Cordless Tools
Cordless tools, technically, are any tool that does not require an electrical power cord. So a cordless tool may be an unpowered screwdriver or a gasoline-powered leaf blower. But in practice, most people think of commonly cord-powered tools that have been re-designed to run off batteries, freeing them from the tangle and restrictions of power cords.
The batteries used in cordless tools may be of the single-use or rechargeable varieties. Most household cordless tools use rechargeable batteries.
Single-use cordless tool batteries do not provide a great deal of power and can be used only on cordless tools intended for very light work. Cordless bead reamers, for example, run on two AA batteries and are used to enlarge the holes in beads that are strung for jewelry. Bead reamers are good enough for removing a bit of stone from the edges and interior of a bead's hole, but are not powerful enough to drill a new hole through stone.
Rechargeable cordless tool batteries are found in everything from screwdrivers to hand drills. Their power is measured in volts; typical voltages are 12v, 18v, and 24v. A 12v cordless tool is suitable for a screwdriver. An 18v battery can power a wood drill adequately. But for drilling through masonry or concrete, a 24v battery is the best choice. The amperage or current that a battery delivers is also a factor in its power; a 12 amp battery provides greater power than an 8 amp battery of higher voltage.
Of course, batteries expend power and then must be recharged. The capacity of a battery determines how long it will last before it must be recharged, and the amount of time it will take to fully recharge it when it is exhausted. Then you should consider the chemical technology of a battery before recharging it.
Some cordless tools use nickel-cadmium (NiCad) batteries. NiCad batteries should be discharged completely before they are recharged. Otherwise, they may not take a full charge due to the well-known "NiCad memory" effect. Modern lithium batteries (Li) can be recharged before they are full discharged without losing their "memory" of what a full charge is.
Black & Decker makes low-power cordless tools suitable for light household repairs and small projects. Heavy-duty cordless tools are made by many manufacturers including Bosch, Ingersoll, Hitachi, Makita, Hilti, Craftsman, Mitsubishi, and others. Generally, the higher the price, the better the quality of a cordless tool.