first; its easier to get more efficency out of a smaller motor [not
saying a big motor can't be just as efficient] two; with two
motors you can parallel/series switch them so for example if you
have one big motor that is equal in power to two small motors then
at X amp and Y volts they have the same power, but you can switch
the two smaller motors and have 2X amps and Y/2 volts for twice the
power at low speeds: basicly its like having a low gear. further
with the swtiching you can have two optium speeds for efficency one
at Z speed and one at Z/2. for me that would 75 mph for the
highway and 37.5 for the city.
The way it was explained to me was:
More volts give you more RPMs
More amps gives you more torque
With a series/parallel controller you start with the motors in series
so they each get as much current as the battery can produce.
They're splitting the voltage but at low RPMs that's not a limiting
factor.
As you speed up you get to a point where available voltage limits the
RPMs.
Now the controller switches the motors to parallel so they each get
the full pack voltage.
The amps are now split so there's less torque but as we approach
cruise speed that's less of an issue.
I like the idea that a properly arranged pair of motors would let you
limp home after one motor died.
Andrew in Ann Arbor Michigan
