I tried to use it the same way (20V constant voltage). I set it to max output current (15.0A) but got no current when I enabled the output. I finally set the current limit to 3.30A and got some current. But the supply could not maintain constant voltage, and fluctuated from 17 to 20 volts, and switched continuously between CV and CC mode. This supply apparently cannot supply enough power to maintain, even if the CC is set as low as 0.50A.