Direct Drive, Voltage to Wattage Ratios?

Buster Bodine

Newly Enlightened
Joined
Mar 8, 2006
Messages
87
Okay, be patient with me please. I'm still new here and the more I read the less I know.

I've already performed my very first mod since joining up, I bought one of Lambda's SMJLED kits for a MM (see, I'm learning the acronyms!) and I was amazed by the results! Lambda rocks too, fast ship, no hassles! :rock:

Anyway, I had never seen an LED light that performed quite that well. It outshined my X1 by a wide margin and had more throw with less sidespill than my X5. (My only two LED lights at the time.)

And then I bought a Dorcy light. I know, they're considered "cheapo" lights by many, but this one has a 1 watt luxeon being driven by 3 AAAs mounted in a cartridge.

The point here, is that I was completely blown away by the performance of the Lux I! I tried comparing it to my other LED lights and it out performed them by such a wide margin that I went back in the house and got my SF 6Z to compare it to. The 6Z (unmodded and probably ready for a new lamp assy)beats the Lux 1 watt for brightness and throw, but not by very much!

So, this has gotten me to thinking about possible mods and searching the forums leaves me with more questions than answers, so I thought I'd give up and try to ask my questions, without further ado, here goes. Please pardon and correct any overt stoopiditty.

1. Can you direct drive a Luxeon 1 watt and does it always need a heatsink?

2. Can you DD a Lux 3 and would this give significantly better performance than using the 1 watt?

3. Is there a general formula for figuring the volts to wattage if I want to DD an LED?

Example, the Dorcy light uses 3 AAAs, giving 4.5v to drive a 1w LED. Presumably, the Dorcy has a board for power management but would this same setup be acceptable in a direct drive configuration?

4. If polishing the dome flat on an MJLED turns it into an SMJLED and such an improvement in throw while still leaving acceptable sidespill, what are the chances this could be done with a Lux 1 or 3?

And I've got many many more but I'll stop there and not abuse my "Oooh Teacher!" priviledges.
 

stjohnh

Newly Enlightened
Joined
Jan 13, 2006
Messages
93
Hmmm...I'm not a pro, but here are some answers:

1. Yes you can direct drive a Lux, but depends on the battery voltage and amps of the battery. no problem with 3 button cells: 4.5 volts but low amps and hi loaded internal resistance. But put the same 4.5 volts in at high current ie lithium AA cells and it will likely blow out.

2. Yes you can DD a Lux III, and probably get more light out if you run it at higher amps (ie more powerful battery), but same considerations apply as in 1.

3. Watts=volts x amps. 4 volts at 1/4 amp= 1 watt.

4. The SMJLED is not a polished down MJLED. Both these start life as a 5 mm standard size LED, called here "uncut". If the top is cut off and polished it is now "cut". The cut versions have the focussing top of dome cut off, and are used with a reflector. The Uncut ones are for use without a reflector. The SMJLED puts out a bit more light than the MJLED. The Lux's don't really have a focussing lens to "cut" in the same way the SMJLED and MJLED do.

Holland
 

Buster Bodine

Newly Enlightened
Joined
Mar 8, 2006
Messages
87
Thanks Holland, as always, the answers raise more questions but I've got a direction to steer my homework in now and at least I know I'm not completely up the wrong tree!
 

Buster Bodine

Newly Enlightened
Joined
Mar 8, 2006
Messages
87
Wow, that's an awesome chart! Of course I'm going to have to go learn some more nomenclature before I understand everything its trying to tell me but what the heck, I've got several more years to live.

Thanks!
:D
 
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