6 million rupee LED flashlight out of a Lithium Battery!

This pocketsized flashlight packs more amphours per ounce into your pocket than anything you could buy... if you dare to make one.

Step 1: "Make an LED flashlight out of ..."

You've seen them. They propagate like syphilis. They are Unoriginal LED Flashlight Instructables.

"Make an LED flashlight out of ...":
an Altoids container!
a Tic Tac container!
a Mini Altoids container!
an empty 9 volt battery container!
an Altoids gum container!
an empty film canister!
a used wad of toilet paper!

Well, this one is DIFFERENT. It's difficult, dangerous, and just plain time-consuming. So don't try this at home, unless your middle name is Danger. And you first name is Nerd. So, you're still interested? Ok, then. Step into the light.

Comments

[sokamiwohali]

how do you re-charge it?

[D5quar3]

 what's the point of a PIC do I really need it

[klee27x]

As I explained, it's only there so I could use a super kewl tiny push button to toggle the flashlight on/off. You could just use a switch, but that would only be kewl. Not super kewl.

[king kolton9]

(removed by author or community request)

[or_ford98]

6 000 000 Pakistan rupees = 64,030.3671 Australian dollars

[or_ford98]

6 000 000 Indian rupees = 114,678.07 Australian dollars
its alot bro

[ElectroFrank]

You programmed a PIC ? I don't want to sound like a wet blanket, but .... isn't it (a lot) cheaper to buy a flashlight than a microcontroller ?

[klee27x]

The whole point was to make something that I cannot buy, and to reuse some "dead" laptop cells. I still use this flashlight, today, with no mods or repairs.

BTW, microcontrollers probably cost less that you think. This one cost me about 60 cents.

[ElectroFrank]

Fair enough, I'm obviously not keeping up with prices going down ! And I guess the practice of programming is always good. BTW, can you recommend any sites where I can pic up PIC programming ?
(I have a good basic training in microprocessors, it would be nice to find a teaching community and coding tips. As the PIC and PICAXE system is well supported as an educational tool, it seems like a good one to get one's teeth into.)

[klee27x]

There are a lot of online tutorials that will get your feet wet. But the most imortant stuff is in the datasheet. I suggest you print out the entire datasheet (all 200-450 pages) and bind it into a book. There is a lot of info in there you'll need to refer to frequently, unless you have a photographic memory.

Microchip has fairly active forums if you have specific questions. But to formulate a specific question, you'll have to read the datasheet. :)

As far as learning assembly coding tricks, Micochip has dev boards and tutorials for various devices. If you can follow the schematics and/or make your own boards, you can then download the turorials for free. They'll cover some basic programming tricks, such as making delays, using interrupts, how to make macros and subroutines, etc.

[elinventor21]

how do you program the thing?

[klee27x]

That's a bit more complex. I suggest you look up some microcontroller tutorials if you are interested in that.

[konger]

What 'bout the PIC program and the circuit diagram?

[maxpower49]

what if my first name is danger and my middlie name is nerd

[klee27x]

Then I'd like to meet your parents.

[hottamaleindustries]

Their names are Toil an Trouble.

[codongolev]

and the father's name is bubble. so now they're bubble and bubble. first names toil and trouble.

her maiden name was schmidt. quite unoriginal.

[roberto sirigu]

me gusta......
Mejor con in poco de funda termoretractil

[nerd12]

are you indian?
what does the title mean?

[RANDOMFISHYFACE]

 just plain awesome but too dangerous for me

[northernmagnet]

 could i use a button battery? (3v x 3) 

[klee27x]

Dunno why you would want to spend that much time on a small disposable battery, but yeah. It would be litte more than a throwie, though. :)

[joeofloath]

You don't know a short circuit until you short a 7.2v, 4.5ah ni-mh RC car back, The wires glow red hot, and the cells go off one by one like shotgun cells.

[joeofloath]

Or a car battery. But I've never done that. Well, apart from that one time with the 5 inch electric motor...

Lwts just say sparks flew, and rather thick metal glowed.

[Redgerr]

""Make an LED flashlight out of ...": an Altoids container! a Tic Tac container! a Mini Altoids container! an empty 9 volt battery container! an Altoids gum container! an empty film canister! a used wad of toilet paper!" AHAHAHAHAHAHAHAHA YESSS -- other than that.. amazing cheif, i really like this and i have a TON of 'dead' laptop batteries around my house (just disasembled 2 laptops and 3 desktops LOL) and id love to try this!! Thanks!

[luketanti]

Hello. I have a bunch of these batteries and i need to know : Can I charge 3 cells in series which makes 11.1volts with a 12.6 volt LM317 charger without any protection circuit? I'm going to use them to power a portable amplifier. The battery model is CGR18650hm Panasonic.

[klee27x]

Well, it could be done, but you'd have to find out yourself what the max current is. A TO-220 lm317 can sustain >2A output if it's properly heatsinked with a fan. So you'd be relying on a nonheatsinked part, possibly of a smaller package (like a Dpak) to limit current to under an amp or so, and it would get very hot. I'm not sure how long a 317 would last if used like this. It's kinda a hack method, and I don't really recommend it to anyone.

It's far better to use a variable output supply and an ammeter, or to use some active current limiting.. or even passive current limiting. A 5 ohm 5 watt resistor in series with the battery would pretty much ensure a safe current limit for a 3 cell battery charged at a fixed 12.6V. But it would also increase the total charge time by quite a bit.

[Sandisk1duo]

how do you charge the battery?

[klee27x]

I use an adjustable voltage power supply and an ammeter. I could wax on about how easy it is to safely charge a lithium battery with a simple LM317 fixed voltage circuit, but then I might get sued. So for the record, I'd recommend you buy a lithium battery charger. You can get them for 10 bucks or so.

[Sandisk1duo]

you won't get sued.... how do you know when the battery it full?

[klee27x]

When the voltage is 4.2V, it's full. If you charge it from a power source with a fixed voltage of 4.2V, then you can leave it on there indefinitely with no damage. Just be careful if your power supply can source current in excess of 1C. Then it could damage the cell when it's first connected. Lithium cells come in different flavors. Lipo cells can often handle 10C+ charge/discharge rates. But the common lappy cells are manganese chemistry. They can typically handle 1.5C without problems. So know your battery and don't exceed the max charge rate, and you'll be ok.

[Sandisk1duo]

1C is how much amps?

[klee27x]

It's basically the capacity of the battery / hours. If the battery capacity is 1Ah, 1C=1A. If the battery capacity is 2AH, 1C=2A.

[Sandisk1duo]

and what's the lowest voltage a li-ion should be discharged to?

[klee27x]

Depends on what kind. Usually around 2.75-3.0V. Some of the cells you buy have a protection circuit built in, so they can't be overdischarged. But with a flashlight like this, there's no need. The FVD of the LED's is about 3.0V, so it can't overdischarge. FYI, under heavy load, a Lithium ion cell charged to 4.2V will put out 3.6-3.7V, and it slowly drains to 3V as it discharges.

[akinich]

hey klee27x are you indian?

[klee27x]

No, but I make a mean lamb curry. :)

[Thornburg]

My middle name just so happens to be Danger.

[ReCreate]

so is mine

[rocketman221]

mine too