Protection circuit-equipped secondary battery

• US 20030134183A1
• Filed: 10/04/2002
• Published: 07/17/2003
• Est. Priority Date: 02/06/2001
• Status: Active Grant

• Current Assignee: Sony Chemicals Corp. (Dexerials Corporation)
• Original Assignee: Sony Chemicals Corp. (Dexerials Corporation)
• Inventors: Furuta, Kazutaka, Kawazu, Masami, Tamura, Hisaya, Iwasaki, Norikazu
• Granted Patent: US 6,917,505 B2
• Time in Patent Office: Days
• US Class Current: 429/62
• CPC Class Codes: H01H 2085/466 with remote controlled forced fusing
• CPC Class Codes: H01M 2200/103 Fuse
• CPC Class Codes: H01M 2200/106 PTC
• CPC Class Codes: H01M 50/574 Devices or arrangements for the interruption of current
• CPC Class Codes: H01M 50/581 in response to temperature
• CPC Class Codes: H01M 50/583 in response to current, e.g. fuses
• CPC Class Codes: H02H 7/18 for batteries; for accumulators
• CPC Class Codes: H02H 9/026 Current limitation using PTC resistors, i.e. resistors with a large positive temperature coefficient
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A heater 13 and a thermistor 14 are connected in parallel, and a main fuse 11 is connected in series with thus formed parallel circuit to form a protective circuit 6. In a secondary battery 5 of the present invention, a charging/discharging current passes through the protective circuit 6, so that current is limited by the operation of the thermistor 14 when the voltage applied during abnormal conditions is relatively low while the main fuse 11 blows when the voltage during abnormal conditions is high.

Claims

1. A secondary battery comprising an accumulator, a protective circuit and external connection terminals,

wherein the protective circuit includes a heater generating heat when a voltage is applied, a main fuse connected in series with the heater in such a manner that it is heated by the heater and breaks at a specified blowout temperature, and a thermistor connected in parallel with the heater and having a resistance value increasing by heating, and

when the external connection terminals are connected to a DC voltage source, a current supplied from the DC voltage source charges the accumulator through the protective circuit, and

when the external connection terminals are connected to an electronic apparatus, a current discharged from the accumulator is supplied to the electronic apparatus through the protective circuit.

2. The secondary battery of claim 1 wherein the main fuse does not reach the blowout temperature under the current passing through the protective circuit when the external connection terminals are short-circuited, but the main fuse heats up to or above the blowout temperature when the external connection terminals are connected to a voltage source 1.5 times or more the rated charging voltage of the accumulator provided that the accumulator is not charged to the full charge voltage.

3. The secondary battery of claim 1 wherein an auxiliary fuse is connected in series with the thermistor and a series circuit consisting of the thermistor and the auxiliary fuse is connected in parallel with the heater.

4. The secondary battery of claim 2 wherein an auxiliary fuse is connected in series with the thermistor and a series circuit consisting of the thermistor and the auxiliary fuse is connected in parallel with the heater.