Homemade batteries are commonly made of common items found around the house. Almost any fluid or moist object containing sufficient ions (charged particles) can serve as the electrolyte for a cell. It is possible to generate small units of electricity from a lemon, potato or glass of soft drink by placing two electrodes into them. A clock by name ‘”two-potato clock” is commonly available in hobby and toy shops. It contains a pair of cells (each with a potato or lemon with two electrodes) wired in series to form a battery with adequate current to operate a digital clock.
When acids are present in water, they produce ions that are the same as the charged particles in electric current. For example, lemon juice contains citric acid. The lemon battery is formed by inserting two metal electrodes (zinc as anode and copper as cathode) into the lemon juice without them touching each other. A potato battery works the same way as a lemon battery. Here, the electrolyte is phosphoric acid. Homemade batteries can also be built from other vegetables and fruits.
Homemade cells of these types have no real practical use, as they generate extremely lower current than commercial batteries. Because of the need for frequent substitution of the fruit or vegetable, they are also inconvenient in most situations. However, the cost of homemade batteries is much lower than commercial batteries.
Clorox bleach battery is a powerful type of homemade battery that can be made using Clorox mixture. It lasts only a week or less, since its electrodes rust very quickly. In the “tap water battery” two special metals (usually made of stainless steel) serve as electrodes it that can be used to light LED bulbs for many days or weeks. There is no need of charging this battery,. Just refuel it with tap water every 4 to 7 weeks.