Battery pack and a method for monitoring remaining capacity of a battery pack

• US 5,955,869 A
• Filed: 05/29/1998
• Issued: 09/21/1999
• Est. Priority Date: 07/17/1996
• Status: Expired due to Fees

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Duracell Incorporated (Berkshire Hathaway Incorporated)
• Inventors: Rathmann, Roland
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US09/087,306
• Time in Patent Office: 480 Days
• Field of Search: 320/136, 320/157, 320/132, 324/427, 324/428
• US Class Current: 320/132
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: H01M 10/42 Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells H01M10/60 takes precedence
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• 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 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/00036 Charger exchanging data with battery
• 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 pack and a method of monitoring remaining capacity of a battery pack. With this method, two different procedures are used to estimate that remaining capacity. In a first procedure, data generated on the battery pack is used to estimate remaining battery capacity; and in the second procedure, data transmitted to the battery pack from a host device is used to estimate remaining battery capacity. The battery pack switches between these two procedures under defined conditions; and for example, with the preferred embodiment described in detail in the present specification, the battery pack switches from the first procedure to the second procedure when the battery current falls below a threshold value.

Claims

1. A method for monitoring remaining capacity of a battery pack used to provide power to a host device, the battery pack including a battery and a processor, the method comprising:

establishing a remaining capacity value;

during first defined periods, using a first procedure to update periodically the remaining capacity value, including the steps of

i) using the battery pack to monitor a battery parameter and to generate data value representing the battery parameter,

ii) using the processor to process the data values generated by the battery pack to update periodically the remaining capacity value;

during second defined periods, using a second procedure to update periodically the remaining capacity value, including the steps of

i) transmitting data values from the host, device to the processor, and

ii) using the processor to process the data values transmitted to the processor from the host device to update periodically the remaining capacity value; and

switching between the first procedure and the second procedure under defined conditions.

2. A method according to claim 1, wherein:

the step of transmitting data values from the host device includes the step of transmitting from the host device to the processor power consumed data values representing the amount of power consumed by the host device; and

the step of using the processor to process the data values transmitted to the processor includes the step of reducing the remaining capacity value by said power consumed data values.

3. A method according to claim 1, wherein:

the first defined periods are when the monitored parameter is above a threshold value, and

the second defined periods are when the monitored parameter is below the threshold value.

4. A method according to claim 3, wherein the monitored battery parameter is the battery current.

5. A battery pack comprising:

terminal means for connecting the battery pack to a battery powered device;

a battery including at least on rechargeable battery cell connected to the terminal means, said battery having

i) a discharging state for supplying electrical power to the battery powered device, and

ii) a charging state for receiving electrical power form the terminal means;

a processor for monitoring remaining capacity of the battery, an including

i) means to establish a remaining capacity value,

ii) means to use a first procedure during the first periods to update periodically the remaining capacity value, wherein the first procedure includes monitoring a battery parameter, generating data values representing the battery parameter, and using the data values generated by the battery pack to update periodically the reminding capacity value,

iii) means to use a second procedure during the second periods to update periodically the remaining capacity value, wherein the second procedure includes receiving data values transmitted to the processor from the battery powered device, and using the data values received from the battery powered device to update periodically the remaining capacity value, and

iv) means to switch the processor between the first procedure and the second procedure under defined conditions.

6. A battery pack according to claim 5, wherein the means to use the second procedure includes means to receive power consumed data values from the battery powered device representing the amount of power consumed by the battery powered device, and to reduce the remaining capacity value by said power consumed data values.

7. A battery pack according to claim 6, wherein:

the means to identify first and second defined periods includes

i) means to monitor a parameter of the battery, and

ii) means to determine whether the monitored parameter is below a threshold value;

the first defined periods are when the monitored parameter is above the threshold value; and

the second defined periods are when the monitored parameter is below the threshold value.

8. A battery pack according to claim 7, wherein the monitored battery parameter is the battery current.