Have a look at this easy to build saltwater cells.
http://www.youtube.com/watch?v=nfeBhrViZ7M
He is using several cells in series to power
one of these new light color changing LEDs.
Nice built !
He is using steel wire for bike gears and copper
foil as the electrodes and saltwater as the electrolyte.
Will probably give him around 0,5 to 0.8 Volts per cell.
As he uses it in straws these cells are pretty compact,
so you can build it easily as a series connection of several
cells.
Of course the electrodes will be consumed, but it might take
a while until this is done..
Regards, Stefan.
This guy explains it very well in english language,
how these selfmade batteries work:
http://www.youtube.com/watch?v=4PxYQYshn4k
The problem is, these generate almost the same voltage as
standard batteries, but not the current, so you can only use
low current needing loads, like LEDs, etc..
Current is determined by metalic surface area... To call that a low current battery is to say the electrodes are too small. Make the surface areas greater and you'll make the current greater too. Good luck on your experiments Volta fans!
~Dingus Mungus
@Harti_berlin
Thanks for the links.
Very pedagogical.
I had a dream.
Joseph Newman was speaking like this guy on the video.
But he was less poetical.
Just kidding.
Best
well since theres a way to increase the current , i wonder how long those batterys would last.
What's stopping us from jamming plates of copper and steel in the ocean and running our houses off of that? It seems hard to believe that it would be possible to deplete the entire ocean of its ions ;)
Well, it could work,
but you would pollute the oceans with lots of copper Chloride
and copper sulfate and the copper and iron electrodes would
get consumed...
But for a test cell this would work quite okay.
As he uses multistranded iron wire the surface of the iron
is much bigger and so he can draw more current,
as if you only take an iron nail.
I have built and tested several of these types of batteries. The current does not change with surface area in any of my tests, nor with proximity of the electrodes. However, using a strong acid will increase the current and shorten the life of the battery. Another unusual effect is that after the LED light has been on for several hours, it will appear to be burning very dimly. When disconnected, the voltage across the battery is found to be very low. Subsequently, it gradually rises over the next 10 minutes or so, back up to full voltage. When the LED is reconnected, it now shines brightly again. My theory for this self recharging effect is that ionized water molecules are being attracted to the negative electrode (iron) and are blocking the electrolyte therby causing a voltage drop. When the load is removed, the solution returns to a uniform mixture of salt and water (i'm using epsom salts and water) One way to test my theory would be to shake the battery and see if the LED gets bright again. But so far all my batteries have been open jars. Im working on a sealed battery with a tiny vent for out-gassing, so i can test this theory, but if some else out there can explain this strange recharging effect to me i'd love to hear from you. Thanks
Quote from: Sunsaver on July 16, 2011, 11:04:59 PM
... theory for this self recharging effect is that ionized water molecules are being attracted to the negative electrode (iron) and are blocking the electrolyte therby causing a voltage drop. When the load is removed, the solution returns to a uniform mixture of salt and water...
Makes sense to me. Similar to the end of a magnet getting 'saturated' with iron filings...
Would like to hear/see more about your projects!
Cheers!
PC
EDIT: I wonder if the water was moving around your electrodes (instead of sitting stagnant) would prevent the drop in voltage? Have you tried just giving the liquid in your jars a gentle 'swirl' instead of disconnecting the LEDs to bring the voltage back up?
Hey Stefan,
Those videos have been removed by the user.
PC