Method and apparatus for expanded battery recognition in a battery charging system

• US 5,696,433 A
• Filed: 03/07/1997
• Issued: 12/09/1997
• Est. Priority Date: 03/07/1997
• 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:
  US08/813,138
• Time in Patent Office: 277 Days
• Field of Search: 320/2, 320/31, 320/35, 320/48, 429/7, 429/90
• US Class Current: 320/106
• CPC Class Codes: H01M 10/4221 with battery type recognition
• CPC Class Codes: H01M 10/4257 Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• 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
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A battery charging system (200) provides an expanded range of battery recognition. Battery (204) includes two zener diodes (224, 226) coupled in a cathode-to-cathode configuration between the battery'"'"'s capacity resistor 220 and the battery'"'"'s thermistor 222. The charger 202 biases the first zener diode (224) while latching the second zener diode (226) such that the value of the latched zener diode can be determined by the A/D ports (234, 236) of the charger (202). The charger (202) then biases the second zener diode (226) and latches the first zener diode (224) so that the value of the first latched zener diode (224) can be determined through A/D ports (234, 236) of the charger. The thermistor (222) and capacity resistor (220) are read by the A/D ports (234, 236) when neither of the diodes (224, 226) is biased. Hence, the charging system (200) provides four battery ID parameters with which to identify the battery.

Claims

1. A method of expanding battery identifier parameters in a charging system having a battery including a thermistor (Rt) and a capacity resistor (Rc) and a charger including first and second analog-to-digital (A/D) ports, comprising the steps of:

at the battery;

providing first and second zener diodes coupled in a cathode-to-cathode configuration in between the thermistor and the capacity resistors of the battery; and

at the charger;

reading the Rt value and the Rc value through first and second A/D ports of the charger respectively;

forward biasing the first zener diode and latching the second zener diode;

determining the value of the second latched zener diode through the first and second A/D ports of the charger;

forward biasing the second zener diode and latching the first zener diode;

determining the value of the first latched zener diode through the first and second A/D ports of the charger;

identifying the battery using the values determined for Rc, Rt, the first latched zener diode, and the second latched zener diode.

2. The method of claim 1, further comprising the step of charging the battery based on the values determined for Rc, Rt, the first latched zener diode, and the second latched zener diode.

3. A battery charging system, comprising:

a charger, including;

first and second A/D ports;

first and second switches coupled to the first and second A/D ports for alternately switching on a supply voltage at the first and second A/D ports;

third and fourth switches coupled to the first and second A/D ports for switching in first and second pull up resistors onto the first and second A/D ports respectively;

a battery coupled to the charger, the battery including;

a capacity resistor coupled between ground potential and the first A/D port of the charger;

a thermistor coupled between ground potential and the second A/D port of the charger;

first and second zener diodes coupled between the capacity resistor and the thermistor in a cathode-to-cathode configuration, the first zener diode having an anode coupled to the first A/D port of the charger, the second zener diode having an anode coupled to the second A/D port of the charger; and

the first zener diode, the second zener diode, and the capacity resistor providing battery identifier parameters to the charging system.

4. A battery charging system as described in claim 3, wherein the charger determines the charge rate based on the battery identifier parameters.

5. A battery charging system as described in claim 4,

wherein the charger determines the value of the first zener diode, through the first and second A/D ports, by forward biasing the second zener diode and latching the first zener diode.

6. A battery charging system as described in claim 5,

wherein the charger determines the value of the second zener diode, through the first and second A/D ports, by forward biasing the first zener diode and latching the second zener diode.

7. A battery charging system as described in claim 3,

wherein the charger determines the value of the thermistor and the capacity resistor, through the first and second A/D ports, by switching in the first and second pull up resistors onto the first and second A/D ports respectively.

8. A charging system, comprising:

a battery including;

first and second zener diodes coupled in a cathode-to-cathode configuration, each of the first and second zener diodes having an anode;

a capacity resistor (Rc) coupled between ground potential and the anode of the first zener diode;

a thermistor (Rt) coupled between ground potential and the anode of the second zener diode;

a charger including;

first and second A/D ports;

a first selectable pull up resistor coupled to the first A/D port;

a second selectable pull up resistor coupled to the second A/D port, the first and second selectable pull up resistors biasing neither of the zener diodes when selected, the first and second A/D ports determining the value of the capacity resistor and the thermistor respectively when selected;

a first switching circuit coupled to the first A/D port for biasing the first zener diode and latching the second zener diode such that the value of the second zener diode can be determined by the first and second A/D ports;

a second switching circuit coupled to the second A/D port for biasing the second zener diode and latching the first zener diode such that the first and second A/D ports can determine the value of the first zener diode; and

wherein the value of the capacity resistor, the value of the thermistor, the value of the first zener diode, and the value of the second zener diode provide battery identification parameters.

9. The charging system of claim 8, wherein the charger utilizes the battery identification parameters to determine a charging rate.