How to test the capacity of lithium battery 18650
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2023/05/24 11:25:02
There are professional battery compartments
If you're an individual, find an adjustable load resistor and a DC power source with an adjustable current to calculate battery capacity by charging and discharging time,
Charging current x charging time = battery capacity (from 2.7V or 3.0V charging to 4.2V)
or
Discharge current x discharge time = battery capacity (from 4.2V discharge to 2.7V or 3.0V)
The no-load voltage of battery was measured by using V-1 voltage tester.
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Add 15Ω resistance load to the V-1 voltage tester and work for 5S to read the load voltage of the battery.
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After a day of placement, the battery was discharged by Xinwei battery discharge tester to test the battery capacity. For 3.0V and 3.6V disposable lithium-ion batteries, set the discharge current to 30mA and cut-off voltage to 2V without interruption in between.
Xinwei battery discharge instrument before discharge Settings, as shown in the following figure
Lithium battery voltage and capacity detection
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After discharge is completed, click the right mouse button, click "Open data", click "File" - "Save as" in the pop-up dialog box, you can save the discharge data with the discharge graph.
Lithium battery voltage and capacity detection
The capacity of the battery cannot be measured with a multimeter.
Explanation: To measure the short-circuit current (if the current value is within the range allowed by the multimeter and the battery), you can only compare the power of the same type of battery. Different models cannot be compared, because the standard internal resistance of different models of batteries is different, even if the memory power is the same, its short circuit current is different.
In addition, the multimeter is also known as the multimeter, multi-purpose meter, three-purpose meter, complex meter, etc., is an indispensable measuring instrument in power electronics and other departments, generally to measure voltage, current and resistance as the main purpose. Multimeters are divided into pointer multimeters and digital multimeters according to the display mode. Is a kind of multifunctional, multi-range measuring instrument, general multimeter can measure DC current, DC voltage, AC current, AC voltage, resistance and audio electrical equality, some can also measure AC current, inductance and some parameters of the semiconductor (such as beta).
Light is not a multimeter, there must be a cross-flow load, such as you want to know how much of a 20Ah battery actual capacity, it is necessary to power down at 1C (20A) current for 1 hour, can be released 1 hour that qualified, can not explain the capacity is not enough. But keep in mind that the lower the discharge current, the greater the discharge capacity. Marked power battery all with 1C as the standard discharge.
1 Taobao search "lithium battery capacity test", 30 or 40 boards can be measured easily!
2 first full to 4.2V, and then the electronic load constant exile to 3V, current set to 0.5A (approximate value), write down the discharge time, put two hours is 1Ah, and so on capacity!
Battery capacity is generally expressed in mAh mah, 1mAh means: 1 mah current discharge for 1 hour
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The total capacity of the battery is represented by C
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Steps/methods
When the battery is fully charged, the voltage of a single lithium battery is 4.2V;
Use a multimeter to discharge the battery at a constant current (0.5C, relative to the capacity of the battery), and set the termination voltage to 3v;
Take the constant discharge time times the discharge current to get the battery capacity;
Test: If the constant current cannot reach two hours, then the nominal voltage is insufficient. Batteries have the possibility of counterfeiting.
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Matters needing attention
Capacity test is based on the full voltage and the set termination voltage as parameters, because the lowest discharge voltage of lithium battery is 2.75V, so the voltage less than 3V has no significance for lithium battery test;
The fixed current discharge is generally expressed by how much C, and the lithium battery is generally tested by 0.5C discharge.
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