Presentation on theme: "UN Informal Working Group Meeting on Lithium Battery Tests Ideas to Address Problems Testing Large and Small Cells and Batteries George A. Kerchner Executive."— Presentation transcript:
UN Informal Working Group Meeting on Lithium Battery Tests Ideas to Address Problems Testing Large and Small Cells and Batteries George A. Kerchner Executive Director Portable Rechargeable Battery Association November 11-13, 2008 Washington, DC
Problems with Tests Not updated in 8 years Do not take into account changes in technology, applications and experience Inconsistent interpretations of UN testing requirements and terminology More harmonization needed with terminology found in international standards (e.g., IEC) Impractical to test large batteries (e.g., for HEV) to the same criteria as small batteries (e.g., for PC)
New Design Type – UN Manual Section Lithium cells or batteries which differ from a tested type by: (a) A change of more than 0.1 g or 20% by mass, whichever is greater, to the cathode, to the anode, or to the electrolyte; or (b) A change that would materially affect the test results, shall be considered a new type and shall be subjected to the required tests.
Changes to for Rechargeable Cells and Batteries Cells or batteries which differ from a tested type by: (a) for primary cells and batteries, a change of more than 0.1 g or 20% by mass, whichever is greater, to the cathode, to the anode, or to the electrolyte; (b) for rechargeable cells and batteries, a change in Watt-hours of more than 20% or an increase in voltage of more than 20%; or (c) a change that would materially affect the test results, shall be considered a new type and shall be subjected to the required tests.
Small and Irregular Shaped Cells and Batteries Vibration and shock tests require three mutually perpendicular mounting positions of the cell or battery Difficult to define 3 distinct planes for very small and irregular shaped cells and batteries Variation needed in sections (vibration test procedure) and (shock test procedure) Variations also may be needed in other testing requirements
Mass Loss in Thermal Test – Section Mass loss may occur due to material used in the battery Mass loss should only be attributable to cell Amend mass loss definition – “Mass loss means a loss of mass from cells that exceeds …. “
Impact Test on Component Cells From Batteries Component cells testing noted only in Test 6 (Impact test) – Section (c)(ii) and (c)(iv) What is intent? UN Model Regulations, IMDG Code and ICAO TI require that cells or batteries be subject to UN tests Add a clarifying “Note” under component cell definition similar to Note under current battery definition
UN Manual of Tests and Criteria “Cell” definition, Section Cell means a single encased electrochemical unit (one positive and one negative electrode) which exhibits a voltage differential across its two terminals. Under these Regulations, to the extent the encased electrochemical unit meets the definition of "cell" herein, it is a "cell", not a "battery", regardless of whether the unit is termed a "battery" or a "single cell battery" outside of these Regulations. Testing Single Cell Batteries
If cell is tested, is it really necessary to re-test single cell battery for classification purposes?
Large Lithium Batteries More realistic definition needed for large and small batteries Impractical to test large batteries and assemblies (e.g., HEV) to same criteria as small batteries (e.g., PC) UN vibration and shock tests problematic for large batteries Modifications to shock and vibration tests needed to account for large batteries and assemblies
Large Lithium Battery Definition Current: > 6200 Wh for Lithium ion and > 500 g for Lithium metal Recommended: > 600 Wh for Lithium ion and > 80 g for Lithium metal Takes into account current technologies, applications and experience of automobile and battery manufacturers
Large Lithium Battery Testing Cost is a major factor when testing large rechargeable batteries 24 rechargeable batteries currently required for testing Reduced to 16 in 2011 as a result of decision on PRBA proposal at July UN meeting 8 large rechargeable batteries is sufficient for classification purposes Same number (8) currently required for primary batteries
“Large” Battery Assembly Testing UN-tested lithium batteries electrically connected to form a battery assembly with more than 500 g or 6200 Wh Assembly does not require testing if - Equipped with a system capable of monitoring the battery assembly and preventing short circuits, or over discharge between the batteries in the assembly and any overheat or overcharge of the battery assembly
“Small” Battery Assembly Testing (< 500 g Li Metal or 6200 Wh) Test one (1) battery assembly in a fully charged state under Tests 3, 4 and 5, in addition, Test 7 in the case of rechargeable battery assemblies Rechargeable battery assemblies must be cycled at least 25 times Assembly must be comprised of cells and batteries that have passed required UN tests
Vibration Test – T3 Current vibration test parameters based on transportation of small cells and batteries Parameters do not realistically apply to larger batteries Example: HEV battery systems are assemblies of electronic controllers, sensors, air flow ducts, cabling, cell mounting fixtures, cells, trays, covers and attachment brackets
Amend Vibration Test Amend vibration tests for batteries > 600 Wh or 12 kg For Large batteries or batteries exceeding 12 kg, the logarithmic frequency sweep is as follows: from 7 Hz a peak acceleration of 1 gn is maintained until 18 Hz is reached. The amplitude is then maintained at 0.8 mm (1.6 mm total excursion) and the frequency increased until a peak acceleration of 2 gn occurs (approximately 50 Hz). A peak acceleration of 2 gn is then maintained ….
Shock Test – T4 Shock values do not realistically apply to larger batteries “Small” cells and batteries subject to a half- sine shock of peak acceleration of 150 g n and pulse duration of 6 milliseconds “Large” cells and large batteries subject to a half-sine shock of peak acceleration of 50 g n and pulse duration of 11 milliseconds
Amend Shock Test Testing of HEV-type battery packs at 150 g n is impractical Recommend limiting acceleration to 50 g n for batteries > 600 Wh or 12 kg
Overcharge Test – T7 Batteries (modules) used to construct battery assemblies frequently designed without overcharge protection Not designed to be or expected to be charged independently by anyone other than the manufacturer Not possible to conduct Overcharge test on batteries (modules) because electronic overcharge protection is designed into battery assembly
Amend Overcharge Test Amend Section (d) by adding following provision: “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.”
Interpretations No defined mechanism for official interpretations Should there be a UN guidance manual on lithium battery testing requirements? How do interpretations get circulated or distributed internationally? Should there be an annual meeting of “experts” on lithium batteries similar to UN experts on explosives? Harmonization with terminology in international standards would provide for more consistency