Almost any electrically powered tool is available either with a power cord or in a cordless, battery powered model. Cordless power tools in the typical tool box might include a drill and/or drill/drivers, table saw, and reciprocating saw.
Small, lightweight, usually handheld, cordless power tools do not need an external power source. Therein lies the practicality of such devices; they can be used anywhere. Such hand-held power tools include a circular saw or trim saw, planer, and jigsaw.
The most common battery used in today’s cordless power tools is the 18 volt (18v) Lithium-ion (Li-ion) battery. Li-ion batteries are square, black, relatively powerful, quickly rechargeable, long-lasting and slow to discharge when not in use. Li-ion batteries, however, are somewhat volatile and easily damaged from being too deeply discharged. Tools that ordinarily use a Li-ion battery would be a portable band saw, a rotary sander, chain saw, nail gun, caulking gun, router, rotary sander, or belt sander.
One of the first cordless power tools to be developed was the electric screwdriver which, at its introduction, was powered by the common, non-rechargeable, alkaline flashlight battery. Then, with the development of the nickel-cadmium (NiCd) rechargeable battery in the mid-1950s, batteries for cordless power tools could be recharged after use instead of being thrown away as is the case with ordinary alkaline batteries. Though less volatile, and impervious to over-discharge, NiCd batteries are incapable of storing the same level of electricity as a Li-ion battery. Thus, a NiCd battery might power an electric screwdriver, hand-held grinder, or staple gun.
While cordless power tools are occasionally called wireless power tools, the term “wireless” is more commonly and appropriately applied to communications technology. Because of the electrical demands of the moving parts common to every power tool, its wiring is most often thicker and heavier than the wiring used for wireless communications, and “cord” is the more common term. Thus, rummaging in the toolbox once more, we may find such cordless power tools as hand-held vacuums, pruning shears. and concrete vibrators.
Two main disadvantages of cordless power tools are their limited torque and relatively short period of peak power. The usefulness of any cordless power tool is only as good as the battery that powers it, and all batteries have their limits. Occasionally, inconvenient re-charging of batteries complicated by comparatively rapid loss of power necessitates the use of a tool with a power cord. When planning a job, it’s always a good idea to know the limitations of the tools to be used.