Why Waterproof and Airtight Testing Matters

Battery packs power EVs and boats ⇱, but if water gets inside due to a failed seal, it can cause short circuits or even thermal runaway—a dangerous overheating reaction. Testing for waterproof and airtight integrity is critical, especially for extreme scenarios like flooding or heavy rain. At Bonnen Battery, we test every pack to meet strict safety standards.

Meeting the Standards

Ensuring battery safety isn’t just good practice; it’s often mandated by strict regulations. Various standards define the requirements for enclosure protection and battery safety.

● IP Ratings ⇱: You might have heard of IP Codes (like IP67 or IP68), defined by standards like GB/T 4208-2017. These codes specify the level of protection against dust and water ingress. Higher numbers mean better protection.

● Mandatory Safety Standards ⇱: To ensure a minimum safety level for new energy vehicles, countries implement specific, compulsory standards. For example, China introduced three key standards effective January 1, 2021:

 ৹ GB 18384-2020 (Electric Vehicle Safety Requirements)

 ৹ GB 38032-2020 (Electric Bus Safety Requirements)

 ৹ GB 38031-2020 (Safety Requirements for Power Batteries in EVs)

 ৹ Global Requirements: Similar stringent safety standards exist in Europe (EU) and the United States (US), ensuring batteries meet high safety benchmarks worldwide.

Contemporary safety standards like China’s GB 38031-2020 mandate leak testing during End-of-Line (EOL) production. Our testing protocols align with:

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How Do We Test for Airtightness?

Air leak testing is the industry standard because it’s effective, non-polluting, low-cost, and easily automated. The basic idea is simple: introduce pressurized air into the sealed object and see if the pressure holds.

Here are the common methods:

Pressure Decay Method ⇱

● How it works: The empty battery casing (or sometimes the full pack) is sealed. Then, dry air or an inert gas is pumped in to reach a specific pressure (e.g., 30 kPa). The air supply is then cut off. Sensitive sensors monitor the internal pressure over a set time (e.g., 10 minutes).

● Pass/Fail: If the pressure drops very little or not at all (e.g., less than 1 kPa drop in 10 minutes), the pack is considered properly sealed. If the pressure drops significantly, it indicates a leak.

● Best for: This is a versatile method suitable for various battery pack sizes and designs, even those with complex shapes.

Bubble Observation Method ⇱ (Water Immersion)

● How it works: This is the classic “dunk test.” The battery pack is submerged in water. Sometimes, air is gently pressurized inside the pack. If you see bubbles escaping, you’ve found a leak.

● Limitations: While simple to understand, this method has major drawbacks. It’s slow, and it’s not very accurate for detecting tiny leaks that could still let in moisture over time. You rely on visually spotting bubbles, which is hard for micro-leaks. For these reasons, it’s largely been replaced by more precise methods.

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Helium Leak Detection ⇱ (Helium Mass Spectrometry)

● How it works: This is a high-precision method. First, the battery pack is filled with helium gas. Helium atoms are tiny and can seep through even microscopic holes. A highly sensitive detector (a mass spectrometer specifically tuned for helium) is then used around the outside of the pack (or the pack is placed in a vacuum chamber connected to the detector).

● Pass/Fail: If the detector picks up any helium escaping, it confirms a leak. These detectors are incredibly sensitive and can find leaks measurable in parts per million (ppm).

● Pros & Cons:

 ৹ Pro: Extremely accurate, capable of finding the smallest leaks.

 ৹ Con: Requires more expensive equipment and can be a more complex process compared to pressure decay.

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Bonnen Battery: Committed to Safety

At Bonnen Battery, we understand that the performance and longevity of your EV or e-boat ⇱ depend heavily on the quality and safety of its power source. That’s why rigorous testing, including ensuring waterproofness and airtightness, is a non-negotiable part of our manufacturing process. We adhere to strict standards to give you peace of mind on every journey.