DC Step-up Boost Voltage regulator (High Ampere)
Ouch.
If the stall current is 130A, the converter now needs to handle over 600A at the input, not merely 100A.
It is time to stop and reflect why you are abandoning a simple solution which works, for a difficult and expensive one which probably won't.
If you want adjustable 5-60V (exceeding 18V only once the motor is running and lightly loaded, otherwise you are only making the stall current problem worse), then start with 60V (15 cells in series) and use a buck converter to reduce voltage (increasing current) instead.