A 100Ah battery is NOT equivalent to another 100Ah battery
A 100Ah battery is NOT equivalent to another 100Ah battery.
In fact, two batteries with the same Ah label can differ in discharge performance by up to 50%. How is this possible?
The Ah label of a battery, or its ampacity, is measured at a specific discharge rate. An Ah must always be accompanied by the number of discharge hours, which is usually 10 or 20 hours and is indicated as C10 or C20.
This means that when comparing batteries by Ah, we should always mention whether it's C10, C20, or C100 rate. These energy storage rates are helpful when comparing for longer discharge applications performance, such as central energy backup systems or solar backup systems.
In faster discharge applications, such as ups systems, where the required backup energy is typically in the 15-30 minute range, is where the performance differences become significant and these Ah labeling and data becomes even less relevant. Some batteries are designed to perform well in long discharge times but lose a lot of their stored energy in short discharge applications.
So what can we do in this case?
We should always refer to the power discharge tables of a battery. Compare the discharge rate, typically given in W/cell at 3 FIXED parameters
1) Discharge Period (Minutes)
2) Discharge Temperature (C)
3) Cell End Volt (V)
This would be the correct way to compare batteries for the amount of energy they can provide at faster discharge times.