U.S. patent application number 09/820192 was filed with the patent office on 2001-12-27 for method to determine capacity of a battery.
Invention is credited to Kurihara, Toshitake, Okada, Tetsuya, Suzuki, Katsuhiro.
Application Number | 20010054879 09/820192 |
Document ID | / |
Family ID | 18609169 |
Filed Date | 2001-12-27 |
United States Patent
Application |
20010054879 |
Kind Code |
A1 |
Okada, Tetsuya ; et
al. |
December 27, 2001 |
Method to determine capacity of a battery
Abstract
This method to determine capacity of a battery computes capacity
in current value and then converts it into capacity in power value,
or computes capacity in power value and then converts it into
current value. This method to determine capacity of a battery
detects either discharge current or charge current or both, and
computes capacity of battery in current value, which is then
converted into capacity in power value by way of multiplication by
the correcting constant which varies in accordance with capacity in
current value. This method to determine capacity of a battery
detects battery voltage or detects either discharge current or
charge current or both of the battery, then computes battery
capacity in power value, and converts capacity in power value so
computed into capacity in current value by way of multiplication by
the correcting constant which varies in accordance with capacity in
power value.
Inventors: |
Okada, Tetsuya; (Hyogo,
JP) ; Suzuki, Katsuhiro; (Hyogo, JP) ;
Kurihara, Toshitake; (Hyogo, JP) |
Correspondence
Address: |
FLESHNER & KIM, LLP
P.O. Box 221200
Chantilly
VA
20153-1200
US
|
Family ID: |
18609169 |
Appl. No.: |
09/820192 |
Filed: |
March 29, 2001 |
Current U.S.
Class: |
320/132 |
Current CPC
Class: |
G01R 31/3828 20190101;
H02J 7/0048 20200101; H02J 7/0047 20130101 |
Class at
Publication: |
320/132 |
International
Class: |
H02J 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 30, 2000 |
JP |
094074/2000 |
Claims
What is claimed is:
1. A method to determine capacity of a battery, comprising the
steps of: (1) detecting either discharge current or charge current
of the battery, or both; (2) computing capacity of the battery
based on the detected electric current value; and (3) computing
capacity in power value by way of multiplying capacity in the
computed current value by correcting constant which varies in
accordance with capacity in current value.
2. A method to determine capacity of a battery according to claim
1, wherein the remaining capacity in current value is computed
based on the multiplication of discharge current and then the
remaining capacity in power value is computed by way of multiplying
the remaining capacity in current value by the correcting constant
which varies in accordance with the remaining capacity in current
value.
3. A method to determine capacity of a battery according to claim
2, wherein the remaining capacity of battery is relative remaining
capacity.
4. A method to determine capacity of a battery according to claim
1, wherein current flowing to the battery is detected by a consumed
current/voltage detector which is electrically connected to the
battery.
5. A method to determine capacity of a battery according to claim
4, wherein output voltage of the consumed current/voltage detector
is A/D converted into digital signals and then the remaining
capacity is computed and corrected by using the digital
signals.
6. A method to determine capacity of a battery according to claim
2, wherein the remaining battery capacity is computed by
subtracting the multiplication of consumed current either from FCC
(Full Charge Capacity), which signifies a fully charged battery
capacity, or from design capacity.
7. A method to determine capacity of a rechargeable battery
according to claim 3, wherein the computing step of correcting
constants comprises the steps of: (1) discharging a fully charged
battery at the constant current till the remaining capacity
measures n%, at which the relative remaining capacity of the
battery in current value is n%; (2) detecting m% of discharge power
by complete discharging at the constant power without recharging,
at which the detected m% is the relative remaining capacity in
power value; and (3) calculating m/n, at which the correcting
constant at n% relative remaining capacity in current value is
calculated.
8. A method to determine capacity of a battery comprising the steps
of: (1) detecting battery voltage and either discharge current or
charge current of a battery or both; (2) computing battery capacity
in power value; (3) computing capacity in current value by way of
multiplying the capacity in power value so computed by the
correcting constant which varies in accordance with capacity in
power value.
9. A method to determine capacity of a battery according to claim
8, wherein the remaining capacity in power value is calculated from
multiplication of discharge power and the remaining capacity in
power value so calculated is multiplied by the correcting constant
which varies in accordance with the remaining capacity in power
value and thus the remaining capacity in current value is
determined.
10. A method to determine capacity of a battery according to claim
9, wherein the remaining capacity of battery is relative remaining
capacity.
11. A method to determine capacity of a battery according to claim
8, wherein current flowing to the battery is detected by a consumed
current/voltage detector which is electrically connected to the
battery.
12. A method to determine capacity of a battery according to claim
11, wherein output voltage of the voltage detector and the consumed
current/voltage detector is A/D converted into digital signals and
then the remaining capacity is computed and corrected by using the
digital signals.
13. A method to determine capacity of a battery according to claim
9, wherein the remaining battery capacity is computed by
subtracting the multiplication of consumed power either from FCC,
which signifies a fully charged battery capacity, or from design
capacity.
14. A method to determine capacity of a rechargeable battery
according to claim 3, wherein the computing step of correcting
constants comprises the steps of: (1) discharging a fully charged
battery at the constant current till the remaining capacity
measures n%, at which the relative remaining capacity of the
battery in current value is n%; (2) detecting m% of discharge power
by complete discharging at the constant power without recharging,
at which detected m% is the relative remaining capacity in power
value; and (3) calculating m/n, at which the correcting constant at
n% relative remaining capacity in current power is calculated.
15. A method to determine capacity of a battery pack, comprising
the steps of: (1) detecting consumed current of the battery by
converting into voltage at a consumed current/voltage detector; (2)
detecting voltage of battery at a voltage detector; (3) converting
analogue signals which are outputted at the consumed
current/voltage detector into digital signals at a first A/D
converter; (4) converting analogue signals which are outputted at
the voltage detector into digital signals at a second A/D
converter; (5) multiplying either consumed electric power of the
battery based on the output signals of the first A/D converter and
the second A/D converter or consumed current outputted at the first
A/D converter by using a multiplier; (6) detecting a discharge
termination voltage based on the signals outputted at the second
A/D converter by using a low battery detector; (7) generating
trigger for converting analogue signals into digital signals to the
first A/D converter and the second A/D converter at the prescribed
intervals by using a timer; (8) computing remaining capacity by
subtracting either consumed current or power from fully charged
capacity by using a remaining capacity calculator; (9) converting
either the remaining capacity computed at the remaining capacity
calculator or the multiplication outputted at the multiplier from
current value into power value, or power value into current value,
by using a converter; (10) transmitting the remaining capacity to
an electronic device at SMBus data communication processor.
16. A method to determine capacity of a battery pack cited in claim
15, wherein the battery pack is connected to the electronic device
such as computer via SMBus.
17. A method to determine capacity of a battery pack cited in claim
15, wherein the consumed current/voltage detector outputs electric
current of the battery as output voltage from a differential
amplifier.
18. A method to determine capacity of a battery pack according to
claim 15, wherein relative remaining capacity in current value is
converted into that in power value by the steps comprising; (1)
inputting the relative remaining capacity in current value from the
remaining capacity calculator into the converter; (2) determining
the correcting constant for the relative remaining capacity so
inputted at the converter; and (3) converting into the relative
remaining capacity in current value by multiplying the relative
remaining capacity in power by the correcting constant.
19. A method to determine capacity of a battery according to claim
15, wherein the steps to convert the relative remaining capacity in
power value into the relative remaining capacity in current value
are made up of: (1) a step to communicate the remaining capacity in
power value to the converter from the remaining capacity
calculator; (2) a step to pick out, at the converter, the
correcting constant for the relative remaining capacity so
communicated; and (3) a step to multiply the relative remaining
capacity in power value by the correcting constant to convert the
relative remaining capacity in power value into that in current
value.
Description
[0001] This application is based on application No. 094074 flied in
Japan on Mar. 30, 2000, the content of which incorporated hereinto
by reference.
BACKGROUND OF THE INVENTION
[0002] This invention primary relates to a method to determine
capacity such as the remaining battery capacity of a battery in
value of electric current as well as in value of electric
power.
[0003] Data such as the remaining capacity of a battery used as the
source for electronic device such as computer is required to be
determined in value of electric current or/and in value of electric
power. The remaining capacity in electric current value is
determined by subtracting the multiplication of discharge current
from the fully charged battery capacity, The remaining battery
capacity in electric power value is determined by subtracting the
multiplication of discharge power from the fully charged battery
capacity. The remaining capacity in electric current value is
calculated from the multiplied value of discharge current. The
remaining capacity in electric power value is computed from
multiplication of the product of multiplication of current value by
voltage. The remaining power in a battery should always be computed
by multiplication of battery voltage by discharge current, followed
by multiplication of the product of multiplication so conducted, as
the voltage of a battery constantly changes as battery continues to
discharge.
[0004] As stated above, the means differ as to calculating the
remaining capacity of a battery in electric current value and in
electric power value; so each means should be practiced separately
in order to obtain the remaining capacity both in current value and
in power value. In such a case calculation requires a very
complicated system and heavy workload, and results in technical and
financial difficulties, which is considered as a shortcoming of the
above stated means.
[0005] The present invention has been developed in order to
overcome the above stated shortcoming. The primary object of this
invention is to provide a method which determines capacity of a
battery in value of both electric current and of electric power in
a very simple way.
SUMMARY OF THE INVENTION
[0006] Method to determine capacity of a battery, according to the
present invention cites either to calculate capacity in electric
current value alone and then to convert it into electric power
value, or to calculate capacity in electric power value alone and
then to convert it into electric current value. Method according to
the present invention calculates capacity in electric current value
and converts it into capacity in electric power value.
Alternatively the method calculates capacity in electric power
value and converts it into capacity in electric current value.
[0007] The method of determining battery capacity calls for either
detecting the discharging electric current or detecting the
recharging current or both, and thus determines battery capacity in
terms of electric current value. Capacity in electric current value
so determined is multiplied by the correcting constant which varies
in accordance with current capacity and thus capacity in electric
power value is determined.
[0008] In the present method, for example, the remaining capacity
of a battery in electric current value is first calculated from the
multiplication of discharge current of the battery and then the
remaining capacity in power value is calculated by multiplying the
remaining capacity in current value so calculated by the correcting
constant which varies in accordance with the remaining capacity in
current value. In this way the remaining battery capacity is
computed as the relative remaining capacity.
[0009] According to the method of determining capacity of a
battery, capacity of a battery is first computed in electric power
value by detecting the battery voltage and multiplication of
discharge current or charge current or both. Capacity in electric
power value so calculated is converted into capacity in electric
current value by way of being multiplied by the correcting constant
which varies in accordance with capacity in power value.
[0010] In the present method, for example, the remaining capacity
of a battery in power value is first calculated from the
multiplication of discharge power and then the remaining capacity
in current value is computed by multiplying the remaining capacity
in power value by the correcting constant which varies in
accordance with the remaining capacity in electric power value. In
this way the remaining battery capacity is calculated as the
relative remaining capacity.
[0011] The method of the present invention to determine capacity of
a battery is distinctly different from others in a way that it
calculates battery capacity in electric current value as well as
electric power value in a very simple way. The reason is that by
this method capacity is determined by calculating capacity in
current value and converting it into power value or calculating
capacity in power value and then converting it into capacity in
current value. In this method of the present invention capacity in
electric power value is calculated by multiplying capacity in
electric current value by the correcting constant which varies in
accordance with capacity in current value. Or capacity in current
value is calculated by multiplying capacity in power value by the
correcting constant which varies in accordance with capacity in
power value. In this way the method of the present invention
assures a simple and inexpensive device for the circuit in order to
obtain battery capacity in electric power value as well as in
electric current value.
[0012] The above and further objects and features of the invention
will more fully be apparent from the following detailed description
with accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 shows a block diagram of the circuit, used for the
embodiment of this invention to determine capacity of a
battery.
[0014] FIG. 2 shows an example of a battery to be used for
determining battery capacity
[0015] FIG. 3 shows a flow chart to illustrate steps of converting
RSOC in electric current value into RSOC in electric power
value.
[0016] FIG. 4 shows a flow chart to illustrate steps of converting
RSOC in electric power value into RSOC in electric current
value.
[0017] FIG. 5 shows a flow chart to illustrate steps of converting
full charge capacity in current value into that in power value.
[0018] FIG. 6 shows a flow chart to illustrate steps of converting
full charge capacity in power value into that in current value.
[0019] FIG. 7 shows a flow chart to illustrate steps of computing
ASOC In both current value and power value from RSOC in current
value.
DETAILED DESCRIPTION OF THE INVENTION
[0020] FIG. 1 shows a block diagram of a circuit stored in a
battery pack for the purpose of determining battery capacity
according to the present method. A battery pack storing this
circuit is to be attached to an electronic device such as computer,
supplying electric power as well as communicating data such as
battery capacity to the electronic device. An electronic device
detects the remaining capacity of battery 1, with information
communicated from the battery pack at the prescribed sampling
timing.
[0021] The battery pack shown in FIG. 1 has a consumed
current/voltage detector 2, which detects consumed current of
battery 1 and converts it into voltage; a voltage detector 3, which
detects voltage of battery 1; a first A/D converter 4, which
converts analogue signals outputted at the consumed current/voltage
detector 2 into digital signals; a second A/D converter 5, which
converts analogue signals outputted at the voltage detector 3 into
digital signals; a multiplier 6, which multiplies consumed electric
power of battery 1 from signals outputted at the first A/D
converter 4 and at the second A/D converter 5, or multiplies
consumed current outputted at the first A/D converter 4; a low
battery detector 7, which detects voltage at the completion of
discharge based on signals outputted at the first A/D converter 4;
a timer 8, which operates trigger at prescribed intervals to the
first A/D converter 4 and the second A/D converter 5 in order to
convert analogue signals into digital signals; the remaining
capacity calculator 9, which computes the remaining capacity by
subtracting consumed electric power or consumed electric current
from fully charged battery capacity; converter 10, which converts
value in power into value in current or the other way round, of the
remaining battery capacity computed at the remaining capacity
calculator 9, or of the multiplication outputted at the multiplier
6; SMBus data communication processor 11, which communicates and
outputs the remaining battery capacity to an electronic device such
as computer. This battery pack is attached to an electronic device
such as computer with SMBus interposed in between.
[0022] The consumed current/voltage detector 2 is provided with an
electric current resistor with low resisting power connected to
battery 1 in series and at the same time provided with a
differential amplifier to amplify the voltage generated at the two
ends of the resistor. This consumed current/voltage detector 2
outputs current in value flowing to battery 1 as voltage outputted
at the differential amplifier. Voltage outputted at the
differential amplifier is the product of multiplication of the
amount of current flowing to battery 1 by the constant.
[0023] Voltage is outputted at consumed current/voltage detector 2
and voltage detector 3 in analogue signals. The first A/D converter
4 and the second A/D converter 5 convert analogue signals into
digital signals and output as such, in order for digital processing
to compute the remaining capacity and make correction. The first
A/D converter 4 and the second A/D converter 5 convert voltage
signals communicated into digital signals upon trigger movement
directed by timer 8, and output as such.
[0024] The multiplier 6 multiplies either consumed current or
consumed power when battery 1 is discharged; and multiplies either
charge current or charge power when battery 1 is charged. This
circuit preferably be used for multiplying current value, as
multiplication of current is performed more easily than
multiplication of power. To multiply electric power, multiplication
of product of the multiplication of current value by power value
should be performed. For this purpose the output at the first A/D
converter 4 and the second A/D converter 5 should be multiplied. To
multiply current value, however, multiplication of the output at
the first A/D converter 4 alone serves the purpose, which proves to
be a comparatively simple computation. Another possible way is to
multiply power at this circuit and then convert the multiplication
in current value into that in power value.
[0025] At the remaining capacity calculator 9 the remaining
capacity of battery 1 is calculated by subtracting the
multiplication of consumed electric current or consumed electric
power from capacity of fully charged battery, so called FCC (full
charge capacity) or design capacity and then the remaining capacity
so compute is outputted to the converter 10. FCC which represents a
capacity of fully charged battery 1 is computed from the
multiplication of charge current. Not all electric current used for
charging battery 1 is expended for the said purpose, so FCC, which
signifies capacity when fully charged, is rightly calculated from
multiplying the multiplication of charge current by the charge
efficiency factor. There are several ways of indicating the
remaining battery capacity; RSOC (Relative State Of Charge)
considers the capacity as 100% charged when a batter is fully
recharged; ASOC (Absolute State Of Charge) considers the design
capacity as 100% charged; or RC (Remaining Capacity) is calculated
by the absolute value of Ah or Wh. As for the way to output in
relative value, there are also a couple of ways available; on is a
way to calculate in current value and another is one in power
value.
[0026] At the circuit illustrated in FIG. 1 the remaining capacity
of battery 1 is detected. However the remaining capacity is not
always necessary to be detected. There are other performances
possible, as multiplying charge current or multiplying discharge
current of battery 1, and calculation by discharged power or its
multiplication. As the remaining capacity is determined by
subtracting discharge capacity from fully charged capacity, the
remaining capacity calculator is indispensable in this circuit.
Multiplication of discharge current or charge current, or
multiplication of discharge power or charge power can be performed
at the multiplier 6, so the signals to perform these calculations
are outputted from the multiplier 6 directly to the converter
10.
[0027] The low battery detector 7, supplied with the output from
the second A/D converter 5, detects whether the voltage of the
battery 1 drops below the discharge termination voltage. This
detector transmits the discharge termination voltage signal to the
converter 10 when the voltage of battery 1 actually drops below the
discharge termination voltage.
[0028] The converter 10 converts the remaining battery capacity
communicated from the remaining capacity calculator 9, from power
value into current value or from current value into power value.
The remaining capacity in power value is calculated by multiplying
the remaining capacity in current value by the correcting constant
and the remaining capacity in current value is calculated by
multiplying the remaining capacity in power value by the correcting
constant. The correcting constants are stored in memory attached to
the converter 10. The Table 1 shows the correcting constants stored
in memory at the converter 10, which correct the remaining capacity
in current value into the remaining capacity in power value.
1TABLE 1 RSOC 100 99- 80- 60- 40- 20- 10- 0 (mAh) 81 61 41 21 11 1
Correcting 100 99 98 97 96 93 93 100 Constants
[0029] Shown in the table above are the correcting constants which
correct the remaining capacity in current value into that in power
value. RSOC signifies the relative remaining capacity established
when fully charged capacity of a battery is considered as 100%
charged, RSOC in current value is converted into RSOC in power
value when multiplied by the correcting constant in the table which
is picked out in accordance with RSOC in current value. When RSOC
in current value stands at 0 or 100%, the correcting constant is
100% that is 1; when RSOC in current value stands somewhere between
0-100 the correcting constant becomes less than 100% that is less
than 1. The device which stores the correcting constants for RSOC
in current value in memory attached to the converter 10 converts
electric current value into electric power value in an easy manner.
A table of correcting constants is not necessary when function for
RSOC in current value is inputted in memory at the converter 10. In
such a case function works for converting current value into power
value.
[0030] The correcting constants which converts current into power
are computed by discharging a battery which is the same type as
used in the circuit in FIG. 1 as a sample and then so computed
correcting constants are stored into memory. For example, the
correcting constants are computed in the following way.
[0031] (1) Fully charged battery 1 is discharged at constant
current till the remaining capacity becomes n%. RSOC in current
value of battery 1 at this stage is considered to be n%.
[0032] (2) Then this battery 1, with no recharging, continues its
discharge at constant power till it completes discharge. In such a
case when discharge power is detected as m%, this m% is considered
to be RSOC in power value.
[0033] (3) the correcting constant at which RSOC in current value
stands at n% can be calculated by calculation of m/n outputs.
[0034] By setting n% at various points in this manner correcting
constants for converting RSOC at 100-0% In current value into that
in power value are computed. The correcting constants thus computed
are stored as a table in memory at the converter 10, or function
for correction is stored in memory at the converter. The converter
10 computes RSOC in power value by way of multiplying RSOC in
current value by the correcting constant.
[0035] While the method stated above states how to convert RSOC in
current value into RSOC in power value, there is a way to convert
RSOC in power value into current value. In this case the correcting
constant for RSOC at m% in power value should be computed by
applying n/m as a correcting constant in step (3) stated above. The
correcting constants are stored as a table or as function in memory
at the converter 10. The converter 10 converts RSOC in power value
into RSOC in current value by way of multiplying RSOC in power
value by the stored correcting constant.
[0036] The way how the converter 10 converts RSOC in current value
into RSOC in power value is stated above. The same converter can
convert ASOC in current value into ASOC in power value, ASOC being
the remaining capacity when nominal capacity so-called DC (Design
Capacity) is considered as 100%. ASOC is computed from calculation
of RSOC which then is converted into ASOC in the remaining
capacity. The difference between RSOC and ASOC lies in the
difference of full capacity upon which calculation is based.
Therefore conversion is easily performed by the following
equation.
ASOC=RSOC.times.(FCC/DC)
[0037] For example in the case when fully charged capacity FCC
drops to 50% of DC, ASOC of battery 1 becomes one half capacity of
RSOC. Standard value for ASOC which is 100% becomes twice more as
in the case above.
[0038] In the circuit shown in FIG. 1 the output at the remaining
capacity calculator 9 is communicated to the converter 10, thus the
remaining capacity of battery 1 is inputted at the converter 10
either in current value or in power value. The method of the
present invention to determine the capacity of a battery is not
restricted to determination of the remaining capacity alone.
Capacity of a battery could be the multiplication of discharge
current or charge current. The multiplication can be performed
either in power value or in current value and then converted by way
of multiplication by the correcting constant. The correcting
constants used in conversion are calculated by detecting electric
power and electric current in charging or discharging a sampl
battery.
[0039] As illustrated in FIG. 2 when a battery with DC of 4.8 Ah
and 56 Wh is charged to show the multiplication of charge current
to be 4.9 Ah and then the same battery is discharged and from the
multiplication of discharge current RSOC in current value is
calculated to be 50%, the converter 10 computes RSOC in power value
in the following way. RSOC in power value is calculated by way of
multiplying RSOC in current value by the correcting constant. When
RSOC in current value stands at 50%, the correcting constant should
be 97% as read in the table. Therefore RSOC in power value is
calculated in the following equation.
RSOC(in power value)=(RSOC in current value).times.(correcting
constant)=50% .times.0.97=48%
[0040] Full charge capacity (Wh) of this battery is calculated as
follows. As DC measured in Ah is 4.8 Ah and FCC is 4.9 Ah, FCC
should be 4.9/4.8 times as much as DC. So FCC measured in Wh is
computed as follows. This computation is performed at the converter
10.
FCC(Wh)=56 Wh.times.4.9/4.8=57.16 Wh
[0041] ASOC of this battery is calculated as follows. This equation
is also performed at the converter 10.
ASOC(in current
value)=RSOC.times.(FCC/DC)=50%.times.4.9/4.8=51%
ASOC(in power value)=48%.times.57.16/56=49%
[0042] RC(remaining capacity) of this battery measured in Ah and Wh
is calculated as follows.
RC(in current value)=FCC(in current value).times.RSOC(in current
value)=4.9 Ah.times.50%=2.45 Ah
RC(In power value)=FCC(in power value).times.RSOC(in power value)
=57.16 Wh.times.48%=27.43 Wh
[0043] The circuit illustrated in FIG. 1 converts RSOC in current
value into RSOC in power value following the steps shown in the
flow chart below which is illustrated in the FIG. 3
[0044] [In the step when n=1]
[0045] RSOC in current value is inputted from the remaining
capacity calculator 9 to the converter 10.
[0046] [In the step when n=2]
[0047] The converter 10 picks out the right correcting constant for
inputted RSOC. The converter 10 determines from the table stored in
memory or from function the correcting constant for RSOC in current
value.
[0048] [In the step when n=3]
[0049] RSOC in current power is multiplied by the correcting
constant to be converted into RSOC in power value.
[0050] The circuit illustrated in the FIG. 1 converts RSOC in power
value into RSOC in current value following the steps shown in the
flow chart below which is illustrated in the FIG. 4,
[0051] [In the step when n=1]
[0052] RSOC in power value is inputted from the remaining capacity
calculator 9 to the converter 10.
[0053] [In the step when n=2]
[0054] The converter 10 picks out the correcting constant for
inputted RSOC. The converter 10 determines from the table stored in
memory or from function the correcting constant for RSOC in power
value.
[0055] [In the step when n=3]
[0056] RSOC in power value is multiplied by the correcting constant
to be converted into RSOC in current value.
[0057] The converter 10 converts ASOC in current value into power
value or ASOC in power value into current value.
[0058] The circuit illustrated in FIG. 1 converts charge capacity
in current value into that in power value following the steps in
the flow chart below which is illustrated in the FIG. 5.
[0059] [In the step when n=1]
[0060] Charge capacity in current value is inputted to the
converter 10 from the multiplier 6.
[0061] [In the step when n=2]
[0062] The converter 10 picks out the correcting constant for the
charge capacity inputted. The converter 10 determines the
correcting constant for the charge capacity in current value from
the table or function stored in memory.
[0063] [In the step when n=3]
[0064] The charge capacity in current value is multiplied by the
correcting constant to be converted into the charge capacity in
power value.
[0065] The circuit illustrated in the FIG. 1 converts the charge
capacity in power value into that in current value, following the
steps in the flow chart below which is illustrated in the FIG.
6.
[0066] [In the step when n=1]
[0067] The charge capacity in power value is inputted to the
converter 10 from the multiplier 6.
[0068] [In the step when n=2]
[0069] The converter 10 picks out the correcting constant for the
charge capacity inputted. The converter picks out the correcting
constant for the charge capacity in power value from the table or
function stored in memory.
[0070] [In the step when n=3]
[0071] The charge capacity in power value is multiplied by the
correcting constant to be converted into the charge capacity in
current value.
[0072] In the similar steps as stated above the discharge capacity
of a battery in current value can be converted into the discharge
capacity in power value.
[0073] The circuit illustrated in the FIG. 1 can also compute ASOC
in current or in power value from RSOC in current value following
the steps in the flow chart below which is illustrated in FIG.
7.
[0074] [In the step when n=1]
[0075] FCC is detected from the multiplication of charge current
measured when battery 1 is fully charged. FCC is computed by
multiplying the multiplication of charge current by the charge
efficiency figure.
[0076] [In the step when n=2]
[0077] The correcting constant is picked out based on RSOC in
current value.
[0078] [In the step when n=3]
[0079] RSOC in current value is multiplied by the correcting
constant to compute RSOC in power value.
[0080] [In the step when n=4]
[0081] RSOC in current value is multiplied by FCC/DC to compute
ASOC in current value
[0082] [In the step when n=5]
[0083] RSOC in power value is multiplied by FCC/DC to compute ASOC
in power value.
[0084] As this invention may be embodied in several forms without
departing from the spirit of essential characteristics thereof, the
present embodiment is therefore illustrative and not restrictive,
since the scope of the invention is defined by the appended claims
rather than by the description preceding them, and all changes that
fall within meets and bounds of the claims, or equivalence of such
meets and bounds thereof are therefore intended to be embraced by
the claims.
* * * * *