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Power supply apparatus with chargeable battery and charge/discharge method

  • US 6,445,164 B2
  • Filed: 01/18/2001
  • Issued: 09/03/2002
  • Est. Priority Date: 02/20/1998
  • Status: Expired due to Fees
First Claim
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1. A power supply apparatus in which a plurality of chargeable batteries are connected in parallel between the node of an external power source, and a load, and the common ground of the external power source and the load, comprising:

  • charge/discharge monitoring means for judging whether the external power source is in a charging state when the load is driven and a sufficient voltage for charging the batteries is outputted, or in a discharging state when a sufficient voltage is not outputted and a discharging current should be supplied from the chargeable batteries to the load;

    switch means connected in series to each of the plurality of batteries; and

    on/off controlling means for controlling the on/off operation of the switches according to the output of the charge/discharge monitoring means and the charging/discharging state of each of the plurality of batteries, further comprising;

    current detecting means for detecting the current flow in each of said plurality of batteries;

    charge completion detecting means for detecting the charging completion state of each of said plurality of batteries from the output of the current detecting means; and

    voltage comparing means for comparing the voltages of said plurality of batteries, and wherein when said charge/discharge monitoring means judges that said external power source is in a charging state, said on/off controlling means performs a first control of switching on only said switch corresponding to a battery with a voltage judged to be the lowest by the voltage comparing means, and then, when the charge completion detecting means detects the charge completion of said battery with the lowest voltage, said on/off controlling means performs a second control of switching off the switched-on switch and a third control of switching on only said switch corresponding to a battery with a voltage judged to be the lowest by the voltage comparing means of the remaining batteries of which the charging completion is not detected out of said plurality of batteries.

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