148 Chapter 12 occurs are the design targets. However, 4 through 7 get a bit more confusing and more difficult to differentiate and generally require more additional system-level protections in order to mitigate failures in these types of events. Level 4 occurs when a cell vents and loses more than 50% of its electrolyte, Level 5 occurs when a flame or fire is detected; Level 6 occurs when there is a rupture of the cell, with or without flame, but there are no flying parts; and finally Level 7 occurs when there is an explosion, defined as flying parts and disintegration of the cell (FreedomCAR Program Electrochemical Energy Storage Team, 2003).
One other safety document that we should talk about briefly is the Pacific Northwest National Laboratory’s “Inventory of Safety-related Codes and Standards for Energy Storage Systems” (Pacific Northwest National Laboratory, 2014). This is a very all-encompassing document that encompasses all laws, rules, codes, standards, and regulations relating to the develop- ment, testing, certification, and installation of energy storage systems (ESSs) for industrial, grid, stationary, and household applications. As more lithium-ion ESS installations continue to get installed the legal and regulatory environment is often still trying to catch up with the technology.
This report does a very good job of evaluating the needs specific to the US market. Certification Testing Certification testing is conducted for two main purposes. First is to certify the product for use according to a specific industry or government application. Examples of this type of testing would include DNV certification for marine-based packs, NHTSA testing for automotive applications, and UL testing for household appliances and applications. The second type of certification testing is done to ensure the safety of people and equipment while the product is being shipped. This mostly falls under the United Nations (UN) Recommendations on the Transport of Dangerous Goods:
Manual of Tests and Criteria (United Nations, 2009) with which most countries have aligned their transportation rules. United Nations Section 38.3 of the United Nations Handbook on the Transport of Dangerous Goods is titled Lithium metal and lithium-ion batteries and covers the testing that is required to be conducted prior to a lithium-ion cell or battery pack being shipped. UN 38.3 describes a very specific set of testing that must be conducted via an accredited test source in order to obtain approval to ship the battery.
This section of the test manual was developed after several major incidents occurred on public air transport when lithium-ion cells were either damaged during shipping or some other failure occurred that drove the cells to fail while they were on a plane. Unfortu- nately, several incidents like this occurred in the early 2000s that drove the need for this type of certification.