DIY rechargable LED

Lifecraft

John McDouall Stuart
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A while ago I got one of these off ebay:
31nmkmA1XyL.jpg

It's a handy little gadget. 9/10 times when I need a light in the dark something like this is sufficient, even though it's not as powerful as a torch.
Unfortunately it's not rechargable, so I don't want to use it regularly (as I don't want to buy batteries if I can avoid it).

So I decided to create a rechargable version I can charge from my portable hiking solar panel.

It's ugly, but it works:
20160418_210132.jpg
20160418_210200.jpg
20160418_210321.jpg

I included the AAA battery in the photo for scale (but no it's not running off an AAA battery).

There's a button switch on the top. A smaller one might have been better but it's the only suitable one I had.

I coated the entire thing in hot glue to insulate the electronics. The only parts exposed are the LED, switch, and USB charging port. I could have done a neater job of that but it doesn't effect how it works.

You can see the red glow indicating it's charging. It switches to blue once it's charged. (That's all built into the charging module.)

It weighs 14 grams according to my kitchen scales. To put that into perspective, the AAA battery in the photo is 11 grams.
It's so light partly because the battery I used is a cheap RC helicopter battery, which is obviously designed to be light.


The whole thing would have cost less than $5 in parts:
- 240mah lipo battery
- lipo charging module
- led
- resistor
- switch
- wire


It's a really simple project that doesn't need any special skills or experience. Even a complete beginner should be able to make it as long as you're prepared to do a little bit of soldering and hot gluing. (You can tell that I'm a novice with the hot glue gun just by looking at it).
If you'd like to have a go at it let me know and I'll post links to the parts (on ebay and/or aliexpress because it's cheap) as well as some diagrams for how to wire it up.

You can use the exact same approach to make USB battery packs and various other rechargable gadgets too. Just swap out the LED for whatever you want. For a USB battery pack just swap it for a 5v boost regulator with a USB socket.
It's also fairly easy to attach small solar panels to the charging module to make gadgets solar powered without an external panel. I used that approach (and same battery/charging module) to make a solar night light (I'm yet to make a post about that).

Once I do a test to see how long the battery lasts I'll post an update.
The specs should be similar to that of an LED throwie because the battery the same as a CR2032 battery used in LED throwies.


Does anyone have any ideas about how to add a lanyard or keychain? Maybe I should have attached that under the layers of hot glue.
I want it to be convenient enough to keep in my pocket or in my pack without losing it.
 
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Lifecraft

John McDouall Stuart
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Thats pretty cool!! If you made it more streamlined too you could heatshrink it to improve its charm.
Yeah heat shrink is a good idea. If I can find another switch which isn't as bulky I might try making another one with heat shrink instead of hot glue.
Not sure how it would go pressing a button through the heat shrink tubing. Maybe I can cut a hole it in, or find some more flexible heat shrink tube than what I've got (it goes somewhat rigid once it shrinks).
 

Bloffy13

Jon Muir
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I like that a lot. Post up the plans. I'd love to have a go at this but am an electronics droob.
Can you "repurpose" a solar light and/or other parts. I have a stack that don't seem to work very well. Would love to see them put to some good use.
Cheers
Bloffy
 

silverback

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How would you go sewing a thin leather pouch around it with cutouts for led and charger. just press thru the leather for on/off.
 

Aussie123

Never Alone In The Bush
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Thats pretty cool!! If you made it more streamlined too you could heatshrink it to improve its charm.
Nice work Lifecraft,

I like the sounds of some of these extra mods too.

Having just seen "everyone" making kit knives I can't help but think of a knife mod !
It sounds silly (and probably is), but anyone who's bought a cordless drill (etc) in the last 5 years will almost certainly have a LED, which can be very handy when you're working in low light conditions.

The ultimate accessory for nocturnal bushcrafting !
 

Lifecraft

John McDouall Stuart
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I like that a lot. Post up the plans. I'd love to have a go at this but am an electronics droob.
This could be a good project then, it's one of the easiest things I've built.
Have a go, the parts are so cheap it doesn't matter if you burn out a few components (I've burnt out plenty while learning, and luckily mostly cheap ones).

Here's a sketch of the schematic, with the parts displayed:

20160420_182806.jpg

If you need more tips on how to actually connect it all up let me know and I'll provide more info.

Basically it's 2 parts:
1) Attach the battery to the battery terminals of the charging module (I cut the connector off and soldered it)
2) Attach the resistor, led, and switch to the output terminals of the charging manager

The order of the resistor, led, and switch doesn't matter. You can put them in whatever order is easiest to build.


Some links to parts....

Lipo charging board:
http://www.aliexpress.com/item/1A-L...harger-Module-DIY-MICRO-Port/32642487652.html

Lipo battery:
240mah: http://www.aliexpress.com/item/3-7V...252-RC-Helicopter-Quadcopter/32355418529.html
720mah: http://www.aliexpress.com/item/Hot-...for-Syma-X5-X5C-H5C-X5SC-X5A/32481877732.html

Button switch:
http://www.aliexpress.com/item/10-P...Button-Switch-AC-DC-250V-1-5A/2024644875.html

LED:
http://www.aliexpress.com/item/10Pc...-Diodes-f5-Ultra-Bright-Lamp/32632091646.html

Resistors:
http://www.aliexpress.com/item/50pcs-56Ohm-56O-56R-1-4W-0-25w-1-Metal-Film-Resistor/32602839623.html
Note: 56ohm is suited to one of these LEDs running off a lipo battery (I actually think it was 48ohm, but 56 provides a small margin of error). If you use a different LED or different type of battery you might need to google "led calculator" to identify the value you need.
If in doubt..... a 330ohm resistor will be sufficient up to 12v I believe.... but it will be less bright.


Can you "repurpose" a solar light and/or other parts. I have a stack that don't seem to work very well. Would love to see them put to some good use.
You could repurpose solar lights but they tend to use outdated technology in those, so it may or may not be worth it.
I've considered ripping out the electronics from a cheap solar light and putting in my own, with a better battery. The solar light enclosure might be more valuable for a DIY project than the electronics, in terms of reusing in a DIY project.

It's worth opening one up and seeing what's available inside to re-use.

It sounds silly (and probably is), but anyone who's bought a cordless drill (etc) in the last 5 years will almost certainly have a LED, which can be very handy when you're working in low light conditions.
I started thinking about a headband which holds it, so I can use it as a head lamp.
Now I'm wondering about a "knife band" to wrap around the knife handle maybe and hold the LED so it shines on whatever the knife is above.
 
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Thrud

Richard Proenneke
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In terms of adding a lanyard, you could encase the torch in Plastimake and drill a hole for a lanyard. Plastimake is a granular thermoplastic. It comes as small beads about the same size as rice, you drop them in boiling water they then go transparent, bring them out, shape them. If it isn't right drop them back in. It can be colored. If you don't colour it it defaults to white when cool. It is non toxic and biodegrades. I bought a big jar of it. If you would like some for free, just pm me and I'll send you what should be enough.


https://www.plastimake.com

No affiliation
 
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