Apparatus for expanding battery recognition in a battery charging system

• US 5,703,467 A
• Filed: 10/04/1996
• Issued: 12/30/1997
• Est. Priority Date: 10/04/1996
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Patino, Joseph
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): Law, Patrick B.
• Application Number:
  US08/726,567
• Time in Patent Office: 452 Days
• Field of Search: 320/13, 320/14, 320/15, 320/30, 320/35, 320/48
• US Class Current: 320/106
• CPC Class Codes: H02J 7/00038 using passive battery identification means, e.g. resistors or capacitors identification by mechanical connections H02J7/0045
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries

Abstract

A battery charging system (300) provides an expanded range of battery recognition between a charger (302) and a battery (304). Two resistors (316, 318) are coupled in series across the positive and negative charging terminals (B+, B-) of the battery (304) such that when the battery is coupled to the charger (302) there is provided a voltage divider to an A/D port (332) which is used to determine the battery type. Initially, the charger (302) disables charge current to the battery (304) and the charger determines the first resistor (316) value by enabling a switching circuit (336) and reading A/D port (332). Current is then enabled through positive charge node (B+) with the switching circuit (336) switched off, and the value of second resistor (318) is determined. The two resistors (316, 318) provide for an expanded range within which the A/D port (332) can determine battery type. A second charging system (400) provides an expanded battery type recognition range in a three contact charging system.

Claims

1. A battery charging system, comprising:

a charger circuit, including;

a positive charging terminal;

a negative charging terminal;

a control circuit for controlling a charge current;

a monitor circuit having an analog to digital converter (A/D) port; and

a switching circuit for switching a pull up resistor on to and off of the A/D port;

a battery having a predetermined battery type, including;

a positive charging contact for coupling to the positive charging terminal of the charger;

a negative charging contact for coupling to the negative charging terminal of the charger;

a first resistor coupled to the positive charging contact;

a second resistor coupled to the negative charging contact, said first and second resistors coupled in series and providing a voltage divider for coupling to the A/D port of the charger; and

the A/D port determining the value of the second resistor when the charge current from the control circuit is disabled and the switching circuit switches the pull up resistor on to the A/D port, and the A/D port determining the value of the first resistor when the charge current from the control circuit is enabled and the switching circuit switches the pull up resistor off of the A/D port, the first and second resistor values providing a range within which the A/D port determines the predetermined battery type.

2. A battery charging system as described in claim 1, wherein the second resistor comprises a thermistor.