Lithium Ion Drills Show Their Stuff
By Tom Inglesby
Superman returned to the theaters this summer and cordless drills, hammer-drills and rotary hammers are returning to the mason's toolbox. What, did you say? Neither was ever gone? Superman might have been taking just a leave of absence, but cordless drills were seen even less.
Cordless was tried and found lacking at the beginning, a decade ago, due to low power, short battery life and limited usability. "The tools, when they first came out, started with 9.6 and 12 volts," recalled Edwin Bender, group product manager for cordless power tools at Bosch Power Tools, Mount Prospect, Ill. "But their development didn't stop there, it kept moving - up to 14 and 18 volts - because when you go into large diameters and into masonry, you need 18-volt power. That is one thing that has changed over the years that has now become the norm, and so the tools are now more reasonable to use. Masons need that level of power to feel like their getting enough productivity out of their tools. Now, lithium ion is taking it to the next level because you're able to double your run time, have twice as much power, and do more tasks than you could before."
Agreeing is Terry Tuerk, product manager for Metabo Corporation USA, Sellersville, Penn. "Today's cordless tools pack is typically 18 to 36 volts. At that power level, the tools are nearly as strong as corded tools, without the weight, the cord or the extension cord, making them most favored in overhead applications, working from a ladder or scaffold, or where an electrical mains source is not available. However, corded tools - particularly rotary hammers - are still the tools of choice when drilling multiple holes, large diameter holes or where the hole being drilled is at the feet.
"Advances in battery chemistry have made cordless tools more practical," he continued. "The first advance was the increase in the amp hour ratings of batteries, first in Nickel Cadmium (NiCad), then in Nickel metal hydride (NiMH) in the past four to five years. The amp hour rating of a battery pack can be equated to the size of the gasoline tank; the higher the number, the longer the battery can provide energy for the application. Today's NiCad and NiMH batteries carry 2.4, 3.0 and higher amp hours, giving the tool the energy reserve needed to make the cordless tool practical."
Cordless power tools for professionals, regardless of industry, are usually made with harsh environments in mind. Peter Hagicostas, director of quality assurance and new product development at Great Neck Saw Manufacturing, Mineola, N.Y., puts it in perspective, saying, "The models designed for the contractor and professional exhibit various attributes to handle the rugged and continuous uses they will face from day to day. They also have developed various voltages to accommodate a variety of tasks. This level of quality is ideal for all trades, including masonry. Certain types, such as hammer drills, are designed with them in mind. The reason is quite simple: They must be affordable, reliable, as well as durable and tested for 'fitness for use.' They are designed to meet the daily challenges of handling, dust, moisture, weather, consistent use and more. Power tools in general are treated quite harsh on the job site; therefore, they must be designed and built to handle this environment."
Taking the discussion a little further is Robert Chetelat, product manager for cordless drills/drivers at Hilti North America, Tulsa, Okla. "Cordless hammer drills are well suited for masonry applications because they operate on a cam-action hammer mechanism. This has less impact force per blow, but high frequency of blows per minutes. Cam-action tools help reduce cracking and spalling when drilling into stone or masonry.
"Electro-pneumatic rotary hammer drills operate with the hammer mechanism riding on a cushion of air, are designed to have greater impact force per blow, lower frequency of blows per minute, and more comfort for the operator. This is better for drilling into concrete, but suitable in masonry."
Everyone seems to agree that lithium ion (Li-Ion) is the battery chemistry of the present and future. Chetelat explained, "With Cordless Power Care (CPC) lithium ion, masonry professionals benefit from double the run time of NiCad batteries and get lighter weight. Hilti has individual cell management for longer lasting batteries and robust battery cells for better performance. There is also a 'state of charge' displayed on the battery so you know how much power you have at any time as well as drop resistant casings to help protect your batteries in job site conditions. The CPC lithium ion batteries allow masonry contractors to get more work per charge of the TE 6A Li for less weight versus a 24-volt tool. With the SFH 151 three-speed cordless hammer drill/driver, for example, a tool that has 35,000 beats per minute, masonry contractors can drill holes for concrete screws, like running a knife through butter. The SFH 151 is great for the many smaller diameter fastening applications that masons encounter."
Indeed, the Li-Ion battery technology leads the list of advances that make cordless a prime-time attraction. In some cases, this technology has allowed companies to introduce cordless units they didn't have before. One is Makita of La Mirada, Calif. "We have a hammer driver drill, which is good for light masonry work," acknowledged Bradley Wheeler, senior product marketing manager for cordless tools at Makita. "We also have a rotary hammer that we're going to launch in the summer of 2006. This is made practical by the lighter weight of the lithium ion battery."
Some cordless rotary hammers are heavy and, since a lot of this work is done overhead, the first advantage of lithium in this application is the lighter weight. "You also have the opportunity to pack in a few more amp hours - 3.0 amps in our case," claimed Wheeler. "It has all the advantages or our corded tool in terms of the clutch that kicks in to protect against over-torquing. It's a three-mode hammer: hammer, hammer drill and drill. It has a variety of things that you don't see on a cordless tool right now."
Lithium ion has some major advantages over both NiCad and NiMH; 40 percent less weight than NiMH and 33 percent lighter than NiCad means that tool can be made more powerful at the same weight level of today's tools. "Li-Ion is 90 to 95 percent efficient in giving up it's energy, where NiCad and NiMH are 75 percent efficient," Tuerk noted. "That gives Li-Ion a huge advantage in running longer. Other advantages of Li-Ion are its ability to absorb energy very quickly in the charging process and the lack of a 'memory effect.' A Li-Ion battery can be put into the charger at any point in its discharge cycle, with no harm to the battery. It also can be taken out of the charger at any point in the charging cycle, again, with no harm to the battery. A Li-Ion battery will retain a charge for up to 18 months, whereas NiCad and NiMH lose up to 25 percent of their charge in a one month period."
While Li-Ion isn't a cure-all, it has become the starting point for a variety of new products. Still, there are trade-offs. As Bender from Bosch stated, "Typically, with the state of lithium ion technology today and what we're trying to accomplish, we have to compromise. Yes, Li-Ion is lighter in general because of the density of the cells, so what all the manufacturers did was say, 'How much power can I pack in now that I'm using lithium ion and maintain that 18-volt kind of weight?' If you were to make an 18-volt Li-Ion, versus an 18-volt NiCad, it would be lighter weight, but generally what you're seeing is that most companies are going to a higher voltage."
For example, 24-volt rotary products doesn't sell that well, even though 24 volts allows you to be a little more productive than an 18-volt unit; it's not enough of an increase in productivity for the weight penalty and the cost you have to pay. "How lithium ion changes the game is that it allows you to get much more productivity, more power and run time, but you don't pay a weight penalty," Bender said.
At least one major supplier is moving in another direction. Milwaukee Electric Tool, Brookfield, Wis., has higher voltage tools. John Sara, senior product manager for Milwaukee, explained, "Our new V28 rotary hammer drill, using 28-volt Li-Ion batteries, can drill over 20 7/8-inch holes on a single battery charge. The tool also features a rotation stop option for light chiseling work. The increases in power have been helpful for driving Tapcon's and drilling holes in metal and wood for forms. In regards to our batteries, our V28 and upcoming V18 Li-Ion batteries come with a five-year warranty. Before our Li-Ion introduction, the tools typically outlived the batteries. Now with our V series batteries (V28 & V18), the packs are starting to living up to the reputation of our tools. Milwaukee and other manufacturer web sites list 'Battery Best Practices' to help users optimize battery life."
What's next? Most manufacturers won't say - competitive secrecy and all that, you know. What we were able to find out sounds like more of the same, only better. "Just like NiCad progressed over time from 9.6 to 18 volts, and the amp hours in the batteries increased from 1.2 to 2.4, " recalled Bender, "I think you're going to see the Li-Ion cells becoming better in terms of capacity - and therefore extending run time - and you'll see them continue to become optimized and stronger. In our mind, right now, 18-volt lithium ion isn't a good idea. It doesn't mean it won't be, but in terms of where the technology is right now, it's not the way you want to go when designing your lithium ion platform."
He quickly added, "We're always going to be working on mechanical improvements to the tools. All those fall into the kind of proprietary aspect that we generally don't talk about until we're ready to launch them. And in terms of the battery platform, everybody is thinking about what's going to be next. The big buzz outside the power tool industry right now is fuel cells. All technologies are being investigated by us."
Both Sara at Milwaukee Electric and Tuerk at Metabo see Li-Ion improvements and new products coming. Sara said, "In the third quarter of 2006, we will be launching our new V18 hammer drill along with our V18 Li-Ion battery platform. The drill offers new levels of power and run-time, plus the Li-Ion batteries will work on our older 18-volt tools."
Tuerk commented, "The use of Lithium Ion has allowed tools with greater voltage to approach the performance of corded tools with out the weight detriment of earlier battery chemistries. This has allowed manufacturers to apply this technology where it wasn't practical in the past; high discharge tools, such as rotary hammers, angle grinders, circular saws and reciprocating saws. In the opposite direction, lithium ion is also making practical very small, lightweight tools with nearly the power of full size tools of the past."
About the Author
Tom Inglesby is a San Diego-based freelance writer whose work has appeared in numerous online and print publications. He is the winner of the Construction Writers Association's 2002 Boger Award for Special Reports.