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Control and termination of a battery charging process Patent #: 5694023
ApplicationNo. 914674 filed on 08/19/1997
US Classes:320/130, Cycling (e.g., discharge/charge cycle, etc.)320/150, With thermal condition detection320/160Multi-rate charging (e.g., plural charge rates before a maintenance charge, etc.)
ExaminersPrimary: Wong, Peter S.
Assistant: Toatley, Gregory J. Jr.
Attorney, Agent or Firm
International ClassH02J 007/00
AbstractA charge pulse (200A) is applied to the battery (B). The open circuit voltage of each cell (C1-CN) is then measured during a first rest period (210A). A depolarization pulse (220A) is then applied to the battery. The open circuit voltage of each cell is then measured during a second rest period (210B). The open circuit voltages for the first and second rest periods for each cell are compared to yield a voltage difference (DELTA Y). This voltage difference is then compared with a threshold voltage (V THRESHOLD). If the voltage difference is greater than the threshold voltage then the cell is being charged too rapidly, or is being overcharged, so one or more of the charge cycle parameters are adjusted. Some of the charge cycle parameters are, for example, the charge pulse current amplitude, the charge pulse duration, the number of consecutive charge pulses, the depolarization pulse current amplitude, the depolarization pulse duration, the number of consecutive depolarization pulses, the duration of the rest periods, or a combination of these. Multiple charge pulses (200A, 200B) and depolarization pulses (220A, 220B, 220C) may also be used. These parameters may be adjusted for the battery as a whole and/or for each cell individually. The adjustment to the charge cycle parameters may also be made on a "worst case" or a "best case" cell basis, with this cell controlling the charge cycle parameters for all the cells. Several techniques for adjusting the charge cycle parameters are disclosed.
Field of SearchCycling (e.g., discharge/charge cycle, etc.)
With state-of-charge detection
With individual charging of plural batteries or cells
Detection of current or voltage differential (e.g., slope, etc.)
Detection of current or voltage amplitude
Multi-rate charging (e.g., plural charge rates before a maintenance charge, etc.)
With detection of current or voltage amplitude