# Geared motor assistance..

#### RussellCart

Joined Jun 3, 2019
1
Good afternoon,

So I am currently new to electronics but not new to coding.
I am building a simple robot - you know, the little ones you always see on instuctables.

I am using an arduino, and 2 yellow small geared hobby motors (3 - 6v). I use a 9v battery to power the arduino and I use 4 AA 1.5v batteries to power the 2 motors through a L298 motor controller.

Apparently the motor specs are - (RPM - 100 @ 3V... 200 @ 5V... 250 @ 6V) and (150mA @ 3V... 170mA @ 5V... 170mA @ 6V) but the motors are spinning crazy slow, maybe 1 rotation every 3 seconds.

I understand the L298 takes 2 volts, then that leaves 4 volts for the motors.

If anyone has any advice or tips I would appreciate it very much as it would help me progress my basic knowledge.

#### drc_567

Joined Dec 29, 2008
1,156
... another thought, not controller related ... probably approaching some kind of forum word limit:

... A typical motor produces power ... a unit defined as work per unit time, as in something like foot-pounds per second, or newton-meters per second in the metric system. In one sense, a motor is a type of converter. It converts electrical input power to an output of mechanical power. Moreover, the mathematical definition of motor power is precisely
P= T*ω
where P= motor power in ft.-lb/sec, T= torque in ft.-lb, and ω= rotational speed In radians/second, or RPM, as long as you keep the units consistent. The motor performance may be simply graphed as a line with a negative slope, extending from a point called the stall torque, at zero speed, to the point called no load speed (free-running), which is the maximum RPM.

However, at either endpoint of the negative sloping performance line, the power generated by the motor is negligible, essentially zero. Since either ω or T is zero on the graph at these particular points. It follows that in order for the motor to produce useful power, it cannot be operated at either endpoint of the performance curve. (The condition described by the thread starter with essentially zero RPM, and a large torque load). Maximum power is generally reached at a speed in between the stall (zero) speed and the free running 'no load' speed.
... So in order to obtain any reasonable power from the motor, the torque load has to be reduced while the rotational speed is increased. As the TS originally suggested, a gear ratio that allows the motor shaft to spin faster should improve the situation.
... Actual motor performance curves will vary from that given above. The underlying principle of motor power production is what is trying to be conveyed here.

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