No. For many motor technologies (brushless DC, permenant magnet DC,
synchronous AC), doubling voltage doubles speed. For wound-field DC
motors, though, speed is only limited by the output torque and input
power. Lowering output torque makes it go faster (lower rolling
resistance and better aerodynamics). Increasing input power will also
make it go faster (increasing current/voltage).
The power required to drive goes up according to speed cubed (plus a
linear term), though, so doubling voltage won't double speed.
There's equations you can use to calculate the approximate power
required to drive at a certain speed, and from there you can use
voltage and current limits to find how fast you can go on a certain
power. You may have to make educated guesses on some of the numbers,
though.
Max power your motor puts out:
A=max amps
V=battery volts
E=efficiency (0.6-0.8 for DC)
P=A*V*E
Power required to drive in 0 wind:
Af=frontal area of your car (google it)
Cd=coefficient of drag for your car (google it)
V=speed the car is traveling
Crr=coefficient of rolling resistance (depends on your tires, roughly
0.01 to 0.03, much much bigger on hills)
P=0.5*Af*Cd*V^2+Crr*V
So you can find out how much power your motor can put out and how much
power your car needs to drive, and this will give you an approximate
top speed.
-Morgan LaMoore
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