Reply To: 1957 Evinrude Big Twin Electric Start Hoods

[David Stanton]

A 12 volt battery should work good with a 6 volt starter. The starter current does not double like a resistive load would due to the complex inductance of the motor spinning. Just don’t crank forever if it’s not starting. It is very common practice on old 6 volt cars to use the same starter on 12 volts, and that is working out fine on my ’51 Buick that I converted to 12 volts. All you have to change is the starter solenoid and either change the choke actuator solenoid to a 12 volt one, or put a resistor in series with it of equal resistance to that of the 6 volt choke solenoid coil. Minimum power rating (watts) of the choke solenoid’s added resistor is critical. The power rating needed for the resistor must be greater than “6 volts squared divided by resistance”, or 36/R. I measured that resistance years ago, but don’t remember what it was.
Dave