Here is a worklight m ade from 150W halogen spotlight. I used 6x CREE Q2 Leds from DX. Each Led is drived from one AMC7135 chip (boards also from DX), so each Led gets 350mA. I builted in charger described here . As power source i used 3x 18650 size rechargeables 2400mAh, 7200mAh total. And calculated battery time is 3,4Hours. As charging PSU - any 9V to 15V 1,5A is suitable.

Front view