Water Powered Flashlight

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Picture of Water Powered Flashlight
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):
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knexpert17005 months ago
Would a 9011 transistor work instead of a 2N3904?
ASCAS (author)  knexpert17005 months ago
Yes it would! :D any general purpose NPNs would work just fine!
xhp265 months ago
Impressionante !
xaviergoby5 months ago
Fantastic :D Love it! Great thinking!
icekid5 months ago
Oh dude thanks for this, voted too! We have an investigatory project for chem class. A project like this would do great. How about: "Testing the feasibility of galvanic batteries" (a.k.a "Water Powered") for the title?
ASCAS (author)  icekid5 months ago
That's a good title :)) Similar to our last year's IP title, about the feasibility of hydroponic planting.
rimar20005 months ago
Brilliant as always, Casimiro!
ASCAS (author)  rimar20005 months ago
Thanks sir rimar!
DanTDM14 days ago

I want to disguise it as a Minecraft torch.

It is not working. What's wrong?
This is a cool build! From checking out your other ibles, it seems that you like to make speakers and water powered things... Why not combine the two? The "Water Powered Speaker!" Could your water cells power a mini Bluetooth speaker? Tell me how you like this idea.

Can I use copper wire instead of copper strip?
ASCAS (author)  franceserikey1 month ago


ngowon1 month ago

pls let have more information on how to purchase. thanks

ASCAS (author)  ngowon1 month ago

I have a second version, a much more stable one and 5x more efficient than the previous version. The new guide will include the to-buy-list.

twenrich2 months ago
Is it water proof?
ASCAS (author)  twenrich1 month ago

This version isn't completely waterproof but my second one (3-celled) is.

yonskiboy2 months ago

That is chool...

arghya92 months ago
great project! the making of joule thief circuit is awesome
yurin3 months ago

it's greats

Electrichound3 months ago
You've made an excellent project, but i don't understand what you mean by "make sure there's a thread on the other side". A clarification would be very useful.Thanks
ASCAS (author)  Electrichound3 months ago
Thanks! By thread I mean the pipe's screw.
Electrichound3 months ago
You've made an excellent project, but i don't understand what you mean by "make sure there's a thread on the other side". A clarification would be very useful.Thanks

makeshiftmech3 months ago
will this work with urine in a survival situation, and would it work with a carbon rod from another battery and copper tape.
ASCAS (author)  makeshiftmech3 months ago
LOL, that's a crazy yet a good question :) I think so, yeah! 2 urine cell's could power a flashlight and 3-5 urine cells could power a small 3V radio.

I didn't have a good experience with carbon rods. They give out weak electricity when given a watery electrolyte, they like the mushy types of electrolytes (like in batteries).
babadipapa3 months ago
I have been trying to do this for the past 5 years....please please please can you email me of where i can find a 3xLED torch, zinc strips, and copper strips? If I can replicate this it would mean the world to me.
ASCAS (author)  babadipapa3 months ago
If you live in the US then Radioshack is a good place to buy one. If not, you can buy from "" they serve free shipping, and sell products with the lowest price that you can imagine.
babadipapa ASCAS3 months ago
I still haven't been able to find the correct torch. I did go to Radioshack and they didnt have one either. Any other suggestions?
bobdude3 months ago
Love it!
If you added citric acid, would it last longer?
ASCAS (author)  bobdude3 months ago
I think so :)) I haven't tried them yet.
ScienceMaster3 months ago
ASCAS do I really need a joule thief?
ASCAS (author)  ScienceMaster3 months ago
Yes! Unless you are willing to spend your time making 3 of these water cells, and connecting them in series.
ScienceMaster3 months ago
ASCAS do I need to use a transistor and resistor because I think they are pretty useless but I just need to make sure if I am right or wrong. If they are useful please tell me why
ASCAS (author)  ScienceMaster3 months ago
Ever heard of the joule thief? It's a simple circuit that uses three simple things, a toroidal core, a transistor and a resistor. Without It, the LEDs wouldn't light up because LEDs have a minimum operating voltage of 3v. Since the battery produces voltages below 3v, you'll have to boost that.
ScienceMaster3 months ago
Thanks ACSAS didn't see my post now I can see it
ScienceMaster3 months ago
I can't see my post do you know why?
ASCAS (author)  ScienceMaster3 months ago
It's written above silly :))
AndyPipkin3 months ago
Why does it only last 30 mins? would it last longer if there was a flow of water?, or is it down to the zinc and coper?
ASCAS (author)  AndyPipkin3 months ago
Well the battery isn't that efficient. I'm using salt water right now. Letting tap water flow through the cell would wash away the remaining salts, but the flashlight still works (dim).

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