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Originally Posted by zeropointbug
Well, GriffinRU did say that it only spikes your batts when the potential is higher than battery voltage, and enough over the voltage drop on the FET diode. I am guessing it is just shorting the motor, and turns it into heat, but the FET's can control the switching of the 'SHORTING', hence proportional braking.
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Yea, the shorting would be easy. You just have heat to dissipate. But if the controller uses the battery as an energy sink to provide braking force then I have to consider the numbers. If it takes, say, 500 Watts to accelerate the car to full speed as quick as possible, surely it's not going to take a large magnitude less power to deccelerate the car back to zero in the same amount of time? Let's assume the controller has to sink only 300 Watts to provide an equal braking speed. Is that 300 Watts going into the battery? If it were a lipo it'd probably puff or be severely damaged.
Is the controller sinking some of the energy to heat and some to the battery? And on what criteria does it perform the split? Are controllers aware enough of battery chemistry to know how much power to limit being generated back into the battery?