When shopping for batteries—whether for a portable generator—you’ll frequently encounter two critical metrics: amp hours and Wh. These values indicate how much energy a battery can hold, but they are not interchangeable—and knowing how they relate can significantly improve your decision-making.

Amp hours, or Ah, quantify the current delivery capacity a battery can supply over time. For instance, a 8 Ah battery can deliver 0.5 amps for 20 hours. This metric gives you a rough idea of runtime under load—but it doesn’t reflect total energy storage. A 12 volt 10 amp hour and a 36 volt 10 amp hour have identical Ah ratings but differ significantly in total capacity.

Watt hours, or Wh, measure total usable energy. It’s calculated by using the formula Wh = V × Ah. So, a 12V 10Ah battery equals 120 Wh, while a 36 volt 10 amp hour battery equals three times more energy. This means the 36V model holds three times the usable power. Watt hours enable accurate evaluations of the actual energy available for tasks—regardless of voltage.

Why does this matter? When shopping for energy storage, always prioritize watt hours if you want to know which suits your device best. Two batteries with matching current capacity but unmatched potential will perform differently. For example, a 20 Ah 12V battery and a 10 Ah 24V battery both provide 240 watt hours, making them equal in capacity despite their disparate current ratings.

Some manufacturers highlight amp hours because the figures seem more substantial, but Wh are the reliable standard for energy storage. Always look for the voltage specification to convert Ah to Wh if it’s not provided. Most reputable brands include both ratings, but if they don’t, you can do the math by applying the simple formula.

In summary, Ah describe electrical throughput, while Wh reveal actual stored power. For informed choices, always rely on watt hours. Whether you’re selecting a battery for خرید یو پی اس your emergency backup, understanding this distinction helps you skip deceptive marketing and ensure optimal performance.