Extreme LED recycling

Flashlight Modding and DIY Parts
1

I read a heated discussion recently about LED vs CFL bulbs
I commented myself about the fact that circuit fails long before the actual LED.
Also I got a lot of great help recently here for my next build.
So I decided to share my experiment.

I used a LED bulb for about 2 yrs in a street light. Daylight sensor failed so it was always on. That is about 730 x 24 = about 18K hours. Since the claimed life is 50K to 100K hours and LEDs were still working fine I felt it would be a waste to throw them away especially given the high cost. So I decided to recycle them into a general purpose mobile lamp. To make it even cheaper I used recycled 18650s from a laptop battery pack.

Album - click here for images

Not sure how to link images so will just describe them, bottom to top.

The bulb was a simple 3 LED setup for total 3W rating. Cells are unprotected 18650s from a laptop pack tested to still work fine. The build is using a simple piece of wood for simple assembly. Metal would be better for heat management, but wood is easier to handle. I made the hole and wedged the bulb into it. Battery holder is at the other end. The batteries provide a great counter weight to LEDs so that lamp is very stable. I have a 3 way switch. At first I used simple resistors for lower levels and direct drive for max. Needless to say LEDs got very hot very fast. Then I added buck driver matching the bulb 3W rating. It still warms up but metal housing is enough to distribute the heat. Then I used a lot of hot glue to fix everything to the wood base. Wood is great for glue which simplifies mounting.

The resistors are printed, 220 and 1000 ohm. Since they are only rated for 1/4W I found these are the lowest resistance that doesn’t heat up. Of course they are inefficient but at such low power level it doesn’t really matter. In fact 1000 ohm drive is so low that 3rd LED doesn’t even light up. This is my “moon mode”

Now I will not restart the low mode debate. Note I use it as a night light in kids room. Younger boy still gets up at night and needs minimal light. The awesome feature of moon mode and low mode is that power used is so low that I often forget to turn it off when leaving for work and it doesn’t matter. It can keep running for a few days before batteries are emptied.

Note that it can be used in couple of different positions. Vertical position can be used as a reading light. 3W is plenty for reading, even without reflector. Horizontal position on a top shelf provides nice general room light. I found 3W sufficient for simple tasks that don’t involve precision of any kind. Kids are bit annoyed and wife just laughs and turns on CFLs.

The best part of this build is cost. Since the highest cost components - LEDs and cells - were free, the total cost ended up being about $5. I just needed to get a driver, battery holder and switches. Resistors were almost free.

For my next build I am using 2 XPGs and a 1A driver. That should at least double light output but also present new challenge regarding heat. So I am looking to add a heat sink component as well. I am very happy with this build but need higher output to properly light up a room.

For the final word, I like having a portable light because both wife and kids always leave fixed lights on. It is simply too annoying to turn them on and off all the time. This one I can carry with me and avoid having to turn fixed light on and off frequently. Flashlights are difficult to position properly and may not be stable. So for this build I wanted rectangular shape that is stable and has position flexibility.

Anyway it was fun to make :slight_smile:

2

I love what you did with the hot glue.

Nice recycling (upcycling?) of components.

3

That is one cool light. Well done.

4

Man - I did not see this one thread before now, but here it is. Great build up. And I'm with Chicago X on this one. It should be up cycling.

5

Now that’s the sort of thing this place needs more of.

Love it! :slight_smile:

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I have one more build done and another TODO. One of these days I will take pics and post another build.

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By accident I got a pair of XPEs instead of XMLs. I decided to use them anyway while waiting for XMLs. This build is almost the same as the old one, except using 2 XPEs. I used virtually the same drvier. Also used 2 resistors, 220 and 100 ohms. Because of the low power rating the 100 ohm resistor gets bit hot; I just don’t use it much.

Anyway here is build:

I recycle several heat sinks from an old monitor. I was planing on adding heat sink for XMLs so I added it to this lamp. It turned out that XPEs at 1W don’t really get all that hot. So this huge heat sink hardly gets warm. Still I wanted to be able to use max mode for a long time and not worry about heat.

This time my wiring is cleaner. The layout is cleaner, but mostly the same as old. It can still be positioned different ways, although the heavy heat sink does change the balance somewhat.

Here is output at 1/25 sec exposure, side by side with the old lamp, starting with max mode:
(XPEs are cold and older lamp is warm)

I am not sure what brand are wram LEDs in the other lamp. Clearly the Cree XPEs are more efficient. 2 XPEs at 2W combined produce clearly more light than 3 LEDs at 3W.

Having used this new lamp for a few weeks now, I find it ideal. The massive heat sink pretty much solves the heat problem. I use it on max mode for 1-2 hours and sink is hardly warm. Light is clearly cold but not an issue when using as reading lamp for instance. Given the 3 18650s have about 25-30 Wh, even at max mode 2W it can run for 10+ hours. Of course the light output is still limited, guessing 200-300ish lumens. So it still cannot provide enough light for entire room. That problem remains for the next lamp using XMLs. Coming soon ….

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Very cool and informative. Thank you for sharing. I’ve been wanting to build some indoor led lighting, but I never get past the vague idea phase. Seems like a way to save in initial purchase of lighting and in electricity. Nice work.

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Here is the final build using a pair of XMLs:

Clearly there is not much recycling involved in this one. Still it is fairly cheap. I decided to go with latest (XML) and drive them properly (max 2.5A). That being said I didn’t want it to melt or like fancy lights step down current due to extreme heat. So I added active cooling, a simple cool looking heat sink with a nice little fan. I don’t remember the current; I don’t thin that the fan actually uses much power. So the power overhead for driving the fan is fairly minimal.

Also this time I went with a proper buck driver, so resistors are gone. There is no point having moon mode on XMLs. This made wiring simpler and neater. Still using the 2 position switch although they are not really needed. Note I positioned driver next to heat sink so it gets some air flow from heat sink fan. Did I mention that heat sink looks cool :slight_smile: :bigsmile:

The LEDs are actually on top of the wood base. Thus there is a very crude reflector that focuses light tiny little but. Wife hates XPE because light spills 180 degrees and she it very sensitive. So this one limits the flood/spill little bit.

Here is light on with fan spinning. The performance is awesome. Heat sink and fan keep LEDs cool and should ensure long lifespan. I stopped checking LED temps because I can never detect any significant heat. The fan does slow down when I place it vertically but still keeps spinning. In fact cells are the ones getting warm since they are still old recycled tired cells, so probably don’t like the load.

Low mode:

Medium mode:

High mode:

I can say that the high mode is now perfectly fine for general room lighting. There is enough light bouncing around to light entire room. The crude reflector can be used to direct light in a specific direction if needed. I actually found the difference between high and medium modes to be underwhelming. I measured 1.7A on high and 0.9A on medium mode at the cells. So medium seems to be about about half power compared to high. I actually use medium often, just because my cells are so weak. Speaking of cells, I chose this configuration to keep load on cells under 1C. Even for older 2.2Ah cells the max mode’s 1.7A is well under 1C. Of course for newer 3+Ah cells it is only 0.5C This way cells are not working too hard and should last longer.

This is the final update. I now have 3 lamps that should last a long time. Funny enough I am actually using all 3.
The 1st weakest lamp is used in kids room. Its weak output is critical in making them sleep. Otherwise with too much light my boys will chat all night and never go to sleep. So moon mode is used the most

XPE lamp is for reading. XMLs actually output too much light for reading. Also passive cooling without a fan is noiseless. Finally it can run for many hours even on max mode without any worries. I actually use XPE lamp a lot. Also low mode is great when I need minimal light but more than moon mode.

XML light is for room, going to bed, etc. Since it generally runs only for 15-20 min at a time I can run it at full blast without worry that unprotected cells will be depleted and blow up. For longer runs I simply use XPE lamp.

Thanks for all the encouragement and kind words. Also I found lots of help and ideas here. This is fantastic site and community.