Working Air Battery

[capthook]

Summary:

To be practical/useful/economical IMO:

1) Graphite rod must be replaced - too expensive, big and heavy
2) Larger reaction surface area
3) improved electrolyte
4) aluminum rather than magnesium?
5) overall decrease in cost, size and weight
6) overall increase in output

Those are my suggestions/recommendations and look forward to seeing how it progresses.

P.S. If only EESTOR would ever finish development on their supposed super-capacitor we will see amazing things - still wondering though if it is just 'vapor-ware' and pie-in-the-sky dreaming!

[markdansie]

@Captain Hook

thank you for the reality check.

However their is always more than one way to skin a cat

http://www.magpowersystems.com/

http://www.cleanteam.ch/blog/tag/magnesium-battery

http://www.physorg.com/news155569564.html


Hope this information is usefull
Kind Regards
mark

[PeteIdl4]

@capthook,

I agree that these air batteries may not be practical for big applications such as the scooter idea, but neither is your standard AA battery. They have the same problem, cost over efficiency, not to mention they are really bad for the environment. However we're just getting started on these air batteries and efficiency/wattage has been improving. My latest replications of lasersaber's designs get about 300ma@1.6v, roughly half a watt and they only weigh in at about 69g. So based on this you should be able to get the 250 watts with about 35kg as opposed to the 250kg. Still not competitive and probably never will, but that won't stop me from improving these to get the most out of them, and to be honest they're just really cool . I like the thought of being able to have a reliable portable power source even if it may only be for two weeks. In a black out or camping trip where you can't recharge your Li-ion's and your regular batteries die out, these air batteries will come to the rescue.

This brings me to a new air battery I made last night. I have a few small pieces of a carbon rod that broke so I decided to make a small one just to see how much power I can get off it. I am able to get about 35-40ma, which kind of surprised me I wasn't expecting that much off an air battery so small. It lights the three LEDs easily as you can see by the picture.

P.S. I have nothing against Li-ion, I have a love hate relationship with them as I know how volatile they can be at times, yet they do come in handy.

-Pete

[markdansie]

@pete
Love the small battery, would be great having one of these trickle charging one of my torches or powering cell phone when I go bush.
i was a little of beam with the scooter idea but camping and remote power its a great idea.
I guess time will tell how long they will last before the magnesium has to be replaced. I think the salt is essential somehow to extend the life.
mark

[conradelektro]

Congratulations Lasersaber, your ideas are great! Please continue posting videos.

I am not so much interested in "efficiency" and "costs" as Capthook seems to be.

It is important to build simple batteries with materials at hand. Even if they are not as efficient as commercially available batteries and even if they are theoretically expensive. First, this makes great science projects and second, it might become necessary in an emergency or during an economic downturn (as we seem to experience at present). Small radios, clocks and even some low level lighting can be driven by these simple set ups.

If one has materials at hand (e.g. for free, because people are throwing things away), costs are not important. And one still gets "some electricity", although there might be theoretical possibilities to get more with different setups. In practice, many things are for free (just collect them) and even little electricity might be a big help.

Also "size" and "weight" is not so important for a battery used at home (e.g. for emergency lighting and as an emergency radio power supply), because such a "thing" can also serve as a designer object or conversation peace. Just throw out some vases or useless furniture. Oh yes, vases, they can be turned into batteries (use salt water and two strips of different metals).

Look at the table in the middle of this page, it gives ideas about the metals to use:

http://www.corrosionist.com/Galvanic_Corrosion.htm

Other nice pages from this site:

http://corrosion.ksc.nasa.gov/galcorr.htm
http://corrosion.ksc.nasa.gov/electrochem_cells.htm
http://www.npl.co.uk/upload/pdf/the_electrochemistry_of_corrosion_with_figures.pdf

Aluminium can be found easily, therefore one should concentrate on it (instaed of magnesium, which is hard to come by for free). Many throw away food containers are made from aluminium or at least some aluminium alloy.

The second metal could be copper, because copper pipes are easy to get (e.g. out of abandoned buildings). Also many grades of steel are good and can be found for free (e.g. out of abandoned cars; the paint has to be scrapped off).

I am working with aluminium as one metal and copper or steel as the galvanic counterpart. Lasersaber's idea of using kitchen paper towels soaked in salt water as an electrolyte is very good and simple. Once my cells are finished I will post them. I am working on practical set ups which allow easy adding of salt water and easy changing of the paper towels (no masking tape). Any paper should work, even newspapers.

I posted an "aluminium - tile cement - copper cell" which already works for weeks. I have to dip it in water every few days or place it outside for an hour when the air is damp to "recharge" it:

http://www.overunity.com/index.php?topic=972.825
Re: Crystal Power CeLL by John Hutchison
« Reply #833 on: May 31, 2010, 11:22:17 PM »

The paper towel soaked in salt water should work much better than the tile cement, altough it is less sturdy and more difficult to maintain over long periods. The tile cement can also be soaked with salt water (which I still have to try, because I do not want to spoil my little set up yet; I want to do a long time test with it as it is).

Greetings, Conrad