# Turn Mag LED into a "hurricane LED"



## NewBie (Aug 28, 2006)

Some of you will remember a few of these photos from this review here, it may be good to review this while I'm describing things:
http://candlepowerforums.com/vb/showthread.php?t=119665&page=1&pp=40

Before you start, it is good to have someone experienced at soldering regular surface mount components to do the work for you, or yourself, if you have the equipment and skills.

Several folks have asked, how can I turn the module down a little. 

Why would a person want to turn down the module, and lower the output, isn't brighter always better? 

Well, for starters, they'd like the flashlight to run for a longer time on a given set of batteries. When all the lights are out in an area, you don't need much light to see by. By turning down the module, you raise the efficiency of the electronics, and the batteries deliver their power more efficiently, especially Alkalines. When you start underdriving a Luxeon (which is used in this module), it becomes more and more efficient at lower current levels, and your lumens per watt go up. Additionally, this module doesn't have the best heatsinking, and heat also lowers the efficiency of the LED. Taken together, the increase in efficiency can be astounding, and greatly increase the runtime of your hurricane flashlight.

We will take a look at the MagLite 2D module.

First, you pull the black plastic retainer out of the PR housing, from the rear or bottom, taking careful note of the orientation in reference to the LED. I mark the metal PR can, and the black plastic holder before I pull it all the way out. Pictures can be found in the review, if you'd like to take a look at how it goes together.

Next, mark the side of the PCB as you pull it out, with a Sharpie, so that it matches your mark on the black plastic holder.

So, you should have something that looks like this (I've marked the thermistor as some folks have asked about that.):








The other side, where you'll want to do your modification looks like this, note the location of the part indicated, called a resistor, which is marked R10 on it:







This is the sense resistor. Old timers, will remember Dat2zip's sandwiches, where a person would change the sense resistor, to adjust the output current of the module. Same thing here.

The function of the sense resistor is to sense the output current of the module, and to regulate the current going to the LED. 

This is the part you change.

I chose to change mine from 0.1 ohms (R10), to 0.39 ohms.

Once changed, put the module carefully back together, aligning the parts properly as you put them back together, the marks you made will serve as a great guide to help you put it back together. If you didn't mark things, you could put it together backwards, and you will blow up your module.

Thats it, simple as that. Drop it into your MagLite and you are done. Enjoy!


-------


So, how does it perform? I hit my light meter with it again, and noticed less than a 30% drop in light output. It is still far brighter than most 5mm PR based solutions.

Well, how about runtime? I took a meter, and hooked it up before the mod, and my module was pulling 1.12 amps. After the mod, the module pulled only 0.33 Amps, which only lowers a slight amount as things warm up. 

This is a whopping 70.54% decrease in current consumption, and it now consumes less than 1/3rd of the power it did before the mod, with only a 30% drop in light output.

I have not had a chance to do a runtime on the modification, but I am expecting greater than a 100 hour runtime.

You can further reduce the output, by increasing the value of the resistor, if you'd like even longer runtimes. As the value continues to increase, there is a loss caused by it, but at low current levels, it's contribution is minor to the big picture. The bigger piece of the puzzle, is that the Luxeon will pick up a little more efficiency due to less current density, and it will run cooler, plus the batteries will become more efficient at delivering power.

Be aware, doing this mod will cause the beam color to typically shift a tiny tad more green at lower currents.

Oh, and the resistor package size that is used in the module for the sense resistor is an 0603.

Examples of what I utilized:
http://www.mouser.com/search/Refine...03 0.39&N=1323038 254363&Ntk=Mouser_Wildcards
http://www.digikey.com/scripts/DkSearch/dksus.dll?Criteria?Ref=449938&Site=US&Cat=35193467


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## AdamW (Aug 28, 2006)

As always, excellent! Thanks for taking the time to document this for the CPF community.

Newbie, did your MagLite 2D module contain a decent LED bin? Better yet, any idea what bin is in it?

Adam


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## Skibane (Aug 28, 2006)

Longer run-time?

I thought that was what the spare bulb holder in the bottom of the Luxeon M*gLites is for: Remove and discard the incandescent bulb, replace with a PR-base SMJLED, and use whichever LED suits your brightness/battery life needs!

(Well, it works just great for the 2-cell M*gLites, anyway! )


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## NewBie (Aug 29, 2006)

AdamW said:


> As always, excellent! Thanks for taking the time to document this for the CPF community.
> 
> Newbie, did your MagLite 2D module contain a decent LED bin? Better yet, any idea what bin is in it?
> 
> Adam




I'm unsure of the Vf bin, as it is hard to measure at home, but I'd put money on it being an XO color bin.

You are quite welcome Adam!


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## Norm (Aug 29, 2006)

Skibane said:


> Longer run-time?
> 
> I thought that was what the spare bulb holder in the bottom of the Luxeon M*gLites is for: Remove and discard the incandescent bulb, replace with a PR-base SMJLED, and use whichever LED suits your brightness/battery life needs!
> 
> (Well, it works just great for the 2-cell M*gLites, anyway! )



I like lateral thinkers, that is a great idea.


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## NewBie (Aug 30, 2006)

Okay, I've done two versions of the mod.

The 0.39 ohms and 0.66 ohms. I am still very surprised at how much light still comes out of this with the mod.

I ran a few efficiency plots, and I was wrong, this particular switcher starts loosing a little bit of efficiency as you continue to take the output current lower.

The 0.66 ohm mod draws 0.226 Amps at 3.0V and 0.211 Amps at 2.5V.

This would extend the runtime to beyond 160 hours.


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## jar3ds (Aug 30, 2006)

very interesting... thanks Newbie for doing this! I've lately got pretty interested in emergency/long running lights... :rock:


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## eebowler (Aug 30, 2006)

Hi Newbie. Do you think long wires connected to a pot or a resistor and a switch would affect the efficiency/operation of the circuit? I know some circuits have problems with long wires.


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## andrewwynn (Aug 30, 2006)

nice conservative design.. i've noticed and others have designed with this in mind.. thanks for all the work n reseach.


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## NewBie (Aug 31, 2006)

eebowler said:


> Hi Newbie. Do you think long wires connected to a pot or a resistor and a switch would affect the efficiency/operation of the circuit? I know some circuits have problems with long wires.



I am not sure what you are doing, but if it is to use a pot/resistor to tweak the value for the sense....

You might consider raising the sense resistor, and putting in parallel, your control. You will need a nice low, low value...twist your wires together, tightly, to reduce the lead length inductance.

There are some other techniques, like pre-biasing the FB point that could be utilized, which would allow a higher value pot/rheostat to be utilized, but you are getting into design type stuff.


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## jburgett (Aug 31, 2006)

Newbie,

It seemed to me that using the MagLED with a proper heatsink would allow you to replace the thermistor with a simple potentiometer. Then adjusting brightness is achieved by simply rotating the pot. (I am assuming that you heatsink the luxeon properly, so that thermal control is not an issue.)

This $18 luxeon/circuit combo is a great place to start a mod.

By the way, do you know the part number or room temperature resistance of the thermistor?

Thanks for the info Newbie!


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## andrewwynn (Aug 31, 2006)

nice conservative design.. i've noticed and others have designed with this in mind.. thanks for all the work n research.


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## NewBie (Sep 1, 2006)

jburgett said:


> Newbie,
> 
> It seemed to me that using the MagLED with a proper heatsink would allow you to replace the thermistor with a simple potentiometer. Then adjusting brightness is achieved by simply rotating the pot. (I am assuming that you heatsink the luxeon properly, so that thermal control is not an issue.)
> 
> ...




In circuit, I measured 30k (no idea of temp), but it moves around with temperature, obviously...


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## eebowler (Sep 1, 2006)

Thanks Newbie  .


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## bombelman (Sep 1, 2006)

Way cool !!


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## NewBie (Sep 1, 2006)

You are most certainly welcome eebowler!

Thanks bombelman!

It is even more impressive in person.


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## jburgett (Sep 5, 2006)

Newbie,

Thanks for the thermister value!

I've been thinking that a 4-cell MagLED modded with a potentiometer in place of the thermister might find a good home inside my River Rock 4AA lantern. There may be room enough to upgrade the heatsink a bit, and install the pot with on/off switch as a single rotary control through the existing hole in the top. Hmmmm. . . . Now if I can find the time . . .

Thanks again!

:goodjob:


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## NewBie (Sep 5, 2006)

jburgett said:


> Newbie,
> 
> Thanks for the thermister value!
> 
> ...



Anytime. I haven't had a chance to measure the thermistor in the buck though, or fiddle with it much (you mentioned 4AA).

When I get a chance, I'd like to do some lux and runtime testing on the modified boost, which should be really interesting. Right now, I'm running tests on another light.


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## etc (Sep 18, 2006)

Very neat, thanks for sharing. I am one of those who seeks better run time at the expense of lumens rather than vice-versa. 100+ hours is very impressive.


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## Handlobraesing (Sep 21, 2006)

NewBie, I would like a clarification on the reference point. The Mag LED module dims over 50% from instant after switch state after it warms up completely. Since the 1.1A current is what you'd expect at first power up, I'm assuming you meant the reference was in cold state when you said "only 30% loss in light output".

So, if the stock module loses over 50% due to throttling in a matter of minutes and the mod only reduces 30% relative to cold state stock and only drops "a little bit" with warm up, it implies that it puts out more light than a fully warmed up stock light. Is this correct?


Also...
The Nite-Ize $10 drop in from Target is also a very good alternative to this if you want LONG runtime.


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## NewBie (Sep 23, 2006)

IMHO, the Nite-Ize seriously sucks in comparision.

I think you are reading way too much into things.


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## Handlobraesing (Sep 24, 2006)

NewBie said:


> IMHO, the Nite-Ize seriously sucks in comparision.


probably, but its a lot cheaper too.



> I think you are reading way too much into things.



I disagree. 

It was your own review data that revealed that the unmodified Mag module drops by 60% in output from cold start to fully warmed, stablized state. The 1.1A current seems consistent with what the module would draw in cold state.

If you say the modification drops the current by 70.5% *relative to cold state*, then it would only be fair to compare the light output relative to the cold state module. Since you said the modified module is loses only 30% in output and doesn't change much in warm and cold state, you are saying that it maintains approximately 70% of output of cold state MagModule. 

Since warm state stock Mag module only maintains 40% of output relative to cold state stock module, when you say it maintains 70%, you're implying the modified module is actually brigher than the fully warmed up stock module.


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## NewBie (Sep 24, 2006)

Handlobraesing said:


> probably, but its a lot cheaper too.
> I disagree.
> 
> It was your own review data that revealed that the unmodified Mag module drops by 60% in output from cold start to fully warmed, stablized state. The 1.1A current seems consistent with what the module would draw in cold state.
> ...


 
Exactly what I said, you are reading way too much into things. Go buy some modules, and make your modifications, then I know you have the equipment and talent to make your own measurements. I'd highly suggest this.

.

Anyhow, I finally got a chance to do a runtime plot on the "Hurricane Mod", my light meter has been busy doing runtimes on other lights.

Here is the actual runtime from a module that was modified to pull 215mA off a set of cells when everything is cool. Note how it doesn't turn the current down that much at all, but fades more with battery voltage. If you look carefully, you will notice the line "warbles" a bit, which is the internal thermistor as it senses the variations in my room temperature:








Of considerable note, the runtime didn't turn out as long as I'd expected, as I not considered my own data, and the MagLED's thermistor cranks down the current in the stock module due to too much heat.

Compare to the stock runtime plot:







But, you do get nearly 3x the runtime out of things, without that much of a penalty for light output levels. One of the really nice things about the Luxeon, is that it's Lumens per watt actually increases when you underdrive it- thus the LED's efficiency actually goes up. One of the added benefits is that the lifetime of the LED also increases, since there is less heat. Contrast this to a 5mm, which has to be overdriven to the point of abuse, in an attempt to hit the same brightness levels, which very drastically shortens the life, and also looses a lot of efficency when overdriven. IMHO, an overdriven 5mm is the poor man's way of doing things, as it is an extremely cheap solution, since 5mm LED costs are under the 20 cent range, in volume. But it does increase profit margins.

The best example of problems with using a 5mm LED is found here:
https://www.candlepowerforums.com/threads/128801&page=1&pp=40


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## McGizmo (Sep 24, 2006)

Great work and explainations! Providing CPF members with a good and viable mod like this is really in the _true_ spirit of CPF. :thumbsup:


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## NewBie (Oct 14, 2006)

Thank you Don.


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## milkyspit (Oct 14, 2006)

McGizmo said:


> Great work and explainations! Providing CPF members with a good and viable mod like this is really in the _true_ spirit of CPF. :thumbsup:



I'll second Don on this. Well said, sir! And well deserved, Newbie!


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## wquiles (Oct 14, 2006)

Outstanding - thanks much NewBie 

Will


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## vortechs (Oct 25, 2006)

Thanks for the Mod instructions for the 2D MagLED drop-in module (boost). 

Have you investigated similar Mods for the 3D or 4D MagLED drop-in modules (buck) yet?


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## NewBie (Nov 4, 2006)

You are very welcome.

No, not yet.


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## modamag (Nov 4, 2006)

Cool! Litterally really Cool!
Great Job Newbie :twothumbs

It's nice to see the reserse philosophy in good use.


Newbie, did Mag change the sense resistor and thermistor of their 2nd LED release? cause a few friends of mine report of decrease but more stable brightness.

The ones that we picked up during 1st week of release is a wicked thrower ... for the first couple of minutes when things are still cold.


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## NewBie (Dec 25, 2006)

You know, I've never really looked. How does one tell the second LED release from the first?


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