Battery cover assembly having integrated battery condition monitoring

• US 20040212342A1
• Filed: 05/25/2004
• Published: 10/28/2004
• Est. Priority Date: 04/06/2001
• Status: Active Grant

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Microchip Technology Incorporated
• Inventors: Batson, David C.
• Granted Patent: US 7,205,746 B2
• Time in Patent Office: Days
• US Class Current: 320/107
• CPC Class Codes: G01R 31/3644 Constructional arrangements
• CPC Class Codes: H01M 10/4257 Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
• CPC Class Codes: H02J 7/0047 with monitoring or indicating devices or circuits
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/005 Detection of state of health [SOH]
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A battery cover assembly having integrated battery condition monitoring for measuring electrical current passing to and from a battery post, including an electrically conductive collar for connecting to a post of a battery, and an electrically conductive terminal for receiving a connector of a load. An electrically conductive resistor having a known resistance extends between outer surfaces of the collar and the terminal. The battery cover assembly is incorporated into a battery, which may also include a voltage measuring device connected between the outer surfaces of the collar and the terminal for measuring the voltage drop across the resistor, memory for storing the known resistance of the resistor, and a digital processor programmed to receive the measured voltage drop from the voltage measuring device, retrieve the known resistance from the memory, and calculate current flow through the resistor based on the measured voltage drop and the known resistance, whereby current flow to and from the battery can be measured. A temperature measuring device may also be incorporated to measure temperature of the resistor located between the outer surfaces of the collar and the terminal. A resistance-temperature table may be stored in the memory and used to calculate the actual resistance of the resistor and then to compensate the current value from the voltage measured across the resistor.

Claims

1. A battery cover assembly, comprising:

a current measuring terminal assembly for measuring electrical current to and from a battery post, wherein the current measuring terminal assembly comprises

an electrically conductive first collar coupled to a first battery post of a battery;

an electrically conductive first terminal for coupling to an electrical load;

a resistor having a known resistance, the resistor being connected between the first collar and the first terminal, wherein current flow from the first battery post travels through the resistor in a first direction and current flow to the first battery post travels through the resistor in a second direction;

a first lead electrically coupled to a first end of the resistor proximate to the first collar, and

a second lead electrically coupled to a second end of the resistor proximate to the first terminal;

an electrically conductive second collar coupled to a second battery post of the battery;

an electrically conductive second terminal for coupling to the electrical load;

a first electrical conductor connected between the second collar and the second terminal;

a third lead electrically coupled to the first electrical conductor approximate to the second collar; and

a current measuring device coupled to the first and second leads.

2. The battery cover assembly according to claim 1, further comprising a voltage measuring device coupled to the first and third leads for measuring voltage between the first and second battery posts.

3. The battery cover assembly according to claim 1, wherein the current measuring device comprises a voltage measuring device coupled to the first and second leads for measuring voltage drop across the resistor, wherein the voltage drop across the resistor is proportional to the current therethrough.

4. The battery cover assembly according to according to claim 1, further comprising:

a first voltage measuring device coupled to the first and second leads for measuring voltage drop across the resistor, wherein the voltage drop across the resistor is proportional to the current therethrough;

a processor coupled to the first voltage measuring device;

a non-volatile memory coupled to the processor and storing the known resistance of the resistor, wherein the processor is programmed to receive the measured voltage from the first voltage measuring device, retrieve the known resistance value from the non-volatile memory, calculate the current flowing through the resistor based upon the measured voltage and the known resistance; and

a communications interface coupled to the processor.

5. The battery cover assembly according to claim 4, further comprising a second voltage measuring device coupled to the process and to the first and third leads for measuring voltage between the first and second battery posts.

6. The battery cover assembly according to claim 5, wherein the processor calculates power from the battery based upon the measured voltages from the first and second voltage measuring devices.

7. The battery cover assembly according to claim 5, wherein the first and second voltage measuring devices are analog-to-digital converters.

8. The battery cover assembly according to claim 4, wherein the communications interface is selected from the group consisting of CANbus, LINbus, RS-485, RS-232 and USB.

9. The battery cover assembly according to claim 4, further comprising:

a temperature measuring device coupled to the processor and in thermal communication with the resistor, wherein the temperature measuring device provides the resistor temperature to the processor; and

a table of temperature coefficients of resistivity for the resistor stored in the non-volatile memory;

wherein the processor calculates a temperature compensated resistance of the resistor based on a known resistance, the temperature coefficient of resistivity, and the measured temperature, and thereby calculates the current through the resistor based upon the measured voltage across the resistor and the temperature compensated resistance.

10. The battery cover assembly according to claim 9, wherein the temperature measuring device is a thermistor.

11. The battery cover assembly according to claim 10, wherein the thermistor is a solid state silicon thermistor.

12. The battery cover assembly according to claim 9, wherein the temperature measuring device is an RTD.

13. The battery cover assembly according to claim 1, wherein the resistance of the resistor is from about 50 microOhms to about 200 microOhms.

14. The battery cover assembly according to claim 1, wherein the resistance of the resistor is about 150 microOhms.

15. The battery cover assembly according to claim 1 wherein material for the resistor is selected from the group consisting of lead, copper, brass, bronze, manganese and manganin.

16. The battery cover assembly according to claim 1, wherein the method of forming the resistor is selected from the group consisting of powdered metal, stamped, machined, cast and forged.

17. The battery cover assembly according to claim 1, further comprising:

a battery case; and

at least one storage cell contained within the battery case for receiving and storing an electrical charge, wherein the first and second battery posts are coupled to the at least one storage cell.

18. The battery cover assembly according to claim 17, wherein the at least one storage cell is selected from the group consisting of Lead Acid, Nickel metal-hydride, Nickel cadmium, and Lithium ion.

19. The battery cover assembly according to claim 1, further comprising a clock coupled to the processor, wherein the processor is programmed to calculate a charge condition of the battery based upon charging current and time thereof.

20. The battery cover assembly according to claim 1, further comprising a clock coupled to the processor, wherein the processor is programmed to calculate a discharge condition of the battery based upon discharging current and time thereof.

21. The battery cover assembly according to claim 4 further comprising:

an electrically insulated battery cover assembly base containing separate compartments for the processor and non-volatile memory, and the first voltage measuring device so as to prevent exposure to external environmental and battery electrolyte;

a plastic cover attached to the battery cover assembly base so as to create a seal around the separate compartment; and

a communications port coupled to the communications interface.

22. The battery cover assembly according to claim 21, further comprising a light emitting diode (LED) display in the plastic cover and coupled to the processor for visually communicating battery condition status.

23. The battery cover assembly according to claim 22, further comprising a switch located on the plastic cover and coupled to the processor, wherein manually activating the switch causes the processor to indicate on the LED display the battery condition status.

24. The battery cover assembly according to claim 22, wherein the LED display comprises a green LED to indicate a healthy battery, a yellow LED to indicate a marginal battery which should be service, and red LED to indicate the battery should be replaced.

25. The battery cover assembly according to claim 4, wherein the processor analyzes starting current to determine changes in battery response.

26. The battery cover assembly according to claim 4, wherein the processor analyzes starting current for determining changes in battery response.

27. The battery cover assembly according to claim 4, wherein the processor analyzes battery internal impedance at high current for determining pending battery failure.

28. The battery cover assembly according to claim 4, further comprising a control output for controlling an intelligent switch, wherein the intelligent switch disconnects the battery from parasitic loads when a low voltage battery condition is detected.