Newbie help on Lux III Cyan

I have tried searching for the answer to this but cannot find it.

I am about to start my first mod. I want to DD a Lux III Cyan (Sorry have no bin number). What is the max voltage it will take? AND what typically would be the current on fresh batteries CR123's.

The reaon I ask is that should this one work out I would like to have an idea at what converter I should use on the next one (current wise)..

If I were to use R123 at 3.7 volts would I still achieve the same current??

Thanks for any reply and help.

the bin number is critical for finding this out. With the bin number you can tell what voltage is dropped (across the diode) at spec current. This can vary widely. Now if you are using a convertor board (current regulated) the Vf of the diode wont really matter. remember, LED's are current driven devices, and therefore have to be current limited. Lithium or Li-ION batteries should hold their current potential to clost to the end of charge.
Hope this helps.
Jeff

Since you do not know the bin, and it is not marked on emitters, you have some estimating to do. If you have a voltmeter, it will be easier.

Step 1 - Temporarily, heat sink the emitter - somehow. This is the most critical thing you will ever do. This might be some thermal grease to the top of a 1/4 inch bolt or some copper rod, etc.

Step 2 - Obtain some kind of battery holder which can hold 3 or 4 C or D cells in series. Also some alligator clips.

Also pick up some 1 and 2 ohm, at least 1 watt resistors. The big axial flameproof ones from radio shack are great for testing.

Strongly consider wearing sunglasses for the testing.

Step 3 - Start with 2 cells in series, and hook them up directly to the Lux III using the alligator clips. Be sure to hook the positive side of the batteries to the anode of the Luxeon - this is the side with the small hole in the secondary little electrode sticking out.

It should light up at least dimly.

Step 4 - Now put 3 cells in series, a 1 ohm resistor, and ideally your voltmeter also in series. It will probably read approx 200 - 400ma. Remember this setting.

Step 5 - Now the same setup with out the resistor - probaby will be around 600 - 800ma. A good place to stop.

Step 6 - Now use the same setup with 4 cells in series and 2 ohms - should also be in the 600 - 800 ma range. If you are much above this, consider adding more resistance.

You are now very similar to the setup of using a "2 x 123 cells, a small resistor, and your nice new Lux III. All without the pain of destroying it.

If you do not have a voltmeter and do not have access to one through a friend, consider using 2 ohms and 2 x 123 cells anyway. While not optimal, it is unlikely that someone would sell you a very low Vf bin Lux III without telling you and charging quite a premium.

Direct driving 2 x 123 with no resistor in a Lux III is done by some people, but the heat sinking needs to be reaaallly good and battery life will be not very good.

Thank you for all this. At last I have a place to start, that will stand in me in good sted for future projects.

There is so much info here, it can be very difficult to know exactly what to ask.

Thanks Again

Tony