This EPTFE acoustic vent membrane is designed for the buzzer speaker inside electric vehicle charging ports, which provides audible feedback for charge status, lock confirmation, and error alerts. The charging port is exposed to rain, snow, and dust whenever the charge door is open, and condensation can occur due to temperature differences during high-power fast charging. The vent completely seals the buzzer opening against these elements while allowing a clear, penetrating tone to be heard by the user even in noisy public charging stations. The material’s excellent dielectric properties prevent any interference with the high-voltage pins nearby. It withstands the rapid temperature swings from cold winter nights to the heat generated during 350 kW DC fast charging without changing its acoustic characteristics. The membrane also meets UL94 V-0 flammability requirements for components adjacent to high-voltage circuits.

Charging port buzzers that fail due to moisture ingress leave users unsure of their charge status, potentially leading to dangerous driving away with a connected cable or unnecessary service calls. This EPTFE vent provides a permanent waterproof seal that maintains the buzzer’s audibility over years of use in all weather. It enables EV manufacturers to offer a reliable charging experience, reducing customer complaints related to silent or erratic buzzer operation.

EV AC and DC charging port buzzer, hydrogen refueling station indicator speaker, charging status alert speaker on public charge points.

The buzzer’s piezo element generates sound that travels through the EPTFE membrane’s open pores. Liquid water encountering the membrane is blocked by surface tension. Because the charging port may experience temperature shocks (e.g., -10°C ambient to +60°C during fast charging), the membrane’s high MVTR also allows internal humidity to escape, preventing condensation on the buzzer element itself.