This video shows 2 flights made during the 2015 Santa Cruz Flats Race in my electric powered Millennium hang glider. I only used the motors to gain initial altitude and then the remainder of each flight was thermal soaring. I used nearly maximum power for the first 200 ft of climb and then minimal power for climbing while trying to stay in lift until I stopped the motors. Both flights were made using the same 2KW battery pack without any recharging between flights. Here are the technical specs for the propulsion system:
Motors: http://www.hobbyking.com/hobbyking/store/__25413__Turnigy_RotoMax_150cc_Size_Brushless_Outrunner_Motor.html
Controller: http://www.hobbyking.com/hobbyking/store/__25202__Turnigy_dlux_250A_HV_14s_60v_ESC.html
Batteries (X16, the pack is 14S (51.8V and 40 AH, approx 2KW-Hr): http://www.hobbyking.com/hobbyking/store/__21374__ZIPPY_Compact_5000mAh_7S_25C_Lipo_Pack.html