Multi-step constant-current charging method for electric vehicle, valve-regulated, lead/acid batteries during night time for load-levelling

Autor: Nobuyuki Sawada, Kazuo Nishiyama, Sakae Takagi, Tetsuya Sakabe, Haruki Yoshioka, Eiichi Kousaka, Yuichi Mita, Kazuyuki Adachi, Hayato Narisoko, Kazuyuki Kobayashi, Masanori Yamashita, Kaoru Ishihara, Tomohiko Ikeya, Satoru Kato, Jun-ichi Murakami
Rok vydání: 1998
Předmět:
Zdroj: Journal of Power Sources. 75:101-107
ISSN: 0378-7753
DOI: 10.1016/s0378-7753(98)00102-5
Popis: For the popularization of electric vehicles (EVs), the conditions for charging EV batteries with available current patterns should allow complete charging in a short time, i.e., less than 5 to 8 h. Therefore, in this study, a new charging condition is investigated for the EV valve-regulated lead/acid battery system, which should allow complete charging of EV battery systems with multi-step constant currents in a much shorter time with longer cycle life and higher energy efficiency compared with two-step constant-current charging. Although a high magnitude of the first current in the two-step constant-current method prolongs cycle life by suppressing the softening of positive active material, too large a charging current magnitude degrades cells due to excess internal evolution of heat. A charging current magnitude of approximately 0.5 C is expected to prolong cycle life further. Three-step charging could also increase the magnitude of charging current in the first step without shortening cycle life. Four-or six-step constant-current methods could shorten the charging time to less than 5 h, as well as yield higher energy efficiency and enhanced cycle life of over 400 cycles compared with two-step charging with the first step current of 0.5 C. Investigation of the degradation mechanism of the batteries revealed that the conditions of multi-step constant-current charging suppressed softening of positive active material and sulfation of negative active material, but, unfortunately, advanced the corrosion of the grids in the positive plates. By adopting improved grids and cooling of the battery system, the multistep constant-current method may enhance the cycle life.
Databáze: OpenAIRE