If 20 amps are necessary for a 12v DC electric motor to supply a particular mechanical power output, then only 10 amps would be needed by a 24 volt engine to attain the same level of performance.
For a simple type of DC electric motor, the rotation is at full speed on simply no load, with rate determined primarily by applied voltage. For that reason, if 24 volts had been applied to a 12v DC electric motor, it could cause some harm by running at two times the speed.
Generally, a 12v DC engine will be comparable in price in comparison with a 24 volt electric motor for the same application. The primary reason is that the physical size of the electric motor can usually determine its power result.
Gleam difference between wiring for a 12-volt motor pitched against a 24 volt electric motor. For example, at 24 volts, smaller sized wire can be utilized for delivering power efficiently, whereas for 12 volts, twice the size of wire is required to provide the same amount of power.