How to determine the battery capacity? Relationship between W and AH

Battery capacity refers to the amount of electricity that a battery can provide under specified conditions. The unit of battery capacity is Ah (ampere hour).

W is the power of the battery, and the unit is W (watt).

The relationship between W and AH can be calculated by the following formula:

W = I * V

Where:

• W: Battery power (W)

• I: Battery discharge current (A)

• V: Battery voltage (V)

In practical applications, the capacity of a battery is usually marked in units of AH. However, the capacity of some batteries may also be marked in units of W.

If the battery capacity is marked in units of W, it can be converted to AH by the following formula:

AH = W / (I * V)

Example:

For example, the capacity of a battery is marked as 17W, its discharge current is 2C, and the voltage is 12V. Then the AH capacity of the battery is:

AH = 17 / (2 * 12) = 0.708Ah

Note:

• The above formula is only applicable for constant current discharge.

• In practical applications, the battery capacity may be affected by factors such as temperature and discharge current.