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Rechargeable Batteries

If you have ever used a gadget that runs on disposable batteries, then you have experienced the frustration of having to replace used batteries with new ones. Over time the cost of replacing batteries in a device can be more than the cost of the device itself! Fortunately, the days of disposable batteries are numbered. All modern digital cameras, including Bigshot, use rechargeable batteries. If they run out of power, you can connect them to a power source to charge them again. In the case of Bigshot, if you happen to be out shooting photos when the battery runs out of charge and you do not have access to a power source, you can simply crank the dynamo to recharge the battery and continue to shoot photos. Let's now take a closer look at how a battery works.

Figure 7: A simple battery

A battery is a device that stores chemical energy in its materials and converts it, on demand, into electrical energy. The two main parts of a battery − the anode and the cathode − are immersed in an electrolyte, which is a liquid or gel with ions (see Figure 7). An ion is an atom or molecule in which the number of electrons is not equal to the number of protons, giving it a net positive or negative electric charge. If the electrolyte is negatively charged, its ions will chemically combine with the material of the anode, producing a residual material and releasing electrons. If the anode is connected to the cathode via an external circuit (the device that the battery powers), the free electrons flow through the circuit to the cathode as electric current. The cathode's material consumes these electrons to produce another residual material. The battery will continue to produce electricity until one of its electrodes or its electrolyte runs out of the material needed for the chemical reaction to take place.

A rechargeable battery produces electricity exactly the same way as a non-rechargeable one. However, rechargeable batteries use special materials for their anode, cathode and electrolyte that allow the chemical reactions described above to be reversed. To recharge the battery, you can connect it to an external electrical power source, such as a dynamo, such that current flows in the reverse direction. The residual materials formed on the anode and cathode as well as in the spent electrolyte will react with the electrons to reproduce the original materials of the anode, cathode and electrolyte. The battery is now recharged and as good as a brand new one!



[1] "Capacitor." Wikipedia, The Free Encyclopedia. [Online]. Available: http://en.wikipedia.org/wiki/Capacitor. [Accessed: Jun 3, 2012].