Batteries are too mainstream, let's make Water Powered ones! The DIY flashlight never runs out of batteries, water is all around us and will never run out. One of today's causes of pollution is the improper disposal of batteries containing heavy metals such as lead and mercury. The answer, using water as electrolyte!

Imagine, running wall clocks for 6-12 months with water, you'll never need to leave your house just to buy batteries and there's no need to recharge them. What could be more convenient than replenishing your batteries with tap water? :D

The flashlight runs 30mins continuously with tap water and 2 hours with saltwater. Not bad for a single celled prototype :D This thing also works well with calculators, clocks & radios Remember, adding a second cell triples the glow and lighting time! 

How Does It Work?
This is a type of battery called the "Galvanic Cell", having 2 different types of metals and is connected by a salt bridge. It works like your typical battery but uses water as its electrolyte. If you want to read more about how batteries work "click here" The output voltage is pretty faint and isn't enough to run a single LED. By the help our trusty "Joule Thief Circuit", the LEDs would glow even at low voltages.

Is It Really Powered By Water?
Well not really, the water serves as an electrolyte, a replacement for toxic chemicals used in regular batteries, which usually ends up in dumpsites. So why call it water powered? Of course no one would be interested in the title "Galvanic Flashlight" plus that's what easily pops up in people's minds. The Redox reaction takes place in this project.

Practical Uses:
1st.) If you got lost and stranded out in the woods, you can't rely on batteries, eventually they run out. A mini version would save stranded people in the woods. Just go to the nearest river and fill her up! Whala, you have light!
2nd.) School science experiment
3rd.) A fun and educational project for all ages!

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A Larger Scale Water Powered Project (a.k.a Galvanic Cell):

Step 1: Gathering Tools & Materials

Parts & Materials:   
- PVC Pipe 4" Long (3/4"‎Ø)  [Local Hardware]
- PVC Coupling 3/4" to 1" [Local Hardware]
- Recycled 3xLED Torch  [Inventory = Free]
- Toroidal Core/ Bead  [Recycled From CFL Bulb]
- 2N3904 Gen. Purpose NPN Transistor [Radioshack] 
- 1K Ohm Resistor (1/4w) [Radioshack]
- Cooper & Zinc Strip  [Local Hobby Shop]
- Magnet Wire/ Copper Wire [Inventory/ Local Hardware]
- 4 Sheets Of Tissue Paper [Toilet/ Bathroom]
- 2x2" Sheet of Acetate [Bookstore/ Office Supplies]

Tools & Equipment:
- Leatherman MultiTool
- Soldering Iron
- Hot GlueGun
- Teflon Tape
- Super Glue
Would a 9011 transistor work instead of a 2N3904?
Yes it would! :D any general purpose NPNs would work just fine!
<p>There are many other very good Instructables detailing how to build a &quot;Joule Thief&quot; and how they work. You could have simplified this one by first referring people to one of those for that portion of the project.</p>
<p>He did!</p>
<p>No, he didn't. This instructable tells how to make a joule thief and does not refer readers somewhere else for that info.</p>
<p>Under the heading 'How does it work?' he's put a link (labelled &quot;Joule Thief circuit&quot; to http://www.instructables.com/id/Making-A-Simple-Joule-Thief-made-easy/</p>
Impressionante !
Fantastic :D Love it! Great thinking!
Oh dude thanks for this, voted too! We have an investigatory project for chem class. A project like this would do great. How about: &quot;Testing the feasibility of galvanic batteries&quot; (a.k.a &quot;Water Powered&quot;) for the title?
That's a good title :)) Similar to our last year's IP title, about the feasibility of hydroponic planting.
Brilliant as always, Casimiro!
Thanks sir rimar!
<p>Would be interesting to incorporate a battery trickle charger, a 50ma battery to &quot;charge&quot; even when the flashlight is off. </p>
What if to make boat running on overboard water?)))
<p>Very neat.</p><p>As an aside, this bugs me whenever I see it: &quot;Whala&quot; or &quot;walla&quot; etc. The word is &quot;voila&quot; - a common French word - and I also don't know why so many people think the word starts with &quot;w&quot; because the &quot;v&quot; IS pronounced - as in VWALLAH. </p>
<p>Thank you! That was driving me crazy.</p>
This is one of my favorites too.... It's usually 'viola' which doesn't make phonetic sense either. Happy to see other voila police out there cleaning up the world.
<p>Great project! More cells, combination of joule thief and cells, electrolytic fluid ( copper sulfide, water, etc..). There are too much to research! Nice strike! </p>
<p>This is a fun science experiment. I probably wouldn't go to all the trouble and mess involved, because there are plenty of better non-battery alternatives, including solar-cell, dynamo, or rechargeable flashlights available.</p>
<p>A flashlight is for use in the dark, so you wouldn't go anywhere with a flashlight on solar-energy, or you need batteries again. For a flashlight this is a very good alternative, I think.</p>
I've never seen a solar-powered flashlight that didn't use a battery. Dynamo flashlights however, are always ready, and don't need anything but muscle power.
for back packing, there is none better, as a avid survivalist, this one is pretty top notch.
<p>please excuse me, but this flash light is not water powered, but chemical powered. <br>And it does runs out of (Battery) it will stop working, when the more inferior metal is gone or oxided.<br>Its just a galvanic Cell.<br>Like these Lemon or Potato &quot;Powered&quot; Things.<br>These all are not powered by their electrolytes (Water, Potato, Lime or other,) but by their metals, &quot;electrochemical series&quot;<br><br>But its nice for emergency things, to keep them until u need it.<br>Its the same principle like those little Lights on Aircraft Life Vests.<br>there is a small Box with two holes, and at the inside two different metals separated by a kind of sponge.<br></p>
<p>He did say that it was a galvanic cell; please read the text again. Look for: &quot;<u>Is It Really Powered By Water?&quot;,</u></p>
<p>yea i over read it, sorry for that.<br>never then less its a nice Project, as everlasting battery Flashlight if not used for in case of full blackout.<br>i was triggered by the headline, sorry also for that.<br></p>
<p>All of that is exactly what the author said in the introduction!</p>
<p>Very good project !!!</p>
<p>I cant seem to get it working ......everything is fine till the joule thief ........ but the power cell is where i get a problem ........i dipped it into water and salt water but my LED did not glow !!! please help !!!! i need to submit this as a science project tommorow !!!!</p>
LEDs only work one way. Try reversing the voltage
<p>Don't ou have to replace the electrodes every once in a while, I heard that they just wear out</p>
<p>Yes, this is an electrochemical reaction and will eventually exhaust the available electrons in the copper. See the other replies for suggestions for ways to make it last longer and be brighter. </p>
<p>That is cool!</p>
<p>Good ideas never die they kept on re-inventing themselves</p>
<p>Good ideas never die they kept on re-inventing themselves</p>
<p>Soooo...</p><p>If we're talking electrolytes here, I'm guessing urine might be right up there as a possible substance. Now THAT is survivalism.</p>
<p>Does this have a switch or is the flashlight always on?</p>
<p>If you used powdered aluminum instead of a solid electrode, your battery will last longer because you are increasing the surface area of interaction. Your batteries lifespan is directly related to the amount of corrosion the aluminum has undergone. Increasing the surface area, increases the amount of aluminum there is to corrode without actually adding more. Flushing the electrolyte merely speeds up the reaction rate, it doesn't actually change the total amount of energy the battery can generate. It changes how fast the battery can deliver it though. Using powder does the same thing, but it is more permanent. This is why most batteries use a chemical paste.</p>
<p>An excellent project.<br><br>In order to use this as an emergency light out in the field, how about putting some granulated (dishwasher) salt in the DRY tube in order to get the best run-time once filled with water.</p>
<p>I have a much simpler 4 pin LED driver 5252F chip that only requires a pre-made coil and one battery to light some LED's: </p><p><a href="http://petesqbsite.com/phpBB3/viewtopic.php?f=4&t=3745&p=22873#p22873" rel="nofollow">http://petesqbsite.com/phpBB3/viewtopic.php?f=4&amp;t=...</a></p>
<p>would a 7805CT transistor work? :)</p>
I know that this post was about a year ago but I'm still going to comment. I think that a 7805 is a 5v regulator.
Trying this one out
<p>can i use 2n2222 or pn2222 instead of 2N3904</p>
<p>Can I do this with my Scout Group? please.</p>
<p>Where could I get a zinc and Copper strip? also what size? Could I also use copper foil instead?</p>
<p>Can you make a tutorial on how you made this certain joule thief and combined it with the lights shown above step by step?</p>
<p>hello . i was wondering if this had an on/off switch. i wouldn't want to keep it on too long</p>
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Works so smoothly. Thanks for this idea.does it work with citrus juice?

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Bio: Hi I'm Angelo! I am a 17 y/o Physics Major at the DLSU and I use my course as an inspiration for making ... More »
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