Briefly describe the internal resistance measurement method of lithium ion battery

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According to the physical formula R = U / I, the test device allows the lithium battery to force the lithium battery to force through a large constant DC current (currently using a large current of 40A to 80A), measurement at this time. The voltage across the lithium battery and calculates the current lithium battery in the formula. 이 측정 방법은 정확도가 높고 통제됩니다.

측정 정확도 오차는 0.1% 이내로 제어할 수 있습니다. However, this method has a significant shortcomings: (1) can only measure a large-capacity lithium battery or a lithium battery, small-capacity lithium battery cannot be loaded with a large current of 40A to 80A within 2 to 3 seconds; (2) When the battery passes the large current, the electrode inside the lithium battery will cause polarization, resulting in polarized internal resistance.

Therefore, the measurement time must be very short, otherwise the measured internal resistance value is large; (3) large current passing through a lithium battery has a certain damage to the electrodes inside the lithium battery. AC pressure drop internal resistance method is actually equivalent to an active resistance because the lithium battery is actually equivalent to a fixed frequency and fixed current to the lithium battery (currently using 1 kHz frequency, 50mA small current), and then samples its voltage After rectification, filtered, the internal resistance value of the lithium battery is calculated by the op amp circuit after a series of processing, etc. The lithium battery measurement time of the AC pressure dropped internal resistance method is extremely short, generally in 100 milliseconds.

이 측정 방법의 정확도도 좋으며, 측정 정확도 오차는 일반적으로 1%~2% 사이입니다. The advantages and disadvantages of this method: (1) Use an alternating internal resistance measurement method to measure almost all lithium batteries, including small-capacity lithium batteries. Notebook lithium battery cell internal resistance is generally in this way.

(2) AC 압력강하 측정방법의 측정정확도는 리플전류에 의해 영향을 받을 가능성이 있으며, 고조파전류에 의한 간섭도 발생할 가능성이 있다. This is a test (3) measurement (3) using this method, which does not have too much damage to the lithium battery itself. (4) AC 압력강하 측정방법의 측정 정확도는 DC 방전 내부 저항 측정방법에 비해 좋지 않다.

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