Battery shutoff valve

Equalization Shutoff Valve



In the event of a thermal runaway within an electric vehicle battery pack, occupants have limited time to escape the vehicle without exposure to harmful gas. The Equalization Shutoff Valve is designed to extend the passengers' safety escape time. 

ev battery pack with thermal runaway up close

As the world embraces the shift towards carbon neutrality, electric vehicles (EVs) have evolved as a solution to combat climate change and reduce dependence on fossil fuels. The consumer demand for these vehicles' relies heavily on advanced lithium-ion batteries. This innovation comes with essential safety measures that guarantee the reliability and integrity of large battery packs.

One of the key challenges in designing high-voltage batteries is managing the internal pressure that can build up during charging and driving. This pressure, if left unchecked, has the potential to cause an explosion or fire. Manufacturers incorporate pressure relief valves into the battery systems to address this concern. Click here to learn about Nifco's Pressure Relief Valves.

Equalization membranes, often made of specialized materials, supplement pressure relief valves by balancing the pressure levels across the whole battery pack. Maintaining consistent pressure contributes to the overall stability and efficiency of the battery, ultimately enhancing its operational lifespan and safety.

Thermal runaway is a critical concern in EV batteries, representing a dangerous series of events that demands attentive control. This circumstance occurs when a battery undergoes an uncontrollable increase in temperature, pressure, and/or energy release. It is often triggered by internal factors such as overcharging, external influences like exposure to extreme temperatures, or even physical damage to the battery.


Nifco Solutions

Once a thermal runaway has occurred, there is no going back. The occupants must immediately run away due to the hazardous gas expelled from the EV battery pack and the vehicle no longer being in driving condition. The chart shows the occupant's window of the escape from the vehicle once a thermal runaway occurs. Globally, the automotive industry's goal is to allow the occupants 5 minutes to escape the vehicle before hazardous gases flood the scene and the vehicle catches fire. The design and technology of the Equalization Shutoff Valve allow OEMs to give occupants at least 5 minutes to remove themselves from the scene safely.

Thermal runaway chart showing time and flame spread

The purpose of the Equalization Shutoff Valve is to give OEMs control of the direction in which the hazardous gases are released, for the safety of vehicle occupants escaping the vehicle and first responders. The Equalization Shutoff Valve is mechanically activated when a thermal runaway occurs in an electric car. It prevents harmful gases from being released through the battery pack's membranes, ensuring the gases are only expelled from the pressure relief valve.

In layman's terms, the Equalization Shutoff Valve product is a high-function equalization membrane used for EV, PHEV, and hybrid batteries.  The small packaging space design with high-flow membranes results in using one Equalization Shutoff Valve to replace multiple membranes. When thermal runaway happens, membranes are shut off, and gases are only released through the pressure relief valve.

Nifco Equalization shutoff valve
design elements of the the equalization shutoff valve

Contact us to create a custom model to fit your hybrid or fully electric vehicle. 

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