Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Reexamination Certificate
2000-05-24
2001-07-10
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
Reexamination Certificate
active
06259232
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to battery packs, and more particularly, but not by way of limitation, to rechargeable battery packs having circuitry for monitoring and accumulating various operating parameters of a battery cell within the rechargeable battery pack, whereby these parameters can be used to accurately determine the remaining operating life of the rechargeable battery pack.
BACKGROUND OF THE INVENTION
Many portable electronic systems, such as laptop computers and cellular phones, utilize rechargeable battery packs to receive their power. Such battery packs have the advantage that they are portable, relatively weight efficient, and can be charged and discharged many times. However, due to certain characteristics of existing rechargeable battery packs, an accurate indication of the remaining charge is very difficult to determine.
As can be appreciated, it is very desirable to be able to accurately determine the remaining operating life of a rechargeable battery pack used in a system such as a laptop computer. This enables a user to get maximum use out of the rechargeable battery pack. This is especially critical when the remaining energy of the rechargeable battery pack falls below the operating threshold of the computer. A user would ideally want to be able to safely shut down the computer prior thereto, thereby preventing any potential loss of information.
The amount of the charge flowing into and out of the rechargeable battery pack during charging and discharging are parameters that can be monitored and used to calculate the remaining charge of a rechargeable battery. As can be further appreciated, the more accurately and reliably this information is measured and accumulated, the more accurate the calculation of the remaining charge of the rechargeable battery.
In addition to the discharge that occurs during regular use of a rechargeable battery pack, a rechargeable battery pack will also have a certain amount of self-discharge when not in use. This self-discharge is very difficult to account for when calculating the remaining charge of the rechargeable battery. In existing rechargeable battery packs, the amount of time the rechargeable battery pack is not being used is very difficult to determine. Additionally, the amount of self-discharge of a rechargeable battery will fluctuate with varying temperatures. As can be appreciated, a problem with existing rechargeable battery packs is that they do not take into account the self-discharge of the battery, nor do they take into account the varying temperatures when calculating the remaining charge of the rechargeable battery.
Therefore, there is a need for a rechargeable battery pack having accurate and reliable gas gauge circuitry that incorporates self-discharge accounting to determine the remaining operating life of the rechargeable battery pack.
SUMMARY OF THE INVENTION
The present invention overcomes the above identified problems as well as other shortcomings and deficiencies of existing technologies by providing a battery pack with highly accurate, oscillator driven gas gauge circuitry used to accurately determine the remaining operating life of the battery pack.
The present invention further provides a rechargeable battery pack with low powered gas gauge circuitry for monitoring and accumulating various operating parameters of the rechargeable battery pack, whereby the determination can be made as to the remaining operating life of the rechargeable battery pack. The rechargeable battery pack includes a current monitor for measuring the charge having flowed into and out of a battery cell within the rechargeable battery. An integrated current accumulator connected to the current monitor is used to maintain a net accumulated total of current flowing into and out of the battery cell. A charging current accumulator, which is also coupled to the current meter is used to maintain a measure of the total charge having flowed into the battery cell, while a discharging current accumulator is used to maintain the total charge having flowed out of the rechargeable battery. A highly accurate oscillator is used to drive the accumulators to greatly increase the accuracy of the gas gauge functions.
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Douglass James M.
Downs Richard E.
Ezell Richard William
Dallas Semiconductor Corporation
Jenkens & Gilchrist a Professional Corporation
Tso Edward H.
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