How do you test the capacity of 18650 lithium battery?

Professional battery compartment

If it is an individual, find an adjustable load resistor and a current-adjustable DC power supply to calculate the battery capacity by charging and discharging time.

Charging current × charging time = battery capacity (charging from 2.7V or 3.0V to 4.2V)

or

Discharge current × discharge time = battery capacity (discharge from 4.2V to 2.7V or 3.0V)

The battery's no-load voltage was measured using a BAV-1 voltage tester.

2

Add a 15Ω resistive load to the BAV-1 voltage tester and operate at 5S to read the load voltage of the battery.

3

After one day of storage, the battery was discharged using a Xinwei battery discharge tester to detect the battery capacity. For 3.0V and 3.6V disposable lithium-ion batteries, the discharge current is set to 30mA, the cut-off voltage is 2V, and the middle is uninterrupted.

Xinwei battery discharge meter is set before discharge, as shown below

Lithium battery voltage and capacity detection

4

After the discharge is completed, click the right mouse button and click "Open Data". In the pop-up dialog box, click "File" - "Save As" to save the discharge data with the discharge graph.

Lithium battery voltage and capacity detection

The capacity of the battery cannot be measured with a multi-meter.

Explanation: Measure the short-circuit current (if the current value is within the range allowed by the universal meter and the battery), and only compare the power of the same type of battery. Different models are not comparable, because the standard internal resistance of different types of batteries is different, even if the memory is the same, the short-circuit current is not the same.

In addition, the multi-meter is also called a multiplex table, a multi-meter, a three-meter, a multi-purpose meter, etc. It is an indispensable measuring instrument for power electronics and the like, and generally has the main purpose of measuring voltage, current and resistance. The multi-meter is divided into a pointer multi-meter and a digital multi-meter according to the display mode. It is a multi-functional, multi-range measuring instrument. The general multi-meter can measure DC current, DC voltage, AC current, AC voltage, resistance and audio level, etc. Some can also measure AC current, inductance and some parameters of semiconductor (such as β) and so on.

It is not possible to have a multi-meter. You must have a cross-flow load. For example, if you want to know the actual capacity of a 20Ah battery, you should discharge it at 1C (20A) for 1 hour. It can be discharged for 1 hour. But remember that the smaller the discharge current, the larger the capacity that is released. All power batteries are marked with 1C as the standard discharge.

1. Taobao search "Lithium battery capacity test", the board of thirty or forty can be easily detected!

2. First fill to 4.2V, then the electronic load constant current discharge to 3V, the current is set to 0.5A (approximate value), record the discharge duration, put two hours is 1Ah, and so on analogy!

Battery capacity is generally expressed in mAh, 1mAh means: 1 mA current discharge for 1 hour

2

The total battery capacity is indicated by C

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Step / method

Fully charge the battery, the voltage of a single lithium battery after charging is 4.2V;

Use a multi-meter to make the battery constant current (0.5C, relative to the battery capacity) discharge, the termination voltage is set to 3v;

Multiplying the time of the constant current discharge by the discharge current is the battery capacity;

Inspection: If the constant current discharge cannot reach two hours, then the nominal voltage is not enough. The battery has the possibility of counterfeiting.

END

Precautions

The capacity test is based on the full voltage and the set termination voltage. Because the minimum discharge voltage of the lithium battery is 2.75V, the voltage less than 3V has no meaning for the lithium battery test.

Fixed current discharge is generally expressed by how many C, and lithium batteries are generally tested with 0.5C discharge.