There are several methods and devices that can be used to test a battery's capacity. The easiest and most common way to test a battery’s capacity is to measure its voltage and current under load. Once the battery is fully charged first, a load is placed on the battery and then the voltage and current of the battery is measured.
Allow the battery to rest: Before measuring the OCV, let the battery rest for a specified period (typically 1-2 hours) to minimize the effects of voltage fluctuations due to load changes. Measure the open-circuit voltage: Use a digital multimeter or another accurate voltage measurement device to measure the battery’s OCV.
It is measured in ampere-hours (Ah) or milliampere-hours (mAh). When examining the battery with a multimeter, one of the key measurements to check is its voltage. Voltage represents the electrical potential difference between the positive and negative terminals of the battery.
If you are needing to test higher capacity or higher voltage batteries you can use the tester below. This capacity tester can test a battery that is up to 200V. It is also a 2-wire tester so it will be more accurate. You can test batteries with a voltage range of 2~200V @ a current of 0.2~20A this is limited to 180W.
A multimeter can be used to measure the voltage of a battery, which can provide an estimate of its remaining capacity. However, this method is not as accurate as a full charge and discharge cycle. To use a multimeter, set it to measure DC voltage and connect the positive and negative leads to the corresponding terminals of the battery.
The voltage setting may differ depending on the type of battery you are testing. For example, if you are testing a car battery, set the multimeter to the range that covers 12 volts. If you are unsure, consult the battery manufacturer’s specifications or user manual.