Battery charger with thermal runaway protection

• US 5,214,370 A
• Filed: 09/13/1991
• Issued: 05/25/1993
• Est. Priority Date: 09/13/1991
• Status: Expired due to Term

• Current Assignee: Lineage Power Corporation (GE Aerospace)
• Original Assignee: AT&T, Inc.
• Inventors: Harm, Charles E., Timm, Kenneth J.
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US07/759,357
• Time in Patent Office: 620 Days
• Field of Search: 320/35, 320/30, 320/31, 320/32, 320/36
• US Class Current: 320/152
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: Y10S 320/32 Voltage divider having diverse elements other than merely plural resistors

Abstract

A battery charger control includes a thermal sensor attached to the battery being charged. If the temperature readings indicate a thermal runaway condition the charging current output is adjusted in accord with the temperature reading by means of voltage injeciton into an output sense lead of the charging circuitry as a means of achieving a control that prevents thermal runaway of the battery while still permitting continuous charging of the battery.

Claims

1. A battery charging circuit comprising:

a power input for accepting an AC energy source;

a power output connected to a battery to be charged and supplying the regulated voltage to the battery; and

a rectifier charging circuit for supplying current at the regulated voltage to the power output, and including a regulation control for controlling teh voltage;

a temperature sensing device located proximate to the battery;

scaling circuitry for converting a value of the temperature sensing device to a voltage magnitude;

a voltage output of the scaling circuitry connected to the regulation control;

wherein the improvement comprises;

voltage sensing leads connected to terminals of the battery being charged and to the rectifier charging circuit;

circuitry included in series with one of the voltage sensing leads for injecting a voltage into a path of the voltage sensing leads;

whereby the voltage injected into the path of the voltage sensing leads alters the charging voltage supplied by the rectifier charging circuit to the battery to compensate for a temperature sensed by the temperature sensing device.

2. A battery charging circuit as claimed in claim 1;

wherein the improvement further comprises;

the circuitry for injecting a voltage comprises amplifier circuitry having an output coupled to inject a voltage into series with the path of the voltage sensing leads.

3. A battery charging circuit as claimed in claim 2;

wherein the improvement further comprises;

the temperature sensing device includes a thermistor physically located proximate to the battery.

4. A battery charging circuit as claimed in cliam 3;

wherein the improvement further comprises;

the thermistor being connected in series with a resistor to form a voltage divider, and

the scaling circuitry includes an amplifier responsive to a divided voltage output of the voltage divider.