Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Reexamination Certificate
2000-08-28
2002-08-13
Toatley, Gregory (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
C320S134000
Reexamination Certificate
active
06433513
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for evaluating the service life of a secondary battery and a computer-readable recorded medium containing a program for executing a secondary battery evaluation process.
2. Description of the Related Art
Secondary batteries are used as a power source in information processing devices and portable information processing terminals with or without the charging section. Because such secondary batteries have a finite service life depending on the of type of battery, it is essential to be able to forecast the service life so that service interruption would not be experienced. For portable information devices and personal computers based on volatile memory, it is especially important to maintain a full power source because the power failure leads to a loss of information stored in the volatile memory.
An example of battery life evaluation apparatuses for evaluating the service life of batteries is disclosed in a Japanese Patent Application, First Publication, Hei7-201370.
This apparatus is designed to evaluate the service life of a battery by recording charging data, such as charging current, charging time, voltage at charge startup, voltage at charge completion and the number of charges performed, in a charging data storage section
1
, and recording the basic operating parameters of the secondary battery in a basic parameter storage section
2
, and the stored data in the charge data storage section
1
and the basis parameter storage section
2
are sent to and compared in an evaluation section
3
.
Another example of battery life evaluation apparatus is disclosed in a Japanese Patent Application, First Publication, Hei7-17966.
This apparatus evaluates service life of storage batteries installed in vehicles, and is designed to evaluate a storage battery
1
in an electric car. In this apparatus, battery usage data such as properties of the battery
1
, conditions of usage, historical data and others are recorded in RAM
8
-
6
, and for evaluation of battery life, the battery
1
is removed from the car and is connected to an external computer, with an intervening interface circuit
8
-
5
, which analyzes the recorded chronological usage data together with the historical data recorded in RAM
8
-
6
through the interface circuit
8
-
5
. The apparatus is then returned to the electric car, and at suitable intervals, the data recorded in RAM
8
-
6
(such as battery properties, conditions of usage, historical data and others) are accessed and compared with real-time data obtained by way of the interface circuit
8
-
6
so as to evaluate the extent of degradation experienced by the storage battery
1
, in other words, to evaluate the remaining service life of the battery
1
.
Therefore, in both of these apparatuses that are disclosed, evaluation is performed according to chronological historical data of secondary battery or storage battery.
However, in both of these battery life evaluation apparatuses, although the service life is supposed to be evaluated according to chronological historical data, many of the essential factors necessary for accurate evaluation of secondary batteries and storage batteries are not being considered in evaluating the service life of the secondary batteries and storage batteries, resulting that accurate determination of battery service life cannot be obtained.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method and an apparatus for providing accurate data on service life and useable time remaining in a secondary battery for use in portable terminal devices, and to provide a recorded medium containing service life evaluation program for a secondary battery.
To resolve the problems outline above, the present invention provides a first aspect of the invention in a method for determining a service life of a secondary battery subjected to repeated charging/discharging cycles; comprising the steps of: storing, in a memory device, pre-measured values of an index related to decrements in service life of the battery, which is fully charged after each discharge event during a charging/discharging cycle, to correspond to discharged amounts produced during charging/discharging cycles experienced by the battery during the respective charging/discharging cycles; computing a discharged amount after each charging/discharging cycle; obtaining an index to correspond to the discharged amount from the memory device; computing a service life remaining after the current cycle of charging/discharging according to a maximum service life of the battery and the values of the index obtained in individual charging/discharging cycles, including the current charging/discharging cycle; and determining whether or not the remaining service life computed is less than a pre-determined reference value, and deeming that the battery has reached an end of the service life when the computed value is less than the reference value.
A second aspect of the invention relates to a method for determining a service life of a secondary subjected to repeated charging and discharging processes, comprising the steps of: storing, in a memory device, pre-measured values of an index related to decrements in service life of the battery and various amounts of charges and discharges produced in charging/discharging cycles corresponding to the charged and discharged amounts experienced by the battery during the respective charging/discharging cycles; computing a charged amount and a discharged amount after each cycle of charging/discharging; obtaining an index to correspond to the computed charged amount and the computed discharged amount with reference to the memory device; computing a service life remaining after the current cycle of charging/discharging according to a maximum service life of the battery and the values of the index obtained in individual charging/discharging cycles, including the current charging/discharging cycle; and determining whether or not the remaining service life computed is less than a pre-determined reference value, and deeming that the battery has reached an end of the service life when the computed service life is less than the reference value.
A third aspect of the invention relates to a method for determining a useable time for one additional use, after a current cycle of charging/discharging of a secondary battery subjected to repeated cycles of charging/discharging, comprising the steps of: computing a service life of the battery remaining after the current cycle of charging/discharging of the battery; computing an average amount of consumed service life by dividing a cumulative value of consumed service life of individual cycles from a first cycle to the current cycle of charging/discharging by a number of cycles of charging/discharging; computing an average use time of the battery from the first cycle to the current cycle; and computing a useable time for one additional use of the battery after the current cycle of charging/discharging, according to the remaining service life computed, the average amount of consumed service life, and the average use time of the battery.
A fourth aspect of the invention relates to the method according to claim
3
, wherein the remaining service life of the battery is obtained by subtracting a cumulative consumed service life including the current cycle of charging/discharging from the maximum service life of the battery.
A fifth aspect of the invention relates to the method according to claim
3
or
4
, wherein the remaining service life of the battery is obtained by: storing, in a memory device, pre-measured values of an index related to decrements in service life of the battery, which is fully charged after each discharge event during a charging/discharging cycle, to correspond to discharged amounts produced during charging/discharging cycles experienced by the battery during the respective charging/discharging cycles; computing a first cumulative discharged amount from individual cycles of char
McGinn & Gibb PLLC
NEC Infrontia Corporation
Toatley Gregory
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