Cordless, but not powerless

Today’s cordless tools keep getting more contractor-friendly

by Kay Falk

Cordless tools have three distinct advantages over conventional tools.

First, they are convenient, allowing workers to move where and when they want without a cord in the way. “Because they’re not tethered by a cord, their range is unlimited,” says Kevin Fairchild, product manager at Hitachi Power Tools.

Second, cordless tools can make your workers more productive. They don’t have to search for scarce electrical receptacles on jobsites or worry about matching the cord’s gauge to the tool’s power requirements.

“Quick set-up at the jobsite means you can get to work faster,” says John T. Sara, cordless product manager at Milwaukee Electric Tool Co. “Going back to the truck to get a generator or extension cord before you drill the first hole wastes productive time.”

“With multiple batteries and a 15-minute charger, you can keep working all day. Crawl spaces or other tight environments don’t complicate projects when working with tools like cordless reciprocating saws, drill/drivers, hammer drill/drivers, rotary hammers, circular saws or jig saws,” says Randall Coe, director of product development at Bosch Power Tools and Accessories.

Cordless miter saws, for example, give carpenters the ability to save time by moving from room to room with the saw, rather than back and forth to a cut station.

Versatility is the third benefit, says Pete Morris, DeWalt director of marketing. “With the continued increases in cordless tools’ usable power, coupled with system expansion tools, many users today can put away their AC tools.”

Innovations for longer run time
These benefits are great if your cordless tool doesn’t run out of juice before you run out of job. Manufacturers have been working on that concern.

“The increase in the number and types of cordless tools has been a result of improvements in battery and charger technology,” says Vince Caito, marketing communications manager at Makita USA.

David Smith, executive vice president at Metabo Corp., further explains the trend. “We’re always working to improve the charging system and battery packs for cordless tools. In the past, you could expect between 250 to 1,000 recharges before your battery was used up, and recharging took up to three hours.”

That has changed. “Today, computer-controlled chargers work quickly with minimum heat, which is what breaks down battery cell chemistry. Users of the new chargers report about 3,000 recharges that take 10 to 30 minutes each, depending on the amp-hour capacity of the battery. Even standard chargers now give 2,000 recharges and they take about 10 to 15 minutes. This means contractors need fewer spare battery packs,” Smith says.

Some manufacturers are switching from nickel-cadmium (Ni-Cd) to nickel-metal hydride (Ni-MH) batteries which are about 15 percent more costly, or they offer both. The advantage of

Ni-MH, according to Smith, is that for the same size cell and battery weight, you get more amp hours of available electricity, thus more capacity.

The battery manufacturer Panasonic’s Web site agrees with Smith. Ni-MH batteries contain more electrical elements, giving them a larger power source than Ni-Cd batteries and a bit more stable power delivery to the end of their charge.

“Today’s Ni-Cd batteries have improved capacity over those originally used in cordless tools,” Sara points out. “We still consider Ni-Cd the gold standard in battery performance due to its cold-weather performance and life vs. Ni-MH.”

Battery manufacturers are investigating lithium ion cells, such as those used in watches and cameras. “These are good for low-drain applications on small tools, but they lose power quickly when a big draw is applied to them,” Smith says.

Although 18-volt tools have only been in the professional market for eight years, this option has matured as the voltage platform for replacing corded power tools, according to Morris. “Over the next few years the trend will continue to be more 18-volt expansion in product development and in end user conversions from corded to cordless,” he predicts. “Beyond the next few years, it’s fair to say that all professional power tool companies are looking at bringing existing battery technologies, such as military, high-end electronics, computers, into the power tool industry. These technologies will ultimately drive more conversions because of run-time gains.”

Greater power, smaller package
When it comes to power, the goal is to deliver as much output power as possible in the smallest package. Morris cites that is how DeWalt pioneered the use of neodymium iron boron magnets in power tools. “These magnets increase power without increasing mass. Like many power tool innovations, these magnets were first used in other industries,” he says.

Fairchild agrees that you get more power because of improved motor technology. “Hitachi’s new driver drill series, for instance, uses rare-earth magnet motors. We believe the naturally formed magnets are more stable, and that the gap between cordless and corded power tools will continue to close.”

Makita’s Caito concurs. “Advances in cordless tools have led to lighter, more powerful and efficient products,” he says. “For example, cordless impact drivers and wrenches now generate much greater torque than cordless drills, so they provide a superior solution for fastening applications.”

Metabo’s Smith points out that with more than one speed, a large number of torque settings and improved motor efficiency, today’s cordless tools can do more jobs without overloading and causing heat buildup. “There’s less energy lost as heat from the battery pack to the tool, so tools last longer and the operator gets the job done more quickly,” he says.

Manufacturers have designed in more features with their latest models. 

Here’s a sample:
• externally accessible carbon brushes to make replacement easier
• belt attachment systems that lock the tool to a work belt or bag so the operator doesn’t have to set a drill down, tuck it under an arm or rest it  on top of ladder so it’s within easy reach until needed
• durable new materials like ABS/nylon housings and unibody powertrains in cordless drills that allow tools to withstand one-story or greater drops
• pistol-grip handles
• improved keyless chucks
• impulse features on drill drivers that turn current on
and off to allow easier finish drives or fastener removal and avoid drill “walking” on smooth surfaces like tile and sheet metal.

“Further advancements in design, motor technology and battery sources are in development to allow efficient use of larger cordless tools like demolition hammers and large rotary hammers,” Coe says. “You can already find smaller masonry and light concrete drilling tools like hammer drills and small rotary hammers as examples of technology moving in this direction. These tools are perfect examples of improvements that provide more power and run time to meet users’ needs.”

Published in the May 2004 issue of Contractor Tools and Supplies magazine.

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