I bought the 30A 1500W model for$23 on ebay. It shipped in 7 days, but it arrived with heat sink bent and an electrolytic capacitor broken off.Negotiating a settlement with the seller. I originally wanted a replacement, but I think I will settle for 25% off, I attached a new capacitor and it does work, except for the fan,
It works like wturber's unit. It's nominally 20A. I using it at 48V off a 36V pack, and it sags to around 40 volts when my 20A 6FET KT sine wave converter asks for full current. I lowered the controllers LVC to 39V.
Why am I using it? I have lots of 36V batteries, and I want to run my 48V TSDZ2 kit. I was also willing to throw put 23 bucks to see what I get. While I haven't installed the TSDZ2, I tried running a 36V/48V Q100H kit at 48V. The throttle response at perked up on 48V. The watts on the LCD3 increased about 20% too. Same set up issues as the OP. Had to tweak the LVC on the KT controller 2 volts lower than nominal because of voltage sag, and it maxes out around 20A.
Edit: Latest test run. Set the output to 50V. Nominal 40V input.
Peak Input Current: 29.35 A
Peak Output Cyrrent: 22,05 A
Vmin Output: 40.5V
Vmin Input: 37.6V
AH input: .80 AH (3 mile run)
AH output: .74 AH
The bikes speed on throttle went from 20 mph to 24 mph. Pulling about 800W. Appears to work nice for a smaller motor.