Power supply apparatus with chargeable battery and charge/discharge method

• US 6,624,613 B2
• Filed: 01/11/2002
• Issued: 09/23/2003
• Est. Priority Date: 02/20/1998
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Kitagawa, Seiya
• Primary Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US10/042,314
• Publication Number:
  US 20020057073A1
• Time in Patent Office: 620 Days
• Field of Search: 320/124, 320/118, 320/127, 320/135, 320/136
• US Class Current: 320/124
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence

Abstract

The present invention provides a battery charging/discharging method for effectively using the battery energy of a power supply apparatus with a plurality of chargeable batteries. The power supply apparatus in which batteries are connected in parallel to the node of an external power source and a load comprises a charge/discharge monitor unit for judging whether the external power source is in a state where a load is driven and sufficient voltage to charge the batteries is outputted or in a state where sufficient voltage is not outputted and a discharge current should be supplied from the batteries to the load, switches inserted in series with each of the batteries, and an on/off control unit for controlling the on/off operation of the switches according to the output of the charge/discharge monitor unit and the charging/discharging state of each battery.

Claims

1. A method for discharging a plurality of batteries in a power supply apparatus with a plurality of chargeable batteries, comprising the steps of:

(a) discharging only the batteries out of the plurality of batteries in which the respective currents flow in a discharging direction when the status of said power supply apparatus indicates a discharging state;

(b) when the discharging time during discharging exceeds a predetermined time, detecting the current direction in each of the batteries which have not discharged;

(c) making the batteries in which the respective current directions detected in step (b) are discharging directions discharge; and

(d) repeating steps (b) and (c).

2. A method for discharging a plurality of batteries in a power supply apparatus with a plurality of chargeable batteries, comprising the steps of:

(a) discharging only the batteries out of the plurality of batteries in which the respective currents flow in a discharging direction when the status of said power supply apparatus indicates a discharging state;

(b) detecting batteries of which the voltages become equal to the voltage of the batteries currently discharging among other batteries than those currently discharging;

(c) discharging the batteries detected in step (b); and

(d) repeating steps (b) and (c).