5-Watt Fire Breathing Dragon Now With Six NEW Batteries (Gulp!)

LATEST LIGHT METER READING, PLUS BEAMSHOT PHOTO VS. SUREFIRE M4 (see latest post at or near end)...

Although the 5-watt in a Legend LX was bright (699fc), I knew it was being way underdriven at only 6V (and probably less as the Sanyo 123s in it were kinda used) and I wanted to bring the 5W closer to its peak performance spec to see what it could do.

I got some very good technical advice from dat2zip and lambda about checking current and then stringing resistors together and testing at each step, but the whole bundle ended up looking like the grand prize winner in some boy scout knot-tying contest, plus I wanted focusing ability which meant everything had to fit through the reflector opening which was too small, and I didn't want to cut off any of the reflector to widen the hole because I'd lose some of the focusing range, and...well, you get the idea.

So I very carefully metered all my used AA batteries and came up with five that measured:

1.274V
1.241V
1,259V
1.499V
1.500V

for a total of 6.773V (I believe max spec on the 5-watts is 6.8V @ 700mA).

I had to build a gigantic heatsink with an extended post (or pedestal, as McGizmo so elegantly put it) to match the height of the stock incandescent bulb's filament so I could retain the focusing range for which the reflector was designed.

The end result was several good things:

1) it has full focusing range, from tight spot to wide flood (with the dreaded MagLite black hole, unfortunately)

2) this particular 5W seems to still be running well below its peak as it does not get hot at all (after being on for a couple of minutes, I unscrewed the head and found the LS/post junction was actually cool to the touch)

3) yet the dang thing metered 2130 lux at one meter, or 2130 foot-candles...

Anyway here are some pics of this jade-green Fire Breathing Dragon, note especially the beamshot pic on the ceiling in broad daylight at 12 o'clock noon, where it puts the original DirectDrive 6V 699-lux 5W cyan Legend LX to shame:



I know some people (Hi Ya Lambda, dat2zip, McGizmo, the other Wayne, et al!) are gonna cringe to hear me say this, but -- after the Arctic Silver completely cures, I'm gonna run it at extended minutes and check temps, and if it's still reasonably cool, I am going to FILL up BOTH of the 3AA battery packs with SIX fresh AAs (using five w/one dummy now) and let'er rip at NINE VOLTS!

(and hope like hell it doesn't literally become a Fire Breathing Dragon...)

Its a dirty job but somebodys gotta do it All in the name of science. Thanks for your reserch Mr. Bulk.

Yeah, and at $28 a pop too, if the Dragon becomes an ember...

Am I brave or what?

Awsome! When you fire her up at 9v, just go outside and point it at the sky. Some of us on the west coast may be able to see your light bouncing off the atmoshere

Nice Mod!

That Garrity didn't last long in its natural state in your hands.

Can't wait to hear what it will do on fresh batteries. Keep us posted, and keep up the great work!

Very cool Charlie. Can you do a set of pics on the pedestal and whatever it is you set it in?

Charlie,

You don't need to wait for the Arctic Silver to cure; you will post cure it with the heat sink

Giv' em Bra!!!!!!!!!!!

Charlie,

I think you still have plenty of room to move. I just measured the 5W I have in the turbo head from 1 meter and got a 3930 lux reading. It's running at 660 mA. Can you measure the voltage drop across the LED when it's on (welders goggles might help ) With a good tight beam, I expect you can get easily over 4000 lux.

Well I'm already measuring other batteries as I write this. Don't want to ramp up the voltage Too quick.

As for the post/pedestal setup, it is simply a post arctic'd to a plate. The finish sanding to the end of the post was critical though, since you want a perfectly flat contact area between the end of a long skinny cylinder and a wide flat plate. I had to use the drill press and some other stuff to get the contact areas perfectly flat and shiny smooth. But I am thinking that having this part machined would be the best way, all in one piece. Plus the post could then be gradually widened as it extended down from the Luxeon for more heatsinking mass.

Nine volts -- soon!

3930 lux, hooboy! Then again my LS might be different from yours...

Now how do I measure the V drop -- stick the leads on the LS tabs (when it's on)?

Charlie,

Yeah, stick the leads on the tabs when It's on and you will know how much voltage is going through the LED. Be interesting to see what the voltage is under load compared to unloaded.

Just measured current, 540 mA...

Just measured voltage across the led leads (had to wear muh shades plus stuck a strip of masking tape over emitter -- shoulda used duct tape, it's like that masking wasn't even there) and got 5.8V...

Does any of this compute?

Comparison beamshot to the brightest 1-watt I have, a white low dome in an LGI which I measured at 800+ lux at one meter. The brightness and contrast were cranked up for this picture in order just to see the LGI's beam -- picture taken from the floor up to the ceiling about 16 feet above:

Mr. Bulk, you having fun yet, or what?

Thanks for the updates!

Nope, need More fun! I substituted the ~1.2V batteries for five fresher ones, all metering around 1.45V+, still one dummy in there, went to the LM631, stood back one meter away and:



Will be doing junction temperature checks soon, but I don't think putting six whole batteries in there (ever) would be very wise...

4680lux for your brightest,



vs. only 309fc for my brightest current LS prototype. I think the LGI will be brighter, but first I have to *find* it.
(No yardstick, so I can't measure directly in Lux yet).

Good job Charlie!!!!

Originally posted by The LED Museum:
I think the LGI will be brighter, but first I have to *find* it.

Click to expand...

<font size="2" face="Verdana, Arial">WHAT???!!! You lost it already? (hmmm, mebbe check the toliet?)

I've been thinking all day about brightness, and heat, and lux, and foot-candles, and focusing -- and I just realized how important FOCUSING is when I went outside now that it's finally dark. I shined the FBD into the trees of the small valley behind my house. And it dawned on me that a properly driven 5-watt Luxeon mounted in a good reflector (no collimators needed), can finally be a match for incandescents. For instance, this tree is thirty-five yeards away:



THIRTY FIVE YARDS AWAY. Best my other LEDs could do was cast a dim, ghostly glow, none of which was reflected back enough to be picked up on camera. When a 5-watt Luxeon is well focused, especially the white ones when they become available, we will see led lights start taking away the one advantage incandescents had up until now.