Protective device for protecting individual battery cells in a batterypack from damages and hazards caused by reverse polarity during discharge cycles

• US 5,683,827 A
• Filed: 11/20/1995
• Issued: 11/04/1997
• Est. Priority Date: 11/20/1995
• Status: Expired due to Fees

• Current Assignee: Mobius Green Energy, Inc.
• Original Assignee: Mobius Green Energy, Inc.
• Inventors: Yu, Ho-Yuan
• Primary Examiner(s): NUZZOLILLO, MARIA
• Application Number:
  US08/561,050
• Time in Patent Office: 715 Days
• Field of Search: 429/1, 429/7, 429/90, 429/61, 429/49
• US Class Current: 429/1
• CPC Class Codes: H01M 50/597 Protection against reversal of polarity
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0047 with monitoring or indicating devices or circuits
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A rechargeable battery pack which includes several battery cells. Each cell has a positive electrode and a negative electrode connected in series. Each of the battery cells further includes a reverse polarity protection device. The protection device includes a low voltage switch connected between the positive electrode and the negative electrode of the battery cell. The low voltage switch is switched on to become a short circuit when a voltage difference between the positive electrode and the negative electrode for each of the battery cells is lower than a threshold switch-on voltage such that the each of the battery cells is bypassed and protected by conducting a current through the short circuit in the low voltage switch.

Claims

1. A rechargeable battery pack includes a plurality of battery cells each having a first terminal in electrical connection with a positive electrode and a second terminal in electrical connection with a negative electrode wherein said battery cells connected in series and each of said battery cells further comprising:

a polarity reverse protection means connected between said first terminal in electrical connection with said positive electrode and said second terminal in electrical connection with said negative electrode of said battery cell for preventing a polarity reverse of said positive and negative electrodes wherein said low voltage switching means is automatically switched on during a discharging cycle to become a short circuit when a voltage difference between said positive electrode and said negative electrode for each of said battery cells is lower than a threshold switch-on voltage whereby each of said battery cells is bypassed and protected by conducting a single-direction discharging current through said short circuit via said low voltage switching means; and

said polarity reverse protection means further includes a low voltage indicating means for automatically providing an indication powered by said single-direction discharging current passing there-through when a voltage difference between said first terminal and second terminal is below said threshold switch-on voltage.

2. The rechargeable battery pack of claim 1 wherein:

said polarity reverse protection means further includes an audio low voltage indicating means for providing an audio alarm powered by said single direction discharging current passing there-through when a voltage difference between said first terminal and said second terminal is below said threshold switch-on voltage.

3. A rechargeable battery pack includes a plurality of battery cells each having a first terminal in electrical connection with a positive electrode and a second terminal in electrical connection with a negative electrode wherein said battery cells connected in and said battery pack further comprising:

a low voltage switch-off means connected between an input terminal and an output terminal of said battery pack for automatically switching off said battery pack when said battery pack generating an output voltage lower than a threshold voltage during a discharge cycle for preventing a polarity reverse between said first terminal and said second terminal in each of said battery cells.

4. The rechargeable battery pack of claim 3 wherein:

said low voltage switch off means includes a transistor low voltage switching means for automatically switching off said battery pack when said battery pack generating an output voltage lower than a threshold voltage during said discharge cycle.

5. The rechargeable battery pack of claim 3 wherein:

said low voltage switch off means includes a silicon controlled rectifier low voltage switching means for automatically switching off said battery pack when said battery pack generating an output voltage lower than a threshold voltage during said discharge cycle.

6. A rechargeable battery pack includes a plurality of battery cells each having a first terminal in electrical connection with a positive electrode and a second terminal in electrical connection with a negative electrode wherein said battery cells connected in series and each of said battery pack further comprising:

a low voltage alarm means connected between an input terminal and an output terminal of said battery pack, said low voltage alarming means further includes a low-voltage switch-on means connected in series therein for automatically switching on said low voltage alarm means when said battery pack generating an output voltage lower than a threshold voltage during a discharge cycle for providing alarm signals whereby said low voltage alarm means is turned on only when said output voltage of said battery pack is lower than said threshold voltage during a discharge cycle.

7. The rechargeable battery pack of claim 6 wherein:

said low voltage alarm means includes a light emitting diode for providing a visual alarm signal powered by an alarm current switched on by said low-voltage switch-on means when said battery pack generating an output voltage lower than said threshold voltage during said discharge cycle.

8. The rechargeable battery pack of claim 7 wherein:

said low voltage alarm means includes a audio alarm means for providing an audio alarm signal powered by an alarm current switched on by said low-voltage switch-on means when said battery pack generating an output voltage lower than said threshold voltage during said discharge cycle.