In actual use, due to regional environment, old age, overcharge, overdischarge, high temperature cycle and other factors, the inconsistency between single cells will become more and more obvious, resulting in low battery efficiency and service life. Shortening, even there are safety hazards such as explosion and combustion. Compared with battery life anxiety, the safety anxiety of pure electric vehicles is a topic that users pay more attention to. Some data show that 80% of the spontaneous combustion accidents of new energy vehicles occur during charging or within 1 hour after being fully charged.