Arctic Cat conversion start torque

[fredtr]

I have two QS138 motors in an Arctic Cat UTV conversion with about 6:1 ratio to wheels. Votol 200 and Fardriver ND72450 controllers. I have very low torque at start with about 80 amps of phase current as the motor tries to turn the driveshaft. I have 5 feet of battery cables 2AWG, that I believe is part of the problem. I have plenty of battery power, does anyone have any suggestions? Thank-you.

 

[E-HP]

Maybe try bumping up the phase current to 200A or so to start with and go higher as needed. 80A is more like what a 30A controller puts out, so probably really sluggish with your setup. The ND72450 is rated for 450A phase current.

 

[fredtr]

Actually that is my problem, it is set to 200 amps. The battery can deliver it, but the controllers don’t deliver it for the first revolutions. And this is the case with both Fardriver and Votol and seems to have something to do with 5 foot battery cable lengths. Binding the +\- battery cables and capacitance at controller end helped but didn’t resolve it.

 

[fredtr]

I added capacitance at the controller end, start current/torque improved significantly. So much so, I was testing just the front drive and I blew the differential.