UL 2596:2022 free download

UL 2596:2022 free download Test Method for Thermal and Mechanical Performance of Battery Enclosure Materials
5.2.2 The test box shall be constructed of A36 structural steel or equivalent to provide the required thermal and mechanical durability required. All joints shall be welded.
5.2.3 Openings in the test box walls are permitted for use as ports for pressure measurement, safety pressure relief, temperature measurement, pressure regulation, or other instrumentation needs. Any ports and unused openings shall be sealed against pressure leakage.
5.2.4 The top side of the test box shall be open and equipped such that a test sample can be secured and sealed to the test box and serve as the sixth “side” of the test box.
5.2.5 The pressure generated in the test box during the test shall be regulated using vent orifices located near the midpoint of one side of the test box as shown in Figure 5.1. The shape and open area of the vent orifices shall be agreed upon with the manufacturer to obtain the targeted max pressure desired.
5.2.6 Instrumentation of the test box shall not interfere with the development or measurement of pressure inside the test box.
5.2.7 A Type K sheathed thermocouple, 0.21 mm 2 (24 AWG), shall be used to measure the internal temperature of the test box. The thermocouple shall be inserted through a port such that the tip of the thermocouple is flush with the interior test box wall, but is positioned such that it is not in contact with the fuel package or test box wall.
5.2.8 AType K thermocouple, 0.21 mm 2 (24 AWG) or 0.05 mm 2 (30 AWG), shall be used to measure the external surface temperature of the test sample. The thermocouple shall be attached on the external test sample surface near the midpoint and secured using polyimide tape, or equivalent
5.2.9 A pressure transducer capable of measuring the max pressure developed during the test shall be used to measure the internal pressure of the test box.
5.2.10 Test instrumentation shall be selected and protected in a way that prevents damage to the instruments and loss of measurement accuracy. Protection measures shall not affect the measurement of test conditions (temperature and pressure).
5.3 Fuel package
5.3.1 A fuel package consisting of twenty-five lithium-ion cells arranged in a 5-by-5 array shall be used for testing. The cells shall be from the same manufacturer and of the same model designation.
5.3.2 The cells utilized in the fuel package shall be lithium-ion 18650 format (nominal 18 mm diameter, 65 mm length) with a capacity between 3300 – 3400 mAh at room temperature and have the propensity to exhibit thermal runaway through external heating. Cell cathode chemistry shall be Nickel Cobalt Aluminum Oxide (NCA). All cells shall be charged to 100% state of charge (SOC). Cells shall not be electrically connected. The rated capacity of each cell shall be verified prior to testing. See Annex A, Cell Capacity Check Procedure.
5.3.3 The cells shall be positioned in direct contact with each other to enable for cell-to-cell propagation of thermal runaway. Cells shall not be constrained in a way that prohibits ejection of cells from the fuel package during and after thermal runaway. 5.3.4 The cells shall be oriented such that the overpressure vents of the cells are facing the test sample.