Although valve-regulated lead acid (VRLA) batteries are low cost, their cycle life has been limited for electric vehicles (EV). With funding from the Advanced Lead-Acid Battery Consortium, the National Renewable Energy Laboratory has worked with Recombination Technologies and Optima Batteries Inc., to improve the cycle life of VRLA batteries, which is strongly influenced by the way they are charged over their lifetime. The purpose of the project was to develop charge algorithms specifically aimed at improving the cycle life of VRLA batteries to 1000 deep discharges. The motivation for the project was based on the hypothesis that VRLA batteries reach end-of-life prematurely with the 'normal' constant voltage charge because of insufficient recharge at the negative plate and the 'oxygen cycle' or recombination reactions interfering with recharge of the negative plate. During Phase 1 of this project, the authors developed zero delta voltage and current interrupt charging algorithms and strategies that improved the cycle life of VRLA modules from 150 - 200 deep discharge cycles to 300 - 350 deep discharge cycles. During Phase 2, the authors implemented a current interrupt charge algorithm on a 24-module battery pack that resulted in 700 deep discharge cycles. The authors found no correlation between operating temperature and failure when batteries stayed below the manufacturer's recommended temperature limit of 60 deg C. However, warmer modules appear to have longer lives.
Charging algorithms for increasing lead acid battery cycle life for electric vehicles
Aufladungsalgortihmen zur Erhöhung der Ladungszyklenzahl von Bleibatterien für Elektrofahrzeuge
2000
17 Seiten, 14 Bilder, 3 Tabellen, 3 Quellen
(nicht paginiert)
Conference paper
Storage medium
English
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