Introduction: How to Make Rechargeable LED Light Diffuser Using Scrap Materials

Picture of How to Make Rechargeable LED Light Diffuser Using Scrap Materials

While I was about to throw my empty bottle of vitamins. I notice that something is still rattling inside, I looked into it and saw that there is this small cylindrical container, inside is some kind of silica sand which I think used as moisture absorbent. At that time actually I was planning to build a signal light for my bike, so it then gave me an idea, why not make a LED light diffuser out of this and see if I can use it as signal light for my bike?

I then looked into my electronic stash to see what I can use to make this LED diffuser. Then I came across to this broken step tracker (the name is "actxa stride") which I tried to fix but no luck. Inside this tracker is a very tiny 1s 60mAh lipo. So I took off the battery and see if I can be able to fit into the silica container, and it actually does. After that I gather couple more things:

Step 1: Gathering Materials

Picture of Gathering Materials

LEDs (blue, white, red)

Silica container
3 way switch

charging socket

charging cable

I think I got these switch, socket and charging cable from one of my broken 1:36 scale rc toys.

Step 2: Gathering Materials

Picture of Gathering Materials

Step 3: Solder the LED to the Switch and Charging Socket

Picture of Solder the LED to the Switch and Charging Socket

Don't be confused with the red LED. Actually at first I want to put red and blue but when I tested it seems that the red is not that bright compare to the blue, so I put white LED instead. Another reason for this is that white led can handle higher voltage than the red, that is why I did not put resistor.

Step 4:

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I forgot to take pictures while soldering, but here is also the fritzing equivalent.

Step 5: Insert It All Inside the Container

Picture of Insert It All Inside the Container

I removed some of the silica to make room for the circuit. I also made some holes at the top to access the switch as well as the charging jack. After that I just rammed everything inside, put the lid back and apply glue in it.

Step 6: Put Magnets

Picture of Put Magnets

To make it hassle free, I then glued on 2 duodenum magnets so I can easily stick it on my bike's metal tubing.

Step 7:

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Step 8: Conclusion

I tried using it while biking at night, but it actually fell short as it does not last long. With that very small battery, I was only able to get 30 minutes or less upon every charge. But nevertheless it can still be used in many other ways. With the attached magnets, you can stick it any metal (example: door knob, cabinet handles, etc.).


frarugi87 (author)2017-08-03

Please beware that

1) that one is NOT an USB-cable. Applying 5V directly to a LiPo battery will, if you are lucky, only produce the "Smoke-effect"(TM). If you aren't, well, check what an exploding LiPo battery does. If you want to charge it in a better way, embed a LiPo charging circuit in your application

2) LiPo batteries should never be overcharged or be used for too long; if their voltage drops below a certain point you will make them unusable (that's what battery monitors are for). Your battey will not last too long without one (unless you constantly keep it well charged)

3) Not putting a resistor in series is a really bad habit. This is the first image I found, and as you can see different LEDs behave differently. And can you see how steep is the curve above 3.4V? Very bad habit...

For the rest.. Well, I particularly like the effect of the silica balls. I will keep it in mind for the future ;) thanks

dgmark (author)frarugi872017-08-03

Thanks a lot for the feedback. I really appreciate it.

For item 1: yes, it is not a USB cable, it is actually similar to those lipo charger which comes bundle with those cheap little quadcopter.

Yupp. those lipo are nasty. I hope this tiny one will not generate much heat if it goes bad.

I have this lipo charging circuit (, but can't able to fit in.

For item 2. it seems that this lipo has a built in protection circuit. Anyway I just used it couple of times, I will update the post when it goes bad.

For item 3. Thanks for this information, I don't really know much about this. What I did is just trial and error and see which one can handle direct connection to the battery. If I remember correctly, different LED colors are made from different materials also, which also can handle different voltage?

frarugi87 (author)dgmark2017-08-04

For item 2 I think you are right.. My bad

As for the led voltage, yes. As a rule of thumb usually red non-high-brightness leds (those with a red transparent cover) are rated at 1.5V, green non-HB at 1.8V, blue, white and high brightness ones (those with a clear cover) around 3V. But they vary a lot with the manufacturing and conditions (current, temperature, ...) even among the same lot. Usually I find cheap chinese torchlights with some (even 8 or 9) white leds in parallel and powered directly by 2 AA. They work, of course, but the LEDs last much shorter than they would if powered properly...

Swansong (author)2017-08-02

That's neat, I have a normal battery one on my bike now but I'd really prefer something rechargable like this. :)

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