15 years ago
studied a little about power, acceleration, work etc...
Since then, I've lost all of my old text books and am trying to
relearn and further my knowledge on this subject. Where I work we
build electric scooters for mobility impaired people. When I asked
the boss, how he worked out the size of the motors that we use, he
said he looked at what was in other scooters on the market, added an
oohaah factor and came up with the final choice. (.250kW @ 1800rpm
The problem seems to have a number of steps.
-Inertia (I remember this well from high school, Mass is 170kg)
-Rolling Resistance in the bearings and wheels
-Torque (the wheels are 15" in diameter)
-Friction losses within the gearbox. (Standard NMRV50 from Motavario)
-Battery Life and Power Consumption (Batteries are 12V 44Amp/Hour with
The drive train consists of two motors driving a wheel each. They are
wired in parralell to the controller providing an electric limited
slip differential. The system is 24Volts, and runs of a standard
forklift controller manufactured by Curtis.
The maximum speed by law for these type of vehicles is 10km/hr,
however we have made some for "private use" rated to 15km/hr by using
different reduction gearboxs. I'm assuming an acceleration to
topspeed in 0.5 sec.
I thought this might be an interesting head scratcher.
View some photos here:
Thoughts, Comments, Suggestion, (Criticism) Welcome.