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Express Charger

IP.com Disclosure Number: IPCOM000014588D
Original Publication Date: 2000-Aug-01
Included in the Prior Art Database: 2003-Jun-19

Publishing Venue

IBM

Abstract

Disclosed is a battery charger for charging a battery with short time. The charger has constant current and constant voltage characteristics and it is possible to charge Li-Ion, Li-Polymer and Pb batteries which require constant voltage and constant current charging method. The constant voltage of charger is set to the maximum allowable voltage of battery, but the charging is terminated before the actual battery voltage reaches the maximum voltage for shortening charge time. Fig,1 shows the charging characteristics of the charger. At first, the charger charges a battery with constant current until the battery capaicty reaches approximate 70%. Then, the charger sets the charge mode to constant voltage charging. The value of charging current goes down after entering into constant voltage mode. If value of constant current reaches a predetermined value, the charging is disabled and battery voltage is measured. If the battery voltage is equal to or higher than a predetermined value which is slightly less than the maximum allowable voltage, the charging is terminated. In case the battery voltage does not reach the predetermined value, the charging is enabled and the charger starts to charge the battery again. If a predetermined time elapses, the charging is disabled and battery voltage is measured to check if it reaches the predetermined value. Thus, enabling and disabling the battery charging are repeated until actual battery voltage reaches predetermined value of voltage. In the result of this control, battery is charged until its voltage tunrs to be the predetermined value prcisely. This means battery charge time is shortened by this control since the charging is terminated before battery voltage reaches the maximum allowable voltage.