ng a partical or complete discharge, by the flow of dissect current through them in a direction opposite to the current flow or discharge. Types of secondary batteries are lead acid batteries, nickel-cadmium, and nickel hydrogen batteries. Secondary batteries are mainly used for portable high-power appliances such as portable computers, power tools, flashlights, and some medical devices. Lead acid batteries are used in camcorders, computers, cellular phones, lawn mower starter, and cars. Nickel batteries are used for rechargeable appliances such as portable power tools, hand held vacuums, and cameras. Batteries are one of the main electricity sources.
             Despite the great demand for batteries every year, disposal of them is far more important. Batteries may seem harmless to the consumer. Heavy metals that are contained within the battery's casing and pose no real risk while the battery is in use. But they can be a concern when discarded with ordinary municipal solid waste. In reality, battery waste is hazardous and causes a number of problems. Batteries are basically steel which holds in a variety of chemicals and metals together. These chemicals and metals carry and direct the electrical charge within the battery. Unfortunately, many of the chemicals and metals within batteries are hazardous if they are released. Therefo
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