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February 2017 - Lithium Ion Batteries

With the advent of today's electronics devices comes a new power source: rechargeable lithium ion (Li-ion) batteries. The technology of Li-ion batteries packs a decided punch in that the power to weight ratio (power density) is substantially higher than prior technologies allowing for devices to be smaller.

Li-ion batteries come in several different chemistries and sizes to fit a wristwatch, cell phone, laptop, power tool, all the way up to those that fit a Tesla. And they also come with an unadvertised price tag: increased fire hazard. Unlike the older technologies which they replace, Li-ion batteries have significant flammability which is inherent in their electrolyte chemistry. On a side note, the modern Li-ion battery chemistry does not contain free lithium, a flammable metal which generates flammable hydrogen gas in the presence of water.

There are many dramatic YouTube videos of exploding and burning laptops and cell phones containing Li-ion batteries. The most recent noteworthy news is the FAA's total ban of the Samsung Galaxy Note7 on all US aircraft. Li-ion battery thermal runaway failures with extreme results can initiate from a variety of battery conditions including: physical damage, overcharging, external heating, short circuit, etc. While these incidents are extremely serious, and potentially life threatening, they pale in comparison to the potential for fire involving bulk warehouse storage of batteries. To date there are no published standards for fire protection of Li-ion batteries in a warehouse configuration, however this is in the process of changing.

In conjunction with several sponsoring partners, most notably FM Global, the National Fire Protection Association's (NFPA) Property Insurance Research Group (PRIG) in 2011 initiated a multi-phase program to characterize, evaluate, and test Li-ion batteries with respect to determining viable fire protection technologies. Phase III was the final and most recent installment of this program, and includes information on large scale fire testing. The three papers published from these efforts are referenced below.

These tests have not yet resulted in publicly published standards, however they are promising in that the sprinkler protection scheme tested was considered successful and capable of controlling a storage fire of Li-ion batteries. Large scale testing of rack storage at 15 ft. under a ceiling height up to 40 ft. was successfully controlled by K22.4 sprinklers at a pressure of 35 psi.

It is worth noting, that as with other commodity testing, the packaging plays a significant role in fire development. The more packaging contains cardboard, or similar materials subject to pre-wetting from sprinkler systems, the lesser the fire severity.

While the papers' authors note that the test results can only be directly applied to the specific type and conditions of batteries, packaging, and storage arrangements used in the tests, there are some reasonable extrapolations which may be made to provide preliminary guidance in the storage and protection of Li-ion batteries.

Future work will likely involve further full scale testing to validate testing already completed, as well as tests using different Li-ion chemistries, packaging, and storage arrangements. Final publicly published standards and recommendations for protection and storage practices are likely to be developed after further testing. If you would like a review of any storage practices at your facility, including Li-ion batteries, contact Risk Logic. We will work with you to determine acceptable options/alternatives and provide published standards as they are available.

References

“Lithium-Ion Batteries Hazard and Use Assessment” July 2011, Fire Protection Research Foundation

“Lithium Ion Batteries Hazard and Use Assessment Phase IIB Flammability Characterization of Li-ion Batteries for Storage Protection” April 2013, Fire Protection Research Foundation

“Lithium Ion Batteries Hazard and Use Assessment - Phase III” November 2016, Fire Protection Research Foundation