Can you Convert to a 12-Volt System Question

I’ve owned Model A’s for 40 years and recently purchased a beautifully restored 1930 Model A De Luxe Coupe with a 12-volt alternator that reads 12-volt negative ground. The car starts easily and spins over fast, but I suspect the wiring is still set up for a 6-volt system. Can you convert to a 12-volt system without changing the wiring? If so, do the bulbs need to be 12-volt as well? I’m not confident with electrical work. Will the stock wiring be sufficient for 12 volts? (Joe Todaro, Bedford Hills, New York)

Answer: The auto industry transitioned to 12-volt systems in the 1950s to reduce manufacturing costs. When you switch to a 12-volt system, the current (amps) required decreases while maintaining the same electrical power (watts). This reduction in current allows for smaller wire sizes, which saves money.

The original wiring in your car, designed for a 6-volt system, is actually heavier than necessary for a 12-volt system, and this doesn’t cause any problems. Typically, light bulbs are also changed to 12-volt versions during such conversions. This change can affect other components like the horn and ignition coil. They would either be rewired for 12 volts or have voltage reducers installed to maintain a 6-volt output.

To fully understand what was done during the conversion, it’s advisable to contact the previous owner for specifics on the modifications made. – Chuck Christensen, 2011 MAFCA Technical Director – posted 12/10/11