Aluminum Can, Saltwater and Charcoal Battery

Step 3 Preparing the cathode

The cathode is a carbon cathode with a copper lead to complete the circuit. The sponge is used to provide a bed to rest the carbon on. The copper mesh is secured to the grid and the carbon is heaped on top of it.

Take the sponge (dry is easier), invert the anode over it and draw a circle.the diameter of the can. Cut a circle from the sponge slightly smaller than the circle. The sponge will expand so you want to leave 1/8" or so all around.

Take the charcoal briquet and break it up into smaller and smaller pieces until you have a reasonably fine powder.

Put the briquet in a 1 gallon plastic garbage and break it with a hammer. Take care not to puncture the bag. I used a short length of PVC pipe as a rolling pin to grind down the charcoal. Remove any unburned particles of wood that you see.

The finer you make the powder the more power transfer will be available. Or at least that's my understanding. Its not clear at this point how much carbon is required in the cathode.

Comments

[kennyhaa]

Would it be possible to use activated carbon granules (i.e. aquarium filter carbon)? It may provide a carbon source that is more pure.

[shanmugammpl]

yes get the charcoal tablets from the pharmacy, it is activated charcoal, powder it and use it. i tried it with aluminium foil and managed to get around 1 volt max.

[egbertfitzwilly]

What charcoal tablets from the pharmacy? Is this a dietary supplement or an aquarium filter thing?

[shanmugammpl]

well this isn't a dietary supplement not its not the aquarium filter as well. It is used for treatment of food poisoning. as the activated charcoal adsorbs the "poison" from your stomach and renders it safe. so just ask them for activated charcoal. it is cheap, then you just powder it.

[egbertfitzwilly]

Thank you very much for this information. I will investigate this alternative and update the instructable if it works out. What form does in come in normally? A solid chunk of carbon would also be extremely useful.

[shanmugammpl]

it is in a form of a pill and you just crush it up. but you can also buy large chunks which are generally way more expensive than the equivalent weight of the tablet. the large chunks are use to deodorize rooms and purify water. P.S is it possible to use soot? like collect a lot of soot as it is very porus?

[egbertfitzwilly]

I will check this out. You may very well be able to simply hot glue the exposed wire to the tablet and use that as an electrode.

Soot would also work, I think. I was thinking about using this in combination with the copper mesh. If the mesh is placed where it gets covered with soot it might make a very nice electrode.

Did you see my other instructable "Easy Carbon Electrode"? I would expect the tablet to work about the same. I'm very interested in gathering data on various shapes and sizes of the electrodes.

[shanmugammpl]

yes i guess the hot glue method will work but then i am not sure if the tablet will absorb enough brine to ensure good connection.

[egbertfitzwilly]

The carbon doesn't absorb the brine, or at least not much of it. All that is required is a good physical connection between the carbon electrode and the electrolyte. If the tablet is firmly seated in the sponge you should get some juice. It would be very interesting to know how this works out.

[shanmugammpl]

but when i did this i didnt use a sponge, maybe the sponge is a bad idea? it increases the distance between the aluminium and air so reaction slower?

[egbertfitzwilly]

So what did you do? Pour the saltwater in the can and float the carbon on it? The sponge provides infrastructure to separate the cathode from the anode. I would expect that just placing the carbon directly onto the aluminum wouldn't work but I could be completely wrong.

[shanmugammpl]

i used aluminium foil, and i placed a heap of the powder then poured brine till it was slightly wet but not too wet that it started flowing. Why do you have to separate the anode and cathode? it worked for me...

[egbertfitzwilly]

How much power did you get out? I would expect the cathode and anode to short out and reduce or eliminate power output. But there are many things about chemical batteries I'm not fully up to speed on.

[shanmugammpl]

Well no they dont short, it might seem ironical but they actually increase the rate of reaction. I dont know the power but i managed to get about 1 volt. i could even power a small motor out of it! you can hook up a joule thief to make a neat little lamp that runs on scrap aluminium. i will go test how long it will las.

[egbertfitzwilly]

Absolutely. Activated charcoal is recommended by several sites. I didn't know that the aquarium filter had it, I will update the instructable. You might take a look at my other instructable "Easy Carbon Electrode" for an alternative.