MRO Today - Cordless tools: Taking charge

Take charge
Cordless tool technology continues to evolve. Heres what youll find in the newest models.

by Clair D. Urbain

When it comes to common tools, cordless power tools lead the parade in new technology.

Its an evolution that has taken the once weak and short-lived cordless drill to levels of power and durability that rival beefy power tools with cords.

With that growth in portable power, tool manufacturers have been adding to their cordless lines, bringing on tools built for a wide range of high-torque jobs.

Where weve come from
The first professional-quality cordless tools debuted about 10 years ago, with 1.2-amp-hour cells and a whopping (then) 9.6 volts of power.

"Weve seen the capacity and power of cordless tools double in the last 10 years," says Doug Bock, Panasonic national sales manager. "Todays tools can do tougher jobs for longer periods between charges."

Which cordless tool for you?
Its easy to get wrapped up in the cordless tool "more power is better" syndrome. When you compare the specs, you can see the 18-volt and 24-volt models rival the power found in corded tools.

But how much power is too much? Its really driven by the jobs you do, says E.J. Loferski, cordless tool manager at Milwaukee Electric Tool Corporation. He offers the following rules of thumb for cordless tool selection.

Consider your needs
"Would you also like a cordless circular saw or a hammer drill? Look at models that allow you to interchange batteries," he says.

Often, manufacturers offer kits that combine two or more tools into a system at a very attractive price. If a circular or reciprocating saw is a must-have tool in your cordless lineup, look to the 18-volt and higher tools. You need that much power to handle a range of sawing jobs effectively.

Go for amp-hours as the distance from your charger increases
"If you want the most run time from your cordless tools, go for the highest amp-hour battery ratings. The amp-hour rating is like the size of your gas tank of your car, the larger the tank (amp-hours), the farther you can go," he says.

Match the voltage rating to the job
For most people, a 12- or 14.4-volt drill/driver is sufficient. "These drills can easily handle screwdriving and can bore up to three-quarter-inch holes in wood and three-eighths-inch holes in steel," he says.

But if your work requires larger holes or sinking lag bolts into decking, a 14.4-volt or 18-volt tool may be better for the job. Likewise, if your work requires only screw tightening for wiring, a 2.4-volt screwdriver type driver may be your best bet.

Match the weight
Even though an 18- or 24-volt drill/driver can handle every one of your job needs, consider what that added weight means as you use tools and carry them around the plant.

Cordless power tool experts interviewed for this article agree cordless tool development truly has been an evolution.

"Advances have been very incremental over the past seven years," says Rich Rapuano, director of cordless tool marketing at DeWalt. "On the outside, the tools look very much like they did five years ago, but they have actually changed at a rate of about 5 percent a year. So over the last five years, you have seen some great improvements in power and run time."

Tool manufacturers develop cordless tools based on the power and durability users expect from the tools corded counterparts.

"Cordless tools must have the same performance characteristics as a corded tool. Its been well proved that users will pay about twice the cost of a corded tool for the cordless convenience, but no more than that," says Bock.

So manufacturers continue to improve the tools, working to keep the tools prices at or under the 2x corded tool cost barrier.

Where we are today
Evolution has made todays cordless drills as beefy, powerful and as strong as their corded counterparts. Its led to the introduction of tools such as reciprocating and circular saws and caulking guns that keep expanding the definition of cordless tools.

The advent of 2.0 amp-hour and higher batteries has allowed manufacturers to develop higher power tools with longer run times. Nickel-cadmium (Ni-Cd) batteries, used in most cordless power tools are generally available in 2.0 amp-hour models; some even offer 2.4 amp-hour ratings.

Nickel metal-hydride (Ni-MH) batteries, which have been introduced in some brands of cordless tools in the last 18 months, offer up to 3.0 amp-hour ratings.

Tool voltage is equal to the amp-hour rating of the battery cell multiplied by the number of cells in the battery pack. Manufacturers are getting the higher voltages by putting more and higher amp-hour battery cells in the battery pack, then designing the tool to best balance the tool in the users hand.

"We have done a nice job of designing these tools ergonomically. If you look at a tool developed 10 years ago vs. todays tool, the difference is dramatic," says Rapuano.

Still, weight is weight, and many believe that top-end cordless tools have reached the limit.

"At what point does a higher voltage tool weigh too much to use? It seems we are reaching that with the 24-volt tools," says Mike Whitman, Porter-Cable product development manager. "Thats why Porter-Cable went with 19.2-volt tools. We believe it gives the best weight, power and cost balance contractors want."

The jobs cordless circular and reciprocating saws, as well as larger hammer drills on the market, do are high-torque, high-drain applications. These tools cant do their jobs without the higher voltage ratings

"Youll feel a significant increase in weight as you move from an 18-volt to a 24-volt tool," says E.J. Loferski, cordless product manager at Milwaukee Electric Tool. "Youll see as much as 1 pound more weight with a 24-volt tool. We are on the verge of the tools getting too big and heavy for anyone to use all day."

DeWalts Rapuano says 24-volt tools have their place. "Our 24-volt circular saw weighs less than its corded counterpart. Youll also find users dont use a 24-volt hammer drill like they use an 18-volt driver/drill. They are used in different applications," he says.

What tomorrow may bring
The cordless tool experts agree that Ni-Cd batteries are getting near the top of their capacity limits.

"Battery manufacturers that make Ni-Cd and Ni-MH batteries believe that further advancements in Ni-Cd are on the horizon, but the long-term potential for Ni-Cd is more limited that the long-term potential for Ni-MH technology. This assumes battery companies can overcome some of the the Ni-MH performance issues," says Rapuano.

Panasonic and others are counting on Ni-MH technology. In general, they offer a longer run time than todays 2.0 or 2.4 amp-hour Ni-Cd batteries. Because they contain no cadmium, they are also considered to be more environmentally friendly.

"Our Ni-MH batteries offer 3.0 amp-hours with the same weight and size as a Ni-Cd battery. In two years, we fully expect to see the Ni-MH batteries have 4.0 amp-hour ratings," says Bock.

Controversy continues to surround Ni-MH battery technology. Opponents claim the batteries have a shorter cycle life (number of times they can be recharged before they wear out) and that they will not work at freezing temperatures.

Higher battery cost also concerns tight-fisted plant departments, although the prices of Ni-MH tools have come down.

Bock disputes these claims. "The reason others have seen shorter cycle life stems from improper battery charging. Ni-MH batteries create heat when they charge, where Ni-Cd batteries absorb heat during charging. Ni-MH chargers must be designed to charge these batteries properly."

Bock acknowledges that Ni-MH batteries will stop working when they reach 14 degrees F. Conversely, Ni-Cd batteries will output power to minus-22 F.

Panasonic tests confirm the batteries lose power at extremely cold temperatures. However, when the cold batteries are charged for three minutes, the batteries in the test had enough power to hole-saw 79 successive 3 1/2-inch holes in half-inch plywood.