March, 2008

Going Cordless, Going Green

New battery technology offers measurable benefits.

By John Wagner

Green batteries? Come on, you can’t call a battery green, can you? 

Honestly, you can. Today’s lithium ion batteries—just a few years on the market and clearly taking over—are much greener than past versions, especially when you consider the power demands of recharging the batteries, the battery life cycles, and what happens to batteries after they are discarded.

The old industry standby batteries, nickel-cadmium (NiCd), deliver high-current capability. But they need frequent recharging and must be carefully recycled because cadmium is a highly toxic chemical. (Nickel-metal-halide batteries don’t contain cadmium, but they cost more and contain nickel that should be recovered in a recycling process.)

Around 2005, a new family of high-performance, lightweight lithium-ion batteries started appearing on the market. They offer up to 400% more energy than the NiCd battery, plus they last far longer—up to 2,000 charges—and don’t need to be recharged as often in typical use.

With these cycle times and better durability, a lithium-ion battery user would buy 80 times fewer batteries over a lifetime. And when lithium-ion batteries wear out, they don’t contribute the same level of toxins, pound for pound, as NiCds, if they end up in a landfill. (That said, lithium-ion batteries should be recycled too.)

How do they perform? Well, after you cover the battery science and the life cycle analysis, lithium ion cordless tools are dream tools, because they offer the same voltage as a NiCd, but with far less overall tool weight. Plus, the lighter weight has given tool-makers an good excuse to reengineer their tools to create smaller, more ergonomic tools.

“There are more than 100 different types of lithium ion batteries,” says Steve Jenson, product manager for DeWalt Cordless Fastening. “They vary by ion chemistry. Our chemistry is Nano phosphate.”

Nano phosphate is different than lithium magnesium or lithium oxide, which Jenson says are older-generation technologies.

DeWalt wasn’t the first to market with lithium ion batteries, testing 13,000 different lithium ion cells before they settled on nano phosphate. Their lithium ion batteries, good for 2,000 charges—a 90% improvement over NiCd, DeWalt says—and are backward compatible to 40 legacy DeWalt tools. (If you do use these in older tools, note that lithium ion works best when its power is managed by electronics in the newer tools. So, to optimize lithium ion battery life, get the newer tools.)

Testing the Tools

I recently tested DeWalt and Milwaukee lithium ion tools and both are remarkably well-made. The DeWalt lithium ion tool I tried (a DC827 18V impact driver) was superbly balanced, very lightweight for the voltage and power it delivers, and with great performance and run-times. I also tested Milwaukee lithium ion cordless tools. The new professional-grade 12- and 18-volt Sub-Compact Drivers are very impressive; lightweight, solid, and balanced, with two batteries and a 30-minute charger. In the 12-volt model, a tool of comparable size with a NiCd battery would be undersized in a trade application. “For Milwaukee tools, our lithium ion offers 10% to 50% performance enhancement in run time,” said Rick Gray, director of marketing for Milwaukee Electric Tool. “Make no mistake, lithium ion is the future of cordless, and the whole industry is in transition to them. That’s why we have backwards compatibility to our tools with the lithium ion products.”

Where to Recycle:

Although lithium-ion batteries can be disposed of without introducing the same level of toxins into the waste stream as NiCd batteries do, they should nonetheless be recycled. NiMH batteries contain nickel, which should be recovered instead of ending up in a landfill or being incinerated. Visit the Rechargeable Battery Recycling Corp. web site (www.Rbrc.org) to find a nearby recycling center.