Calculation Of Capacity

Calculation Of Capacity

Date:Apr 06, 2021

The battery capacity is usually expressed in amperes and hours (abbreviated as AH, 1A.h=36000C). The calculation formula for battery capacity C is C=I∫t0tdt. The battery capacity is divided into actual capacity, theoretical capacity and rated according to different conditions. capacity. The minimum capacity provided for discharge at a certain discharge rate at 25°C to the final voltage is the battery capacity specified during design and production, which is called the rated capacity of a certain discharge rate RH.

The battery capacity is generally calculated by AH (ampere hour), and the other is calculated by CELL (unit plate) several watts (W). (W/CELL)

1. AH (Ampere Hour) calculation, the definition is based on 20 hours as the standard. For example, a 7AH battery refers to a continuous discharge current of 0.35A and a continuous time of 20 hours.

2. W (W (power consumption) / CELL (unit plate)) calculation, the definition is based on 15 minutes as the standard. For example, the 1221W battery is 12V (6 CELL), and each CELL can supply 21W power for 15 minutes.

3. The charging time is 10 hours as the standard, and the charging current is 1/10 of the battery capacity. Fast charging will reduce the battery life. The battery capacity refers to the amount of power stored in the battery. The unit of battery capacity is "mAh", and the Chinese name is milliampere-hour (when measuring large-capacity batteries such as lead storage batteries, for convenience, it is generally expressed as "Ah", and the Chinese name is Ah, 1Ah=1000mAh).

If the rated capacity of the battery is 1300mAh, if the battery is discharged with a current of 0.1C (C is the battery capacity), that is, 130mA, then the battery can work continuously for 10 hours (1300mAh/130mA=10h); if the discharge current is 1300mA, then power supply The time is only about 1 hour (the actual working time is somewhat different due to individual differences in the actual capacity of the battery). This is an analysis in an ideal state. The current of a digital device in actual work cannot always be constant at a certain value (take a digital camera as an example, the working current will be larger due to the opening or closing of the LCD display, flashlight and other components. Therefore, the battery can only provide an approximate value for the power supply time of a certain device, and this value can only be estimated through actual operating experience.


The discharge capacity of a battery refers to the amount of power output by the battery within the allowable range of discharge.

Capacity = discharge current × discharge time

The capacity of a battery is related to the size of the discharge current and the temperature of the electrolyte. Therefore, the nominal capacity is obtained at a certain discharge current, a certain end voltage and a certain electrolyte temperature. There are two types of standard capacity.

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