Preliminary Study on the Mechanism of Lithium Ion Battery Pack under Water Immersion

Battery pack may result in disastrous hazards if being intruded by water. However it is difficult to study on the behavior of pack under water due the complexity of this system. A supplement experiment of battery pack under water immersion was proposed. A battery charger was used to provide a simulated voltage of battery pack and connected with single cell in series. Through experiments conducted by different types of cells, electric arc under water is considered as the most probably cause of battery failure in pack under water immersion. The arc can fuse the battery poles or shells, leading to electrolyte leakage. The test results verified that the leaked electrolyte was ignited by arc and then burned on water surface. Both concentration of solution and contact area have great impacts on arc appearance. And current density is considered as the vital factor that affects the appearance of arc.