Abstract: A prismatic battery cell or an electronic component comprising an electrode plate group of alternately stacked positive and negative electrode plates, wherein adjacent electrode plates of opposite polarity are insulated by an insulating separator, and electrode plates of one polarity are bent to converge at a common joining location for connecting together as a lead portion, the lead portion being joined together to a current collector of that one polarity, characterized in that the electrode plates are bent after the electrode plates are stacked and held or bundled together. Shaping the electrode plates to form the lead portions while the electrode plates are held in a stack means it is not necessary to handle pre-shaped electrode plates, since handling pre-shaped electrode plates in a production line could be tedious because the electrode plates are quite easily deformable.

Abstract: A method of determining the state of charge (SOC) of a rechargeable battery, the method comprising charging the battery using a substantially constant charge current; measuring the battery temperature; and conducting a first measurement of the battery voltage at a time interval, t1, from the start of the charging, and a second measurement of the battery voltage at a time interval, t2, from the first measurement.

Abstract: A method of determining the state of charge (SOC) of a rechargeable battery, the method comprising charging the battery using a substantially constant charge current; measuring the battery temperature; and conducting a first measurement of the battery voltage at a time interval, t1, from the start of the charging, and a second measurement of the battery voltage at a time interval, t2, from the first measurement.