[m.137]

Has anyone wired up a battery to have a low voltage and high current optimized for low speed then added in a box that has relays and resisters set up so that it can up the voltage so that the batteries are optimized for higher speeds?

I know there is this balance between current and voltage and you would want higher current for low speed and higher voltage for high speed, so why not make a box that can do both? You could get even crazier and have the switches for the change in voltage be setup to the gear shifter so that when you put the car in higher gear it will change the voltage to be optimized for that speed.

Has this been done? I had trouble searching for it, I bet I just don't know the name of this thing.

[Harlan]

There's a thread on elmoto.net discussing this. It starts at post #8:
http://www.elmoto.net/showthread.php?t=1115

[EVfun]

Series/parallel switching of battery pack used to be one of the main forms of speed control. It is not often used for on-road EVs anymore because it isn't very smooth and contactors (large relays) that can handle the power required are large and expensive.

For EVs built in the last 20 years (or so) we wire the pack in series for maximum voltage let the motor controller buck the voltage down to what is desired at the motor. When the motor voltage is less than the battery pack voltage the motor current is higher than the battery current. The controller is handling the desired function.