When it comes to batteries and power tools, voltage is often the first thing that comes to mind. But is voltage alone enough to determine the true power and efficiency of a battery? The answer is no. There's a crucial aspect of power that often gets overlooked—watt-hours.


So, what exactly are watt-hours, and why do they matter? Let's break it down.

What Are Watt-Hours?

Watt-hours (Wh) are a measure of electrical energy over time. While voltage tells you the force behind the electrical current, watt-hours indicate how much power you get over a certain period. It's like the fuel capacity in your car—it determines how far you can go on a single charge.

How to Calculate Watt-Hours?

Calculating watt-hours is simple. Just multiply the voltage by the battery capacity in amp-hours (Ah). For example, a 40V battery with a capacity of 5 amp-hours would have a watt-hour rating of 200 Wh (40V x 5Ah = 200Wh).

Why Do Watt-Hours Matter?

Battery Performance Comparison:

When assessing battery performance, it's not just about the voltage. Amps matter too. Take, for instance, our HART 40V 4.0Ah Battery (160Wh). It provides more power for longer compared to a 60V competitor with a 2.5Ah Battery (160Wh). This is because watt-hours take into account both voltage and amp-hours, giving you a more accurate measure of a battery's performance.

Estimating Device Runtime:

Knowing the watt-hour rating of a battery helps you estimate how long your device can run before needing a recharge. This is especially crucial for power tools and other devices that require continuous operation.


Next time you're in the market for battery powered lawn & garden equipment, don't just focus on voltage. Look beyond and pay attention to watt-hours. They provide a more comprehensive understanding of power and can help you make informed decisions when choosing batteries for your devices.

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