The battery energy capacity is the **entire energy that may be taken from a fully charged cell or battery, measured in watt hours** (kilowatt hours). A cell’s energy reserve changes depending on factors like temperature, rate, age, and cut-off voltage. System designers use this phrase more frequently in the battery industry, where capacity is typically expressed in ampere hours.

Battery capacity is measured in ampere hours and is defined as the total quantity of electricity produced by electrochemical reactions inside the battery. For instance, a 5 Ah battery can be discharged at a steady rate of 1 C (5 A) for one hour. A discharge current of 0.1 C (500 mA) can be extracted from the battery for 10 hours using the same battery.

Cells of varying capacities with the **same C ratio value behave similarly for a given cell type**. The capacity of a battery refers to the amount of energy it can store and release during the discharge process. The letters Ah stand for “ampere hour,” which is the unit of capacity.

**What is Battery Power Capacity?**

The battery’s power capacity is the amount of energy it can hold. Watt-hours are frequently used to measure this power (the symbol Wh). A Watt-hour is equal to the voltage (V) and current (Amps) that a battery can produce for a specific period of time (generally in hours). **Wh = Voltage * Amps * Hours**.

Due to the internal chemistry of a battery type (alkaline, lithium, lead acid, etc.), voltage is essentially set, therefore frequently only the Amps*hour measurement, given in Ah or mAh (1000mAh = 1Ah), is printed on the side. **Multiply the Ah by the nominal voltage to obtain Wh**.

Let’s use a 3V nominal battery with a 1Amp-hour capacity as an example. It has a 3 Wh capacity. According to theory, 1 Ah allows us to draw 1 Amp of current for one hour, 0.1 Amp for ten hours, or 0.01 Amp (also known as 10 mA) for one hundred hours.

**Also Read: **What is Barrier Energy?

However, the power capacity (or actual amount of electricity we can draw) from a battery is frequently constrained. For instance, a coin cell with a 1 Ah rating can’t truly deliver 1 Amp of current for an hour; in fact, it can’t deliver even 0.1 Amp without going over its limit.

It’s like claiming a person is capable of travelling up to 30 miles: running 30 miles is very different from walking, of course! Similar to this, a coin cell with a capacity of 1 Ah can easily deliver 1 mA for 1000 hours, but if you try to take 100 mA from it, it won’t last more than 10 hours.