Briefly describe the internal resistance measurement method of lithium ion battery

著者：Iflowpower – Dodavatel přenosných elektráren

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. Qhov tseeb ntawm txoj kev ntsuas no yog siab thiab tswj tau.

Kev ntsuas qhov tseeb yuam kev tuaj yeem tswj tau li ntawm 0.1%. 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.

Qhov tseeb ntawm txoj kev ntsuas no kuj zoo, thiab qhov kev ntsuas qhov yuam kev yog feem ntau ntawm 1% mus rau 2%. 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) Kev ntsuas qhov tseeb ntawm AC siab poob ntsuas txoj kev yuav cuam tshuam los ntawm ripple tam sim no, thiab tseem muaj peev xwm cuam tshuam nrog kev sib haum xeeb tam sim no. This is a test (3) measurement (3) using this method, which does not have too much damage to the lithium battery itself. (4) Kev ntsuas qhov tseeb ntawm AC siab poob ntsuas txoj kev tsis zoo li DC tawm hauv qhov ntsuas tsis kam.

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