The Challenge of Surge Protection for LiFePO4 Batteries Using Varistors

This letter examines the current-sharing behavior of a single-cell lithium iron phosphate ( ${\mathrm { LiFePO}}_{4}$ ) battery connected in parallel with a zinc-aluminum varistor, aimed at protecting against fast-front impulse currents. Through experimental data analysis and ATP-EMTP simulations, the study explores the transient behavior of the protective varistor stack and the cylindrical ${\mathrm { LiFePO}}_{4}$ battery under surge events. Key factors considered include the determination of charge transferred to both the varistor and the battery as well as the voltage across their terminals. The findings highlight the challenges associated with surge protection against fast-front transients that threaten the reliability and lifespan of modern energy storage systems, particularly in safeguarding against lightning strikes and electromagnetic pulses.