Battery charge with temperature-sensitive cut-off switch

• US 5,250,892 A
• Filed: 03/31/1992
• Issued: 10/05/1993
• Est. Priority Date: 04/05/1991
• Status: Expired due to Fees

• Current Assignee: Tai-Her Yang
• Original Assignee: Tai-Her Yang
• Inventors: Yang, Tai-Her
• Primary Examiner(s): HICKEY, ROBERT
• Application Number:
  US07/861,003
• Time in Patent Office: 553 Days
• Field of Search: 320/35, 320/36, 320/2
• US Class Current: 320/107
• CPC Class Codes: H02J 7/007194 of the battery

Abstract

A battery charger includes a battery compartment removable from the charger socket. The battery compartment includes a temperature-sensitive switch which opens when the temperature of the battery exceeds a predetermined value during charging, thereby cutting off the main charging current. A permanent magnet is positioned on the socket portion of the charger. The magnet latches the temperature-sensitive switch in an open position after charging so long as the battery compartment is in the socket. The switch can be reset by separating the battery compartment from the socket. A current limiting resistor is connected in parallel with the switch to maintain a small charging current when the temperature-sensitive switch is open.

Claims

1. In a battery charger which includes two separable parts and a temperature-sensitive switch arranged to open when a temperature sensed by the switch exceeds a predetermined temperature, said temperature-sensitive switch being positioned in a first of two separable parts, the improvement comprising:

magnetic latching means positioned on a second of said two parts for latching the temperature-sensitive switch in an open position when said first part and said second part are joined together and said switch has opened as a result of an increase in said temperature beyond said predetermined temperature, said magnetic latching means maintaining said switch in said open position after the temperature of the battery falls below said predetermined temperature so long as the two separable parts are together whereby said switch can be reset to a closed position by separating said two parts.

2. A battery charger as claimed in claim 1, wherein said temperature-sensitive switch is connected in parallel with charge maintaining means including a current-limiting resistor for supplying a limited current to the battery, said limited current being sufficient to maintain a charge on the battery while the temperature-sensitive switch is open.

3. A battery charger as claimed in claim 1, wherein said magnetic latching means comprises a permanent magnet.

4. A battery charger as claimed in claim 1, wherein the first part is a battery containing compartment, and the second part is a socket into which the battery containing compartment fits and which is connected to a power supply arranged to supply charging power to the battery when the battery containing compartment is inserted into the socket.