CHAPTER 12 Battery Abuse Tolerance Now that we have reviewed all of the major subsystems in the lithium-ion battery, we need to discuss testing and abuse of the battery system. In all cases, the battery system is designed to optimize the performance and protect the lithium-ion cells. However, there are occurrences that drive the cells out of their normal operating range. Most of these have been discussed in relation to the design guidelines around them, but now we will discuss in relation to the Design, Validation Plan & Report (DVP&R) planning and testing that must be conducted in order to successfully ensure that the cells safely operate within their predetermined range.
Lithium-ion battery testing generally falls into one of three different categories: (1) character- ization and performance testing, (2) abusive testing, and (3) certification testing. Character- ization and performance testing is focused on evaluating how the battery will perform under a specific set of testing criteria. Characterization testing is most often conducted at the cell level in order to understand the basic performance of a cell and at the module, pack, or system level in order to evaluate how the pack will operate during specific performance profiles.
Abuse testing involves forcing the battery into situations that will drive it to fail and evaluating the results in order to make changes in the design to mitigate these failures. Abuse testing may include overcharge testing, overvoltage testing, nail penetration testing, short-circuit testing, and even drop testing. Abuse testing is done in order to find the limits of safe performance of the cells and packs. Finally, certification testing is done by completing a very specific set of tests that are determined by the relevant certification body and have various focuses.
Exam- ples of certification testing include tests such as the United Nations (UN) testing guidelines for the transport of hazardous goods in order to certify that the product can be shipped via public or private air or road transportation. During the design process and throughout the ongoing discussions with the customer, the battery test engineer should gather enough information to begin developing a DVP&R plan. The DVP&R plan will include the specifics of all testing to be completed, including the quantity of units to be tested, the duration of the test, the location of the test, and the pass/fail criteria for each of the three types of testing.
In the sample report below ( Table 1 ), you see an example of what a DVP&R plan may look like. The DVP&R plan should include all of the tests required to be completed and link them to a specific set of requirements or certification criteria as well as the criteria that will indicate that the test was passed. The plan should also include a section on the test report to ensure that all test results are accurately documented. This document becomes a living tool that is The Handbook of Lithium-Ion Battery Pack Design. http://dx.doi.org/10.1016/B978-0-12-801456-1.00012-9 Copyright © 2015 Elsevier Inc. All rights reserved. 139