Results of the Charger Test Project conducted by Arizona Public Service (APS) indicated the importance of the charger/charge algorithm/battery interface with respect to battery capacity. It also indicated that EVs rapidly charged demonstrated longer cycle life in field testing without reduction in capacity. Additional testing conducted by APS has shown that cycle life of the batteries is strongly related to the charging scheme utilized. Application of results of laboratory charging to the charge scheme utilized in this testing has been hampered by extremely long test periods in field tests designed to cycle batteries to the end of life. Development of a predictive method of cycle life extrapolation based upon microscopic analysis promises to reduce the time required for battery cycle life testing.