I think you might be asking the impossible from a 10kW motor with that amount of weight
and fixed gearing, which would need at least an 18" outer diameter tyre and the 8:1 gear ratio in order to reach 55kmph with the motor running at ~5,100rpm.
Now let's take a look at the following diagram:
To move a 1,500kg vehicle up a 12 degree slope you would need to exert a force of at least 312kg
(1,500 x Sin 12) and that's without allowing for frictional forces at the tyres, mechanical losses through the gear-train and wind resistance etc.
I put some test figures into
my spreadsheet, and discovered that the motor would need to develop at least 88Nm of torque before the vehicle would even move, let alone accelerate up the slope.
I estimate, the motor draws around
5Amps/Nm @ 120V, therefore 88Nm x 5Amps = 440Amps
(52.8kW)I estimate, the motor draws around
8.5Amps/Nm @ 72V, therefore 88Nm x 8.5Amps =
748Amps (53.8kW)Either way, I think 53kW is probably expecting a bit too much from a 10kW motor.
In order to provide a greater gear reduction for hill climbing and a lower gear reduction for speed, I really think you would need to incorporate a manual gearbox so you could easily select the best gear ratio to suit the actual load on the motor.
Alan
