A dry cell battery holds a semi-solid paste within the casing of the battery. This electromagnetic substance is the source of stored energy within the battery. Dry cell batteries have many practical uses, but there are also disadvantages and dangers involved with their use.
Dry cell batteries are categorised into two broad categories: primary and secondary. Primary batteries cannot be recharged. They transfer their stored energy to the equipment using them (such as a flashlight) in an irreversible pattern. Secondary batteries transfer their energy in a pattern that can be reversed, and can therefore be recharged. Primary batteries are less expensive initially than secondary batteries, but must be replaced, adding to their expense in the long run. Secondary batteries cost more initially, and while they last longer than primary batteries, they also eventually lose the ability to be recharged and must be replaced.
Explosion and Corrosion
Dry cell batteries are prone to explosion if handled improperly. Never throw batteries into a fire. Attempting to recharge a disposable battery also runs the risk of explosion. When replacing dry cell batteries, replace all batteries at the same time. Mixing old and new batteries increases the likelihood that the batteries will leak. Do not store batteries in a pocketbook or in your pocket, as they could discharge or even rupture if they become overheated.
Environmental and Health Concerns
Dry cell batteries contain a number of toxic substances that can cause health problems and also present serious environmental concerns. These substances include nickel, cadmium, mercury, zinc, lead and lithium. Discard batteries separately from regular trash if at all possible. Many communities have provisions for battery disposal.