Hobbies And Interests
Primary Storage Batteries
Among the different types of internal voltage sources, primary storage batteries are the simplest and easiest to recognize. They consist of an anode, a cathode and an electrolyte, and they use their chemical make-up to supply DC power in various voltages and current ratings. The materials used in the cells determine the battery's characteristic voltage: 1.2V for nickel-cadmium (NiCd) and nickel-metal hydride (NiMH) cells, 1.5V for alkaline cells and 3.6V for lithium ion cells. Primary storage batteries power devices such as watches, clocks, TV remotes, electric toothbrushes and toys.
Accumulator Batteries
Accumulator batteries, also known as "secondary-storage" or "rechargeable batteries," are internal voltage sources designed to be recharged multiple times. Like primary storage batteries, their operation depends on electrochemical reactions; the difference is that reactions in accumulator batteries are reversible. These batteries require a DC flow -- usually from the mains -- passing through them opposite to the direction of discharge in order for them to recharge. This type of internal voltage source is common among electronic gadgets such as cameras, mobile phones, laptops and portable video game consoles.
Alternators (AC Generators)
Alternators primary internal voltage sources, generating electricity by virtue of magnetic induction. Unlike batteries, no electrochemical reactions are involved in an alternator's operation. Instead, mechanical input causes a magnet to turn, which induces the flow of current in a coil of stationary conductors positioned around the magnet. Though often acting as separate devices for emergency power systems, alternators also serve as internal voltage sources in automobiles, boats and other engine-powered equipment.
Capacitors and Supercapacitors
Capacitors and supercapacitors resemble accumulator batteries in that they are designed to undergo multiple charge and discharge cycles. Unlike batteries, they store energy not through an electrolyte but through a static electric field formed across the dielectric when their plates are charged. Capacitors and supercapacitors are most often used as internal voltage sources in conjunction with batteries, keeping the latter from overheating and extending battery life. In many cases, they supplant the battery as the main energy source. Applications that use capacitors and supercapacitors include cameras, portable media players, hybrid and electric cars and engines for tanks and submarines.