This is a 10W LED torch powered by 4*18650 for 4 hours if 18650 have 2 Ah capacity. The 18650 is charged by an eBay 3 trimmer power supply set for 16.8 V out 0.5 current limit and 50 mA stop charging. But the power supply it does not actually stop charging the 18650 !!! So a circuit is added to stop charge the 4*18650. A optocoupler from charging LED is drive a N channel mosfet that stops the charging. A other N mosfet is added to stop discharging the 18650 if voltage is drop below 9.3 V. The unit is powered from a 19 V laptop power supply. The 10 W LED is powered from a ready eBay PT4115 power supply. Using pin 8 of PT4115 is possible to adjust the brightness of the LED.

 Circuit and final assembly will follow ...