributor system. The magneto generated alternating current, which fed the car’s trembler coils and produced the high voltage needed at the spark plugs.

Ford did not generally provide or encourage a starting battery on the earliest cars. Electric lighting appeared in 1915, and an electric starter became available in 1919; cars equipped with that system used a 6-volt battery and positive-ground electrical layout. Thus, “6 volts” is the standard specification quoted for the Model T’s battery electrical system, even though the magneto itself produced variable alternating voltage rather than a fixed 6-volt output.

This distinction causes a common mix-up. A 12-volt battery may be fitted to a restored or modified Model T, but that is a later conversion, not the factory standard. The Model T’s original low-voltage design was part of its mechanical simplicity and helped it operate without a battery during much of its early production.