18650 Battery Capacity Testing Method.
The most accurate and safe method to test the capacity of 18650 lithium-ion batteries is to use a specialized battery capacity tester/analyzer. Although manual testing is feasible, it is complex to operate, has low accuracy, and carries certain risks.
Here are several detection methods, sorted from recommended to not recommended:
Method 1: Use a professional battery capacity tester/analyzer (the most recommended, accurate, and safe)
This is the best method for measuring battery capacity. This type of device can automatically complete charging, discharging, and capacity calculation.
Prepare tools:
Intelligent battery charger/tester: such as Opus BT-C3100, LiitoKala Lii-500/Lii-600, SkyRC MC3000, etc. Ensure to select models that support capacity testing functionality.
18650 battery to be tested.
Operation steps:
Check the appearance of the battery: Ensure that there are no physical damages such as bulges, leaks, or damage to the battery. The contact points are clean.
Place the battery into the tester: pay attention to the correct direction of the positive and negative poles.
Select testing mode: Select "Capacity Test" or similar mode on the tester (usually "Test", "Capacity Test", "NOR Test", etc. in English).
The NOR Test mode is usually a standard process: first fully charge the battery ->discharge it to the cut-off voltage with the set current, record the discharge capacity ->finally fully charge the battery. The displayed capacity is measured during the discharge process.
Set discharge current: Testers usually allow you to set the discharge current.
Standard test current: It is usually recommended to use 0.2C (C represents the nominal capacity of the battery). For example, a 2500mAh battery, 0.2C is 500mA.
Common test current: For convenience, 500mA or 1000mA (1A) is commonly used as the test current. Note that the larger the discharge current used, the slightly lower the measured capacity is usually due to the more significant voltage drop caused by internal resistance.
Start testing: Start the testing program, and the tester will automatically perform the complete process of charging, discharging, and recharging.
Waiting for results: This process takes a long time, depending on the battery capacity and the set discharge/charging current (which may take several hours or even tens of hours).
Read capacity: After the test is completed, the tester screen will directly display the measured battery capacity, usually in mAh (milliampere hour) units.
