Hello,
There are numerous studies showing the usefulness of supercapacitor banks to recover brake power in automotive transport. The idea is pretty simple: brake power come in short bursts which cannot be stored in batteries, but supercaps can. Conversly, the startup of any e-motor requires a peak torque: here the stored energy from supercaps comes very handy. Basically an electrical flywheel.
What I'm wondering is if the same principle could be applied to ebikes. Most of the regen energy is lost / cannot be used, especially in stop-and-go situations like city commuting. If we could store some of the energy lost at each stop, and use it again to kick start the motor when the light turns green, we could certainly save some battery power. Since medium capacity Double Layer supercaps are becoming quite cheap, it wont cost an arm and a leg to try it.
A 48V Bank (actually 54) would require 20 supercaps in series. If we use samwha 100F caps, that's around 500g (including balancing circuit), 0.4L and 60$ for 5F total capacity. 200F/cap would double the total capacity to 10F, but I've not found cheap ones yet.
Assuming 5F are loaded to 54V, that's (W = 1/2 C V2 ) 7290J storage capacity.
Assuming the bank is fully loaded, and discharges in 1s, the useful power would be around (P = dW / dt ) 7KW - plenty enough to start a motor.
What do you think ?
There are numerous studies showing the usefulness of supercapacitor banks to recover brake power in automotive transport. The idea is pretty simple: brake power come in short bursts which cannot be stored in batteries, but supercaps can. Conversly, the startup of any e-motor requires a peak torque: here the stored energy from supercaps comes very handy. Basically an electrical flywheel.
What I'm wondering is if the same principle could be applied to ebikes. Most of the regen energy is lost / cannot be used, especially in stop-and-go situations like city commuting. If we could store some of the energy lost at each stop, and use it again to kick start the motor when the light turns green, we could certainly save some battery power. Since medium capacity Double Layer supercaps are becoming quite cheap, it wont cost an arm and a leg to try it.
A 48V Bank (actually 54) would require 20 supercaps in series. If we use samwha 100F caps, that's around 500g (including balancing circuit), 0.4L and 60$ for 5F total capacity. 200F/cap would double the total capacity to 10F, but I've not found cheap ones yet.
Assuming 5F are loaded to 54V, that's (W = 1/2 C V2 ) 7290J storage capacity.
Assuming the bank is fully loaded, and discharges in 1s, the useful power would be around (P = dW / dt ) 7KW - plenty enough to start a motor.
What do you think ?