I'm in a project that uses a DC motor (toy motor, 3-6 V, 70-250 mA) and since it will run on batteries, I want it to last as long as possible. I don't need a permanent activity, so I was thinking about toggling the motor on and off every 2-3 seconds. That is: 1s on, 2s off, 1s on, 2s off, ...: will this cause problems to the motor? Will it die soon? Will this lower power comsumption or it will be negligible?
A lot depends on how much the motor slows down during the OFF phase. There is an inrush current to accelerate the motor which will push up the integrated power consumption and this value might well exceed the steady state consumption.
Can it be the inrush power will exceed that of a 1:2 duty cycle? I thought my main issue was harnessing the motor's inner circuit with this frequent on/off.
Consider I'm working on the 3.3V with an analogWrite of about 150-200, so there's not much speed on the motor.
You need to better define if you want to actually stop the motor or simply reduce its speed
Both are accomplished via forms of PWM the former being extremely slow which permits the motor to stop or fast which relies on motor inertia to "iron out" the pulses
Its a toy motor, it won't last forever whatever you do because it is cheap, don't worry about it, just have
a spare. It will outlast your batteries!