Originally Posted by RONALDO_UK
....Easy Star where a 2200kv inrunner seems a popular upgrade choice. Some guys seem to run it on 2S and some on 3S, but in both cases with a 6x4 prop. ...
....question - with same motor/ same prop and 2S or 3S batteries supplying the same power....
The two situations => two different power levels.
With the 3S, the motor will be drawing/providing much more power.
To draw the "same power" with the 3S (as compared to the 2S), the propeller pitch and/or diameter would need to be reduced.
You would need to measure the actual currents being drawn by the motor to determine the actual power difference. A "Wattmeter" is a very desirable piece of equipment if you want to avoid burning up motors and/or ESCs.
....what is the difference with the 2S where the prop is (presumably) turning slower?....
With the 2S (vs 3S) and same prop, less power is being drawn by the motor and provided to the prop. => less thrust is available at full-throttle; available top speed is reduced; available climb-rate is reduced.