Detection Method for Soft Internal Short Circuit in Lithium-Ion Battery Pack by Extracting Open Circuit Voltage of Faulted Cell

Abstract

Early detection of internal short circuit which is main cause of thermal runaway in a lithium-ion battery is necessary to ensure battery safety for users. As a promising fault index, internal short circuit resistance can directly represent degree of the fault because it describes self-discharge phenomenon caused by the internal short circuit clearly. However, when voltages of individual cells in a lithium-ion battery pack are not provided, the effect of internal short circuit in the battery pack is not readily observed in whole terminal voltage of the pack, leading to difficulty in estimating accurate internal short circuit resistance. In this paper, estimating the resistance with the whole terminal voltages and the load currents of the pack, a detection method for the soft internal short circuit in the pack is proposed. Open circuit voltage of a faulted cell in the pack is extracted to reflect the self-discharge phenomenon obviously; this process yields accurate estimates of the resistance. The proposed method is verified with various soft short conditions in both simulations and experiments. The error of estimated resistance does not exceed 31.2% in the experiment, thereby enabling the battery management system to detect the internal short circuit early.

Ventilation System Influence on Hydrogen Explosion Hazards in Industrial Lead-Acid Battery Rooms

“…The simulation results are shown in Table 5. It can be noticed that, although all analysed ventilation systems fulfil requirements of standard BS EN 62485-2014 [2], their effectiveness is markedly different. The simulations results presented in Table 5 show that each ventilation system gives a different hydrogen removal effectiveness.…”

“…As a model for analysis, a battery room with a total volume of 20 m 3 was assumed, in which 20 open lead batteries with a capacity of 2100 Ah each were powered. The calculations were based on the requirements outlined in the standard; BS EN 62485-2014 [2].…”

“…As a first step of calculation, hydrogen emission from the batteries was estimated as 9.7 × 10 −5 m 3 /s [2].…”

“…Based on standard BS EN 62485-2014 requirements of [2], the volume of mechanical air extraction was received as 42.3 m 3 /h and area of opening for natural ventilation of 0.12 m 2 . Because the standard does not give accurate design recommendations, different ventilation systems were compared on the base of CFD simulations results.…”

“…Electric batteries are used more and more often for electric vehicles, and an energy storage system used for industrial grids [1][2][3][4][5].…”