The total, (or gross) capacity of a battery pack is the amount of energy it can store when it's fully charged to 100% The usable capacity is how much energy the user is allowed to access.
For instance, consider a battery with a capacity of 50 kWh. If it's charged at a 1C rate, it's charged at a rate that fills the battery's full capacity in one hour, so 50 kW. Charging at a higher rate, like 2C, would mean it charges in half the time, i.e., 30 minutes, with a power output of 100 kW.
The fully charged battery is discharged at a controlled rate, often specified by the manufacturer, to measure how long it provides a designated amount of power. During the discharge process, the total energy output reflects the battery's capacity in ampere-hours (Ah) or milliampere-hours (mAh).
Battery capacity is determined through a series of tests and measurements. These are the key steps: The fully charged battery is discharged at a controlled rate, often specified by the manufacturer, to measure how long it provides a designated amount of power.
A typical car battery operates at 12 volts and has a capacity of around 48 amp hours. This capacity allows it to deliver 1 amp for 48 hours or 2 amps for 24 hours when fully charged. Knowing the voltage and amp hour rating helps assess the battery's power delivery and performance in a vehicle. To understand total power, you can calculate wattage.
The rate is dependent on the amount of current being transferred by the battery as the voltage is usually constant. So scientifically it is denoted as only Ah. For example, the Mahindra e20 has 10kWh energy stored in the battery. It can deliver approx. 208 Ampere current for one hour, at a rated voltage of 48V. How battery capacity affects range?
How many times can a battery be charged & discharged?
Each time a battery is charged and discharged, it undergoes a cycle. Over time, the battery's capacity will decrease until it reaches the end of its useful life. The Anker SOLIX F1200 is rated for 3000 charging cycles, which means it can be fully charged and discharged 3000 times before its capacity starts to degrade.