There have been a lot of explanations on this, but instead of getting all sharty on you, I’ll keep it simple.
Motor amps is directly related to torque/take off speed. The higher the number, the higher the take-off speed.
Battery amps is related to the total power that can be delivered. For additional reading, Trampa has a detailed version of this explanation
Example on a 12s system:
Battery amps set at = 50A
Motor amps set at = 100A
From a dead stop, you pull full throttle in “current control” mode and the duty cycle/RPMs will climb as the motor spins up and you accelerate.
10% duty cycle / 10% RPMs
Motor = 5v, 100A or 500w
Battery = 50v, 10A or 500w
25% duty cycle / 25% RPMs
Motor = 12.5v, 100A or 1250w
Battery = 50v, 25A or 1250w
50% duty cycle
Motor = 25v 100A or 2500w
Battery = 50v, 50A or 2500w
Up to this point, your acceleration has been impressive and linear. We’ve now hit the battery max of 50A. The system’s total power will no longer increase, but the motor will continue to spin up to full RPMs and top speed.
Voltage at the motor will continue to increase, but amps will decrease to match the battery’s 50v 50A (2500w) limit.
Basically this means your rate of acceleration will slow until you reach top speed as you are now capped at 2500w and running into more and more wind resistance.
75% duty cycle
Motor = 37.5v 66.6A = 2500w
Battery = 50v 50A = 2500w
100% duty cycle
Motor = 50v 50A = 2500w
Battery = 50v 50A = 2500w
If we set both battery and motor to 100A, our acceleration curve would be more linear from 0-top speed and we would reach a total of 5,000w… if our components were capable of this.
If we set battery amps to say 25A as b264 is suggesting and keep the motor at 100A, we limit the total system to 1250w. Since we use the most power during acceleration, and not to maintain a cruising speed, this should improve range at the cost of acceleration, though we won’t notice the difference until 25% duty cycle/25% RPMs.
Your battery amp setting is usually limited to the max amp discharge of the cells in your battery before they overheat.
Your motor amp setting is usually limited to the MFGs motor amp rating.