What is a battery discharge test?

Among all the tests, the discharge test (also known as load test or capacity test) is the only test that can accurately measure the true capacity of a battery system and in turn determine the state of health of batteries.

What is a discharge test for a lead acid battery?

A discharge test carried out immediately after installation or commissioning of the string is called an acceptance test. For lead acid batteries, the measured percent capacity must be at least 90% of the rated capacity for the battery to pass the test. The results obtained from this test can be used as the baseline for future measurements.

Can a battery pause be counted in a discharge test?

Only one pause is allowed for the duration of the test and the pause time should not be counted in the total discharge time2. Once the test is completed, determine the battery capacity. The test equipment can then be disconnected. While performing the discharge test, one should be prepared to bypass weak cells approaching polarity reversal.

Do you need a battery discharge test?

Although the discharge test is a true test of the battery and provides valuable information, people are generally reluctant to do discharge testing, primarily because it is labor-intensive and time-consuming. It is also one of those tests that needs to be done right the first time on that day.

How does a battery discharge curve work?

Current is drawn from the battery in a controlled manner, and the battery discharge is monitored. As the test progresses, the battery voltage begins to gradually drop down to its end voltage. The time taken for the battery to reach the end voltage is used to determine the capacity of the battery. Figure 1 shows a typical battery discharge curve.

What is a battery capacity test?

Although many tests can be performed to assess the condition of the batteries such as ohmic testing, specific gravity, state of charge etc., only the capacity test, commonly referred to as the discharge or load test, can measure the true capacity of the battery system and in turn determine the state of heath of the batteries.