LS seems to be indestructable

[Ed]

Hi all,

I was infected by all the luxeon star hype
in the cpf, so I decided to see if I could
buy one. It turned out to be too expensive to buy just one, so I bought 10!

I am now the proud owner of 5 white and 5 cyans.

Because I had only really wanted to build one or two luxeon flashlights, I had the luxury of a few extra units I could fry while experimenting.

I just wanted to say that I have not managed
to fry any of them and I have been really nasty to them.

I have directly driven a white luxeon
mounted on a crude home made heatsink
with 4 Alkaline D cells. Admittedly, they were slightly used batteries, but I was still getting 5.1 Volts to the Luxeon.

It got really hot - almost too hot to touch,
but I left it on for over an hour

The batteries had only depleted to 5.0 volts.

On to test number 2 ....
I have a cheap variable power supply.
I'm sure it's not current regulated.
I very slowly dialed up 12 volts on the same luxeon after it cooled down from my first test.
This wasn't maintaned for more than a second or two, because I noticed that the brightness
did not increase at all when driven over 4 volts.
The luxeons seemed to 'eat' anything above 4 volts and convert it to heat - not light.

I'm sure this has a lot to do with current not voltage, but in any case, the luxeon star
has the same brightness on 3 D cells as it
does on 4 D cells, only on 4 D cells it runs
a helovalot hotter.

I've found that optimal brightness is achieved from 3 cells. 2 Cells (3 volts) is
underdriven, and 4 Cells (6 Volts) is overdriven, but no brighter than 3 NEW cells (4.5 Volts).

The more I experiment (play) with these
luxeon stars, the more I think I could
just attach them to giant heatsinks and
run them off car batteries. They are
incredible! I can't wait for the 5 watters now!

Unless someone stops me, I'm going to mount
a white luxeon with a seriously thick
aluminum heat sink into my 4 D Cell
Scubapro diving torch. No resistors.
It's a simple mechanical mod.
I would use a resistor, but I wouldn't
know what value to use or even if it would
be beneficial. I want the luxeon to be
supplied with maximum voltage. Brightest
light from one luxeon is what I'm trying
to achieve.

Does anyone have any ideas how long this
might burn for - presuming it doesn't burn out ?

Would I be better off using a resistor to
get similar brightness and longer burn times?
Maybe a dummy battery?? I certainly don't
want to go to the trouble and expense of
fitting a step down circuit - or do I

cheers,
Ed

 

[ElektroLumens]

Hello Ed,

As you've observed, after a certain point, the current is converted (wasted) to heat. Try mounting 2 or 3 Luxeon Stars on a huge heat sink like one I've made. You'll be amazed at how bright it is! One single Luxeon does have limits of how much light it can produce, although it is a lot.

Also, if you let them get hot, the life expectancy will shorten, and also the ime they shine brightly will be reduced. So, use lots of heat sink.

Your testing is indeed interesting!

Wayne www.elektrolumens.com

 

[lambda]

Hey ED,

Great work, and a lot of guts there to risk frying your Luxeons to see what they can take. But sometimes, no risk, no gain.

Your on your way to a real addiction there; your going to become a Modaholic, I can tell these things. Seek professional help. And overdrive two Luxeons and call me in the morning..........

 

[Silviron]

Gee, I wish that the 5 that I have destroyed had read your post. I guess they just didn't realize how much they could be abused.

I have destroyed two cyans by accidentally hitting them with about 5 V, (one with reversed polarity) and two whites with about 5V also, and one white with the accidental application of 8 V.

Fortunately, was able to "ressurect" four of them with the little technique I posted in a couple of earlier threads....

Seems like the LSs are really varied. Some very sensitive to over spec situations and others don't seem to care what you do to them.

 

[dat2zip]

Ed,

You certainly sound like a good risk taker. I've never applied as much voltage to an LS as you have. I can't believe you have not let the secret smoke out of the LS. There must be some magic smoke in there somewhere!


I must warn others that the standard "diode" function built into most DMM nowdays applies 15-20mA of current and reads out the voltage drop. Apparently this is more than enough to break the reverse protection circuit on the LS. I was too lazy to look up the data sheet to see which one was the anode and which one was the cathode. Just grabbed the meter and turned it to the diode function. Poof. This unit new measures 110 ohms in both directions.

The luxeon are a very rugged little beast. Being able to overdrive these shows how much the packaging can actually take and survive.

 

[Ed]

Wow! The famous guys are replying to me!
I am truly honoured. I treasure every word.

Here is an update on my attempts to turn
the luxeon star a puddle of metled plastic.

I just started luxeon overdrive test number 3....

One white luxeon, One huge heat sink,
heaps of thermal grease, and a power supply.
My multimeter is reading 6 Volts with a 850-900ma draw.

As I write this it has been on for
10 minutes and is starting to smell or is that the thermal grease

Its hot ... really really hot!
Even the heat sink is getting hot at
the back and its a 1 inch thick aluminium block!
Will I keep up this abuse??
You bet I will!! I'm going to leave this on
all day - or until it blows up or melts.
Cruel isn't it?

I noticed this little luxeon is glowing
'pea green'. I hope this is because I have abused it, and not because I have a batch
of 'pea greens' as they were all on the same
strip. The 'Cyans' are more Green than Cyan.
But they are a lot brighter than the white.
They cast the beam a lot further.
Interesting that they have different lens shapes for the optics. At least one of the Cyans will be put through similar grueling tests when I get around to it.

Pretty soon I'll be able to light my
cigaratte off this white test luxeon.
I'll get back to you all if I haven't
burn't the house down

BTW ... The reason I am doing these tests is
to see if a luxeon can run on direct drive
in my scubapro 4 D Cell torch. It looks like
the luxeon will stand up to it with a big
enough heat sink, but I think I'm going to build a METAL flashlight. My scubapro dive torch is an expesnive, waterproof beast made of impact proof plastics - I'm sure it is not MELT proof. A figured a scubadiving flashlight made of metal could keep the luxeon nice and cool - especially if the heatsink incorporated the flashlight body. Otherwise, I'll have to use a dummy battery or resistor. I am still keen to hear from the experts on this.

I hope my tests have been useful to somebody.
Cheers, and thanks for your input.
Ed

 

[Daniel Ramsey]

For all that effort to get the most light perhaps one should just get a P61 120 lumen Surefire lamp?

If you really want to have fun try connecting at least 4 together in series...and try diferent voltages, like using an 18volt power tool battery pack.

 

[lambda]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Ed:
BTW ... The reason I am doing these tests is to see if a luxeon can run on direct drive in my scubapro 4 D Cell torch. It looks like the luxeon will stand up to it with a big enough heat sink, but I think I'm going to build a METAL flashlight. My scubapro dive torch is an expesnive, waterproof beast made of impact proof plastics - I'm sure it is not MELT proof. A figured a scubadiving flashlight made of metal could keep the luxeon nice and cool - especially if the heatsink incorporated the flashlight body. Otherwise, I'll have to use a dummy battery or resistor. I am still keen to hear from the experts on this.

I hope my tests have been useful to somebody.
Cheers, and thanks for your input.
Ed<HR></BLOCKQUOTE>

With a metal body flashlight, and being underwater for rapid cooling, I can't imagine how much power a Luxeon could take and stay cool. Never really thought about "under water lights"; hmm, with the flashlight cooled in water, how much could a Luxeon take..............

 

[Ed]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR> If you really want to have fun try connecting at least 4 together in series...and try diferent voltages, like using an 18volt power tool battery pack.

<HR></BLOCKQUOTE>

Sorry, this might be a dumb question...
Why series as opposed to parallel?
Wouldn't I get a brighter light in parallel?

cheers,
Ed

 

[Silviron]

Originally posted by hotfoot:
...I think I tried technique you mentioned: Is it blasting a "blown" luxeon with ridiculousy high input?...

<font size="2" face="Verdana, Arial">No, that's not it- Here is the old topic:http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=002050[/UR L]

I have noticed that the ones that I have resurrected this way usually require more voltage than normal to achieve full brightness- I always assumed that it was due to a less than perfect electrical connection to the heat sink slug (using silver conductive paintin the center and super glue around the edge to attach it to a heatsink), but there may be more to it than that, given your experience.
-------------------------

Rod is, of course, correct about current being the key, but voltage is what drives the current, and without actively measuring current at the moment of "ZAP" the voltage figure is much easier to obtain.

I have occasionally had a current of up to 1.6 amps run through a LS for a few seconds- every time has been accidental- picking up the wrong battery pack etc. (gotta quit working on multiple projects simultaneously)

That shade of blue/violet out of a white Luxeon scares the crap out of me, and I break the connection as soon as I realize that I've been stupid ONCE AGAIN

 

[Silviron]

What in the heck is wrong with the UBB code???- I have edited that link in the post above seven times, and it keeps inserting a space between the R and the L in the closing code when I submit.

Guess you will have to "Copy & Paste" the URL to get there if you want to see it.

 

[Silviron]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Ed:
Sorry, this might be a dumb question...
Why series as opposed to parallel?
Wouldn't I get a brighter light in parallel?

cheers,
Ed<HR></BLOCKQUOTE>

LEDS in Parallel essentially pull the same voltage but current draw multiplies X # of LEDs.

LEDs in series essentially draw the same current but voltage to drive that current multiplies X # LEDs

 

[yclo]

Lemmne try:
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=002050

 

[Silviron]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by yclo:
[QB]Lemmne try:
http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=002050[/QB ]<HR></BLOCKQUOTE>

Hmm- that's odd. Can't imagine what caused the problem. I think I need a new keyboard- my {Ctrl} key quit working a few days ago, although I can't see how that would effect this. Well, thanks for making the link work.

 

[hotfoot]

Silviron,

I think I tried technique you mentioned: Is it blasting a "blown" luxeon with ridiculousy high input?

I had this particular LS that blew whenever I overdrove it beyond a certain point. I'm sure its a flaky one 'cos the one right next to it on the same reel was fine with the abuse. Whenever it "fried", I just hooked up three 9V cells in series and hooked the sucker up - and it would spring back to life! Bright as new! Kinda like using a defibrillator to restart a non-pumping human heart...

I even abused one unit with *FOUR* 9V cells in series and it ran hot, flickered wildly, changed color - but utterly refused to die even after 5 agonising minutes!

But yeah, I think even while their durability varies from unit to unit, they are generally much much tougher than their official specs would suggest.

I haven't, as yet, been able to really do in a Luxeon star completely to the point where it can't be revived yet.

 

[hotfoot]

This prob is no biggie - just cut and pasted the URL into the location bar and I found (and posted) on the thread of yours

 

[**DONOTDELETE**]

All this talk of applied voltage......
It's the current we're concerned with. (Primarily) Although applied voltage gives us some idea of what's happening, it's the current through a semiconductor which does the "work".

 

[hotfoot]

Rod - you're right. I guess the reason why voltage comes up more readily than current is because its more visually "accessible".

For instance, when you hook up 3x9V batteries, you're pretty certain about the sort of voltage you getting. With current, you'd need a meter to see what those LEDs are drawing under load.

 

[dat2zip]

Ed,

You know if you really want more light out of one LS you might want to consider the 30lumen HD that should be out shortly. I believe it is still 3.X Volts but requires 400mA of current, but, it puts out 30 lumens vs the current 18 lumens.

I'm not sure what a dive light beam profile should be but another option is changing the optics to a narrow beam angle to focus more light in less space.

A standard 18lm LS is I believe 20 degrees and if it focused down to 5-10 degrees makes a darn bright light.

 

[ElektroLumens]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Ed:


BTW ... The reason I am doing these tests is
to see if a luxeon can run on direct drive
in my scubapro 4 D Cell torch. It looks like
the luxeon will stand up to it with a big
enough heat sink, but I think I'm going to build a METAL flashlight. My scubapro dive torch is an expesnive, waterproof beast made of impact proof plastics - I'm sure it is not MELT proof. A figured a scubadiving flashlight made of metal could keep the luxeon nice and cool - especially if the heatsink incorporated the flashlight body. Otherwise, I'll have to use a dummy battery or resistor. I am still keen to hear from the experts on this.

I hope my tests have been useful to somebody.
Cheers, and thanks for your input.
Ed<HR></BLOCKQUOTE>

When I run the Luxeon Star from 6 volts, I use 3 ohms resistance, and it works fine. Haven't tried to go with less resistance. You gotta measure the current, though. Four AA's at 6 volts might not supply as much current as 3 'D' cells, even though it's 6 volts compared to 4.5 volts? I hooked up 2 Luxeon star's in parallel, to my 5 amp power supply, and at 4.5 volts, it was supplying 2.6 amps. Three alkaline 'D' cells seem to max out at about 1.6 to 1.8 amps, because of internal resistance.

It seems like 2 Luxeon Star's at 1,500mA are brighter than one single Luxeon Star at 1,500mA, and it is a lot easier on the Luxeon with only 750mA/each.

Wayne www.elektrolumens.com