EV Battery Pack Pressure Equalization Vent Bolt Waterproof Breathable Metal Threaded

The EV battery pack pressure equalization vent bolt is a critical safety component for electric vehicle battery enclosures. It combines a precision metal threaded body with a waterproof ePTFE membrane and an optional burst disc. During normal operation, it balances internal pressure caused by altitude changes and thermal cycling. In the event of a cell thermal runaway, the burst disc activates to safely release pressure and prevent catastrophic housing rupture. This component is validated to automotive functional safety standards.

Battery packs are sealed to protect sensitive cells from water and dust, but they must withstand extreme pressure differentials. Driving over a mountain pass or an aircraft cargo hold can create a difference of over 15 kPa. Without venting, this stress deforms the housing and fatigues sealing gaskets. More critically, a single cell failure can generate gas that rapidly increases internal pressure, potentially leading to explosion if not vented.

The metal threaded vent bolt installs directly into the battery pack lid or side wall. The ePTFE membrane provides continuous equalization, keeping the housing at ambient pressure. The burst disc is calibrated to open at a specific overpressure, directing hot gases and particulates away from the vehicle cabin. After a venting event, the membrane retains IP67 protection to prevent secondary damage from firefighting water ingress.

• Thread: M20x1.5 or custom
• Body: Anodized aluminum or stainless steel
• Membrane: ePTFE, oleophobic
• Burst pressure (optional): 30 kPa ±5
• Waterproof rating: IP67 / IP6K9K
• Airflow: 800 ml/min @ 70 mbar
• Operating temperature: -40°C to 150°C

Designed for lithium-ion battery packs in passenger EVs, electric buses, energy storage systems, and off-highway electric machinery. Can also be used in power electronics enclosures for motor inverters and DC-DC converters where pressure differentials risk housing integrity.

Under normal conditions, the ePTFE membrane allows air to pass bidirectionally, keeping pressure equal. Temperature changes and altitude variations are compensated instantly. If internal pressure rises rapidly beyond the burst disc threshold due to a fault, the disc ruptures in a controlled manner, releasing gases. The remaining membrane still filters particles and prevents water ingress after the event, helping to contain the incident.

Define the required equalization flow rate based on the pack’s internal free air volume and maximum temperature change rate. Select burst pressure based on the housing’s design strength; it must open well before the housing deforms. Consider the mounting location; if exposed to direct wheel spray, choose IP6K9K-rated bodies. Consult with the supplier for thread customization to match your existing boss design.