# Should nominal or stall current be used for power supply selection for BLDC?

I'm working with a custom 24V BLDC and I'm trying to find the right power supply to use for it.

The motor is rated for 2A continuous and in normal operation we will be operating under that, however there will be times when it needs high torque instantaneously and will draw 5A very briefly.

When selecting a power supply, I've heard you are supposed to use the nominal current (so we would need a power supply of 24V, >2A output) and to rely on capacitors to provide the high current at short bursts (stall current). Is this true and if so why ? I'm assuming it's a money issue (if you can get away with a cheaper power supply then you should do that), but is there an engineering reason ?

Using a power supply rated for the nominal current is also mentioned in this question here but I'm looking for a more in depth explanation of why: Proper power supply for BLDC motor

• 5A for how long? 5A for 1 second = 5 Coulombs : this and the definition of capacitance dQ = c* dV allows you to calculate the capacitance you need to supply the required charge at the acceptable voltage drop. Try it. You may decide it's better to rate the supply at 5A. Or you may find power supplies with a surge current rating designed for motors.
– user16324
Commented Sep 10, 2020 at 10:30