U.S. patent application number 09/789513 was filed with the patent office on 2001-08-23 for battery charging control unit and method for controlling battery charging.
This patent application is currently assigned to HONDA GIKEN KOGYO KABUSHIKI KAISHA. Invention is credited to Ishikura, Takashi, Mita, Yoshinori, Okamoto, Kazuhisa, Watanabe, Kazunori, Watanabe, Kenji, Yagi, Kazuhiko.
Application Number | 20010015636 09/789513 |
Document ID | / |
Family ID | 18568955 |
Filed Date | 2001-08-23 |
United States Patent
Application |
20010015636 |
Kind Code |
A1 |
Yagi, Kazuhiko ; et
al. |
August 23, 2001 |
Battery charging control unit and method for controlling battery
charging
Abstract
A battery charging control unit which controls electric power
and supplies it to a battery via a charger. The battery charging
control unit includes: a charging capacity insufficiency detection
unit, a charging capacity restoring determination unit, and a
supplemental charging unit. The charging capacity insufficiency
detection unit detects an insufficiency in charging capacity of the
battery based on the previous charging condition of the battery.
The charging capacity restoring determination unit determines if
the insufficiency in charging capacity of the battery will be
restored by carrying out a supplemental charging process on the
battery. The supplemental charging unit carries out the
supplemental charging process for the battery if the charging
capacity insufficiency detection unit detects the insufficiency in
charging capacity of the battery and the charging capacity
restoring determination unit determines that the insufficiency in
charging capacity of the battery will be restored by the
supplemental charging process.
Inventors: |
Yagi, Kazuhiko; (Wako-shi,
JP) ; Ishikura, Takashi; (Wako-shi, JP) ;
Okamoto, Kazuhisa; (Wako-shi, JP) ; Mita,
Yoshinori; (Wako-shi, JP) ; Watanabe, Kenji;
(Wako-shi, JP) ; Watanabe, Kazunori; (Wako-shi,
JP) |
Correspondence
Address: |
ARENT FOX KINTNER PLOTKIN & KAHN, PLLC
Suite 600
1050 Connecticut Avenue, N.W.
Washington
DC
20036-5339
US
|
Assignee: |
HONDA GIKEN KOGYO KABUSHIKI
KAISHA
|
Family ID: |
18568955 |
Appl. No.: |
09/789513 |
Filed: |
February 22, 2001 |
Current U.S.
Class: |
320/132 |
Current CPC
Class: |
H02J 7/0069 20200101;
Y02T 90/14 20130101; B60L 53/14 20190201; Y02T 10/7005 20130101;
Y02T 10/705 20130101; B60L 2240/545 20130101; Y02T 10/70 20130101;
Y02T 10/7072 20130101; B60L 58/16 20190201 |
Class at
Publication: |
320/132 |
International
Class: |
H02J 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 23, 2000 |
JP |
2000-046564 |
Claims
1. A battery charging control unit which controls electric power
from a power source and supplies it to a battery via a charger,
comprising: a charging capacity insufficiency detection unit which
detects an insufficiency in charging capacity of said battery based
on the previous charging condition of said battery, said charging
capacity insufficiency detection unit being capable of memorizing
the detected insufficiency in charging capacity of said battery; a
charging capacity restoring determination unit which, after said
charging capacity insufficiency detection unit detects an
insufficiency in the charging capacity of said battery, determines
if said insufficiency in charging capacity of said battery will be
restored by carrying out a supplemental charging process for said
battery; and a supplemental charging unit which carries out said
supplemental charging process for said battery if said charging
capacity insufficiency detection unit detects said insufficiency in
charging capacity of said battery and said charging capacity
restoring determination unit determines that said insufficiency in
charging capacity of said battery will be restored by said
supplemental charging process.
2. A battery charging control unit as set forth in claim 1, wherein
said charging capacity restoring determination unit determines if
said battery will be restored by said supplemental charging process
based on at least one of a battery temperature and an outside air
temperature.
3. A battery charging control unit as set forth in claim 1, further
comprising: an integrated calendar, wherein said charging capacity
restoring determination unit determines if said battery will be
restored by said supplemental charging process based on said
integrated calendar.
4. A battery charging control unit as set forth in claim 1, further
comprising a point counter, wherein said charging capacity
insufficiency detection unit is capable of calculating a degree of
said insufficiency in charging capacity of said battery by adding
certain predetermined points, which is based on said previous
charging condition of said battery, to said point counter, and said
supplemental charging unit is capable of carrying out said
supplemental charging process when points on said point counter
exceeds a predetermined value.
5. A battery charging control unit as set forth in claim 4, wherein
said charging capacity insufficiency detection unit adds a certain
number of points to said point counter if a charging process for
charging said battery is terminated before completion.
6. A battery charging control unit as set forth in claim 5, wherein
said charging capacity insufficiency detection unit adds a certain
number of points to said point counter if a charging process for
charging said battery is temporarily stopped due to a temperature
rise in said battery exceeding a first predetermined
temperature.
7. A battery charging control unit as set forth in claim 6, wherein
said charging capacity insufficiency detection unit adds a certain
number of points to said point counter if the temperature of said
battery is greater than a second predetermined temperature upon the
completion of said charging process.
8. A battery charging control unit as set forth in claim 1, wherein
said supplemental charging unit determines a charging manner in
said supplemental charging process based on the level of charging
capacity insufficiency detected by said charging capacity
insufficiency detection unit.
9. A battery charging control unit as set forth in claim 7, wherein
said charging capacity insufficiency detection unit subtracts,
after the completion of said supplemental charging process by said
supplemental charging unit, a certain number of points from a point
value accumulated on said point counter.
10. A battery charging control unit as set forth in claim 9,
wherein said points subtracted from said point value on said point
counter are predetermined in accordance with the temperature of
said battery at the completion of said supplemental charging
process.
11. A battery charging control unit as set forth in claim 10,
wherein said points subtracted from said point value on said point
counter are predetermined in accordance with the charging magnitude
of said supplemental charging process.
12. A battery charging control unit as set forth in claim 11,
wherein said points subtracted from said point value on said point
counter are predetermined in accordance with the number of said
supplemental charging processes performed by said supplemental
charging unit.
13. A method for controlling battery charging by controlling
electric power from a power source and supplying it to a battery
via a charger, comprising the steps of: (a) carrying out a charging
capacity insufficiency detection process to determine whether the
charging capacity of said battery is insufficient or not; (b)
carrying out a restoring effect determination process by which it
is determined if the charging capacity insufficiency in said
battery will be restored by a supplemental charging process; and
(c) carrying out a supplemental charging process of said battery to
restore the charging capacity insufficiency of said battery if it
is determined that the charging capacity of said battery is
insufficient in said charging capacity insufficiency detection
process and that said battery will be restored by said supplemental
charging processes in said restoring effect determination
process.
14. A method for controlling battery charging as set forth in claim
13, wherein whether said battery will be restored by the
supplemental charging process in said restoring effect
determination process is determined based on information of at
least one of a battery temperature, an outside air temperature, and
an integrated calendar.
15. A method for controlling battery charging as set forth in claim
13, wherein said charging capacity insufficiency detection process
comprises the steps of: (i) determining if the charging process is
terminated before the completion of the charging process, and
adding a certain number of points if it is determined that the
charging process is terminated before completion; (ii) determining
if the charging process is temporarily stopped because of the
temperature rise in said battery higher than a first predetermined
temperature, and adding a certain number of points if it is
determined that the charging process is temporarily stopped because
the temperature rise in said battery is higher than the first
predetermined temperature; and (iii) determining if the temperature
of said battery is higher than a second predetermined temperature
when the charging process is completed, and adding a certain number
of points if it is determined that the battery temperature is
higher than the second predetermined temperature.
16. A method for controlling battery charging as set forth in claim
15, wherein said charging capacity insufficiency detection process
further comprises the steps of: (iv) accumulating the points
obtained in the steps (i) through (iii) and determining if the
accumulated point is greater than a first predetermined point; and
(v) correcting the accumulated point, if the accumulated point is
greater than the first predetermined point, so that the accumulated
point be just the first predetermined point.
17. A method for controlling battery charging as set forth in claim
16, wherein said supplemental charging process comprises the steps
of: (i) determining if the accumulated point is greater than a
second predetermined point when said supplemental charging process
is started; (ii) carrying out a supplemental charging process of
said battery in a relatively heavy manner if it is determined that
the accumulated points are equal to or greater than the second
predetermined point in step (i); and (iii) carrying out a
supplemental charging process of said battery in a relatively light
manner if it is determined that the accumulated points are smaller
than the second predetermined point in step (i).
18. A method for controlling battery charging as set forth in claim
17, further comprises the steps of: (d) carrying out a point value
correction process which comprises the steps of: (i) determining
whether the battery temperature is equal to or higher than a third
predetermined temperature, and subtracting a certain number of
points if it is determined that the battery temperature is equal to
or higher than the third predetermined temperature; (ii)
determining whether the battery temperature is lower than a fourth
predetermined temperature, and subtracting a certain number of
points if it is determined that the battery temperature is lower
than the fourth predetermined temperature; and (iii) determining
whether the battery temperature is in the range between the third
and the fourth predetermined temperatures, and subtracting a
certain number of points which corresponds to the charging
magnitude and the number of charging processes performed if it is
determined that the battery temperature is in the range between the
third and the fourth predetermined temperatures.
19. A method for controlling battery charging as set forth in claim
18, wherein said point value correction process further comprises
the steps of: (iv) calculating the total of the points obtained in
the steps (i) through (iii) of said charging capacity insufficiency
detection process and the points subtracted in the steps of (i)
through (iii) of said point value correction process and
determining if the accumulated point is greater than a third
predetermined point; and (v) correcting the calculated total point,
if the total points is less than zero, so that the calculated point
is zero.
20. A method for controlling battery charging as set forth in claim
19, wherein whether the charging capacity of said battery is
insufficient or not in said charging capacity insufficiency
detection process is determined based on the calculated total
points.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to battery charging control
units and methods for controlling battery charging. More
specifically, the present invention relates to a battery charging
control unit for batteries used, for instance, for an electric
vehicle, and a method for controlling the charging of such
batteries.
[0003] 2. Description of Related Art
[0004] In general, processes of charging, discharging, and
recharging batteries are repeated when batteries are used. If the
batteries are used for a certain period of time and these processes
of charging and discharging are repeated a considerable number of
times, the level of a full charge, i.e., the level at which the
batteries are a fully charged to their maximum charging capacity,
as compared with the initial level of full charge of the batteries,
will decrease.
[0005] If this decrease in the charging capacity is caused
temporarily by such factors as memory effect, it is known that the
batteries can be restored to some extent by carrying out a
supplemental charging (i.e., a complete charging/discharging) of
the batteries.
[0006] As disclosed in the Japanese Unexamined Patent Application,
First Publication No. 62-260531, for instance, the decrease in the
charging capacity of the batteries can be restored by carrying out
a supplemental charging process (or an even charging process) each
predetermined number of times that the battery is charged.
[0007] However, among the environments in which the battery is
used, there are cases in which, depending on the condition of the
battery, supplemental charging of the batteries should not be
carried out. In particular, when the battery is installed in an
electric automobile, for example, the environments in which it is
used may vary drastically. The batteries may be used in a harsh
temperature environment wherein the temperature of the batteries
reaches more than 40.degree. C. during summer and less than
-10.degree. C. during winter.
[0008] Also, when batteries are in a high temperature environment,
there is a danger that the batteries may be damaged by the
supplemental charging process because in such an environment the
charging current may be consumed in generating heat that increases
the temperature of the batteries rather than being used to charge
the batteries. Moreover, since a certain amount of the charging
current is consumed for generating heat, the electric power is
wasted and is economically ineffective.
[0009] In consideration of the above, an object of the present
invention is to provide a battery charging control unit which is
capable of eliminating the problem of the insufficient charging
capacity of batteries by carrying out a supplemental charging
process reliably at a suitable timing so that a highly efficient
state of the batteries may be maintained and the lifetime thereof
may be extended.
SUMMARY OF THE INVENTION
[0010] The present invention provides a battery charging control
unit which controls the electric power from a power source and
supplies it to a battery via a charger, comprising: a charging
capacity insufficiency detection unit which detects an
insufficiency in charging capacity of the battery based on the
previous charging condition of the battery, the charging capacity
insufficiency detection unit being capable of storing the detected
insufficiency in the charging capacity of the battery; a charging
capacity restoring determination unit which, after the charging
capacity insufficiency detection unit detects an insufficiency in
charging capacity of the battery, determines if the insufficiency
in charging capacity of the battery will be restored by carrying
out a supplemental charging process for the battery; and a
supplemental charging unit which carries out the supplemental
charging process for the battery if the charging capacity
insufficiency detection unit detects an insufficiency in the
charging capacity of the battery and the charging capacity
restoring determination unit determines the insufficiency in
charging capacity of the battery will be restored by the
supplemental charging process.
[0011] As shown in FIG. 8, the restoring of a battery having a
charging capacity insufficiency carried out by a supplemental
charging process is confirmed to be effective if such a charging
operation is performed after the temperature of the battery has
been lowered, for instance, to an ordinary temperature. In
consideration of this fact, the above battery charging control unit
according to an embodiment of the invention has a structure capable
of reliably restoring a battery having a charging capacity
insufficiency by performing a suitable supplemental charging
operation.
[0012] Specifically, the charging capacity insufficiency detection
unit of the above battery charging control unit stores the charging
condition (or state) of the battery in the previous charging
operations in memory and carries out a supplemental charging
operation based on the data of the previous charging condition
stored in the memory. Also, the charging capacity restoring
determination unit determines if the insufficiency in charging
capacity of the battery will be restored by carrying out a
supplemental charging process for the battery. This is because the
restoring of the battery having a charging capacity insufficiency
is difficult even with the supplemental charging operation if the
temperature is high, as mentioned above, and the charging capacity
restoring determination unit determines to carry out a supplemental
charging process by the supplemental charging unit only when the
restoring of the battery by the supplemental charging operation may
be expected based on the battery temperature or the outside air
temperature.
[0013] That is, the supplemental charging process is carried out
only when the charging capacity insufficiency is detected and the
restoring of battery is expected. Accordingly, it becomes possible
to avoid performing a supplemental charging process when
unnecessary. Also, harmful effects to the batteries, such as a
temperature increase thereof due to the supplemental charging
process or the waste of charging time and energy, may be
avoided.
[0014] Moreover, since the charging capacity insufficiency
detection unit only detects and stores in memory the generation of
charging capacity insufficiency and does not carry out a
supplemental charging process if the charging capacity restoring
determination unit determines that the restoring of the battery is
not expected, i.e., the supplemental charging process is carried
out only when the restoring of battery is expected, and thus it
becomes possible to carry out the supplemental charging process
reliably.
[0015] Further, problems associated with a conventional periodic
supplemental charging process, in which the process may be carried
out unnecessarily, may be eliminated, simply resulting in an
increase in the temperature of batteries that may shorten their
life.
[0016] In accordance with another aspect of the invention, the
charging capacity restoring determination unit determines if the
battery will be restored by the supplemental charging process based
on at least one of the battery temperature, and the outside air
temperature.
[0017] According to the above battery charging control unit, since
the charging capacity restoring determination unit determines if
the battery will be restored by the supplemental charging process
based on at least one of a battery temperature, and an outside air
temperature, reliably carrying out the supplemental charging
process to restore the battery when the restoring thereof is
expected becomes possible.
[0018] Also, causing harmful effects to the battery, which may
occur if a supplemental charging process is carried out when the
temperature of battery or outside air is extremely high, may be
avoided. Moreover, saving the time and energy that would be wasted
if an unnecessary supplemental charging operation is performed
becomes possible.
[0019] In yet another aspect of the invention, a battery charging
control unit further includes: an integrated calendar, wherein the
charging capacity restoring determination unit determines if the
battery will be restored by the supplemental charging process based
on the integrated calendar.
[0020] According to the above battery charging control unit, data
for dates, months, or seasons, or information relating to annual
temperature change may be input into the integrated calendar so
that the charging capacity restoring determination unit may
determine if the battery will be restored by a supplemental
charging process based on the data contained in the integrated
calendar. Therefore, it becomes possible, for instance, to
effectively restore the battery by carrying out supplemental
charging processes mainly in spring or fall, when the restoring of
the battery is highly expected, and avoid a season such as summer
or winter, when there is little expectation of the restoring of the
battery.
[0021] In yet another aspect of the invention, a battery charging
control unit further includes a point counter, wherein the charging
capacity insufficiency detection unit is capable of calculating a
degree of the insufficiency in charging capacity of the battery by
adding a certain predetermined point, which is based on the
previous charging condition of the battery, to the point counter,
and the supplemental charging unit is capable of carrying out the
supplemental charging process when points in the point counter
exceed a predetermined value.
[0022] According to the above battery charging control unit, the
previous charging condition or state of the battery may be
converted into numerical points and the points may be accumulated
in the point counter so that a supplemental charging process by the
supplemental charging unit may be reliably carried out for the
battery based on the information obtained from the accumulated
points.
[0023] In yet another aspect of the invention, the charging
capacity insufficiency detection unit adds a certain number of
points to the point counter if a charging process for charging the
battery is terminated before being finished.
[0024] According to the above battery charging control unit, the
effect of terminating a charging process before being finished may
be converted into a point and this point is accumulated so that
such an effect may be reflected in subsequent charging processes to
carry out the processes reliably.
[0025] In yet another aspect of the invention, the charging
capacity insufficiency detection unit adds a certain number of
points to the point counter if a charging process for charging the
battery is temporarily stopped due to a temperature rise in the
battery exceeding a first predetermined temperature.
[0026] According to the above battery charging control unit, the
effect of temporarily stopping a charging process due to a
temperature rise in the battery exceeding a first predetermined
temperature may be converted into a point and the point is
accumulated so that such an effect may be reflected in subsequent
charging processes. That is, since the increase in battery
temperature during a charging process can be a factor for causing a
charging capacity insufficiency, the factor is converted into a
point and the point is accumulated so that a subsequent charging
process may be carried out reliably.
[0027] In yet another aspect of the invention, the charging
capacity insufficiency detection unit adds a certain number of
points to the point counter if the temperature of the battery is
greater than a second predetermined temperature upon the completion
of the charging process.
[0028] According to the above battery charging control unit, the
effect of the temperature of the battery greater than a second
predetermined temperature upon the completion of the charging
process may be converted into a point and the point is accumulated
so that such an effect may be reflected in subsequent charging
processes. That is, since an extremely high temperature of the
battery at the completion of the charging process can be a factor
for causing a charging capacity insufficiency, the factor is
converted into a point and the point is accumulated so that a
subsequent charging process may be carried out reliably.
[0029] In yet another aspect of the invention, the supplemental
charging unit determines a charging manner in the supplemental
charging process based on the level of charging capacity
insufficiency detected by the charging capacity insufficiency
detection unit.
[0030] According to the above battery charging control unit, the
supplemental charging unit may reliably restore the battery by
carrying out a supplemental charging process using a most suitable
charging manner (i.e., charging current, charging time,
ampere-hour, etc.) for the battery based on the level of charging
capacity insufficiency detected by the charging capacity
insufficiency detection unit. That is, if the level of the charging
capacity insufficiency is large, the supplemental charging
magnitude is increased to achieve an early restoring of the battery
and, if the level of the charging capacity insufficiency is small,
the supplemental charging magnitude is decreased to achieve a
restoring of the battery in an unforced manner.
[0031] In yet another aspect of the invention, the charging
capacity insufficiency detection unit subtracts, after the
completion of the supplemental charging process by the supplemental
charging unit, a certain number of points from the point value
accumulated in the point counter.
[0032] According to the above battery charging control unit, since
a certain number of points, which corresponds to the level of
battery restoring by the supplemental charging process, are
subtracted from the point value in the point counter by the
charging capacity insufficiency detection unit, the level of
battery restoring by the supplemental charging process may be
reflected as points so that the state or condition of the battery
may be reliably accumulated in the point counter as a numerical
point value.
[0033] In yet another aspect of the invention, the points
subtracted from the point value in the point counter is
predetermined in accordance with the temperature of the battery at
the completion of the supplemental charging process.
[0034] According to the above battery charging control unit, since
the subtracted points which correspond to the degree of restoration
of the battery by a supplemental charging process are predetermined
based on the battery temperature, the points subtracted may be
increased in the temperature range in which a significant restoring
of the battery is expected and the points subtracted may be
decreased in the temperature range in which there is little
expectation that the battery will be restored. Accordingly, the
difference in the level of battery restoring due to the difference
of the battery temperature may be accurately reflected as
subtracted points, and the points may be subtracted from the point
value in the point counter so that the state or condition of the
battery may be reliably accumulated in the point counter as a point
value.
[0035] In yet another aspect of the invention, the points
subtracted from the point value in the point counter is
predetermined in accordance with the charging magnitude of the
supplemental charging process.
[0036] According to the above battery charging control unit, since
the subtracted points, which correspond to the degree of
restoration of the battery by a supplemental charging process, are
predetermined based on the charging current of the supplemental
charging process, the level of restoring of the battery
corresponding to the charging magnitude of supplemental charging
process may be accurately reflected as a subtracted points by
increasing the subtracted points when the charging magnitude is
large and decreasing the subtracted points when the charging
magnitude is small, and the point may be subtracted from the point
value in the point counter so that the state or condition of the
battery may be reliably accumulated in the point counter as a point
value.
[0037] In yet another aspect of the invention, the points
subtracted from the point value in the point counter are
predetermined in accordance with the number of the supplemental
charging processes performed by the supplemental charging unit.
[0038] According to the above battery charging control unit, since
the subtracted points, which correspond to the degree of
restoration of the battery by a supplemental charging process, are
predetermined based on the number of supplemental charging
processes, the level of the restoring of the battery, which
decreases as the number of supplemental charging processes
increases, may be accurately reflected as subtracted points, and
the points may be subtracted from the point value in the point
counter so that the state or condition of the battery may be
reliably accumulated in the point counter as a point value.
[0039] The present invention also provides a method for controlling
battery charging by controlling a power from a power source and
supplying it to a battery via a charger, including the steps of:
(a) carrying out a charging capacity insufficiency detection
process to determine whether the charging capacity of the battery
is insufficient or not; (b) carrying out a restoring effect
determination process that determines if the charging capacity
insufficiency in the battery will be restored by a supplemental
charging process; and (c) carrying out a supplemental charging
process of the battery to restore the charging capacity
insufficiency of the battery if it is determined that the charging
capacity of the battery is insufficient in the charging capacity
insufficiency detection process and that the battery will be
restored by the supplemental charging process in the restoring
effect determination process.
[0040] In accordance with another aspect of the present invention,
whether the battery will be restored by the supplemental charging
process is determined in the restoring effect determination process
based on information of at least one of a battery temperature and
an outside air temperature.
[0041] In yet another aspect of the invention, the charging
capacity insufficiency detection process includes the steps of: (i)
determining if the charging process is terminated prior to the
completion of the charging process, and adding a certain number of
points if it is determined that the charging process has been
terminated before completion; (ii) determining if the charging
process has been temporarily stopped because of a temperature rise
in the battery that is higher than a first predetermined
temperature, and adding a certain number of points if it is
determined that the charging process is temporarily stopped because
of a temperature rise in the battery that is higher than the first
predetermined temperature; and (iii) determining if the temperature
of the battery is higher than a second predetermined temperature
when the charging process is completed, and adding a certain number
of points if it is determined that the battery temperature is
higher than the second predetermined temperature when the charging
process is completed.
[0042] In yet another aspect of the invention, the charging
capacity insufficiency detection process further including the
steps of: (iv) accumulating the points obtained in the steps (i)
through (iii) and determining if the accumulated points are greater
than a first predetermined number of points; and (v) correcting the
accumulated point, if the accumulated point is greater than the
first predetermined point, so that the accumulated points is set
equal to the first predetermined point.
[0043] In yet another aspect of the invention, the supplemental
charging process including the steps of: (i) determining if the
accumulated point is greater than a second predetermined point when
the supplemental charging process is started; (ii) carrying out a
supplemental charging process of the battery in a relatively heavy
manner if it is determined that the accumulated point is equal to
or greater than the second predetermined point in step (i); and
(iii) carrying out a supplemental charging process of the battery
in a relatively light manner if it is determined that the
accumulated point is smaller than the second predetermined point in
step (i).
[0044] In yet another aspect of the invention, a method for
controlling battery charging further includes the step of: (d)
carrying out a point value correction process which includes the
steps of: (i) determining whether the battery temperature is equal
to or higher than a third predetermined temperature, and
subtracting a certain number of points if it is determined that the
battery temperature is equal to or higher than the third
predetermined temperature; (ii) determining whether the battery
temperature is lower than a fourth predetermined temperature, and
subtracting a certain number of points if it is determined that the
battery temperature is lower than the fourth predetermined
temperature; and (iii) determining whether the battery temperature
is in the range between the third and the fourth predetermined
temperatures, and subtracting a certain number of points which
corresponds to the current magnitude and the number of charging
processes performed if it is determined that the battery
temperature is in the range between the third and the fourth
predetermined temperatures.
[0045] In yet another aspect of the invention, the point value
correction process further including the steps of: (iv) calculating
the total of the points obtained in the steps (i) through (iii) of
the charging capacity insufficiency detection process and the
points subtracted in the steps of (i) through (iii) of the point
value correction process, and determining if the accumulated point
is greater than a third predetermined point; and (v) correcting the
calculated total point, if the total point is less than zero, so
that the calculated point be zero.
[0046] In yet another aspect of the invention, whether the charging
capacity of the battery is insufficient or not in the charging
capacity insufficiency detection process is determined based on the
calculated total points.
[0047] As mentioned above, it is confirmed that the restoring of a
battery having a charging capacity insufficiency carried out by a
supplemental charging process is effective if such a charging
operation is performed after the temperature of the battery is
lowered, for instance, to the ordinary temperature. In
consideration of this fact, the above method for controlling
battery charging according to an embodiment of the invention is
capable of reliably restoring a battery having a charging capacity
insufficiency by performing a suitable supplemental charging
operation.
[0048] That is, the charging capacity insufficiency detection
process and the supplemental charging process in the above method
for controlling battery charging of the present invention may be
carried out based on data of the previous charging condition stored
in memory. Also, in the charging capacity restoring effect
determination process, it is determined if the insufficiency in
charging capacity of the battery will be restored by carrying out a
supplemental charging process for the battery. This is because the
restoring of the battery having a charging capacity insufficiency
is difficult even by carrying out the supplemental charging process
if the temperature of battery or that of outside air is high.
Accordingly, a supplemental charging process is performed only when
the charging capacity insufficiency is detected and the restoring
of battery is expected. Therefore, performing a supplemental
charging process when unnecessary can be avoided. Also, harmful
effects on the batteries, such as a temperature increase thereof
due to the supplemental charging process or the waste of charging
time and energy, may be avoided.
[0049] Moreover, since a supplemental charging process is not
carried out if it is determined that the restoring of the battery
is not expected by the restoring effect determination process,
i.e., the supplemental charging process is carried out only when
the restoring of battery is expected, the supplemental charging
process can be reliably carried out.
[0050] Further, problems associated with a conventional periodic
supplemental charging process, wherein the process may be carried
out when it is unnecessary and simply result in an increase in the
temperature of batteries which may shorten their life, may be
eliminated.
[0051] In addition, since if the battery will be restored by the
supplemental charging process is determined in the restoring effect
determination process based on information of at least one of the
battery temperature, the outside air temperature, and the
integrated calendar, the supplemental charging process to restore
the battery when the restoring thereof is expected can be reliably
carried out.
[0052] Also, the harmful effects on the battery that may be caused
if a supplemental charging process is carried out when the
temperature of battery or outside air is extremely high become
avoidable. Moreover, the time and energy that would be wasted if an
unnecessary supplemental charging operation is performed can be
saved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] Some of the features and advantages of the invention have
been described, and others will become apparent from the detailed
description that follows and from the accompanying drawings, in
which:
[0054] FIG. 1 is a schematic diagram showing an electric vehicle in
which a battery charging control unit according to an embodiment of
the present invention is mounted;
[0055] FIG. 2 is a block diagram for explaining the function of the
battery charging control unit according to the embodiment of the
present invention;
[0056] FIG. 3 is a flowchart for explaining a control of battery
charging using the battery charging control unit according to the
embodiment of the present invention;
[0057] FIG. 4 is a flowchart for explaining a charging capacity
insufficiency detection process carried out by using the battery
charging control unit according to the embodiment of the present
invention;
[0058] FIG. 5 is a flowchart for explaining a supplemental charging
process carried out by using the battery charging control unit
according to the embodiment of the present invention;
[0059] FIG. 6 is a flowchart for explaining a point value
correction process carried out by using the battery charging
control unit according to the embodiment of the present
invention;
[0060] FIG. 7 is a table showing subtracted points which may be
used in the point value correction process carried out by using the
battery charging control unit according to the embodiment of the
present invention; and
[0061] FIG. 8 is a graph for explaining the basis of using the
table shown in FIG. 7 in the point value correction process carried
out by using the battery charging control unit according to the
embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0062] An objective of the present invention is to provide a
battery charging control unit which does not have the
above-described problems.
[0063] Another objective of the present invention is to provide a
battery charging control unit which is capable of eliminating
problems of an insufficiency of the charging capacity of batteries
by carrying out a supplemental charging process reliably at a
suitable timing so that a highly efficient state of the batteries
may be maintained and the lifetime thereof may be extended.
[0064] Yet another object of the present invention is to provide a
method for controlling battery charging by which a battery having a
charging capacity insufficiency is reliably restored by a suitable
charging operation and harmful effects on the battery, such as a
temperature increase thereof due to the charging process or the
waste of charging time and energy, may be avoided.
[0065] The invention summarized above and defined by the enumerated
claims may be better understood by referring to the following
detailed description, which should be read with reference to the
accompanying drawings. This detailed description of a particular
preferred embodiment, set out below to enable one to build and use
one particular implementation of the invention, is not intended to
limit the enumerated claims, but to serve as a particular example
thereof.
[0066] The inventors of the present invention confirmed that a
decrease in charging capacity of batteries due to an early charging
process may be caused by various factors, such as the manner of
charging, or the temperature of the batteries during or after the
charging process. The inventors of the present invention, after
thorough study, discovered that it is difficult to restore the
decrease in charging capacity of batteries even by carrying out a
supplemental charging process if the temperature is extremely high,
and that the restoring may be made if the supplemental charging
process is carried out when the temperature is lowered to some
degree, for instance, to ordinary temperature (refer to FIG.
8).
[0067] The inventors of the present invention have successfully
completed making a battery charging controlling unit which is
capable of reliably restoring batteries of decreased charging
capacity by performing a supplemental charging process by taking
into account the above-described phenomenon. Also, the inventors of
the present invention discovered a method for controlling charging
batteries suitable for restoring such batteries.
[0068] FIG. 1 is a diagram showing an electric vehicle 1 for
explaining an embodiment according to the present invention. As
shown in FIG. 1, the electric vehicle 1 has a drive motor 2,
batteries 3, a plug 4, a charger 5, and a battery charging control
unit 11 (hereinafter also referred to as ECU). The batteries 3
supply electric power to the drive motor 2. That is, a vehicle S is
driven by the drive motor 2, which is operated by the electric
power supplied from the batteries 3.
[0069] The batteries 3 are connected to the charger 5, which is
provided with the plug 4 that may be inserted into an outlet for
commercial power supply. That is, the electric power from a
commercial outlet may be used to charge the batteries 3 via the
charger 5 by inserting the plug 4 into the outlet.
[0070] The ECU 11 is connected to the charger 5 so that the
charging current, charging time, and charging level of the
batteries 3 may be controlled by the ECU 11 via the charger 5.
[0071] As shown in FIG. 2, a charging capacity insufficiency
detection unit 12, a charging capacity restoring determination unit
13, and a supplemental charging unit 14 are provided with the ECU
11. Also, a point counter 15, a consecutive supplemental charging
number counter 16, and an integrated calendar 17 are provided with
the ECU 11.
[0072] A battery temperature sensor 21 which detects the
temperature of the batteries 3 is provided with the ECU 11 so that
a battery temperature T.sub.BATT may be detected by the battery
temperature sensor 21. Also, an outside air temperature sensor 22
is provided with the vehicle S so that an outside air temperature
T.sub.A may be detected by the outside air temperature sensor
22.
[0073] The battery temperature sensor 21 and the outside air
temperature sensor 22 are connected to the ECU 11, and detection
signals from the battery temperature sensor 21 and the outside air
temperature sensor 22 are transmitted to the ECU 11.
[0074] The ECU 11 outputs a control signal to the charger 5 based
on the detection signals from the battery temperature sensor 21 and
the outside air temperature sensor 22 so that the charging of the
batteries 3 by the charger 5 may be controlled by the ECU 11.
[0075] Next, the flow of charging control process by the ECU 11
when the batteries 3 are charged in the above electric vehicle 1
will be explained with reference to FIGS. 3 through 6. Note that in
the following explanation of processes according to an embodiment
of the present invention, numerical points added to or subtracted
from the point counter 15 are assigned only as examples and may be
arbitrary altered in so far as the spirit and scope of the
invention are maintained.
[0076] Step S1: inserting the plug 4 provided with the electric
vehicle 1 into an outlet of the electric power such as a commercial
power supply.
[0077] Step S2: detecting the remaining charge of the batteries 3
by the ECU 11 and determining whether the remaining charge is less
than a predetermined value.
[0078] If the remaining charge of the batteries 3 is equal to or
less than the predetermined value, the flow proceeds to Step S3,
and if it is greater than the predetermined value, the flow
proceeds to Step S10 and terminates the charging process. Note that
the remaining charge of the batteries 3 may be indicated by, for
instance, 10 segments of an indicator lamp and the predetermined
value may be indicated by the 9th segment of the lamp in this
embodiment. That is, if the remaining charge of the batteries 3 is
greater than the predetermined value, the battery charge is
regarded as nearly full and a charging process is not carried out
even if the plug 4 is inserted into the outlet.
[0079] Step S3: controlling the charger 5 by the ECU 11 and
starting a charging process (i.e., a normal charging process in
this embodiment) of the batteries 3.
[0080] That is, a predetermined current from the power supply is
supplied to the batteries 3 via the charger 5 to carry out a normal
charging operation of the batteries 3. The ECU 11, then, terminates
the normal charging process based on the detection signal from the
battery temperature sensor 21 when the gradient of the temperature
rise of the batteries 3 reaches a predetermined value (i.e., for
instance, dT/dt=1.5). This is because the temperature of the
batteries 3 is increased due to the fact that some of the electric
power supplied to the batteries 3 is not used for the charging
process and discharged as a heat instead. The ECU 11 calculates the
timing for terminating the normal charging process based on the
gradient of the temperature rise of the batteries 3.
[0081] Step S4: carrying out a charging capacity insufficiency
detection process of steps S4-1 through S4-9 shown in FIG. 4 by the
charging capacity insufficiency detection unit 12 after the
termination of the normal charging process of the batteries 3. Note
that although the charging capacity insufficiency detection process
by the charging capacity insufficiency detection unit 12 is carried
out after the termination of the normal charging process in this
embodiment, the timing of performing the charging capacity
insufficiency detection process is not limited and may be carried
out at any suitable time.
[0082] Step S5: determining whether the charging capacity of the
batteries 3 is insufficient or not, based on a point value counted
by the point counter 15.
[0083] If the point value of the point counter 15 is, for instance,
equal to or greater than 20 points, the ECU 11 commands the flow to
proceed to Step S6, and if the point value is less than 20 points,
the ECU commands the flow to proceed to step S9.
[0084] Step S6: carrying out a restoring effect determination
process that determines if the batteries 3 will be restored by a
supplemental charging operation at this stage.
[0085] According to an embodiment of the present invention, the
charging capacity restoring determination unit 13 of the ECU 11
acquires a battery temperature T.sub.BATT and an outside air
temperature T.sub.A based on detection signals from the battery
temperature sensor 21 and the outside air temperature sensor 22. If
the battery temperature T.sub.BATT is less than 35.degree. C. or
the outside air temperature T.sub.A is less than 30.degree. C.,
then it is determined that a supplemental charging of the batteries
3 will be effective and the flow proceeds to step S7. If the
battery temperature T.sub.BATT is equal to or greater than
35.degree. C., or the outside air temperature T.sub.A is equal to
or greater than 30.degree. C., then it is determined that a
restoring of the batteries 3 by a supplemental charging process
cannot be expected at this stage and the flow proceeds to step
S9.
[0086] Step S7: carrying out a supplemental charging process of
Step S7-1 through S7-3 shown in FIG. 5 by the supplemental charging
unit 14 of the ECU 11 that controls the charger 5.
[0087] Step S8: carrying out the point value correction process of
Step S8-1 through S8-10 shown in FIG. 6 after the termination of
the supplemental charging process by the supplemental charging unit
14 of the ECU 11.
[0088] Step S9: clearing the consecutive supplemental charging
number counter 16 of the ECU 11, which counts the number of
consecutive supplemental charging processes performed. This is
necessary because a charging process of the batteries 3 is
terminated without carrying out a supplemental charging
process.
[0089] Step S10: pulling out the plug 4, for instance, manually or
mechanically from the outlet and returning it to the original
position when the charging process of the batteries 3 is
completed.
[0090] Next, the above-mentioned charging capacity insufficiency
detection process (i.e., step S4), the supplemental charging
process (i.e., step S7), and the point value correction process
(i.e., step S8) will be explained in more detail.
[0091] (1) charging capacity insufficiency detection process
[0092] Step S4-1: determining if the charging time has continued
for more than one hour. If it is determined that the charging time
has continued for more than one hour, then the flow proceeds to
step S4-2. If it is determined that the charging time has continued
for less than one hour, the charging capacity insufficiency
detection process is terminated.
[0093] That is, if the charging time is less than one hour, an
accumulation of points, which will be described later, is not
carried out since the effect of the charging process on the
batteries 3 is very minor and unlikely to be a factor for the
charging capacity insufficiency of the batteries 3.
[0094] Step S4-2: determining if the charging process is terminated
before completion (i.e., for instance, a manual termination) by
pulling out the plug 4 from the outlet prior to the completion of
the charging process.
[0095] If it is determined that the charging process is terminated
before completion, the process proceeds to step S4-3. If it is
determined that it is not terminated before completion, the process
proceeds to step S4-4.
[0096] Step S4-3: adding one point to the point counter 15 and
proceeding to step S4-8.
[0097] Step S4-4: determining if the charging process is
temporarily stopped in order to protect the batteries 3 (i.e., a
high temperature stop) because the temperature has risen higher
than a first predetermined temperature (i.e., for instance,
approximately 45.degree. C.).
[0098] If it is determined that the process is stopped due to the
high temperature of the batteries 3, the flow proceeds to step
S4-5, and if it is determined that the process is not stopped due
to high temperature, the flow proceeds to step S4-6.
[0099] Step S4-5: adding 8 point to the point counter 15 and
proceeding to step S4-8.
[0100] Step S4-6: detecting the battery temperature T.sub.BATT of
the batteries 3 when the normal charging process (or any other
charging process) of the batteries 3 is automatically stopped
(i.e., when the gradient of the temperature rise in the batteries 3
reaches, for instance, about dT/dt=1.5) and it is determined if the
battery temperature T.sub.BATT is higher than a second
predetermined temperature (i.e., for instance, approximately
35.degree. C.).
[0101] If it is determined that the battery temperature T.sub.BATT
is equal to or higher than the second predetermined temperature,
35.degree. C. in this embodiment, then the flow proceeds to step
S4-7. If the battery temperature T.sub.BATT is lower than the
second predetermined temperature, then the flow proceeds to step
S4-8.
[0102] Step S4-7: adding 10 points to the point counter 15 and
proceeding to step S4-8.
[0103] Step S4-8: determining if the point value accumulated in the
point counter 15 is greater than, for instance, 100 points or
not.
[0104] If it is determined that the point value exceeds 100 points,
then the flow proceeds to step S4-9. If it is determined that the
point value does not exceed 100 points, then the charging capacity
insufficiency detection process is terminated.
[0105] Step S4-9: correcting the point value exceeding 100 points
in the point counter 15 to just 100 points and terminating the
charging capacity insufficiency detection process.
[0106] That is, in the charging capacity insufficiency detection
process, points are added to the point counter 15 according to the
manner of termination of the charging process of the batteries 3
and the temperature at which the charging process is
terminated.
[0107] Points are added to the point counter 15 in the charging
capacity insufficiency detection process because all of the
above-described cases can be a factor for generating a charging
capacity insufficiency due to an early charging caused by memory
effect. Specifically, the above-described cases include (1) the
normal charging process is manually terminated, (2) the normal
charging process is temporarily stopped in order to protect the
batteries 3 due to the temperature rise in the batteries 3, and (3)
the temperature of the batteries 3 is extremely high at the
termination of the normal charging process.
[0108] (2) supplemental charging process
[0109] Step S7-1: determining if the point value in the point
counter 15 is, for instance, equal to or greater than 50 when a
supplemental charging process is started.
[0110] If the point value is equal to or greater than 50 points,
then the flow proceeds to step S7-2. If the point value is less
than 50 points, then the flow proceeds to step S7-3.
[0111] Step S7-2: carrying out a supplemental charging process of
the batteries 3 by the charger 5, for instance, at about 1A for 8
hours. After that the supplemental charging process is
terminated.
[0112] Step S7-3: carrying out a supplemental charging process of
the batteries 3 by the charger 5, for instance, at about 2A for 2
hours. After that the supplemental charging process is
terminated.
[0113] As explained above, according to an embodiment of the
present invention, the level of current and a time for carrying out
the charging operation are changed in accordance with the points in
the point counter 15 in the supplemental charging process. That is,
a relatively heavy supplemental charging process is carried out
using an effective current level and a charging time when the point
value is relatively high since the magnitude of insufficiency in
the charging capacity due to the memory effect is also large. On
the other hand, a relatively light supplemental charging process is
carried out using a relatively low current and short charging time
when the point value is relatively small since the magnitude of
insufficiency in the charging capacity due to the memory effect is
also small.
[0114] (3) point value correction process
[0115] Step S8-1: determining whether the battery temperature
T.sub.BATT is, for instance, equal to or higher than 40.degree. C.
If it is determined that the battery temperature T.sub.BATT is
equal to or higher than 40.degree. C., then the flow proceeds to
step S8-2. If it is determined that the battery temperature
T.sub.BATT is lower than 40.degree. C., then the flow proceeds to
step S8-3.
[0116] Step S8-2: subtracting 2 points from the point counter 15
and proceeding to step S8-5.
[0117] Step S8-3: determining whether the battery temperature
T.sub.BATT is, for instance, lower than 15.degree. C. If it is
determined that the battery temperature T.sub.BATT is lower than
15.degree. C., then the flow proceeds to step S8-4. If it is
determined that the battery temperature T.sub.BATT is equal to or
higher than 15.degree. C., then the flow proceeds to step S8-6.
[0118] Step S8-4: subtracting 5 points from the point counter 15
and proceeding to step S8-5.
[0119] Step S8-5: maintaining the count number on the consecutive
supplemental charging number counter 16 as it is and proceeding to
step S8-10.
[0120] Step S8-6: selecting a subtracted point in accordance with
the supplemental charging current and the number of supplemental
charging operation performed if it is determined that the battery
temperature T.sub.BATT is, for instance, in the range between
15.degree. C. and 40.degree. C. (i.e., 15.degree.
C..ltoreq.T.sub.BATT<40.degree. C.) by the processes described
in the above S8-1 and S8-3.
[0121] The practical subtracted points may be determined, for
instance, by referring to a predetermined subtraction value table
shown in FIG. 7, which depends on such factors as the capacity or
the kinds of the batteries 3.
[0122] That is, when the charging magnitude (i.e., for instance,
ampere-hour) in the above-mentioned supplemental charging process
(i.e., step S7) is 8 Ah, the subtracted points shown in the upper
row of the table in FIG. 7 may be used. On the other hand, when the
ampere-hours in the supplemental charging process are 4 Ah, the
subtracted points shown in the lower row of the table may be
used.
[0123] Also, it is set so that the subtracted points are decreased
as the number on the consecutive supplemental charging number
counter 16 is increased.
[0124] Step S8-7: subtracting the points selected in the above step
S8-6 from the point counter 15.
[0125] Step S8-8: adding one to the count number on the consecutive
supplemental charging number counter 16, and proceeding to step
S8-9.
[0126] Step S8-9: determining if the point value in the point
counter 15 is less than zero and, if it is determined to be less
than zero, proceeding to step S8-10. On the other hand, if the
point value is equal to or greater than zero, then the point
correction process is terminated.
[0127] Step S8-10: resetting the point value in the point counter
15 to zero.
[0128] As mentioned above, in the point correction process, a point
value, which corresponds to the restoring degree of the batteries 3
by the supplemental charging process, is subtracted from the point
counter 15. It is recognized that the restoring of the batteries 3
by the supplemental charging process is significantly effective if
it is carried out when the batteries 3 are at an ordinary
temperature. Accordingly, in this embodiment, two points are
subtracted when the battery temperature T.sub.BATT is relatively
high (i.e., 40.degree. C..ltoreq. T.sub.BATT), and five points are
subtracted when the battery temperature T.sub.BATT is relatively
low (i.e., T.sub.BATT<15.degree. C.) since the degree of
restoration of the batteries 3 is considered to be low in such
cases.
[0129] Also, when the temperature is in the ordinary temperature
range (i.e., 15.degree. C..ltoreq.T.sub.BATT<40.degree. C.), in
which the restoring of the batteries 3 is considered to be
effective, a subtracted point, which may correspond to the charging
magnitude (i.e., for instance, ampere-hour) of the supplemental
charging process and the number of consecutive supplemental
charging processes, is selected from a predetermined subtracted
point table and the points are subtracted from the point counter
15. That is, points in the subtracted point table differ in
accordance with the charging degree used in the supplemental
charging process. Thus, the subtracted points are relatively high
for the cases where a relatively heavy supplemental charging
process (i.e., for instance, 1A, 8 hour) is carried out, and the
points are relatively low for the cases where a relatively light
supplemental charging process (i.e., for instance, 2A, 2 hour) is
carried out.
[0130] Moreover, it is known that the degree of restoration of
batteries 3 by a supplemental charging process differs depending on
the number of such charging process continuously carried out. As
shown in FIG. 8, when the supplemental charging process is carried
out for the first time, the degree of restoration of the batteries
3 is largest and subsequently the degree of restoration gradually
decreases as the number of supplemental charging process increases.
For this reason, the subtracted points shown in the subtracted
point table decrease as the number of consecutive supplemental
process increases.
[0131] As mentioned above, according to an embodiment of the
battery charging control unit of the present invention, since the
supplemental charging unit 14 performs a supplemental charging
process after the termination of a normal charging process, based
on charging data in the previous charging operation which is
accumulated by the charging capacity insufficiency detection unit
12, it becomes possible to more reliably restore the batteries 3 as
compared with a conventional supplemental charging process in which
a supplemental charging of batteries is carried out based on
information about the batteries obtained only when an abnormality
occurs, or a supplemental charging process is simply carried out
periodically.
[0132] That is, according to an embodiment of the present
invention, the past charging data is converted into point values
and each point value is accumulated in the point counter 15 so that
a supplemental charging process by the supplemental charging unit
14 may be carried out in an reliable manner for the batteries 3 by
referring to the accumulated point.
[0133] More specifically, according to an embodiment of the present
invention, the effect of: (1) the normal charging process being
compulsory terminated; (2) the temperature of the batteries 3 being
increased during the normal charging operation and reaching a
predetermined temporarily charging stop temperature (i.e.,
approximately 45.degree. C.); and (3) the temperature of the
batteries 3 being higher than the predetermined temperature (i.e.,
approximately 35.degree. C.) at the termination of the normal
charging process, may be converted to points and accumulated so as
to be reflected to a subsequent supplemental charging process. That
is, factors for causing a charging capacity insufficiency as
mentioned above are converted into numerical points and accumulated
so that they may be reflected in carrying out a suitable
supplemental charging process reliably.
[0134] Also, according to an embodiment of the present invention,
the charging capacity restoring determination unit 13 determines,
based on the condition at the charging operation, if the batteries
3 will be restored by a supplemental charging process, and the
supplemental charging process is carried out only when the charging
capacity restoring determination unit 13 determines that the
batteries 3 will be restored. Accordingly, the supplemental
charging process is not performed when the restoring of the
batteries 3 is not expected and, hence, harmful effects on the
batteries, such as a temperature increase thereof due to the
supplemental charging process or the waste of charging time and
energy, may be avoided.
[0135] In other words, problems associated with a conventional
periodic supplemental charging process, wherein the process may be
carried out when it is unnecessary and simply results in an
increase in the temperature of batteries possibly shortening the
life of the batteries, may be eliminated.
[0136] Moreover, according to an embodiment of the present
invention, the charging capacity restoring determination unit 13
determines if the batteries 3 may be restored by a supplemental
charging process based on one of the battery temperature T.sub.BATT
and the outside air temperature T.sub.A. Thus, it becomes possible
to restore the batteries 3 reliably by carrying out a supplemental
charging process only when the restoring of the batteries is
expected.
[0137] Accordingly, the harmful effects on the batteries 3 which
may be caused, for instance, by carrying out a supplemental
charging process when the temperature of the batteries 3 T.sub.BATT
or the outside air T.sub.A is high, may be avoided. Also, it
becomes possible to save time and energy that would be wasted if
unnecessary supplemental charging operation is performed.
[0138] Note that although data obtained from only one of the
battery temperature T.sub.BATT or the outside air temperature
T.sub.A is used in the above embodiment, the charging capacity
restoring determination unit 13 may determine if the batteries 3
may be restored by a supplemental charging process based on
detection data from both the battery temperature T.sub.BATT and the
outside air temperature T.sub.A.
[0139] Further, the charging capacity restoring determination unit
13 may determine the expectation of restoring of the batteries 3
based on date (or month, or season) information obtained from the
integrated calendar 17 which is provided with the ECU 11. Also, it
is possible to input data of annual temperature changes into the
integrated calendar 17 so that the charging capacity restoring
determination unit 13 may determine the expectation of restoring of
the batteries 3 by a supplemental charging process based on the
annual temperature change data as well as the calendar data. If
such a method is adopted, the batteries 3 can be effectively
restored by carrying out supplemental charging processes mainly
during spring or fall, when the restoring of the batteries 3 is
expected to be high, and avoid during a season such as summer or
winter, when the restoring of the batteries 3 is not expected.
[0140] In addition, the determination of the charging capacity
restoring determination unit 13 may be based on the above-mentioned
battery temperature T.sub.BATT and outside air temperature T.sub.A
in association with the data of the integrated calendar 17.
[0141] Also, the supplemental charging unit 14 may carry out a
supplemental charging process by using the most suitable charging
magnitude for the batteries 3 having a certain number of points
based on the point value of the point counter 15 so that the
batteries 3 may be restored reliably. That is, for cases where the
point value is large (i.e., for instance, 50.ltoreq.point value),
the magnitude of the supplemental charging may be increased so that
the batteries 3 may be restored in a quick manner and, for cases
where the point value is small (i.e., for instance, point
value<50), the magnitude of the supplemental charging may be
decreased so that the batteries 3 may be restored in an unforced
manner.
[0142] Moreover, since the charging capacity insufficiency
detection unit 12 subtracts a certain number of points from the
point value in the point counter 15, which corresponds to the
restoring of the batteries 3 after the termination of the
supplemental charging process carried out by the supplemental
charging unit 14, the degree of restoration can be reflected by the
supplemental charging process as numerical points. Accordingly, the
state of the batteries 3, which is converted into numerical points,
may be reliably accumulated in the point counter 15.
[0143] Further, since the subtracted points that indicate the
degree of restoration of the batteries 3 by the supplemental
process may be predetermined in accordance with the temperature of
the batteries 3, it becomes possible to accurately reflect the
difference in the degree of restoration due to the temperature of
the batteries T.sub.BATT by converting it into a certain number of
subtracted points and subtracting such points from the point value
in the point counter 15. The subtracted points, for instance, may
be high in the temperature region where a large restoring of the
batteries 3 is expected (i.e., for instance, 15.degree.
C..ltoreq.T.sub.BATT<40.degree. C.) and may be low when such
restoring cannot be expected (i.e., for instance,
T.sub.BATT<15.degree. C. or 40.degree.
C..ltoreq.T.sub.BATT).
[0144] Also, since the subtracted points are predetermined in
accordance with the number of consecutive supplemental charging
processes, it becomes possible to accurately reflect the degree of
restoration of the batteries 3, which decreases as the number of
consecutive supplemental processes increases, as a certain
numerical value in the point counter 15 by subtracting the
corresponding points from the point counter 15.
[0145] Moreover, since the subtracted points are predetermined in
accordance with the charging magnitude of the supplemental charging
process, it becomes possible to accurately convert the degree of
restoration of the batteries 3 corresponding to the charging
magnitude of the supplemental charging process into a certain
number of points by, for instance, increasing the subtracted value
when the charging magnitude is large (i.e., for instance, about 8
Ah) and decreasing the subtracted value when the charging magnitude
is small (i.e., for instance, about 4 Ah), and reflecting the
degree of restoration by a certain point value in the point counter
15 by subtracting the corresponding points from the point counter
15.
[0146] That is, according to an embodiment of the present
invention, the degree of restoration of the batteries 3 which
differs depending on an individual case may be accurately converted
into a certain number of subtracted points, which is predetermined
in accordance with such factors as the battery temperature
T.sub.BATT, the number of consecutive supplemental charging
processes, or the charging magnitude of a supplemental charging
process, and the degree of restoration may be reflected in a
certain point value in the point counter 15 by subtracting the
corresponding subtracted points from the point counter 15.
Accordingly, the state of the batteries 3 may be reliably
accumulated as a certain numerical point value in the point counter
15.
[0147] Note that the degree of restoration of the batteries 3 by a
supplemental charging process may be varied by factors other than
the battery temperature T.sub.BATT, the number of consecutive
supplemental charging process, and the charging current. Thus, the
subtracted points may be predetermined based on the factors other
than the ones explained above.
[0148] Having thus described an exemplary embodiment of the
invention, it will be apparent that various alterations,
modifications, and improvements will readily occur to those skilled
in the art. Such alterations, modifications, and improvements,
though not expressly described above, are nonetheless intended and
implied to be within the spirit and scope of the invention.
Accordingly, the foregoing discussion is intended to be
illustrative only; the invention is limited and defined only by the
following claims and equivalents thereto.
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