I bought 3 used batteries today, so here's a test at 60 volts. I got it up to around 115 motor amps. There's no noticeable heating of the base plate or bus bars. Gate to source turn on looks pretty nasty, like the driver has fits barreling through the miller knee, but it's turning on fast, so maybe it doesn't matter. Maybe I need a new driver? The total turn on capacitance per driver is like 85000pF, and it's rated for 60000pF, but it works fine with the 500amp controller, which is driving over 100000pF. Maybe not all picofarads are created equal:
EDIT: This paper suggests that the gate oscillation is the result of the switching from drain to source. I could reduce the oscillation if I slow down the switching, but I've already seen similar oscillation (but more minor I think) with 15 Ohm gate resistors.
http://ieeexplore.ieee.org/xpl/freea...number=1713572
The way I see it, what do I care if there's gate ringing as long as the mosfet is getting turned on and off fast, and the gate turns on fast too, and the gate to source voltage is clamped by a transient voltage suppressor. The TVS diodes respond in like 5 picoseconds.