Because carpenters must often work in places far from power outlets, they had to find other ways to power their tools when an extension cord just was not sufficient. Tight spaces such as attics and less-accessible ones such as rooftops meant that carpenters needed tools that were more versatile and portable than previous incarnations. So cordless power tools were born, utilizing heavy duty batteries that could be quickly recharged to continue the job. One of the most vital of these tools is the cordless circular saw.
The corded variety of circular saw has been an industry presence for decades, and is still primarily used today because of its power capabilities that are greater than a cordless circular saw. Many professional carpenters are still skeptical of the cordless circular saw because of this drawback, but recent advancements in battery technology has brought the cordless circular saw into the realm of feasible tools even for the pros.
A standard corded circular saw runs off 120 volt AC power from an outlet, thereby allowing enough power to make clean cuts consistently. There is no battery, and therefore there is no battery drain, causing a gradual loss of power; also, because of the power a corded circular saw is allowed to draw from the outlet, the power output is greater than that of a cordless circular saw. This allows the corded variety to cut through thicker wood than a cordless circular saw, making the corded saw more vital to larger projects such as framing houses.
However, cordless circular saw batteries have made advancements. The advent of 18 volt batteries have given cordless circular saws more power than in the past, and though it still may not cut the mustard for building an entire house, it can be useful for smaller projects such as remodeling or smaller projects involving framing. Cutting through 1/4 inch (6 mm) stock used to be all the cordless circular saw could handle, but today, with the right blade, a cordless saw can cut through framing lumber up to a certain depth. The cordless saw is more reliant on a strong blade than a corded saw, however, because there is no excess power supply to force the blade through a thick board.
Though the cordless circular saw probably won't replace the corded saw any time soon, it is a useful tool for smaller projects and home remodelers. Capable of clean cuts and portability, the cordless saw is a great tool for amateurs, and a useful one for professionals working smaller projects or in tough locations.