Lithium-ion battery packs, which are becoming more common in electric vehicles, energy-storage, network back-up devices, and other industrial applications, can become overpressured if gas accumulates inside. This can be dangerous and risks damaging equipment. To prevent such overpressurizations, engineers at Freudenberg Sealing Technologies in Wienheim, Germany, developed a simple pressure-control valve which is now offered at Freudenberg-NOK Sealing Technologies, Plymouth, Mich.
The lightweight valve uses an engineered EPDM seal, which opens when pressure inside the battery pack exceeds a specific limit, but there is no loose hardware during such releases because the valve is permanently tethered to the battery pack. The valve must be manually replaced to reseal the battery pack. The valve can also be manually opened, which can be handy when shipping battery packs by air. Otherwise, pressure changes during ascents and descents could damage the battery housing. And if a battery fails and causes overpressurization, the valve can be reset to protect interior components during transport to a recycling center.
The overpressure valve is not adjustable. Its fixed pressure release/open point is designed into the geometry of the valve. However, valves can be developed to meet customer-specific requirements.
The EPDM seal resists leaking and swelling and withstands temperatures from –40 to 80°C. Users can add components which will add protection against impacts from stones and other road debris or let it survive industrial cleanings.