Know the Cordless Drills of Today
Drills of various shapes, materials and designs have been in use since pre- Egyptian times. There have been discoveries of drill type devices found that look like no more than a rock honed to a rounded chisel type point, that was spun between the user's hands. To more modern units discovered in China that were powered by human, water, wind or animals, that were of a belt driven nature. There has even been drill devices uncovered, dating back to about 215 BC in China, that were made of wood. These primitive drill devices were designed such that they could drill through stone.
In the mid 1800's, with the advent of the electric motor, a team of inventors from Australia designed the first electric drill and soon thereafter a German inventor designed the first hand-held electric drill. A US based Company. Black & Decker jumped into the market with their first pistol grip, trigger handled, portable electric drill around 1917, the drill design that we are familiar with today.
As the development of battery technologies became more pervasive, drills followed suit. Initially the 7.2v units were powered by a nickel-cadmium and as batteries were able to provide more power, the technology would also be adapted to cordless frills. Today replaceable battery packs range from the original output of 7.2 volts, which are hard to come by anymore, to the 36 volt units. Currently the 18 volt units are the most prevalent followed by the 24 and 28 volt units.
The Lithium-ion batteries are the much preferred technology due to their short charge time and their long use time, about 15 minutes charge time will provide about 1 hour constant use time. Whereas the opposite holds true for the original nickel cadmium batteries, internal shorting issues, short use life and disposal issues. About the only advantage a NICd (nickel cadmium) drill battery has over the lithium-ion units are price. Because they have been on the market longer they are less expensive.
Today's cordless drills are one of the items that all homeowners and handy-man will have to have in their tool-kits, with a few spare power tool batteries. The many uses are as varied as there are jobs to be done. One of the many tasks that cordless drills are well adapted for are driving screws. Due to the built in clutching assembly that most corded units lack, the cordless units are better suited for this task. Corded units, for the most part, do not have a clutch assembly and could end up driving screws right through the underlying material. The clutch on the cordless units allows the unit to stop the drill when it reaches a certain torque.
Overall the variety and power of these cordless units are what drive the price, the higher the voltage the higher the price. There are occasions when one can get great deals on higher voltage units you just need to watch local flyers or websites for these deals. Also, look at last years models or even sometimes available are open box units that you can pick up for a steal.