I'm building a regenerative braking circuit for a bicycle generator hub (AC, .6A max, 30V open circuit, ~3W). The higher power of my two power circuits for this, starts out with a bridge rectifier, then a smoothing cap, then goes into 30V TVS diode, then into a small super capacitor bank in series. I have six 5.5V, 1.5f supercapacitors that I want to be able to charge to the 30V my TVS diode will allow.
The best circuit I've seen for balancing this bank is this one, at instructables:
However, I'm wondering if I couldn't do the same thing with some 5W (or less) zener diodes. The max voltage on a given supercapacitor is 5.5V, so I figure a 5.1V zener will protect that as far as voltage. My current at this step really can't go above 600mA, so I figure my maximum power is 3W, the stated power of the generator anyway. I'd like to avoid the complication of the comparator, MOSFETs, etc. (I'm a software jockey), but I don't know what I don't know about using zeners like this to balance this supercapacitor bank. Can anyone tell me why I don't want to do that?
The best circuit I've seen for balancing this bank is this one, at instructables:
However, I'm wondering if I couldn't do the same thing with some 5W (or less) zener diodes. The max voltage on a given supercapacitor is 5.5V, so I figure a 5.1V zener will protect that as far as voltage. My current at this step really can't go above 600mA, so I figure my maximum power is 3W, the stated power of the generator anyway. I'd like to avoid the complication of the comparator, MOSFETs, etc. (I'm a software jockey), but I don't know what I don't know about using zeners like this to balance this supercapacitor bank. Can anyone tell me why I don't want to do that?