Cordless Tools: Is it Time to Cut the Cord?
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Cordless Tools: Is it Time to Cut the Cord?

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Power tools have certainly changed over the last 40 years.

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You’ve seen the ads — cordless tools changing the world, one battery, more power, durability, etc. I can remember when the world consisted of two professional air tool manufacturers (who shall remain nameless). Now, there are at least 12 that come quickly to mind, with probably eight or nine of them offering cordless tools. Cordless tools provide the professional air tool manufacturers an excellent way to extend their lines and build on core capabilities. And cordless tools give you an alternative to bulky air lines and extension cords.

If you already own a cordless tool, it’s probably a couple of years old. Like my desktop computer, it’s already outdated. The new technology available for today’s cordless tools lies primarily in the battery design. There are other features that are unique to each manufacturer (handle grip, battery engaging design, body materials, range of product offering and warranty are just a few), but the most critical improvements center around the battery.

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Batteries: Longer life, lighter weight = better performance + easier to use for long periods of time.

Nickel-cadmium (NiCd) rechargeable batteries have been popular for toys and portable electronics for many years. First developed in 1899, it has undergone many improvements over time. All have led to this latest generation of NiCd rechargeable batteries. NiCd batteries typically require a complete discharge before recharging, however one cordless tool manufacturer claims the “renew” feature on their charger refreshes batteries by sensing and eliminating memory effect in NiCd batteries, thereby extending battery life up to 300%. NiCds are better suited for high current applications. They have a significantly lower series resistance, allowing them to supply high surge currents.

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These are several reasons why they are an optimum choice for cordless power tools. As the use of battery-powered electronics and tools has grown, so has the market for rechargeable NiCd batteries. Advances in manufacturing make this a low-cost alternative and, as a result, NiCd batteries commanded the largest market share for rechargeable batteries in consumer electronics — until lately. Nickel Metal Hydride (NiMH) and Lithium-ion batteries have become more commercially available and cheaper, though they are still more expensive than NiCds.

Lithium-ion: Lithium-ion batteries are generally lighter in weight than the nickel-cadmium batteries. On a comparable size basis, the Li-Ion battery can be as much as 40% lighter than the NiCd battery. Li-Ion batteries also have no memory effect. This mean they can be charged at any time. A Li-Ion battery also accepts more recharges and lasts longer than a NiCd battery. As more and more products have been developed to work with rechargeable batteries, the manufacturing technology behind Li-Ion has improved, so the cost has come down. They are still more expensive than NiCds, but when energy density is important (such as with cordless tools), Li-Ion batteries are the preferred technology. This is especially true when the cost of the battery is small compared to the cost of the tool. (See chart.)

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Besides Batteries, What’s Different about Cordless Tools?
In addition to batteries, the chargers themselves have been re-engineered. Some manufacturers have developed battery chargers that “read” the battery to determine battery voltage and chemistry. The charger has become the battery diagnostic center. For instance, some chargers have been designed to tell the technician if the battery has been used and discharged 20 times or 200 times. It can also determine the amount of life left in the battery. With this type of information, the charger can optimize its charge to improve the performance and longevity of the battery.

Many manufacturers have added features to the charger to quickly show the user the condition of the battery or the charging condition — lots of blinking green and orange lights. It’s a nice feature because you can look at the charger to determine how much longer you have to wait for a full charge — not unlike the chargers we’ve all become accustomed to with our video and digital cameras.

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Another big development in cordless is the materials used in the housing. The materials generally are a metal (aluminum, steel or a composite metal) and a plastic or polymer. One company features reinforced composite materials with resistance to grease and oils. This is important in a shop atmosphere where grease and oils are used on a daily basis. Another manufacturer touts its over-molded cushion grip and tapered ergonomic grip. Most manufacturers will say they have an “ergonomic design.” Ergonomic design means one thing to a person with large hands and another thing to a person with smaller hands. I would recommend you physically handle several different models before you make your decision. Sometimes, you just have to go with what feels right.

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Key Benefits When You Go Cordless
How will you benefit by going cordless in 2007? The new tools of 2006 and 2007 are going to be lighter than previous cordless tools, making those repetitive jobs easier to do. They also have the benefit of portability. There’s no need for electricity or long extension cords, cumbersome air lines or regulators to get your job done. These make great tools to keep on the service truck.

Many technicians are quickly discovering that the new generation of cordless tools is more durable, faster, more powerful and extremely handy in a larger number of professional applications than the previous generation of cordless tools. They generate significant power with an easy-to-recharge system. All these factors combine to make cordless tools an important part of your toolbox.

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Are you thinking about buying a new cordless air tool? Even if you are not familiar with all the types of cordless tools that are available, based on what we’ve seen, there’s a cordless tool in your future.

Battery Specifications*
Nickel-Cadmium (NiCd) Lithium ion (Li-Ion)
Energy/Weight ~30 Wh/kg ~150 Wh/kg
Energy/Size ~75 Wh/L ~250 Wh/L
Self-Discharge Rate 20%/month 5%/month
Time Durability Long
Cycle Durability >300
Normal Cell Voltage 3.6 Volts
Battery Advantages & Disadvantages*
Nickel-Cadmium (NiCd) Lithium ion (Li-Ion)
Still relatively expensive More expensive than NiCd
Can be formed into a wide variety of shapes and sizes, so they can efficiently fill space in the tools they power.
Require less care and are difficult to damage. Not as durable as NiCd, can be dangerous if damaged.
Usually generate more cycles Higher energy-to-weight ratio
Can often be discharged or charged at a faster rate than gel-cell lead acid batteries. Low self-discharge rate. Should never be fully discharged.
Are not damaged if left in a deep discharge or complete uncharged condition for a long period of time. Life span is dependent upon aging from time of manufacturing, regardless of whether it was charged, and not just on the number of charge/discharge cycles.
Can accept a charge of up to 80% of its amp-hour rating. May often abruptly fail rather than slow down because the battery’s overall capacity determines the maximum power that can be continuously drawn in high-powered applications.
*Battery specification and information on advantages and disadvantages is for general use only. For more specific data, please refer to the individual manufacturer’s product information.

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