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How to get electricity from vegetables and fruits

Once on an uninhabited island, modern Robinson could not deny himself the pleasure of using a player, smartphone or flashlight, provided that he was able to extract electricity from coconuts and bananas. 

For sure many of the course of physics remember or heard that from ordinary potatoes, and not only from it, one can get a little electricity. 
What is necessary for this, and is it possible to light a low-power flashlight, a LED clock, powered by round-the-clock batteries, or to make the radio work? 

And, yes and no, let’s understand more.

To understand that the tension of potatoes is not an invention, but a very real thing, it is enough to stick a single potato sharp probes from the multimeter and you will immediately see on the screen a few millivolts. 

If you complicate the construction a little, for example, insert a copper electrode or a bronze coin into the tuber and, on the other hand, something aluminum or galvanized, the voltage level will increase substantially. 

Potato juice contains dissolved salts and acids, which are essentially a natural electrolyte. 

By the way, with the same success you can use for this lemons, oranges, apples. Thus, all these products can feed not only people, but also electrical appliances.

Inside such fruits and vegetables, due to oxidation, electrons will flow out from the immersed anode (galvanized contact). And they will be attracted to another contact – copper. In this case, do not confuse, the electricity here is not formed directly from potatoes. It is well developed precisely because of the chemical processes between the three elements:

    • zinc
    • copper
    • acid

And it is zinc contact that serves as an outflow. All electrons are flowing from it. Under certain conditions, even earth soil can give electricity. The main condition is its acidity. 

Earth battery

Increased soil acidity is a problem for agronomists, but a joy for electrical engineers. The content of hydrogen and aluminum ions in the ground allows you to literally stuck in a pot two sticks (as usual, zinc and copper) and get electricity. Our result is 0.2 V. To improve the result, the soil should be watered.

It is important to understand: electricity is not produced from lemon or potatoes. This is not at all the energy of chemical bonds in organic molecules, which is absorbed by our body as a result of food consumption. Electricity arises from chemical reactions involving zinc, copper and acid, and in our battery it is the nail that is used as an expendable material. 

Assembling a battery of potatoes

So, that’s what is needed to assemble a more or less capacitive battery: 

Potatoes, a few pieces, since there will not be much use from one. 

Copper, preferably single-core wires, the larger the cross-section, the better. 

Galvanized and copper nails or screws (you can use just a wire).

Nails just the same and will play a major role in the generation of electricity for a flashlight, galvanized – this is a negative contact (anode), the copper-clad is a plus (cathode).

If you use simple nails instead of galvanized, then you will lose in tension up to 40-50%. But as an option, it will still work. 

The same applies to the use of aluminum wire instead of nails. In this case, the increase in the distance between the electrodes in one potato does not play a special role. 

Take copper wires (mono vein) section 1,5-2,5mm2, length 10-15cm. Peel them from insulation and tie them to a carnation. 

The best course is to solder, then the voltage loss will be much less. 

One copper nail on one side of the wire, and a galvanized one on the other.

Further lay out the potatoes and consistently stick nails into them. In this case, different nails are stuck in each tuber, from different pairs of wires. That is, in each potato you need to stick one zinc contact and one copper. 

Connect different tubers to each other, only through nails from various materials – copper + zinc – copper + zinc, etc. 

Voltage measurements

Let’s say you have three potatoes, and you connected them together in the manner described above. To find out what voltage was obtained, use a multimeter. 

Switch it to the DC voltage measurement mode and connect the test leads to the conductors of the extreme potatoes, i.e. to the initial plus (copper) and final minus (zinc).

Even on three medium-sized potatoes, you can get almost 1.5 Volts. 

If, on the maximum, reduce all the transient resistance, but for this:

    • As a copper electrode, use not the nail, but the same wire that the circuit is going to use
    • in contacts apply soldering

then only 4 potatoes are able to give up to 12 volts! 

If your cheap flashlight is powered by three finger batteries, then to successfully illuminate it you will need about 5 volts. That is, potatoes with the use of conventional wires need at least three times more. 

For this, by the way, it is not necessary to look for additional tubers, it is enough to cut existing ones into several parts with a knife. After that, do the same procedure with wiring and studs. 

In each cut tuber, consistently insert one galvanized and one copper stud. As a result, it is quite possible to obtain a constant voltage of more than 5.5V.

Is it possible, theoretically, from one single potato, to get 5 volts and at the same time to ensure that the entire assembly is not larger than a finger battery? It is possible and very easy. 

Cut the small pieces of the core from the potatoes, and lay them between flat electrodes, for example, coins of different metals (bronze, zinc, aluminum). 

In the end, you should get something like a sandwich. Even one piece of such an assembly is capable of giving up to 0.5V! 
And if you collect them several pieces together, then the required value of up to 5V is easily obtained at the output. 

Current strength

It would seem everything, the goal is achieved, and it remains only to find a way to connect the wiring to the power contacts of the flashlight or LEDs.

However, after doing this procedure and collecting not a weak design from several cards, you will be very much disappointed with the final result. 
Low-power LEDs will of course glow, after all the voltage you still got. However, the brightness level of their glow will be catastrophically dim. Why is this happening? 

Because, unfortunately, such a galvanic cell gives an insignificantly low current. It will be so small that not even all multimeters can measure it. 

Someone will think, if there is not enough current, you need to add more potatoes and everything will turn out. 

Of course, a significant increase in tubers will raise the working tension.

With the successive combination of tens and hundreds of potatoes, the voltage will increase, but there will not be the most important – sufficient capacity to increase the current. 

And the whole construction will not be rationally suitable. 

A practical way with cooked potatoes

But still, is there an easy way how to increase the power of such a battery and reduce the size? Yes there is. 

For example, if you use raw and potatoes for this purpose, then the power of such a source of electricity increases several times! 

To assemble a convenient compact design, use the housing from an old C (R14) or D (R20) battery. 

Delete all the contents inside (of course, except for the graphite rod). 

Instead of the filling fill the entire space with boiled potatoes.

After that, assemble the battery in the reverse order. 

The zinc part of the old battery case, here plays a significant role. 

The total area of ​​the inner walls is much greater than just stuck in carrots. 

Hence the high power and efficiency. 

One such power source will easily give out almost 1.5 volts, as well as a small finger battery. 

But the most important thing for us is not volts, but milliamps. So, such a “boiled” modernization, is capable of providing a current of up to 80mA. 

Such batteries can be powered by a receiver or an electronic LED watch. 

And the whole assembly will work not for a second, but for a few minutes (up to ten). More batteries and chips, more autonomous working time. 

Lemon battery

The vinegar battery. A mold for ice will help to design a multi-cell battery with vinegar as an electrolyte. Use zinc-plated screws and copper wire as electrodes. Filling the battery with vinegar and connecting the LED lamp to it, try to gradually fall asleep and stir the salt in the cells: the brightness of the glow will grow on the eyes.

Juicy fruit, young potatoes and other food products can serve as food not only for people, but also for electrical appliances. To get electricity from them, you will need a galvanized nail or a screw (that is, almost any nail or screw) and a piece of copper wire. To fix the presence of electricity, we will need a household multimeter, and more clearly demonstrate the success of an LED lamp or even a fan, powered by batteries.

Smash the lemon in your hands to destroy the internal septum, but do not damage the peel. Insert a nail (screw) and a copper wire so that the electrodes are located as close as possible to each other, but do not touch. The closer the electrodes are, the less likely they will be separated by a septum inside the fruit. In turn, the better the ion exchange between the electrodes inside the battery, the greater its power. 

The essence of the experiment is to put copper and zinc electrodes in an acidic environment, whether it’s a lemon or a bath with vinegar. The nail serves us as a negative electrode, or an anode. We assign copper wire to a positive electrode, or cathode.

In an acidic environment, an oxidation reaction proceeds on the surface of the anode, during which free electrons are released. Two electrons leave each zinc atom. Copper is a strong oxidizer, and it can attract electrons liberated by zinc. If you close the electric circuit (connect a light bulb or multimeter to an improvised battery), electrons will flow from the anode to the cathode through it, that is, electricity will appear in the circuit. 


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