Sensor technology throughout the battery pack is key to maintaining the battery in the short and long term. Sensor technology allows the thermal management system in an EV to start working as soon as it registers a temperature outside of the comfort zone range. Temperatures that are too hot or too cold can have a similar effect on EV batteries and their health. Excessive temperatures can affect EVs in a number of ways, including: 1. Reduced charge capacity 2. Reduced range 3. Reduced charge retention 4. Reduced battery life.

While the BMS continuously monitors the voltage and current to and from the battery pack, it also controls systems external to the battery pack to manage temperature, e.g., refrigerant, coolant circuits. To manage these systems, the BMS uses coolant, temperature sensors inside and outside the battery pack cooling panels, as well as cell and bus temperatures inside the battery pack. This also extends to monitoring coolant temperatures in the external heat exchanger, as well as pressure and temperature at key points in the expansion valve and refrigerant circuits. This high level of sensor monitoring provides critical data to control the precise amount of heating and cooling from these systems to optimize battery pack performance while minimizing parasitic energy losses from operating pumps, compressors, and auxiliary heating and cooling components.

Preventing Thermal Runaway | Electric Vehicle Detection and Mitigation

"Although rare, thermal runaway of lithium-ion batteries can lead to damage to the vehicle battery pack and the vehicle itself, and cause serious injury to any occupants." Once considered a barrier to the mass market entry of alternative energy vehicles, thermal management - or more specifically, preventing thermal runaway - of lithium-ion battery packs remains a critical component of the long-term viability of electric vehicles.

What does thermal runaway look like in electric vehicles?

Typically triggered by a short circuit, overcharge, or other source of battery stress, thermal runaway occurs when a lithium-ion battery overheats and its cells disintegrate. The excess heat triggers an uncontrolled chain reaction that spreads to the rest of the EV battery pack. When runaway occurs and the battery cell fails, runaway can result in the release of flammable gases such as: hydrogen, volatile hydrocarbons, carbon monoxide. Other harmful gases released during thermal runaway include: hydrogen fluoride, carbon dioxide, dimethyl carbonate, and acetonitrile. Once thermal runaway begins, it is difficult to stop because its chain reaction cascades through the battery pack, often leading to smoke and fire. With rapid intervention, we can limit the impact of thermal runaway on the battery pack and the rest of the vehicle. While many of the materials used in battery packs are designed to reduce the risk of fire spread, once the battery has vented gas, a hazardous situation exists within the pack that must be identified and addressed to prevent the risk of fire.

电动汽车的热失控预防需要三管齐下的方法：

1. 从一开始就防止失控出

2. 识别电池内是否或何时发生热失控

3. 阻止失控扩散到电池组的其他部分

无论如何，通过两种方法阻止电池热事件发生——主动和被动热管理系统：主动热管理，依赖于将电池组保持在最佳温度的冷却系统。当电池在充电和放电的过程中开始升温时，主动热管理系统会使用空气货带有传统汽车冷却剂货制冷剂的冷却板从电池中提取热量，以降低温度。被动热管理，系统侧重于防止热失控的后期阶段。被动系统（隔热罩或隔热材料）不是让受热的电池保持凉爽，而是阻止过多的热量从单个的电池传递到电池组其余部分并继续进行连锁反应。