Lux III + trustfire 3.7v x2 + 3.9 ohm 5w resistor

[Jedi-Diah]

You should really consider using less voltage. The wasted energy is turning into a hot resistor.

i used the resister chart on TCSS and i used the one for the 7.2 volts. im running 7.4 so it IS overdriven but not by much so this setup seems to work fine and to my surprise even the Hasbro board without a resister works fine at 7.4 volts. this thing is like a tank only having 1 problem, the LED is brighter but comes at a price of one toasty resister. should i consider getting a higher wattage resister?

[MoonDragn]

Well the reason I asked which leads you measured the current on is because you measure current with your meter in SERIES with the resistor. Not across the two leads in parallel

Also since the lux III forward voltage is around 3V, the voltage drop across the resistor has to be around 4.4 volts. Depending on which Lux III you use, to get 1 amp flowing to the lux III you'll need a resistor of 4.4/1 or 4.4 ohms, for the 1400 mA lux IIIs you need about a 3.3 ohm resistor.

Its much better if you just use the two trustfires in parallel with a resistor. Then it is only 3.7 volts and the led will last longer.

In that 2nd setup you can use a rectifier diode instead of a resistor. The typical voltage drop across a rectifier diode at that voltage is .7 volts which will bring you to about 3v.