Jozzer wrote:Mark @ Team hybrid asked me about increasing the ramp time on the controllers, since he uses them in handcycles. Are there any dangers in increasing the cap size? And by how much?
the supply to the cap is current limited so you should be able to increase it almost indefinitely, but the transistor inside the ka3525 pwm chip that discharges the cap when shutdown is asserted will probably blow at some much higher capacitor value from the extra energy it has to discharge. i would try 22, then 33,47,68 uf, all standard values and anything over 10v, if you are careful you can change this cap with the board attached to the metal plate. if you are increasing the value you can leave the existing cap in and just add more in parallel between pin 8 of the 3525 and ground.
you might run into the situation where it starts up so slowly that it always shuts down "thinking" that the motor is not turning.
the soft start cap is really only intended to ramp up the power when you release the brake, or if you power up with the throttle at a high setting. more sophisticated controllers have mechanisms to adjust the throttle response curve, but here it is just a simple RC time constant, so changing the resistor that charges the cap or increasing the cap will have the same effect. you have to remove the board from the plate to get to the resistor so it is a bit more work, but replacing the resistor with a pot would let you adjust the ramp time.
I do not approve of this group any longer and regret what it has become. I could once share ideas here freely that is no longer possible.