# How to select power supply without knowing all specs

I am looking at using 4 of these Neo Brushless Motors.

The specs don’t give a rated current or power. Just a stall current and a stall power out. Also this data sheet is for 12V. I want to run these motors higher at 48V, and I am trying to calculate the required PSU for this. Because of the logistics of our project we will not know the exact req’d torque before we must order the PSU, but we assume the Neo motor will be capable. We also know it will be high torque/low RPMs.

My thought was to take the stall torque data on the highest test they did (see pic below). We probably don’t want to exceed this due to overheating. This shows an input current of 25A with 10V. So that’s a power requirement of 250W. So I would say that’s what we need per motor, therefore we need a PSU of 250*4 = 1000W. Is this reasonable? Not sure what to do when don’t give rated levels, just max levels.

Also, in the data sheet (link at the top) it lists inputs at max as 105A and 12V which is 1260W. But in the stall torque plot below, it is hitting basically the same torque listed in the spec (approx. 2.5 N-m) with a power of 10V * 25A = 250W. What is the discrepancy here? How is the motor producing similar torque with such different power?

Please disregard the large “stall current” values, that assumes that you blindly put in 12V at 100% duty, which you would never do.

I think 250W * 4 is reasonable as per your interpretation.