| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to inject more electric charges into a battery charger for lithium ion secondary batteries. SOLUTION: With respect to battery chargers for constant-current, constant-voltage (CC-CV) charging, the Battery Association of Japan recommends that charging voltage Vx should be 4.25 V at up to 45°C, 4.15 V at higher temperatures, and 4.10 V at 50°C or higher as indicated by reference codeα1. In this invention, meanwhile, the charging voltage is determined from Vx=ä[(Tlim-Tx)/(Tlim-Tctl)]×(Vctl<SP>2</SP>-Ve<SP>2</SP>)+Ve<SP>2</SP>}<SP>1/2</SP>, where, Tx is the temperature of a battery cell; Tctl is the temperature (=45°C) at which the suppression of charging voltage should be started because of high temperature; Vctl is the maximum charging voltage permitted in the battery cell at temperature Tctl; Tlim is the maximum temperature permitted in the battery cell in terms of safety; and Ve is the discharge termination voltage of the battery cell. Therefore, the charging voltage is as indicated by reference codeα2 and charging can be additionally carried out by the amount equivalent to the portion hatched with oblique lines. COPYRIGHT: (C)2010,JPO&INPIT |
