Batteries are the key to any cordless power tool, whether choosing a cordless drill, hedge trimmer, leaf blower, or any other type of cordless tool. Battery voltage is not the single most important factor to consider when choosing cordless power tools. With cordless tools available all the way up to 36 volts, amperage/hour, and battery type must also be taken into account. Many 14.4 volt tools will outperform 19.2 volt tools due to battery type and amp/hr rating.
Battery Rating Basics
Amperage hours and voltage are used to rate a cordless tool battery. Amperage hours are used to determine how long a battery will last and voltage refers to the flow or strength of the electrical current. As I was taught in high school shop class the theory of electrical current is easier to understand if you think of it as water being pumped through a pipe.
- Voltage is used to measure the speed at which water is flowing through the pipe.
- Amperage represents the size of pipe that will be filled to capacity.
- Amperage hour rates how long the flow can be maintained or how long the battery will last.
As you can see by using this analogy the higher the voltage in conjunction with higher amp/hr the stronger the battery. Cordless power tool batteries are usually available in 1.4, 2.4, and 3.0 amp/hr. The amp/hr rating of the battery can be found on either the side or bottom of most batteries.
Battery Types
There are three types of batteries used in modern cordless power tools.
- Ni - Cad ( Nickel - Cadmium ) are the oldest type used and are prone to developing a memory and early failure. Even when properly maintained they are lucky to be recharged 400 times before failure occurs.
- Ni -MH ( Nickel Metal Hydride ) are a newer design than Ni - Cad and can develop a memory, though not as quick. The worst issue discovered with this type of battery, the higher the amp/hr rating, the fewer charge cycles before battery failure occurs.
- Li - Ion ( Lithium - Ion ) are the newest type available and much better, compact, and expensive than the other two types. Memory is not a problem, and manufacturers claim up to 1,200 charging cycles before replacement.
Charging Time
Is another important consideration when considering cordless power tool batteries. Many older batteries need charging after only an hour or less of work and require six hours of charging time. If you have a lot of work to perform can you afford to wait for your batteries to recharge? There are Lithium - Ion batteries available that only require 15 minutes to recharge.
Stability and Maintenance
With the high cost of replacement batteries for cordless tools it pays to follow manufacturers recommendations for the care and maintenance of these tools. Cordless power tool batteries are just like any other piece of equipment and have an expected service life. When they become worn out and need replacing it is sometimes more economical to replace the entire tool kit. The cost of two replacement batteries is often times more than a new cordless tool with charger and two batteries.
The author of this article has 29 years of experience working in the highly competitive housing market of the west and southwest suburbs of Chicago as a carpenter. His job titles have included Master Roof Cutter, Apprentice, and everything in between. Most of his experience is in the high end custom home marketplace, including all aspects of fine homebuilding, from footings to ridge cap. His website contains more information on House Framing and Cordless Power Tools
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