5 watt luxons/ho w many volts.

How many volts are required to run this thing. If the 120 Lumens are accurate, this will be a great bright led. Just wondering what the power source should be and what kind of runtimes expected with various power options.

Hi Jon,

Any LED light needs a constant current supply instead of constant voltage. It means it needs a power supply can limit the current flow instead of controlling the voltage, of course there a minimum voltage for forwarding the current flow through the LED.

From the datasheet, LS 5W nominal is driven at 700 ma or 0.7 Amp, and the forward voltage is between 5.43 to 7.83 V.

Visit here for finding the correct resistor to safely drive the LS 5w, in the "LED Voltage" field just enter 6.84 , the current at 700 and your supply voltage in the"Total Voltage". You will find the correct resistor to drive it.

LED Series Resistance Calculator

Currently there is a discussion on powering this beast at the "Electronics Forum. Batteries Included" forum.

Best Chip/Step Up Circuit Design for the new 5W Luxeon Star?

Vic

Lumileds specs the 5W as follows.

700mah recommended max current, 1000mah pulsed.

5.43 min - 7.83 max input voltage. With a min. light output of 87 lumens and average of 120 lumens, with a 25C junction temperature.

Odd part is, if you go further down the sheet they have a relative light output -vs- junction temp chart. That seems to indicate the only way to get 120 lumens out of it is to have the junction temp at -20C. At reasonable running temps (20-40C) the chart lists 95-100 lumens. Seem contradictory of the above statement.

I think this tells me what I wanted to know. was thinking that this would likely be used in a light powered by two 123's of four 1.5 volt batteries. Am I correct?

Wouldn't they run off of even lower voltages than the so called minimum? I run LS's off 2AA NiMHs with no problem. If they're four 1 watt chips in series/parallel, it seems they should also run OK off 4AA NiMH (4.8V).