For instance, Ryobi's 18V ONE+ battery comes in 1.5Ah, 2Ah, 4Ah, 6Ah, 8Ah, and 12Ah variants. Meanwhile, DeWalt's 20V MAX* XR POWERPACK includes a 4Ah and 8Ah model.

While a battery's amp-hour directly correlates to its runtime and not power, actual tests have shown that a higher Ah can still provide increased performance. When Ryobi evaluated its 4Ah and 8Ah ...