For lithium batteries, there are some popular standards that Battery Lab tests to most often. In this sequel of articles we are going to discuss about these popular standards one by one. Today we are going to discuss about the UL 2054– UL Standard for Safety of Lithium Batteries (the abnormal charging test).

UL 2054
Abnormal charging test:

1. Lithium-ion batteries discharged to the battery manufacturer’s estimated capacity are to be used for this test. The lithium-ion batteries are to be tested in an ambient temperature of 20 ± 5°C (68 ± 9°F).

Exception: At the battery manufacturer’s preference, test currents more significant than the specified three times rated Ic can be applied to expedite the test timeframe, with the minimum charging times as seven hours.

3. When a protective device that has been examined for the purpose, actuates during the test, the test shall be repeated with the battery supply connected to the maximum load that does not cause the protective device to open. Protective equipment that has not been investigated for the purpose shall be short-circuited.

4. The lithium-ion batteries shall not explode or catch fire. For lithium-ion battery pack samples, tests shall not result in chemical leaks caused by cracking, rupturing, or bursting of the series casing.

5. The lithium-ion cells are to be tested in an ambient temperature of 20 ± 5°C (68 ± 9°F). Each lithium-ion battery shall be discharged at a constant current of 0.2 C/1 hours, to a manufacturer specified discharge endpoint voltage.

6. The lithium-ion cells are to be charged with a constant maximum specified charger output voltage and a current limit of three times the maximum current Ic, particularized by the battery manufacturer. Charging duration is the time required to reach the manufacturer’s specified end-of-charge condition plus seven further hours.

7. A lithium-ion cell is to be tested without the assistance of protective devices unless such protective mechanisms are either integral to the cell constructions or have been investigated for the purpose. A piece of re-settable protective equipment that actuates during the test shall be allowed to reset, and the examination shall be resumed, cycling as often as necessary to complete the test. When a protective device operates during the test (whether re-settable or not), the test is repeated with the same charging time, but with the lithium-ion cell connected to the maximum load that does not cause the protective devices to operate. A piece of protective equipment that is not integral to the cell, and that has not been investigated for the purpose is to be short-circuited.

8. The lithium-ion batteries are to be tested in an ambient temperature of 20±5°C (68±9°F). A thermocouple is to be attached to the lithium-ion cells of each test sample battery. Each lithium-ion battery shall be discharged at a constant current of 0.2C/1 hour, to a manufacturer specified discharge endpoint voltage.

9. Each of the test sample batteries are to be subjected to the following overcharge states, in sequential order. a) The lithium-ion battery is to be initially charged using a constant current charging mode with a current limit of three times the highest current Ic, particularized by the battery manufacturer until the maximum specified charger output voltage is reached. At that point, the lithium-ion battery is to be charged with a constant maximum specified charger output voltage and a current limit of three times the maximum current Ic. Charging duration is the time required to reach the manufacturer’s specified end-of-charge condition plus seven additional hours. The temperature on the lithium-ion cell casing shall be monitored. A re-settable protective device such as a PTC that actuates during the test shall be allowed to reset, and the examination shall be resumed, cycling as often as necessary, but no less than ten times, to complete the test. Automatic reset devices are allowed to cycle during the trial. When an over current protective device operates during the trial, the test is repeated with the same charging time, but with the battery connected to the maximum load that does not cause the protective devices to operate. b) The charge condition in accordance with (a) shall be conducted with each single component fault that is likely to occur in the charging circuit and which would result in overcharging of the battery. Exception No. 1: A protective device determined to be reliable may remain in the loop without being faulted. Exception No. 2: For batteries without protective devices, the overcharge condition(s) in (b) does not apply.

10. The lithium-ion batteries shall not explode or catch fire. For lithium-ion battery pack samples, tests shall not result in chemical leaks caused by cracking, rupturing, or bursting of the internal cell casing.