The larger the battery size, the better for your tools, right? Not necessarily. There are two main things to consider when choosing the correct battery for the job: runtime and power.

The amp hour (Ah) of a battery determines its runtime. The larger the amp hour, the longer the runtime. For example, a one amp-hour battery should be able to provide one amp of power for an hour, or two amps of power for a half-hour.

Stephen Blain of Stanley Black & Decker said, “Compare it to the size of a gas tank on a vehicle. If you have a 40-litre tank and an 80-litre tank, and the same vehicle, you would expect to get twice as far with the larger tank.” In other words, when a job requires a long battery life, it is recommended to use a higher amp-hour battery as it will last longer.

The higher the amp hour and volts on a power tool, the more power and performance it is capable of delivering. Some tools draw as much as 60 volts of power, while others only draw 20 volts. When you use a higher voltage battery on a higher voltage tool, you will get the most power.

Although more power sounds excellent, higher energy batteries carry more weight. While a three amp-hour battery usually only weighs around one pound, a 12 amp-hour battery weighs around three pounds. This two pound difference can have an impact on the fatigue of your arm when working over longer periods. A job requiring a short duration of time should factor in tools with a lower amp-hour and voltage-rated battery to reduce the overall weight of the tool. When you need continuous power and want to avoid having to swap batteries mid-job, a higher amp-hour battery, like the new DeWalt FLEXVOLT^® 20V/60V MAX 12.0 amp hour battery will be the best choice as it provides higher power and longer runtime.

Flexvolt batteries can be a convenient option with lower voltage power tools. For example, when using a 20-volt tool on a job where increased runtime is important, a Flexvolt battery’s capacity (available in six, nine, and 12 amp hours) will produce a much better runtime than the tool’s standard battery (which are often only between 1.5 and three amp hours). A Flexvolt battery will automatically adjust its voltage to match the tool it’s powering.

Blain added, “On 60-volt tools, you get power, and on 20-volt tools, you get the runtime.”

Knowing the differences between the various lithium-ion batteries on the market today can help ensure you are using the right power source for the job. Weight, available power and maximum runtime are all important factors to consider. Ensure you are using the right combination of battery properties before starting your next job.

See the experts at your local Co-op Home Centre to help you decide which batteries will best suit your power tools and construction projects.