if what you consider is a DC permanent magnet motor, if you turn it on rated RPM you will get 5V, if you increase the RPM further it will go up & saturate at a certain value..this is due to magnetic characteristic.
when you go for more voltage out, then the current you can consume is limitted lower than rated value.
A big DC permanent magnet motor needs more power, so it also generates more power when it behaves as a generator, and it is so for a small motor. Also counting in the factor of speed, friction, etc.
I'd say let him build the thing anyway. It'll be a learning experience playing with stuff like that.
A big DC permanent magnet motor needs more power, so it also generates more power when it behaves as a generator, and it is so for a small motor. Also counting in the factor of speed, friction, etc.
I'd say let him build the thing anyway. It'll be a learning experience playing with stuff like that.