making the brightest lux III mag?

[Chop]

GarageBoy,

The downboy converter is a buck converter and should be used in situations where the Vin will exceed the Vf of the luxeon. Using a buck converter is also the best way to get 1000mA to the Lux III (which is not overdrive, but to maximum spec). You could do this by getting yourself a couple of 3AA or 4AA to D cell adapters. Using 6 or 8 AA cells in a 2D mag light driving a Lux III at 1000mA will get you where you want to go.

 

[GarageBoy]

6AAs nimh = 7.2v or 8 @ 9.6v so i guess i'll go that route. will the puny little AAs supply enough current?

 

[3rd_shift]

They sure will.
I have built several mods with a 3watt, georges80 1000 milliamp buck converter, and 6-8 cells.
In fact I'm running one now with a SYAJ side emitter, 2D mag, Georges80 buck 1000, 2 3-D's.
It's getting 1000ma to the led, but is only taking 560-600 milliamps from the 6 AA batteries.

A good buck converter draws progressively less current with higher voltage from the source batteries.
The led still sees 1000ma all the same with same brightness.

An 8-2D adaptor draws about 500 milliamps.

To put it this way;
6-8 AA alkaline batteries with your setup will get devoured down to thier bones before the flashlight starts to finally dim. /ubbthreads/images/graemlins/wink.gif

 

[Pajamas]

Where do you get a Georges80 buck 1000 and can they be used in a 3D Mag to "improve" a direct drive setup?

 

[3rd_shift]

The buck circuit maintains an even 1000 milliamps to the led as long as the battery voltage is higher than the led's required voltage.
pj, yours will need three 3-to-D's with shamefully cheap AA batteries for a buck circuit to work right in a 3D light.
But it will work quite well that way.
Plus the Georges80 1000 buck circuit boards are easy as pie to epoxy into the back of an Osink.

www.taskled.com

 

[Chop]

Pajamas,

Going with regulation is always better than going with direct drive. With a converter, you don't have to worry about Vf shift or Vin/Vf matching and you get a steady amount of light. If you want to run 3 D cells, you might want to consider going with a buck/boost converter like the Wiz2. I'm a big fan of "stock" battery configurations. You can avoid the cost of A to D adapters and it greatly simplifies battery changes in the field. Swapping 3 D cells is alot easier than swapping 9 to 12 AA cells in adapters. If you want to stick with a strictly buck converter, you could use a couple of pieces of PVC pipe to make an adapter/sleeve to convert the mag light to a 123 light. I don't know how many will fit, but the downboy is good for up to 16v. I can't comment about George's converters. I've heard very good things about them, but haven't used any of them.


3rd Shift,

Are you saying that you have indeed verfied the output of the Mag mod, in lumens? I'm really curious. If you've found access to an integrating sphere, I'd be interested too.

 

[3rd_shift]

No integrating sphere here yet.
Most here cannot afford /ubbthreads/images/graemlins/broke.gif one.
But 700 milliamps at 67+lumens, add 500 milliamps, puts even the worst T bins quite close to 100 lumens with the head off on a bad day.
Heat is the enemy of leds.
Lower forward voltage = less heat at a given amperage.
For those without U*** bins, a low voltage ***H bin is a good alternative for now.

I have used Georges80 converters quite a bit.
They are awesome /ubbthreads/images/graemlins/buttrock.gif
That I can verify. /ubbthreads/images/graemlins/wink.gif

 

[Chop]

OK, I didn't realize that you were extrapolating performance figures.

Assuming that a Lux III will put out 65 lumens (typical luminous flux according to Lumileds) at 700mA, you'd need to drive the luxeon to 1400mA to get to 98 lumens. Of course, I'm just extrapolating figures here, but a luxeon's output does not increase in a linear manner, as current is increased.

Of course, Lumileds' performance figures also assume a perfect "test" world environment. All of their performance figures assume a 25C junction temp. In the real world, performance will suffer greatly as the junction temp rises above 25C. Add to that losses suffered in the collimator and lens, and the real world output doesn't even come close to Lumileds' published performance numbers.

For any given amount of output at any given current level, you'd need to double the current going through the luxeon to get a roughly 50% increase in output. The rest of the energy is wasted as heat.

I also have to disagree on the point that luxeons with lower Vfs will run cooler than those with a higher Vf at any given current level. I haven't found that an L Vf luxeon running at 700mA will run hotter than a J Vf luxeon running at 700mA. Of course, I could be wrong about this. I just haven't noticed it.

Ahhh, everything that I said above is just my understanding of things. All always, I could be wrong. I do not have an integrating sphere, nor a laboratory, so I cannot prove or disprove any of it.

 

[VidPro]

well sum up all the experience you have here, and DD isnt such a bad deal, as it does lower a bit after longer run times, it will not overheat as much, Plus you get the added advantage of not having a driver thing that also puts out heat.
you get bright bursts at first, and longer running as cooler, and when your batteries are aboutto croak it goes into automagic conserve mode . best of all world.

before it gets to hot, its cooling down.

course he didnt ask that, he want Extreeme brightness with 1, put 3 in and run easy on them, not the same.
1 vrses 3 running at 1/3rd, is a good balance over heating one up, i think the life of the leds will be much better.

 

[GarageBoy]

ok, so 1 amp is pushing it. the wiz2 hits the led with how much current and can i get one for 1 amp? i really want to stick with a stock configuration with a buck converter, since boosts seem to not be able to supply enough current. (well the nexgen falls into safe mode)

 

[scudinc]

Buck drivers are nice, but for maximum throw you can't beat DD on NiMHs. I strongly suggest that you reconsider it.

 

[Chop]

1A is not pushing it. 1A would be driving the luxeon to spec. Running it at 1.5A would be pushing it.

Whether a boost converter can supply the current necessary to run an led at a particular bias is usually a matter of whether the batteries are up to the task.

The reason that the NexGen won't do it from 2D cells is because it drops into safe mode when the input current rises above 1.2A, which will happen when trying to get 1A to the emitter from a 3v power source. If you up that power source to about 3.7v, the NexGen will happily do the job.

You just need to decide what battery configuration it is that you want to run, then decide on the converter that you want to use.

Although direct drive is nice and inexpensive, it is very limited. You have to watch the batteries that you use and the output isn't constant.

If you set the light up so that you get 1A to the LED on fully charged batteries, that maximum output is going to be short lived. If you put a luxeon on a sink and wire it up to a set of NiMH cells and run it through a DMM, you'll see what I mean. The current to the LED drops fast as the batteries discharge.

I'm not saying that direct drive isn't nice. It is, for what it is. A low cost alternative to a regulated light.

If you want insane brightness without giving up all sanity, you could try this.

Assuming that you are going to be using a 2 D light. Get an o-sink. Put a T or U bin Lux III on top of it. Get a couple of 3 AA or 4 AA to D adapters. Get a downboy converter biased for 1500mA and throw it all together. That will be insanely bright.

Alternatively, you could go with a 3 D light and just run D cells in it with a buck/boost converter. I'm just not sure if the Wiz2 will run at 1.5A without self destructing. With this setup, you'll be able to run alkalines or NiMH cells in it.

I'm just not real keen on making a light that will only run on rechargeables because there are times when you can't recharge your batteries. This is why I like regulation.

 

[GarageBoy]

ok, regulation is the way to go. I was gonna build a lux V basic space needle, but I want throw!!

"Assuming that you are going to be using a 2 D light. Get an o-sink. Put a T or U bin Lux III on top of it. Get a couple of 3 AA or 4 AA to D adapters. Get a downboy converter biased for 1500mA and throw it all together. That will be insanely bright."

how much runtime will i get and how much LED life?
thanks, that sounds like an option I want to go with, set at 1000mA

 

[Chop]

Well, if you go with 1000mA, that will be to spec and the Lux will not be overdriven at all, so the life of the LED would be whatever it is that lumileds rates it at. The runtime should be a LONG time. I can't tell you how long though.

 

[GarageBoy]

Good! I heard 8hrs to 50% with DD. So DB1000 with a few AA to D adapters it is. (I keep thinking that 700 is spec)

 

[Chop]

According to lumileds, the Lux III is rated at 700mA (65 lumens) and 1A (80 lumens).

 

[GarageBoy]

Thank you!!

 

[AuroraLite]

Just a friendly reminder--do consider to put in a connector between the lux and the board(or even another connector between the battery and borad). It just make swapping lux on top or any repairing job easy.

Some board does require you to epoxy the board to the body for heat issue, but some doesn't(for ex, potting is not necessary or good for nflex).

For those that doesn't require potting, I would suggest to apply nail polish to the board when you have finished all the soldiering job to reduce chances for shorting inside the tube body.

Good luck! /ubbthreads/images/graemlins/smile.gif

 

[GarageBoy]

Downboys need to be potted, right?
If I put a connector under the o-sink, how do I get the o sink out w/o damaging the board?

 

[AuroraLite]

I think for potting, it is mostly for the issue of either heat or because of structural design(for ex, sandwich). My only experience with DB917 comes from Aleph, and it only gets warm after 10+ min without touching--but I think most of the heat could be coming from the Lux.

One good and easy way to determine whether potting is necessary is to simply run the board and lux together before placing them into the body; check frequently to see how much heat generated from lux and board, and then decide whether you will need to pot the board or not.

If you do decide to pot the DB, one easiest way is probably to pot it under the hotlip or o-sink. And leave lots of wires and place an connector between the switch assembly and the board for easy swapping. But there is always pros and cons about potting, and doing a search about 'downboy' in Shoppe board probably will yield some results.

For a picture about the connector idea, check out my humble Mag 2C nflex mod writeup here

Hope this helps! /ubbthreads/images/graemlins/smile.gif