Cordless Update

A look at the state of the art in rechargeable-battery tools.

By Gordon Bock and Kathleen Fisher

	Photo Courtesy of Ryobi

An old-house owner doesn't have to be a vintage human being to remember when a battery tool packed more novelty than practicality. The first cordless drill didn't appear until the Kennedy Administration and, for a long time after, getting a few dozen 1/4 holes out of a charge was a lot to ask. A battery's recharge time was nearly equal to its owner's sleep cycle.

The industry has come a long way. Power and run time have increased steadily over the years, while creative design has reduced tool weight and improved usability. The latest cornucopia of quality cordless tools includes several that, until now, were impossible to power without a cord. In fact, manufacturers offer such an array of new tools sizes, voltages, and power ratingsÑon top of earlier-generation tools that still sell wellÑthat anyone working on a house can get confused about what all the numbers mean in terms of actually getting things done. If you're in the market for a cordless tool, here's a breakdown of the latest developments you'll encounter in this broad and growing industry as you survey your choices.

Vive la Difference
The Race to Reincarnate All Tools as Cordless
If there's one trend that's obvious to even casual shoppers it's the amazing variety of cordless tools. A lot of traditionally corded tools are now going cordless, notes Jane Van Bergen, marketing director at Ryobi Technologies. Indeed, there seems no bounds to the jobs that sophisticated combinations of motors, batteries, and blades can do. Once limited to making light-duty holes or cuts in wood, cordless tools can now handle all-day use in framing lumber or dense building materials like plywood, metal, and even masonry. For working in tight spaces, such as attics, manufacturers have come up with cordless reciprocating saws capable of rough-in work or demolition. Cordless routers are now a reality and at least two makers are breaking new ground with power miter sawsÑtools that were originally not only corded but also stationary.

The growth of the cordless tool market, as well as its technology, is even spawning some tools with no strict precedent in the corded world. What at first glance seems to be an unending proliferation of T-handled battery drills is, on closer inspection, the appearance of a related but different breed of tool: the impact driver. Popular for many years outside the United States (particularly in Japan) and rapidly adopted by American construction trades, cordless impact drivers are now coming on strong with consumers for all kinds of applications.

Sharing some mechanical principles, but little else, with hammer drills and air-powered impact wrenches, impact drivers look like a svelte version of a cordless drill without the traditional three-jaw chuck or internal clutch. Unlike hammer drills, impact drivers help drive screws, lag bolts, and similar fasteners by adding rotational impactÑthat is, striking the fastener in the direction of turn, rather than into the surfaceÑwhen the fastener reaches a certain torque (turning power) resistance. This percussive action makes the work easier to perform (you don't have to strenuously grip or brace the tool), and it helps seat the fastener head properly into the surface. Impact drivers quickly became the tool of choice for commercial installation work, such as driving heavy lag bolts for anchoring garage doors, but now are equally popular for anchoring decking and molded plasterwork.

Trying to analyze why rechargeable-battery tools are so popular has, interestingly, inspired at least one manufacturer to explore new directions in corded tools. While freedom from electrical outlets is certainly key, Craftsman believes that another cordless appeal has been the clutch, which lets users adjust the amount of torqueÑespecially important for driving screws into soft material. As a result they've introduced some corded drills that feature clutches and dual-range gearboxes, but which are compact and lightweight to an extent difficult to achieve with cordless tools.

New Package Deals
Tools Improve Ergonomic Bodies and Expand to Families Because corded tools have to carry their power source with them, getting the most muscle and service from the smallest, lightest-weight package has always been a goal. While greater power was everyone's objective just a couple of years ago, the beefier motors, gearboxes, and batteries they required came at the cost of attendant bulkiness and heft.

Biggest may be best for some specialized construction professionals, who will need the newer 24-volt power tools with their greater torque and rpm capacity for, say, daily fence building. However, general-purpose users like old-house restorers, who are now both more discriminating and more realistic about their needs, have helped establish 18 volts as an all-around comfortable balance between power and comfort. In fact many users, especially women, find 9.6-volt tools among the easiest to hold.

Ray Holbrook, portable power tools buyer for Craftsman, notes that about 32 percent of the shoppers in tool departments are women. We do a lot of research with end users to find out what they're looking for. Power is their number one concern, but they also mention ergonomicsÑgood weight and balance to make the tool easier to hold and use. Steve Cole, product manager for Bosch, says this improved ratio of greater power and lighter weight could go on indefinitely, in terms of currently available technology, but not without pushing tool prices beyond acceptability to potential buyers.

What today's consumer seems to be lapping up is the combo kit, says Christine Potter, production manager for DeWalt. The most common package includes a drill, a reciprocating saw or circular saw, and a flashlight. Cole says Bosch's new products will stress commonalityÑnot only will all the tools in a kit be compatible with one charger, but buyers can power up a new drill/driver with the charger from a previously owned model. We want to keep users in the Bosch family, he explains.

Assault on Batteries
Improving Performance of Cells and Chargers
The Holy Grail for today's cordless manufacturers is not higher tool voltage per se, but battery performance or deliveranceÑhow much work you can get done on one charge. While several characteristics can contribute to this quality, the most closely watched number is the amp-hour rating. Amp-hour rating is what continues to change, says Todd Craft, cordless product manager at Porter-Cable/Delta. Everybody's going up. Vince Caito, marketing communications manager at Makita Tools, agrees. The current ceiling [on voltage] seems to be 24 volts, while battery and charger run-time and performance seem to be the growth areas. As an example, manufacturers whose tools claimed a 2.0 amp-hour rating a couple of years ago are now offering a 2.4 amp-hour rating for the same voltage battery pack. The thing for tool buyers to remember is that while a manufacturer may have improved the amp-hour rating on its latest or most powerful lineÑits 19.2-volt toolsÑthat does not necessarily mean its 18-volt or 14.4-volt batteries are upgraded as well.

How does a manufacturer squeeze more work out of a battery? In simple terms, by innovations in the chemistry or construction of the individual cells and sometimes their chargers. One approach is switching from nickel-cadmium (NiCd) chemistry to nickel-metal-hydride (NiMH) chemistry, an area of great debate. Another is enhancing construction and electronics. Makita, for example, by reengineering the individual NiMH cell package, has reduced its size from that of a common C cell to that of an AA battery. To the battery package they've added a heat sink and an electronic chip that talks to the charger.

HeatÑa byproduct of rechargingÑis the big killer of batteries, and manufacturers deal with the overheating issue in different ways. Some chargers contain a monitor that will say yes or no to recharging a too hot battery. Bosch's high-end computerized chargers use fuzzy logic to constantly monitor the battery temperature and adjust the current accordingly. DeWalt has a fan-cooled system to charge its 24-volt battery. Chargers for its lower-voltage batteries employ what the company calls a tune-up mode that keeps the batteries from developing memory effect (a phenomenon, produced by repeated shallow discharging, that reduces the effective capacity of the battery).

Panasonic batteries are cooled while charging through the simple expedient of ventilation holes. Their self-diagnostic 45-minute charger shows the status of the charge through an array of LED lights.

One thing all manufacturers seem to agree on is that with new technologies and cordless tool use expanding every year, they will continue to monitor the market. If the future is anything like the recent past, that means there are even more efficient and job-specific cordless tools to come.

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