I've increased the voltage on my scooter from 48V to 60V/72V (switchable), however the regen doesn't work at the higher voltage (for some odd reason, it does work going backwards at 60V/72V?....just rolling backwards, there is no reverse gear). When I switch back down to 48V, it works fine (forwards and backwards). The controller is a JH BLDC motor controller....I think it's from Taiwan. It has 3 poles, with 5 4107 MOSFETS per pole (3 for driving, 2 for regen, 15 total). The controller gets a bit sketchy at 72V (as the FETS are underated at that voltage, so I only use it on the flats for short periods on crazy speed...70km/hr last speed check. The main surge caps are rated at 63V and I plan on upgrading a controller to 100V caps and adding some water cooling in the future.
Anywaym back to the regen problem, my guess is that the 3 50V caps used to open the regen MOSFET gates are under powered? On the picture above, they are the small caps seen just under the black and blue wires, just below the big 63V caps. (BTW, I'm just completely guessing at this one by staring at the circuit board). Just beside the shunt bars, there seems to be a couple triacs (one for each MOSFET, series repeated 3 times) and a bunch of passive stuff.
Here is a picture of the bottom of the controller.
So does anyone know how to modify this circuit and/or what would be the likely problem? Any explanations to go along? As mentioned, my totally unscientific guess is an undersized 50V cap to open the gate but if so, why does this occur?