| 摘要 |
PURPOSE:To enable indication of residual capacity of a battery based on a discharge rate by calculating it based on a open voltage-to-discharge rate characteristic after a terminal voltage of the battery is measured. CONSTITUTION:A push button 9 is turned ON at the time to and a switch 7 is closed to let discharge current flow to a dummy fixed load 8 from a battery 6. During the closure thereof, the terminal voltage of the battery 6 lowers by a fixed value. When the push button 9 is turned OFF and the switch 7 is opened, the voltage returns to he open voltage plotting a smooth transient characteristic curve because of effect of an internal resistance, namely, discharge rate. Here, when a time tau is selected appropriately, the terminal voltage V is almost regarded as the open voltage of the battery 6 after a fixed time tau from the opening time t1 of the switch 7. This voltage is read by a microcomputer 12 to calculate the discharge rate based on a data of the open voltage-to-discharge rate in an ROM of a memory 12c. Thus, a residual capacity of the battery 6 corresponding to the discharge rate is indicated on a display unit 16.
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