Rechargeable batteries have cut the cord for power tools.
The electrical needs of power tools make single use (carbon or alkaline) batteries impractical, so, for years, the only power tools on the market were corded. Rechargeable batteries allow toolmakers to fashion cordless tools for the DIYer on the go.
Unfortunately, power tool makers have yet to develop a standard for rechargeable batteries. This can make it difficult to convert from one battery type to another. When choosing a cordless power tool, take some time to price replacement batteries. Over the life of the tool, replacement batteries could drive up the cost the tool you buy.
The Granddaddy of Rechargeable Batteries
Nickel-Cadmium (NiCd) batteries were the first rechargeable batteries to come to market. Resistant to high loads or surges, NiCd batteries can be recharged hundreds of times.
Unfortunately, NiCd batteries are prone to "memory effect," which can reduce the charging capacity of the battery over time. NiCd batteries also contain cadmium, an environmental toxin. For this reason, spent NiCd batteries should always be recycled and never thrown in the trash.
We Need More Power!
Nickel metal hydride (NiMh) batteries are similar to NiCd batteries, but with better performance. NiMh rechargeable batteries hold up to three times the power of NiCd batteries. NiMh batteries are much less vulnerable to memory effect. In fact, with proper charging, a NiMh rechargeable battery will work at full capacity for its full lifespan.
The big disadvantage of NiMh rechargeable batteries is that they have a short shelf life. A NiMh battery will lose its charge after a few months of inactivity. If you only use your tools occasionally, NiMh batteries might not be right for you.
Powerful, But Delicate
Lithium-ion (Li-ion) batteries offer the latest in power and size. Li-ion rechargeable batteries offer double the performance of NiMh batteries. Li-ion batteries weigh less than similarly powered batteries. Li-ion rechargeable batteries have a long shelf life and have no memory effect issues.
Li-ion rechargeable batteries are very sensitive to temperature, however. High temperature can reduce a Li-ion batteries service life. Improper charging can also be dangerous with Li-ion batteries.
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