Bob, the contacts are now not opening at ANY engine speed. The series winding is simply not doing it's job of throwing out the contacts when the current from the dynamo falls away. I shall pay a visit to my local auto electrician tomorrow. He has a soft spot for old cars and may be able to rewind the cut out if that is what's needed.
As I mentioned before, it is ironic that before I had the cut out restored my only form of voltage control was a simple "hot wire". A heavier gauge insulated wire (it should ideally be nickel chrome) connected between the dynamo and the battery via the ignition switch and resistance calibrated. What was originally intended as a temporary measure but worked faultlessly for 20 years or more.!!
The theory is that as the battery reaches its fully charged state, resistance builds up in the transmitting resistance wire, which as suggested, heats up in a controlled manner. As the wire warms, the current to the battery slows. The dynamo is protected in the same way as the battery; by resistance slowing the current flow. The only thing to remember is that the ignition switch should never be left on for an extended period and the battery must be disconnected when being charged up.
I wouldn't go back to the hot wire set up again because it was carefully calibrated and installed by my late Father in Law who was an ingenious auto electrician.
As I mentioned before, it is ironic that before I had the cut out restored my only form of voltage control was a simple "hot wire". A heavier gauge insulated wire (it should ideally be nickel chrome) connected between the dynamo and the battery via the ignition switch and resistance calibrated. What was originally intended as a temporary measure but worked faultlessly for 20 years or more.!!
The theory is that as the battery reaches its fully charged state, resistance builds up in the transmitting resistance wire, which as suggested, heats up in a controlled manner. As the wire warms, the current to the battery slows. The dynamo is protected in the same way as the battery; by resistance slowing the current flow. The only thing to remember is that the ignition switch should never be left on for an extended period and the battery must be disconnected when being charged up.
I wouldn't go back to the hot wire set up again because it was carefully calibrated and installed by my late Father in Law who was an ingenious auto electrician.