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Gearmotors compared -- efficiency
To further this process, I invented my own metric of motor efficiency -- deg / mW-sec. Analogous to km / liter or miles / gallon for a car, this measure looks at motor speed (deg / sec) given by a particular power consumption (mW). Note that many BEAM uses require a motor to turn a given angle one way or another, so an efficiency metric that takes motor speed into account should be a better measure of efficiency than just raw motor current. Let's see how all the motors compare using this measure:
Here you'll see one definite "outlier" -- the microcassette worm-drive motor is extremely efficient (although this comes at a cost, as you'll see later). Again, most gearmotors are down a bit lower -- let's zoom in again:
As you can see, the Omron "mini gearhead" motor is the
least efficient of the bunch. The motors used in B.I.O. Bugs
are nearly twice as efficient -- surprisingly good for "toy"
motors, and comparable to many servos. The floppy eject
motors (both Tokyo Micro and Omron) are both good at higher
voltages. The winners here, though, are the Copal and Nihon
("BG Micro") motors.