How feasible is it to rewind a starter motor for 48 V? It's a series-wound motor, and presumably the field windings and the armature would both need about 4 times as many windings with about 1/4 the cross sectional area, giving it around 16 times the resistance.
Don't they actually make 48V starter motors?, certainly 24V are common for HGV's, and there's been a degree of movement towards high voltages in car electrical systems.
My Mild Hybrid Suzuki Vitara has a 48V generator/motor, but it's just used to give a boost to the petrol engine during acceleration and setting off, and to restart the engine seamlessly after stop/start operation. The initial starting of the engine is done by a conventional 12V starter and battery, and there's an extra 48V Li-Ion battery pack for the hybrid motor.
Many of the latest starter motors uses a PM field construction now.
The older style was a wound field, series motor, Very High torque at zero/low RPM.
If re-winding for 48v, would not go as low in gauge and as high number of turns
Starting requires very high current and usually is for a very short period, Typically it is almost impossible to run an automotive starter of this kind for any lengthy period due to battery voltage decreasing rapidly with time. it is very unlikely that any damage will come to it with less turns. While maintaining as much power as possible at start.