# Mini Mag Lite: Forever LED mod



## AnAppleSnail (Oct 11, 2012)

Minimag: Forever LED mod

Recently I mentioned a modified Mini Mag Lite I built for some children I know who want flashlights. The needs were:

*Durable
*Very long battery life
*Cheap
*Simple modification
*Only bright enough to use in the dark

Interested? Read on:

I replaced the bulb in an incandescent Mini Mag Lite with an LED that uses barely-modified optics. This gives me a low-cost, durable host, with low power consumption and a fairly useful beam. First: Runtime discussion.

Most white LEDs will light dimly at about 2.5-2.7v. Two AAs in a Mini Mag Lite give about 3v, which will light most white LEDs dimly. You will have to confirm (By testing in place or measuring before) that the LED you plan to use works in this underdriving situation. I have had good luck with Eneloops and all Alkaleaks. Note that alkaleaks leak! Check periodically, or use NiMHs that you recharge every other month. Most AAs at low drain have about 2 amp-hours capacity, and multi-week runtime at low levels.

The brightness of this light will follow a direct-drive pattern, dimming down to a low tail. Mine start at about 3-5 lumens, which is plenty for young eyes in dark areas. The focusing ability of the Mag Lite gives respectable reach with this output, as well. Finally, candle mode is maintained, although it _is_ easier to knock the LED out of place than with the bulb.

The LEDs come from Christmas lights and other decorations. You want 'Cone-Tip' LEDs, which have a distinctive look and output pattern:





Note the cylindrical overall shape and the cone-shaped dimple on the end. This redirects light outwards, simulating a blob of light rather than a flat diode source.




This blob of light can be adapted to reflectors quite easily since it is similar to a filament, optically speaking. Amazon.com has warm-white LEDs (String of 100, $6) like this, as do many stores. Here is a picture of some "correct" LEDs. You will need an image showing the LEDs themselves to check the type. They are often called 'Fairy Light String.' 




Watch out for ones with resistors soldered on. This makes it harder to get enough wire length to connect to the bulb holder.





The light modification:
After you clean and lubricate the threads and O-rings, you need only widen the opening at the reflector's base. This allows the LED to pass through and press on the Mini Mag's bulb holder. Drill bits have not served me well!

I use a Swiss-Army Knife-sized knife blade to ream the reflector wider. Carefully avoid touching the reflective surfaces, and blow debris away rather than wiping it off. Hold the reflector carefully and turn the knife like a key in a lock. Rotate the reflector as you do this, and the knife will grind the plastic away. Don't let the knife bite in, as this will split the plastic. Once the reflector's hole lets the LED pass fairly freely, the LED must be placed in the bulb holder.

Pinch the leads so that they are slightly closer together. They need to be parallel and closer together than they are originally to fit in the socket. I use needlenose pliers to grab the lead and move it slightly inwards about half a millimeter on each lead. Then carefully press the LED into the bulb holder. If it does not light, remove and rotate the LED half a turn to correct polarity. If it still does not light, you have poor contact in the bulb holder. Slightly bowed or canted leads seem to work best, and I find 8-10mm to be the most reliable length. Stand the LED up completely straight in the holder, then carefully replace the head with reflector and window.


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## AnAppleSnail (Oct 12, 2012)

Overall layout and LED leads shown





Reflector bored out





LED mounted





LED lit





Focuses quite well


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## dealgrabber2002 (Oct 12, 2012)

Thanks AnAppleSnail for taking the time to show us this mod. I am waiting for my 3mm LED to arrive and I'll try to do one as well.


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## darkknightlight (Oct 12, 2012)

Great photos and tutorial! I too have made one of these great mods  I ordered some Nichia GS 5mm leds awhile ago from overseas; I believe they are of the 36 lumen 120 degree variety. I used a rotary tool to open up the reflector. Off of two fresh alkalines it puts out a very respectable amount of light while maintaining the focusing function of the standard incan bulb. I mostly use it as my dedicated moonlight mode light; I run it off of "dead" alkalines from my wireless optical mouse. It puts out maybe 1 lumen for a loooong time.


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## dealgrabber2002 (Oct 12, 2012)

darkknightlight said:


> Great photos and tutorial! I too have made one of these great mods  I ordered some Nichia GS 5mm leds awhile ago from overseas; I believe they are of the 36 lumen 120 degree variety. I used a rotary tool to open up the reflector. Off of two fresh alkalines it puts out a very respectable amount of light while maintaining the focusing function of the standard incan bulb. I mostly use it as my dedicated moonlight mode light; I run it off of "dead" alkalines from my wireless optical mouse. It puts out maybe 1 lumen for a loooong time.



Nichia GS 5mm can go up to 36 lumen? Also, is it a round tip or flat tip LED? I remembered somewhere that said round 5mm doesn't focus well... I could be wrong tho.


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## AnAppleSnail (Oct 12, 2012)

dealgrabber2002 said:


> Nichia GS 5mm can go up to 36 lumen? Also, is it a round tip or flat tip LED? I remembered somewhere that said round 5mm doesn't focus well... I could be wrong tho.



The stock minimag reflector is meant to focus a spherical-radiating light source well within the reflector's parabola. The cone-tipped LED I use works well with this reflector. A deeper reflector profile (Seen in the LED minimag) is needed to focus light from a diode's surface. Finally, bullet-shaped LEDs may not shine much light on the reflector, so that the reflector does not affect beam shape greatly.

If you have a need for $10 (Parts and labor) stocking stuffers for budding flashaholics, these work. I would expect more like 3 lumens than 30, though. My 2-year-old loves to either take hers apart (Hasn't eaten the LED yet) or shine it on the GITD stars in her room.


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## darkknightlight (Oct 12, 2012)

Yeah, according to the tech specs at LedRise the nichia 570GS makes 36.5 lumens and has a 120 degree viewing angle. It also says its a 5000k led, but the light that mine puts off is an ugly purple white; doesn't matter to me since i use it as my dedicated moonlight mode. Also yes, it is the round top variety. Mine focuses great in the reflector because of the viewing angle of the led i believe. It also retains the flood to throw function of the incan lamp. I just enlarged the reflector opening slowly and kept checking the fit until the led just made it through. The smaller reflector of the aaa maglite can't focus the light though; that is a better candidate for a 3mm led with a tight viewing angle i would think. 


Sent from my DROID RAZR using Tapatalk 2


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## ToyTank (Oct 23, 2012)

Great mod I did the same with the flat/cut 5MM HCRI I bought from eala. Been running it constant since Sept 1 and the eneloops are @ 1.267v! I had to drill a larger hole in the reflector but it was easy. Sweet light considering <$9.


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## Lynx_Arc (Oct 23, 2012)

If you want brighter light you can use lithium primaries, for dimmer light use nimh. I've adapted several 2 cell lights that use wheat type bulbs to direct drive LED use and using normal (non LSD) nimh cells they run continually for close to a month before getting too dim to be useful as a ceiling bounce night light they can run close to 3 weeks. I use a nichia 120 degree LED in mine and one host that works pretty good is the dollar tree swivel head 2AA light although it is cheap and tends to have contact issues at times you can remove the bulb cartridge ream out the reflector and replace the wheat bulb with an LED but you have to tinker with it to get the focus right. I also have a telescoping magnetic pickup light I put a generic 5mm LED in it I got a some 35kmcd long ago from someone selling them in the forum and off a pair of L91s it does fine.


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## bshanahan14rulz (Oct 23, 2012)

If you have a bunch of LEDs to play with and don't have any side emitters like the OP, you can snip the dome offa the LED. I used pliers, but those with more time might consider the chop-sand-polish route.


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## Lynx_Arc (Oct 23, 2012)

bshanahan14rulz said:


> If you have a bunch of LEDs to play with and don't have any side emitters like the OP, you can snip the dome offa the LED. I used pliers, but those with more time might consider the chop-sand-polish route.


You can use standard 5mm ones you just won't get quite the same beam pattern in it all as a wide angle LED does reflecting.


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## dealgrabber2002 (Oct 31, 2012)

ToyTank said:


> Been running it constant since Sept 1 and the eneloops are @ 1.267v!



ToyTank,

So you ran it almost a month and the eneloops are @ 1.267v? I am assumming it's each eneloop is @ 1.267v because if that is for 2, then ea will be ~.6v and that's really bad for the batteries. I thought eneloop is max at 1.2v each.


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## AnAppleSnail (Oct 31, 2012)

dealgrabber2002 said:


> ToyTank,
> 
> So you ran it almost a month and the eneloops are @ 1.267v? I am assumming it's each eneloop is @ 1.267v because if that is for 2, then ea will be ~.6v and that's really bad for the batteries. I thought eneloop is max at 1.2v each.



Eneloops hold about 1.4v per cell for quite a while at low drain.


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## dealgrabber2002 (Oct 31, 2012)

Thanks!


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## ToyTank (Nov 3, 2012)

dealgrabber2002 said:


> ToyTank,
> 
> So you ran it almost a month and the eneloops are @ 1.267v? I am assumming it's each eneloop is @ 1.267v because if that is for 2, then ea will be ~.6v and that's really bad for the batteries. I thought eneloop is max at 1.2v each.



It has been just over 2 months now and yes that voltage I state is per cell. I imagine it will run at least another month. The current is so low I can not measure it. I'm not sure what the minimum voltage is for this LED to emit. @ 1.267 the eneloops are just now hitting the nominal voltage. Peak voltage can be as high as 1.5v. When I started they where about 1.35v each(full charge then sitting for a couple weeks)


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## ToyTank (Dec 21, 2012)

ToyTank said:


> Great mod I did the same with the flat/cut 5MM HCRI I bought from eala. Been running it constant since Sept 1 and the eneloops are @ 1.267v! I had to drill a larger hole in the reflector but it was easy. Sweet light considering <$9.



Just an update to anyone interested. Still doing runtime test today is day 112 and each eneloop now has 1.229v . Still lots of runtime left. 

I also have a ZL H502 for comparison. It is much brighter than the .01 lm setting and noticeably brighter than the .06lm setting. I'd guess it is .10 lumen with very good focus so quit useful still at night. Anyone who is on the fence this really is a nice easy and useful mod.


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## dealgrabber2002 (Dec 26, 2012)

Thanks for the update ToyTank!


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## AnAppleSnail (Nov 20, 2013)

ToyTank said:


> Just an update to anyone interested. Still doing runtime test today is day 112 and each eneloop now has 1.229v . Still lots of runtime left.
> 
> I also have a ZL H502 for comparison. It is much brighter than the .01 lm setting and noticeably brighter than the .06lm setting. I'd guess it is .10 lumen with very good focus so quit useful still at night. Anyone who is on the fence this really is a nice easy and useful mod.



I have lost two of these to different grandmas keeping it when the kids visit. How is yours doing?


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## davesc (Nov 21, 2013)

Thanks for posting this for us to read...Apple! 

I am as dumb as a box of rocks and you have made it easy for someone like me to get started. I have a couple of the AA's laying around and now I'm going to mess with them.


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## AnAppleSnail (Nov 23, 2013)

I haven't mentioned: if you sort your LEDs by forward voltage, you get the brightest light in this setup. I upgraded one by connecting several dozen LEDs on a breadboard to about 2.5v (2 weak alkaline batteries). Pick the brightest, slap glow paint on the back, and the output goes to almosto ten lumens. That's a useful level of light on fresh cells... Too bright to be a nightlight!


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