When a hybrid battery malfunctions, there are usually several obvious signs, including a significant drop in pure electric driving range, abnormally prolonged charging time, and a sharp rise in battery temperature during charging. If the charging gun interface becomes hot during fast charging or the Battery Management System (BMS) triggers frequent alarms, it may indicate the risk of an internal short circuit, and charging should be stopped immediately for inspection and repair. In addition, when the battery health drops below 80%, its performance will decline significantly, manifesting as reduced power output and increased fuel consumption (the fuel consumption of some plug-in hybrid models may rise by 30%-50% after battery failure). For hybrid electric vehicles (HEVs), complete battery failure may prevent the vehicle from starting, while plug-in hybrid electric vehicles (PHEVs) can switch to fuel mode for driving, but with sluggish power response and a potential 15%-20% increase in braking distance. It is best to regularly monitor battery health through the vehicle's system, avoid maintaining a charge level below 20% or above 80% for extended periods, and conduct professional testing every two years to mitigate thermal runaway risks. For instance, a range-extended electric vehicle (REEV) will lose all propulsion after battery failure, whereas a 48V mild hybrid system only affects the start-stop function, with fuel consumption increasing by approximately 10%.
