Ah yes, and the voltage drop is pretty bad. Since the power(in Watts)is calculated as UxI (voltage times amperage), the difference in power for Les' example would be:
70mm2 @ 0,68Mv-A-M / 450 Amp / 4m Cable = 1,22 Volts drop = 10,78 Volts times 450 Amps = 4,851 kilowatts = 6.6 HP
35mm2 @ 1,35Mv-A-M / 450 Amp / 4m Cable run = 2,43 volts drop = 9,67 Volts times 450 Amps = 4,306 kilowatts = 5.8 HP
Which means that you effectively lose almost 1 HP from your winch motor.
/tony