Overcharge preventing device and overdischarge preventing device for a secondary battery

• US 5,304,915 A
• Filed: 04/24/1992
• Issued: 04/19/1994
• Est. Priority Date: 04/26/1991
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Sanpei, Akira, Murano, Kanji
• Primary Examiner(s): HICKEY, ROBERT
• Application Number:
  US07/872,986
• Time in Patent Office: 725 Days
• Field of Search: 320/13, 320/18, 320/14, 320/40
• US Class Current: 320/116
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 50/569 Constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals battery terminal connectors with integrated measuring arrangements G01R31/364
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

An overcharge preventing device and an overdischarge preventing device for a nonaqueous electrolyte secondary battery having voltage detectors and are provided to respectively detect terminal voltages of batteries connected in series. A switch is provided in series to the batteries between a common terminal and a charge terminal. When the terminal voltage of at least one of the batteries exceeds a battery design voltage in charging the batteries, the switch is turned off in response to an output from the corresponding voltage detectors, thereby cutting off a charging current. Further, a voltage detector is provided to detect a terminal voltage of the series connected batteries. A switch is provided in series to the batteries between the common terminal and a discharge terminal. When the terminal voltage of the batteries becomes equal to or less than a set voltage in discharging the batteries, the switch is turned off in response to an output from the voltage detector, thereby cutting off a discharging current.

Claims

1. An overcharge preventing device for a battery having a battery voltage changing with a battery capacity, the improvement comprising:

voltage detecting means for detecting a voltage between opposite terminals of said battery; and

switch means provided in series with said battery between said battery and a charge terminal, wherein when said voltage between said opposite terminals of said battery exceeds a predetermined value during charging of said battery, said switch means is turned off in response to an output from said voltage detecting means to cut off a charging current wherein said switch means comprises an n-channel FET and a parasitic diode.

2. An overdischarge preventing device for a battery having a battery voltage charging with a battery capacity, the improvement comprising:

voltage detecting means for detecting a voltage between opposite terminals of said battery; and

switch means provided in series with said battery between said battery and a discharge terminal, wherein when said voltage between said opposite terminals of said battery becomes equal to or less than a predetermined value during discharging of said battery, said switch means is turned off in response to an output from said voltage detecting means to cut off a discharging current wherein said switch means comprises an n-channel FET and a parasitic diode.

3. A battery pack having an overcharging preventing device and an overdischarging preventing device comprising:

a first battery and a second battery connected in series;

a first voltage detector and a second voltage detector provided to detect battery voltage of said first battery and said second battery, respectively;

a third voltage detector provided to detect battery voltage of said series connected batteries;

a first switch provided in series with said batteries between a common terminal and a charging terminal, said second switch comprising a second n-channel FET and a second parasitic diode; and

a second switch provided in series with said batteries between said common terminal and a discharging terminal, said first switch comprising a first n-channel FET and a first parasitic diode;

wherein when battery voltage of at least one of said first battery and said second battery exceeds a battery design voltage during charging, said first switch is turned off to cut off charging of a current supply, and when voltage detected by said third voltage detector becomes equal to or less than a set voltage during discharging, said second switch is turned off to cut off discharge of the current supply.