Battery Abuse Tolerance 149 It is important to note that the U.S. Department of Transportation (U.S. DOT) and most other countries recognize this as certification as the only approved certification in order to ship. However, it is not entirely globally recognized and some countries may require that the testing be done “in country” if the battery is being manufactured there. The specific UN testing regime is different depending on the size of a battery (either a cell, module, or a complete pack) but generally follows the following eight tests: Test T.1: Altitude Simulation Test simulates air transport under low-pressure conditions Test T.2:
Thermal test Test assesses the cell and battery seal integrity and internal electrical connections using rapid and extreme temperature changes Test T.3: Vibration Simulates vibration during transport Test T.4: Shock Simulates impacts during transport Test T.5: External short circuit Test simulates an external short circuit of the cell or pack Test T.6: Impact Simulates an impact Test T.7: Overcharge Evaluates the ability of a rechargeable battery to withstand an overcharge condition Test T.8:
Forced discharge Tests the ability of a primary or rechargeable cell to withstand a proceed discharge condition Not all eight of the tests need to be conducted, but each must be assessed to determine if it does need to be completed. For instance, in regard to the T7 overcharge test the UN Manual states: Batteries not equipped with overcharge protection that are designed for use only in a battery assembly, which affords such protection, are not subject to the requirements of this test. (United Nations, 2009, p.
397) The reason for this disclaimer is that much of the battery industry pushed back against this test as part of the UN certification as most all cells and small assemblies would fail this test as they are designed to be used in larger assemblies that will have the proper overcharge protec- tions. So conducting an overcharge test on a cell that has no possible way to overcharge during transport seemed a bit unreasonable.
Similarly, as conducting the number of tests required on a very large pack—consider a PHEV, BEV, or even stationary pack that could have a cost of $10,000–$15,000 USD or more would be extremely cost prohibitive, the United Nations added another provision that if the cells and modules have all passed the UN testing, the packs do not need to again go through this testing regimen. The UN manual states: When batteries that have passed all applicable tests are electrically connected to form a bat- tery assembly in which the aggregate lithium content of all anodes, when fully charged, is more than 500 g, or in the case of a lithium-ion battery, with a Watt-hour rating of more than