Luxeon questions

From looking at some of the posts on the Luxeon it seems that it is the way to go for any application where light output is the main consideration. Can anyone help with a few basic questions? Actually I'm looking for answers I've got questions, but if I'm asking the wrong ones let me know.
I'm not technicaly inclined so I'm trying to go with direct from battery juice.
Can it operate on 3 volts, Actually two cells?
Would running two in series from a 6v lantern battery or gell cell work?
4 from 12v deep cycle or gell cell?

I dont think they run very bright on only
3 volts, and besides, once the voltage runs
down even a little the brightness would
die out even more.
Normally you need a step up circuit
like the one in the Zetex thread, or else
using 3 batteries in series with a dropping
resistor. My guess is that you need maybe
1 to 3 ohms for the resistor. Perhaps
someone else has already done this and has
a value worked out?

Good luck with it,
Al

Actually, I think they run plenty bright on just 2 cells.

I have a 3V DoubleBarrel mod with a luxeon star on the Mods pages on my site. Click the graphic below. My mod, running directly off the batteries, was about as bright as a 2AA minimag. More than enough for negotiating a dark house or apartment.

Of course, the more voltage you pump through these things, the more amperage they draw and the more heatsinking (and ventilation) you'll need. I find that 3V is about has high as I can push my luxeons without excessive heat building up in a sealed flashlight head.

My site's Q&A pages has some info on the luxeons as well.

I've done two conversions using Luxeons; one white, one amber. Both utilizing Dorcy Coolblues (Turtlelight I). This provides a 6V source. The ratings on the two Luxeons are different, but using bench testing, fresh batteries, inline resistors, and sensitive fingertips to detect heat, I found that about 340mA thru the White and 250mA thru the amber gives pretty near maximum light output.

I've done two conversions using Luxeons; one white, one amber. Both utilizing Dorcy Coolblues (Turtlelight I). This provides a 6V source. The ratings on the two Luxeons are different, but using bench testing, fresh batteries, inline resistors, and sensitive fingertips to detect heat, I found that about 340mA thru the White and 250mA thru the amber gives pretty near maximum light output.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Quickbeam:
Actually, I think they run plenty bright on just 2 cells.

... My mod, running directly off the batteries, was about as bright as a 2AA minimag. ...
<HR></BLOCKQUOTE>

Doug, I have some questions:
1. Do you know if such a Luxean Star would fit in 2AA Minimag?
2. Would it be as bright as in your 3V DoubleBarrel mod (i think it was the Energizer)?
3. And last but not least: Would there still be enough space for a DC-DC converter/constant current LED driver in the Minimag? I know such a converter is not a must in this case but would be nice and help to squezze the batteries with an almost steady brightness.

I'm asking these question because we try to make a good Minimag conversion in another thread (Converting Minimag (2AA version) -> http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=001221&p= ). A Luxeon Star is one of the possibilities I see for the Minimags. One of the problems could be the heat from the LS so maybe 4 - 7 LED's driven with 30 - 40 mA would be a colder and maybe brighter solution.

By the way I have to make a little bit promotion for this Minimag-conversion thread: It would be very nice if some bright (beams) and experienced guys like you would help us in this topic! My target is, that all who want to convert a Minimag can find a really good solution in this thread. As I am not an engineer I do need that help from other guys.

1) yes, if you remove it from the board
2) Yes, same voltage
3) probably not.

Someone else already did this conversion. Did you use the "search" link at the top of the page? They had to remove the LS from the board, solder the negative lead to a washer (to serve as a heatsink), run the postive lead through the hole in the washer, and solder little leads to it to poke it right into the bi-pin socket.

Ahhhh... Here it is: http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=000696

You really need more room in the head of the light to squeeze in a converter. That's why I used the DoubleBarrel for my conversion that includes the LM2621 converter board. BTW, that conversion light is the one that sees the most use in my house over all my other LED lights - it worked out great.

Do you really think the luxeon would be the same brightness with only 2AAs, as opposed to 4? I'm thinking not. Atleast you have another 2AA's in the double barrel, so this is why your luxeon might be bright. I tried running off 2AA's, and it was kind of weak. The luxeon I used was a good (low voltage) one, too....with a voltage drop of 2.95V.

it seems to me that two sets of seriesed AAs run in parallel will have less resistance/be able to supply more current...since the voltage of batteries drops as the load on them increases by parallelling two sets of batteries you halve the strain on one set and therefore drop less voltage under load...

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by papasan:
it seems to me that two sets of seriesed AAs run in parallel will have less resistance/be able to supply more current...since the voltage of batteries drops as the load on them increases by parallelling two sets of batteries you halve the strain on one set and therefore drop less voltage under load...<HR></BLOCKQUOTE>

That theory is just about right on the money-the Luxeon LED in my DB-4AAA is about 15% brighter with 4-AAAs, compared to running it with just 2 cells in one barrel

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>That theory is just about right on the money-the Luxeon LED in my DB-4AAA is about 15% brighter with 4-AAAs, compared to running it with just 2 cells in one barrel <HR></BLOCKQUOTE>

Hmmmmmm... I never really thought about it, but I know why I never noticed a difference... I use regulator circuits on all my LS mods now! DUH 2 batts or 4, AAA's or D's the brightness is the same...

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Quickbeam:
Hmmmmmm... I never really thought about it, but I know why I never noticed a difference... I use regulator circuits on all my LS mods now!

DUH

2 batts or 4, AAA's or D's the brightness is the same...<HR></BLOCKQUOTE>

I guess I really should have specified: NO resistors in my light

Ah, Quickbeam. I just came from your mod site. Where is the regulator that you mention?

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Al:
I've done two conversions using Luxeons; one white, one amber. Both utilizing Dorcy Coolblues (Turtlelight I). This provides a 6V source. The ratings on the two Luxeons are different, but using bench testing, fresh batteries, inline resistors, and sensitive fingertips to detect heat, I found that about 340mA thru the White and 250mA thru the amber gives pretty near maximum light output.<HR></BLOCKQUOTE>

Were can I find more info on this mod of the Dorcy Cool Blue? Do you have any pictures? What size and watt resistor did you use, etc...?

Is it much brighter than the LED it comes with?

Thanks for the input. I was hoping to be able to just use straight power as I am greatly lacking knowledge and skill in electronics (probably <1 hr with soldering iron in 41 yrs ). I had forgotten about the voltage drop as the batteries depleted. How hard for a neophyte are these circuits? Has any one put a couple luxeons in a 6v battery lantern? With lots of space would a plastic housing be OK? That is, wired in series so they'd be getting ~3v.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Do you really think the luxeon would be the same brightness with only 2AAs, as opposed to 4? <HR></BLOCKQUOTE>

The DoubleBarrel does not drive the Luxeon Star at 6 volts (4 batteries in series). It drives the LS at 3 volts (2 banks of 2 batteries in parallel). The Doublebarrel doubles the mAh capacity (the runtime) using 4 batteries, not the voltage.

If you take out 2 of the 4 batteries the Luxeon Star will run at exactly the same brightness, just half as long.

Therefore, it is almost exactly the same brightness (3 volts) as a 2-AA battery application.

Now, if you put all 4 batteries in SERIES (6 volts) the Luxeon star would be VERY bright... ...for about 10 seconds before it fried.

BTW, in subjective comparisons, at 3 volts, it seems about as bright as 4-5 Nichia white LEDs. Yes, it's weak compared to bigger led lights (or an incandescent), but until we figure out a way to dissipate the heat without compromising the integrity of the flashlight by drilling holes for ventilation, we're stuck with low voltages and low brightnes. If you don't mind holes in your light that water can get into, you can drive the LS to pretty bright levels.

Right, I understood this (I have a double barrel). I was just thinking that using 4AA's in series/parallel would reduce the "sag" on the voltage, in comparison to using only 2AA's.
I had better output with 2D cells, compared to 2AA's.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
I had better output with 2D cells, compared to 2AA's.<HR></BLOCKQUOTE>

That's probably because your LS was being "restricted" in it's draw by the internal resistance of the AA battery compared to the D. The D will have lower internal resistance and as a result, is more "willing" to allow the LS to draw more mA (up to the max it will draw at that voltage).

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by phred:
Ah, Quickbeam. I just came from your mod site. Where is the regulator that you mention?

<HR></BLOCKQUOTE>

Because of an unknown reason I can't open Quickbeam's page. But in the mod section you will find two topics about a regulator (LM ...).

There are some other pages dealing with this issue, eg:
- Zetex ZXSC300 single-cell LED driver http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=000983
- Converting Minimag (2AA version) http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=001221
(the thread you're already involved)

http://thelightsite.tripod.com/mods/dblslm.htm
http://thelightsite.tripod.com/mods/2621.htm

Please excuse the quality of the pics... this was before I had the digital camera and was using a webcam.

If you have trouble opening my page, click on the graphic at the bottom of my posts. If you type it in, don't put in "WWW." - just type "thelightsite.tripod.com" in your browser address bar.