Instructables

Quick and Easy Battery in 5 Minutes

Ever wanted to make a battery but didn't have the time or the parts? Well here you go. You can literally make this in 5 minutes with only 4 parts. It is sealed and doesn't require chemicals... what more could you want!
 
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Step 1: Parts and Tools

Picture of Parts and Tools
Not much is needed for this instructable, but you will need:

A film canister (or similar container)
Aluminium Foil
Tissue paper or kitchen roll
Carbon rod (Pencil led or battery rod)
Electrolyte (Salty water or other salt in water)
Some wire
Tape

As for tools,

Scissors
Multimeter if you want to check it.

Step 2: Making the Cathode

The cathode is the negative terminal of the battery. For us, it is made of aluminium foil.
Start by cutting a strip of foil just slightly shorter than the film canister, but long enough to make a full ring inside with plenty of overlap.

Tape a wire to the foil so that it won't be facing inwards, but is against the side of the canister.

Try to curl the foil so that it will easily fit into the canister. Pulling it gently over a sharp edge does this nicely.

Insert it into the canister and leave it for now.

Step 3: Making the anode and electrolyte medium

The positive 'side' of our battery will consist of a carbon rod surrounded by electrolyte. The carbon rod is the hardest part to get right, as it needs to have large surface area and low resistance. I used the carbon rod from an old 'C' cell battery. Although I haven't tried it, a artist pencil led may also work.

The anode needs to be surrounded by electrolyte, which we achieve by saturating tissue paper with salty water. I use bicarbonate of soda in water, but any salt in water will do.

Start by taking two sheets of kitchen roll or other tissue paper and folding them into a narrow band slightly shorter than the film cannister. You may need to trim the height with a pair of scissors.

Now place the carbon rod along with a stripped wire end on one end of the paper. Roll the tissue paper as tightly and as neatly as you can.

On to the next step!
deathwisher6 months ago
and you also need to use charcoal as it is more porous and will speed up the reaction
deathwisher6 months ago
first your battery will eventually loose power as the aluminium oxidises.you could speed up the rate by adding hydrogen peroxide or any other oxidiser like kno3.and also connecting a number of them in parallel to get more amps or in serier for voltage
graml1 year ago
well seeing as an LED uses a small amount of power i would say for a fairly long time
lukeD2 years ago
how long will it work?
martzsam3 years ago
Can I use a copper rod instead of a carbon rod?
depotdevoid4 years ago
Very nice, Coggz. This is well documented, easy to understand, and cool! I think I'll use this for a science experiment with my daughter.
sageserver4 years ago
cool, you can make a mini boat that runs purely on ocean water.
PKM sageserver4 years ago
Well, not exactly- the energy comes from the aluminium oxidising to form aluminium oxide. The salt water is just a part of the battery that doesn't contribute energy, because the energy you are releasing is actually the energy that was used by the electrolysis plant to make the aluminium in the first place. Coggz, if you have the relevant electrical theory and the equipment to test it could you find out the internal resistance of this battery? I'm interested to see how much current it could supply, and of course how long it will run for.
sageserver PKM4 years ago
But you need the salt water/ionic solution. I know the anode would corrode about 1/2g per hour(i guess), but the boat gets powered by the ocean/saltwater.
Coggz (author)  PKM4 years ago
I'm not sure quite what you mean ,but when measuring the resistance across the two terminals with a multimeter i get around 53kohm resistance. Is that what you mean?
PKM Coggz4 years ago
Not quite- this is what I meant. Any battery cannot supply infinite current so has a theoretical resistance associated with it.

Think of a battery as a perfect voltage source and a resistor connected together (and that can't be separated)- the resistor will limit the current that the battery can provide. A car battery can supply hundreds of amps so has a very small internal resistance, a coin cell has a high internal resistance so cannot provide a high current (which is how they can power LED throwies without burning out the LED).

The internal resistance defines how much power you can draw from a battery- in my example you couldn't power a car starter motor from 12V worth of coin cells, because they can't provide the hundreds of amps required, and I suspect your cell also has a high internal resistance.
klee27x PKM4 years ago
Umm, I don't get it. The foil is already covered in aluminum oxide. So what turns the aluminum oxide back into aluminum to allow this reaction in the first place?
PKM klee27x4 years ago
My mistake- the aluminium actually forms aluminium hydroxide, Al(OH)3.
More about the chemistry

I'm not sure how it deals with the oxide layer, I assume it either takes part in the reaction or is porous enough to allow the electrolyte to react with the pure Al underneath. Either way, the aluminium is supplying the energy.
warp_kez4 years ago
BiCarb soda or salt?
Coggz (author)  warp_kez4 years ago
Either will work, any mineral salt will work as long as the water is saturated with it (i.e no more can dissolve) I just used bicarbonate of soda as I had it handy
How long can it run an led for?
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