Since this is a particularly confusing part of measuring batteries, I'm going to discuss it more in detail. Power capacity is how much energy is stored in the battery. This power is often expressed in Watt-hours (the symbol Wh).
Power capacity is how much energy is stored in the battery. This power is often expressed in Watt-hours (the symbol Wh). A Watt-hour is the voltage (V) that the battery provides multiplied by how much current (Amps) the battery can provide for some amount of time (generally in hours). Voltage * Amps * hours = Wh.
For example, a battery with a capacity of 1000 mAh and a voltage of 3.7 volts would have an energy storage capacity of 3.7 watt-hours (Wh). It is important to note that battery capacity is not the same as the power output of a battery.
The energy stored in a battery, called the battery capacity, is measured in either watt-hours (Wh), kilowatt-hours (kWh), or ampere-hours (Ahr). The most common measure of battery capacity is Ah, defined as the number of hours for which a battery can provide a current equal to the discharge rate at the nominal voltage of the battery.
The energy stored in a battery is calculated by multiplying the voltage of the battery by the capacity of the battery in ampere-hours. For example, a battery with a capacity of 1000 mAh and a voltage of 3.7 volts would have an energy storage capacity of 3.7 watt-hours (Wh).
Energy or Nominal Energy (Wh (for a specific C-rate)) – The “energy capacity” of the battery, the total Watt-hours available when the battery is discharged at a certain discharge current (specified as a C-rate) from 100 percent state-of-charge to the cut-off voltage.