Large-capacity temperature points monitoring of lithium-ion battery pack via ultra-weak fiber Bragg grating array

•Large-capacity temperature monitoring method based on ultra-weak fiber Bragg grating array.•Real-time temperature changes at different locations on the battery are monitored and analyzed.•The optimal temperature monitoring positions of lithium-ion battery are the electrodes.•The fixed arrangement method of ultra-weak fiber Bragg grating sensor is given. Accurate and comprehensive temperature monitoring is essential for the safe operation of lithium-ion batteries. To solve the problem of insufficient temperature monitoring and the lack of guidance on the optimal temperature monitoring location in energy storage power stations, a large-capacity temperature monitoring method based on ultra-weak fiber Bragg grating (UWFBG) array is established in this paper. The effectiveness of the method is verified by monitoring the temperature of six surfaces and two electrodes of each cell in a battery pack composed of six cells in series. The experimental results show that the temperature difference between the batteries can reach 4 °C under normal conditions, and the temperature of the electrode can even rise sharply at a rate of 32.5 °C/min under fault conditions. Further analysis shows that the two electrodes of the battery are the primary core positions for temperature points monitoring, followed by the adjacent surfaces between the cells.