Simple Explanation Of Lead Acid Battery Capacity

Lead-acid battery capacity is often specified with reference to the hour rate discharge, typically measured in ampere-hours (Ah). This rating indicates how long a battery can deliver a specific current before reaching its endpoint voltage. The hour rate discharge is essential for estimating how long a battery can power a device or system under different load conditions.

For example, if you have a lead-acid battery with a capacity rating of 100Ah at the 20-hour rate discharge, it means that the battery can provide a continuous current of 5 amperes (100Ah divided by 20 hours) for 20 hours before its voltage drops to a specified endpoint, often around 1.75 volts per cell for automotive batteries.

Here's why the hour rate discharge is important:

Real-world Application: Many devices and systems have different power requirements, and the hour rate discharge helps users estimate how long a lead-acid battery will last in a specific application. For example, if a device draws 10 amperes, you can estimate that the 100Ah battery will last approximately 10 hours (100Ah divided by 10A) under that load.

Comparative Analysis: Battery specifications can be compared more easily when rated at the same hour rate discharge. This allows consumers and engineers to make informed decisions when selecting a battery for their needs. Comparing batteries with different hour rate discharge ratings would be like comparing apples to oranges.

Battery Life Estimation: The hour rate discharge also plays a role in estimating battery life. Frequent deep discharges or operating the battery at higher currents than its rating can lead to reduced capacity over time. So, understanding the hour rate discharge helps users use and maintain the battery properly to maximize its lifespan.

In summary, lead-acid battery capacity, expressed in ampere-hours (Ah) at a specific hour rate discharge, indicates how long the battery can deliver a specific current before reaching its endpoint voltage. This information is crucial for choosing the right battery for an application, estimating runtime, and ensuring proper battery maintenance for long-term use.