UN 38.3 Test Summary Requirements for Lithium Battery Shipping
UN 38.3 test summaries supply ten mandatory technical data points verifying cell safety across global freight networks under international shipping laws.
Overcharge T7
Meaning
Electrical stress evaluations determine the safety margin of a cell when subjected to a charging current that exceeds its rated capacity. The overcharge t7 test is a mandatory part of the un 38.3 protocol for rechargeable lithium ion batteries. It ensures that the battery can handle a failure in the charging circuit without causing a fire or a violent rupture.
Current Stress
Test conditions require the application of a current that is twice the manufacturer’s recommended maximum for a set period. During the overcharge t7 procedure, the battery management system is often disabled to simulate a worst case failure scenario. The battery must withstand this treatment for 24 hours without exhibiting any sign of leakage or disassembly.
Thermal Runaway
Excessive voltage leads to the decomposition of the electrolyte and the release of heat and gas inside the cell. If a battery passes the overcharge t7, it demonstrates that its internal safety features like current interrupt devices are functioning correctly. These components are designed to break the electrical circuit before the temperature reaches a critical level.
Monitoring the internal pressure and temperature is essential for understanding the safety limit of the cell. Engineers use these results to set the parameters for the battery protection electronics.
Compliance Limit
Safety certification is only granted if the battery remains physically intact and does not ignite during the test or the following observation period. Because overcharge t7 is a pass or fail requirement, it is a primary hurdle for new battery designs entering the market. The final test report is a necessary document for all commercial battery shipments.