For what it’s worth…On my 1601 I got a series /parallel switch from “Antique Battery”” that provides 12v for starting and 6v the rest of the time. Starter turns over great and no more problems. On my 1703 I use two Optima red top batteries in parallel and that resolved a slow cranking problem.
Ron Freeman”
Do you have to manually switch it each time you start the car and
what happens if you forget to switch it back to 6 volts? I hope your
response isn’t shocking!
No.The relay switches the two 6v batteries to series for 12v and then back to parallel for 6v as soon as the engine starts. You don’t have to do anything.