Rechargeable Batteries for Power Tools

House Doctor | Gary Dymski

October 24, 2002

Q. I have had virtually no success with rechargeable batteries that come with cordless power tools. I bought a new drill that came with two batteries, and within three years both batteries are dead. Now, I have a great drill but can't use it unless I spend another $70 or so for a new battery. Is this a racket? Am I doing something wrong?

-B.R., East Meadow

A. You could be doing something wrong. Then again, there is also consumer pressure on manufacturers of cordless power tools to provide stronger, longer-lasting batteries.

Be sure you are charging your battery correctly. Different batteries have specific recharging instructions; improper recharging can reduce a battery's lifespan. It should get about 1,000 individual charges, so unless you're a professional contractor, you might want to examine your recharging practices.

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You also could be overextending your drill. For example, using a 9.6-volt drill on heavy-duty jobs could be wearing out not only the battery but the components of the drill. Your owner's manual should provide some guidelines on jobs your drill is best-suited to perform.

Now, for more specific information on batteries: Many power tools, especially drills and saws, are powered by battery packs that range from 6 volts to 24 volts. Usually, a higher voltage rating signifies a more powerful tool and a battery that works longer between recharging. Traditionally, nickel-cadmium (NiCd) rechargeable batteries were used to power cordless tools, but the batteries needed frequent charging. Newer cordless tools are beginning to be powered by longer lasting nickel- metal hydride (NiMH) batteries, more environmentally friendly than NiCd batteries, which should be recycled.

If you are replacing a nickel-cadmium battery, you should be aware that the newer versions are designed to be more efficient and longer lasting. Old NiCd batteries were most efficient when their power was used completely before recharging. Unlike the old batteries, the new NiCd versions aren't damaged when partially used and then recharged. If you like your drill, invest in a new battery.

But remember that newer cordless tools have some nifty features. Quick-charge power sources are now being manufactured. These power packs revive battery life quickly, usually in an hour or so, and automatically stop charging the battery when it becomes fully charged. Another new feature on cordless tools is a built-in meter that monitors battery usage.