AH is a measure of how much current a battery can discharge over a certain period. It’s the ratio between current (A) and time – hour (H). For example a 100AH battery means the battery can discharge a current of 5 amps over a period of 20 hours. It can also mean the battery can discharge a current of 10 Amps over 10 hours. However the capacity of a battery that discharges 5 amps over 20 hours is less than that of a battery that discharges 10 amps over 10 hours, even though both are arithmetically 100AH. This is because higher the current discharge, the more the energy loss and hence lower the time it can discharge.
That’s why it’s important to understand the standard of discharge to ensure accurate understanding of the rating. The industry standard is ’20 hours’. Therefore the rating of any battery means the quantum of current the battery can discharge over a period of 20 hours. A few examples are given below for understanding.
A 7AH battery means it can discharge 0.35 amps for a period of 20 hours
A 26AH battery means it can discharge 1.3 amps for a period of 20 hours