How much can a motor lift? How fast can it spin?
It all depends on everything. A good rule of thumb is that a motor can lift the weight of the battery that drives it; or that a motor can lift its own weight. Remember that motors can either spin slow and be strong (near stall), or can spin fast and be weak (at no load). You can’t have both. Motors will spin faster and be stronger the higher the battery voltage. A good test of whether you are driving a motor too hard is to feel it. If it is hot, turn down the voltage or reduce the load. Also, many motors will wear out their bearings if run for more than a few seconds at their no load speed. Gearmotors have a built in gear train transmission. This means the shaft will spin much more slowly at no load conditions with considerable output torque. Consider gearmotors if you have a vehicle for which you want to attach the wheels directly to the motor shaft. In all cases, test your motor in a mockup of the intended load conditions and using the intended battery before you get too far along in
