LI-ION CELL PTC DEVICE CHARACTERIZATION FRANK DOLJACK OF RAYCHEM HAS PUBLISHED (IEEE TRANSACTIONS ON COMPONENTS, HYBRIDS, AND MANUFACTURING TECHNOLOGY) 4, 732, 1981) A METHOD TO FULLY CHARACTERIZE THE STEADY STATE (EQUILIBRIUM) AND THE TRANSIENT (NON-EQUILIBRIUM) STATE OF THEIR PTC RESISTORS. THIS DATA WILL ENABLE MATHEMATICAL MODELS OF FULL LITHIUM ION CELL DESIGNS TO BE MORE ACCURATE IN PREDICTING CELL BEHAVIOR IN OVER-CURRENT CONDITIONS. THE EQUILIBRIUM AND DYNAMIC RESPONSE CHARACTERISTICS OF 2 CELL POSITIVE THERMAL COEFFICIENT (PTC) DEVICE DESIGNS INSIDE LITHIUM ION CELLS WILL BE CHARACTERIZED AS A FUNCTION OF TEMPERATURE. THIS INVOLVES DETERMINING THE ULTIMATE TRIP CURRENT OF EACH DEVICE AS A FUNCTION OF TEMPERATURE AND THE HEAT DISSIPATION RATE IN THE TRIPPED STATE. FIFTEEN (15) CELLS OF EACH DESIGN (PANASONIC CGR-18650C AND MOLI ICR-18650J) WILL BE PROVIDED BY NASA. THESE CELLS HAVE VIRGIN PTC DEVICES. MINIMUM AND MAXIMUM BASE RESISTANCES VERSUS TEMPERATURE THE MINIMUM VALUE SHALL BE OBTAINED BY SELECTING NEVER TRIPPED (VIRGIN) HEADER ONLY DEVICES AND MEASURING THE RESISTANCE TO 5% DURING A SLOW CONTINUOUS SWEEP OF TEMPERATURES BETWEEN 5 & 180 C WITH EMPHASIS IN THE 120 TO 140 C REGION. THE MAXIMUM VALUE SHALL BE OBTAINED BY THE SAME METHOD EXCEPT USING DEVICES THAT HAVE BEEN TRIPPED ONCE AND ALLOWED TO RECOVER FOR AT LEAST 24 HOURS PRIOR TO TEST. CURRENT VS VOLTAGE CHARACTERIZATION OF IN-CELL PTC DEVICES THIS TASK REQUIRES MEASURING THE VOLTAGE DROP ACROSS THE PTC DEVICE OF LITHIUM ION CELLS WHILE INSIDE AND OUTSIDE THE CELL. POWER DISSIPATION RATE THIS TASK CONNECTS THE CELL UNDER TEST IN SERIES WITH A POWER SUPPLY LIMITED TO 21 1V. A TEST REPORT SHALL BE PROVIDED WITH METHODS USED AND ALL TEST RESULTS WITHIN 2 MONTHS AFTER CONTRACT START DATE. THE TEST REPORT REQUIREMENTS ARE: PLOT OF MINIMUM AND MAXIMUM BASE RESISTANCE VS TEMPERATURE FOR EACH CELL DESIGN OR COMBINED ON THE SAME PLOT. PLOT OF CURRENT VS VOLTAGE CURVES AT EACH TEMPERATURE FOR A CELL DESIGN, SIMILAR TO FIG 8 OF DOLJACK S PAPER. PLOT OF THE POWER DISSIPATION RATE VS TEMPERATURE CURVES FOR BOTH CELL DESIGNS ON THE SAME PLOT.