Method for calculating DC internal resistance of lithium ion batteries in same batch

Abstract

The invention discloses a method for calculating the DC internal resistance of lithium ion batteries in the same batch, and the method comprises the steps: carrying out the cycle test on a sampled battery at a set temperature, building a Uaveage-DCIR linear relation between the average voltage difference Uaveage of each cycle and the DC internal resistance value DCIR measured by each set cycle number in the cycle process, and obtaining a linear formula DCIR = x * Uaveage + k; and then substituting the average voltage difference calculated by a certain lithium ion battery in the same batch under the set number of circulation turns into the linear formula DCIR = x * Uaverage + k to obtain a calculated value of the DC internal resistance DCIR under the set number of circulation turns. According to the method, the damage to the lithium ion batteries caused by repeated pulse current discharge tests is avoided, the test time cost of the same batch of lithium ion batteries is reduced, the deviation between the calculated DCIR value and the actually measured DCIR value is very small, and the accuracy is high.

Description

technical field [0001] The invention relates to the field of lithium battery testing, in particular to a method for calculating the DC internal resistance of the same batch of lithium ion batteries. Background technique [0002] Lithium-ion batteries have been widely used in industries such as consumer electronics, electric tools and electric vehicles, and have the advantages of high working voltage, high energy density, long cycle life, high power and environmental protection. With the cycle and aging of lithium-ion batteries, the internal resistance of lithium-ion batteries continues to increase, so how to quickly detect the DC internal resistance of lithium-ion batteries becomes very important. In the DC internal resistance test, in order to distinguish the ohmic internal resistance and activation internal resistance of the lithium-ion battery, the lithium-ion battery will be discharged with a larger pulse current after a certain number of cycles. Ion batteries will caus...

AI Technical Summary

Problems solved by technology

In the DC internal resistance test, in order to distinguish the ohmic internal resistance and activation internal resistance of the lithium-ion battery, the lithium-ion battery will be discharged with a larger pulse current after a certain number of cycles. Ion batteries will cause certain damage; at the same time, the process of adjusting the SOC before the test is also time-consuming, which prolongs the test time within the set number of cycles

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