Method for measuring direct current internal resistance of battery

Abstract

The invention relates to a method for measuring the direct current internal resistance of a battery. The method includes the following steps: 10, detecting that the current change value delta Delta Inof the current battery is larger than the rated current change value I0; 20, In a predetermined time T, the current and voltage of the battery are detected for w times. The average value of current change and the average value of the voltage change are calculated; 30, the DC internal resistance DCIRn of the battery is calculated by the following formula; 40, repeating the steps 10 to 30 to obtain a plurality of battery DC internal resistances DCIR1......DCIRn. Arranging the DCIR1... DCIRn according to the value size and selecting the DCIRm which is arranged in the middle as the direct current internal resistance of the current battery. By detecting the current and the voltage of the battery in a preset time T for several times, calculating the average value of each current change and theaverage value of the voltage change and further obtaining the DC internal resistance of the battery in the pre-set time T. The direct current internal resistances of a plurality of batteries are arranged in sequence according to the magnitude of values. The direct current internal resistance of the battery arranged in the middle is selected as the direct current internal resistance of the currentbattery. The method has the advantages of small error, accurate measurement and calculation efficiency and the like.

Description

technical field [0001] The invention relates to the technical field of battery internal resistance calculation, in particular to a battery DC internal resistance measurement method. Background technique [0002] The existing internal resistance test is to test the internal resistance of the AC, and judge the health status of the battery according to the internal resistance of the AC; however, each test needs to use testing equipment to measure the AC internal resistance of the battery; With the increase of the number of cycles, the change range of the AC internal resistance is not large, so it is relatively simple to judge the health status of the battery simply by the AC internal resistance. [0003] For this reason, people have invented a method of judging the state of health of the battery by obtaining the DC internal resistance of the battery, thereby further judging whether the battery pack can continue to be used. For example, Patent No. CN201110393460.1 discloses an ...

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Problems solved by technology

[0004] However, there are other defects in this patent: 1. A certain time T is taken. When the battery pack has no change in voltage and current during this period of T, then Umax=Umin, Imax=Imin. At this time, if it is also calculated according to this patent , the error is large, and its value is not correct

2. Because the load of the battery pack is dynamic, that is, Imax and Imin are changing, and Umax and Umin are also changing. At this time, using Imax-Imin alone will bring a relatively large error to the DC internal resistance of the battery pack.

[0005] R=(Umax-Umin) / (Imax-Imin)=(Umax1-Umin1) / (10-1)=(Umax-Umin) / 9, this patent is suitable for testing constant current loads; once the load is dynamic, There will be a relatively large error

3. At the same time, after obtaining the DC resistance R, the software does not process the obtained R, and the error is relatively large

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