Quote:
Originally Posted by Daox
If you are going to go with 12 12v cells, why not go up to 144V? You'll still have the amp hours avaliable, but twice the voltage. I understand the controller would cost more (unsure of actual price), but maybe its worth it?
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Yeah, mostly the big consideration is cost. A Curtis 144V controller is $1400. A slightly used NEV 72V controller is 300.
Also, the motor I am using is originally designed for 36 volts. I will be running higher quality brushes in there, and eventually advancing the timing as well. I really have no idea how the motor would handle 144V.
I actually have considered the idea of using a PWM controller in combination with contactors to make a very controllable vehicle at lower speeds, and then having it kick over to a "direct connection" for a higher voltage "overdrive".
I wouldn't be able to use the controller when the pack is configured in the higher voltage configuration. It would just be a "cruising gear". Could be activated with a momentary on dead-man's switch - as soon as you let go of a button on the steering wheel, or trigger on the stick shift, it would drop down to the lower voltage, controller-run mode, which would give you full speed control over the motor again.
Another reason why I am thinking 72 volts is that I already have a high-amp 36 volt charger. I could rig up the pack to be split in half for charging (2 36V legs). For 144V I would need a big fancy 144v charger or a dozen 12 volts. That is just one more thing to add to the cost of the project.