Since batteries are the most costly part of EVs, leak testing throughout EV manufacturing is necessary to assure battery performance and safety.
The Traction Battery
Just as the combustion engine is the powerhouse of classic automobiles, the traction battery can be considered the same for electric vehicles (EVs). The electrolyte-filled battery cell is the smallest manufacturing unit in the traction battery. Three types of battery cells are frequently used in the industry that includes the round cells, prismatic cells, and pouch cells.
The individual cells are grouped into battery modules which are combined to form battery packs. The battery packs are jointly placed in a single housing at the end of the manufacturing process. Leak testing is important at every stage of the process.
Leak Testing throughout EV manufacturing
Below are the steps involved in battery installation in electric vehicles and the corresponding leak testing steps needed for each step.
Test methods for battery cells
To ensure an extended service life, very low leak rates must be maintained. This level of low leak rate allowance is possible with precise leak testing techniques like vacuum leak testing, burst leak testing, and accumulation chamber leaking testing.
Leak tightness of battery modules and packs and housings
Usually, battery modules and battery packs are cooled using a water-glycol mixture or refrigerant from the AC system of the vehicle. If there isn’t sufficient leak proofing, the cooling medium can leak and cause short circuits. Because battery packs housings, protect the battery cells and models, the housings must meet the IP 67 and IP-69K ingress protection standards.
Leak testing cooling components
The service life and operational safety of an EV battery depend on reliable cooling because batteries heat up during charging or driving mode. Modern batteries use passive air cooling and active liquid cooling using refrigerants. The refrigerant is routed in a cooling circuit around the cells to remove maximum heat from the circuit. If leaks are present, refrigerants can leak in the cells, causing short circuits.
Electric drive motor
The electric drive motors used in EVs also must be leak proof because they are frequently exposed to rainwater or water jets during cleaning. Leak testing ensures that neither water enters the motor from the outside nor the water inside the cooling jacket escapes into the motor. The motor housings are tested in accordance with the IP 67 and IP 69 standards.
In addition, modern electric motors are using a water-glycol mixture for active water cooling that ensures the optimum motor temperature. The cooling jacket must be leak tested to avoid water penetration into the electrical components of the engine. Similarly, a loss of coolant can occur if it seeps out of the cooling circuit.
To find out how Zaxis can help you leak test your EV batteries, contact us.