U.S. patent application number 12/896126 was filed with the patent office on 2011-01-27 for method and apparatus for charging a battery to an enhanced capacity.
This patent application is currently assigned to MOTOROLA, INC.. Invention is credited to Andrew F. Burton, Joseph Patino.
Application Number | 20110018503 12/896126 |
Document ID | / |
Family ID | 43496711 |
Filed Date | 2011-01-27 |
United States Patent
Application |
20110018503 |
Kind Code |
A1 |
Patino; Joseph ; et
al. |
January 27, 2011 |
Method and Apparatus for Charging a Battery to an Enhanced
Capacity
Abstract
A lithium-ion battery (126) is normally charged using a constant
current/constant voltage charge regime (206, 210), where the
battery is charged to a preselected normal voltage level (210)
whereupon the voltage is maintained at the limit while the charging
current diminishes. The battery charge capacity can be selectively
increased by charging the battery to an enhanced voltage level
(212) and it can recorded that the battery voltage passed the
normal voltage limit. The enhanced charging mode is selected by a
user via a device user interface (112), or alternatively by a
broadcast command (304) transmitted to the device.
Inventors: |
Patino; Joseph; (Pembroke
Pines, FL) ; Burton; Andrew F.; (Coral Springs,
FL) |
Correspondence
Address: |
MOTOROLA MOBILITY, INC
600 NORTH US HIGHWAY 45, W2-55BB
LIBERTYVILLE
IL
60048-5343
US
|
Assignee: |
MOTOROLA, INC.
Schaumburg
IL
|
Family ID: |
43496711 |
Appl. No.: |
12/896126 |
Filed: |
October 1, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11553559 |
Oct 27, 2006 |
|
|
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12896126 |
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Current U.S.
Class: |
320/162 |
Current CPC
Class: |
H02J 7/045 20130101 |
Class at
Publication: |
320/162 |
International
Class: |
H02J 7/04 20060101
H02J007/04 |
Claims
1. A method of charging a battery to provide enhanced capacity,
comprising: selecting an enhanced capacity charge mode for the
battery coupled to a portable device, wherein the enhanced capacity
charge mode comprises: charging the battery with a constant
charging current until a battery voltage reaches an enhanced
voltage limit that is higher than a normal voltage limit, and then
charging the battery at a constant voltage substantially equal to
the enhanced voltage limit; and recording that the battery voltage
passes the normal voltage limit in a memory associated with the
battery.
2. The method of charging a battery as defined in claim 1, wherein
the selecting is performed via a user interface of the portable
device.
3. The method of charging a battery as defined in claim 2, wherein
the selecting is performed via a graphical user interface of the
portable device.
4. The method of charging a battery as defined in claim 1, wherein
the selecting is performed in response to the portable device
receiving a control command.
5. The method of charging the battery as defined in claim 4,
wherein the control command comprises an emergency
notification.
6. The method of charging the battery as defined in claim 4,
wherein the portable device is a mobile communication device, and
wherein the control command is received from a fixed equipment
network with which the mobile communication device is
communicatively connected.
7. The method of charging the battery as defined in claim 4,
further comprising: alerting a user of the portable device upon
receipt of the control command.
8. The method of charging the battery as defined in claim 4,
wherein the control command includes a broadcast command received
from a base station.
9. The method of charging the battery as defined in claim 4,
wherein the control command includes a wireless control
command.
10. The method of charging the battery as defined in claim 1,
wherein the constant charging current is a substantially constant
charging current.
11. The method of charging the battery as defined in claim 1,
wherein the recording is used to modify a warranty of the
battery.
12. A portable device system, comprising: a portable device; a
battery, coupled to the portable device, and having a battery
voltage; and a charge controller, coupled to the battery, which
charges the battery according to either a normal charge regime or
an enhanced charge regime based on a control command; wherein the
normal charge regime comprises: charging the battery with a
constant charging current until the battery voltage reaches a
normal voltage limit and then charging the battery at a constant
voltage substantially equal to the normal voltage limit; wherein
the enhanced charge regime comprises: charging the battery with a
constant charging current until the battery voltage reaches an
enhanced voltage limit that is higher than the normal voltage
limit, and then charging the battery at a constant voltage
substantially equal to the enhanced voltage limit; and wherein the
battery includes a writeable memory in which each instance of the
battery voltage exceeding the normal voltage limit is recorded.
13. The portable device system as defined in claim 12, wherein the
battery is removeably coupled to the portable device.
14. The portable device system as defined in claim 12, wherein one
of the normal charge regime and the enhanced charge regime is
selected using a user interface of the portable device.
15. The portable device system as defined in claim 14, wherein the
user interface comprises: a graphical user interface.
16. The portable device system as defined in claim 12 further
comprises: a receiver, of the portable device, for receiving the
control command including an emergency notification, from a base
station, to use at least one of the normal charge regime and the
enhanced charge regime.
17. The portable device system as defined in claim 16, wherein a
user of the portable device system is alerted upon receiving the
control command.
18. The portable device system of claim 12 further comprising: a
power supply, coupled to the charge controller, for providing the
constant charging current and voltage to the battery, wherein the
battery is a lithium ion battery.
19. The portable device system as defined in claim 18, wherein: the
power supply is external to the portable device and coupled to the
portable device.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to the following U.S. patent
application: U.S. patent application Ser. No. 11/553,559 (Docket
No. CE15727JEM) filed on Oct. 27, 2006 and entitled "Method and
Apparatus for Charging a Battery to an Enhanced Capacity". The
related application is assigned to the assignee of the present
application and is hereby incorporated herein in its entirety by
this reference thereto.
TECHNICAL FIELD
[0002] This invention relates in general to portable battery
powered devices and more particularly to methods of charging
batteries for use with such devices.
BACKGROUND OF THE INVENTION
[0003] There are a variety of portable electronic devices in common
use by many people for a number of different tasks. Not the least
of which is the cellular or radio telephone and other mobile
communication devices. These devices are all battery powered, and
because of their relatively high power consumption they typically
employ rechargeable batteries due to the high operating cost that
would be incurred with primary batteries.
[0004] Rechargeable batteries are typically recharged according to
a charge regime, meaning prescribed voltage and/or current levels
and limits are applied to the battery, and other factors such as
change in voltage, current, temperature, or a combination of these,
may be taken into account to determine when the battery is finished
charging. For example, nickel-based batteries are often monitored
for temperature and voltage changes. Lithium-ion batteries are
typically charged using a constant current to constant voltage
regime, where the voltage level during the constant voltage phase
is carefully controlled.
[0005] In charging lithium-ion batteries, it has been found that
the voltage level used during the constant voltage phase affects
cycle life of the battery. The higher the voltage limit used, the
more the cycle life of the battery is reduced. Since manufactures
often warranty battery cycle life, the charge voltage limit as
carefully selected to balance optimum charge capacity with cycle
life of the battery. However, at the expense of cycle life, a
lithium ion battery may be recharged to a capacity higher than its
nominal capacity by setting the charge limit voltage higher than a
standard or normal level. Since battery cycle life is warranteed,
though, chargers and charge controllers for lithium-ion batteries
are designed with a fixed charge voltage limit. In some situations,
however, users may wish to achieve higher capacity at the sake of
cycle life, and possibly altering or voiding a battery warranty.
Therefore there is a need for battery charger that allows
selectivity in recharging a lithium-ion battery with regard to
charge voltage limit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 shows a block schematic diagram of a portable device
system, in accordance an embodiment of the invention;
[0007] FIG. 2 shows a charging diagram of voltage and current
verses time for a normal charge mode and an enhanced charge mode,
in accordance with an embodiment of the invention;
[0008] FIG. 3 shows a communication system for enabling an enhanced
charging mode in a mobile communication device, in accordance with
an embodiment of the invention; and
[0009] FIG. 4 shows a flow chart diagram of a method of charging a
battery coupled to a portable device, in accordance with an
embodiment of the invention.
DETAILED DESCRIPTION
[0010] While the specification concludes with claims defining the
features of the invention that are regarded as novel, it is
believed that the invention will be better understood from a
consideration of the following description in conjunction with the
drawing figures, in which like reference numerals are carried
forward.
[0011] The claimed method and apparatus addresses the problem of
under-utilizing battery capacity for the sake of cycle life by
allowing the battery to be charged using an enhanced capacity
charge regime. The battery is initially charged normally, using a
constant current applied to a lithium ion battery or battery cell.
The constant current portion of the charge regime conventionally
lasts until the battery voltage reaches a preselected voltage limit
V.sub.n, at which time a charge controller determines if the
enhanced mode is enabled. If the enhanced mode is enable, the
constant current charging continues until an enhanced voltage limit
V.sub.e is reached. The enhanced voltage limit being higher than
the normal voltage limit. Once the appropriate voltage limit is
reached for the present charging mode, the charging regime changes
from a constant current to a substantially constant voltage regime,
maintaining the battery voltage at either the normal voltage limit
of the enhanced voltage limit. Alternatively, in the enhanced mode,
upon the battery voltage reaching the enhanced voltage limit, the
charging may continue using a constant voltage regime at the normal
voltage limit. When the enhanced mode is used, and if the battery
or battery pack contains a memory, the charge controller may
indicate that the enhanced mode was used in the battery memory for
warranty purposes.
[0012] Referring now to FIG. 1, there is shown a block schematic
diagram of a portable device system 100, in accordance an
embodiment of the invention. The portable device may be any
portable electric or electronic device that is powered by a
rechargeable battery. In the present example, the portable device
is a mobile communication device, such as, for example, a cellular
telephone. The mobile communication device comprises a
communications transceiver 102 for transmitting and receiving
communication signals in conjunction with an antenna 104. At the
level of abstraction used here, the transceiver may include signal
processing elements, modulation elements, and so on. The mobile
communication device further comprises a controller or processor
106 which supervises operation of the mobile communication device
and its various subsystems in accordance with instruction code
stored in a memory 108, as is well practiced. The mobile
communication device may also contain an audio processor 110 for
processing audio information. The audio processor receives digital
audio signals from the transceiver 102, and converts them into
analog audio signals to be played over an audio transducer or
speaker 114 as part of an overall user interface 112. The audio
processor may also synthesize sounds to be played from audio files
stored in the memory 108. The audio transducer may be an earpiece
speaker or other audio device for generating sound. Similarly, the
audio processor receives audio signals from a microphone 116 and
coverts the received analog audio signal to a digital audio signal
for transmission by the transceiver 102. The user interface 112 as
shown here is simply an abstraction of hardware and software
elements allowing user interaction with the device, including, for
example, drivers, filters, switches, and so on. The user interface
further supports a display 118 and a keypad and other buttons 120.
The display is used to present graphical information in a visually
perceptible format, while the keypad allows the user to input
information, select options, and otherwise operate the device.
[0013] The device may be adapted to receive electrical power from
an external source 122. The external power is used by a charge
controller 124 to recharge a battery 126 used to power the device
when the external power supply is not present or connected to the
device. The charge controller controls the application of electric
current and voltage to the battery according to a charge regime,
and determines when to commence charging, when to cease charging,
perform maintenance charging, and other charging-related functions.
In the case of a lithium ion battery, the charge controller
typically applies first a constant current charge regime until the
battery voltage reaches a preselected voltage limit. Upon reaching
the voltage limit, the charge controller maintain the battery
voltage at the voltage limit, allowing the current to diminish as
the battery continues to recharge.
[0014] According to an embodiment of the invention, the charge
controller is capable of charging the battery to either a normal
charge capacity, or an enhanced capacity. The enhanced capacity
charging mode may be selected by, for example, the user via the
user interface, or it may be selected via a control command
received over the air, or both. Assuming a discharged lithium ion
battery, upon connection to the external power supply, the charge
controller first applies a constant or substantially constant
current to the battery. The charge current is typically of an
amperage corresponding to the rated capacity of the battery. So, if
for example the battery has a rated 1000 milliamp-hour capacity,
the initial charge current would typically be 1000 milliamperes.
The constant current charge regime continues until the battery
voltage reaches a normal voltage limit, which is a preselected
limit to allow the battery to reach its rated capacity of recharge.
Upon reaching the normal voltage limit, however, according to an
embodiment of the invention, the charge controller checks to see if
the enhanced charging mode has been selected. Determining if the
enhanced charging mode has been selected may be performed by, among
other means, querying the controller 106, checking a system flag in
memory, checking a flag in the charge controller 124 set by the
controller 106, checking a bit field in a battery memory 128 in the
battery that may be adjusted by the controller 106, and so on.
[0015] If the enhanced charging mode is selected or otherwise
indicated, the charge controller continues to apply the constant
charging current, allowing the battery voltage to exceed the normal
battery voltage limit, until the battery voltage reaches an
enhanced voltage limit. Once the battery voltage reaches the
enhanced voltage limit, the charge controller may maintain the
battery voltage at the enhanced voltage limit, allowing the charge
current to diminish as the battery charge continues to
increase.
[0016] Alternatively, once the battery voltage reaches the enhanced
limit, the charge controller may drop the charge current such that
the battery voltage drops to the normal charge voltage limit, and
continue charging with a constant voltage charge regime at the
normal charge voltage limit. By allowing the battery voltage to
reach the enhanced level, and then continuing to charge at the
normal charge voltage limit rather than at the enhanced voltage
limit, the battery will be recharged faster than it would using the
normal charge mode, but will not attain a substantially increased
charge capacity as when the battery voltage is maintained at the
enhanced charge voltage limit. Thus, either increased capacity, or
decreased charging time may be selected as an enhanced charging
mode.
[0017] Since charging the battery using the enhanced charging mode
reduces the battery's cycle life (the number of charge-discharge
cycles), use of the enhanced charging mode could exceed the
warranty conditions of the battery. Manufacturers would therefore
want to know how often or how many times a battery had been
subjected to the enhanced charging mode in determining whether a
given warranty return battery is indeed faulty or not. Therefore,
according to an embodiment of the invention, the battery may
contain a battery memory 128 in which to store various information,
including, for example, the number of times the battery has been
charged using the enhanced charging mode. A bit field in a
designated memory location in the battery memory may be used to
keep a count of the number of times the battery has been charged
using the enhanced charging mode, and the charge controller 124 may
maintain or increment the count whenever the enhanced charging mode
is enabled, and the battery voltage actually exceeds the normal
battery voltage limit. By not incrementing the count unless the
battery voltage exceeds the normal battery voltage limit, even if
the enhanced charging mode is enabled, such as may occur if the
external power supply is disconnected before the battery voltage
reaches the normal charge voltage limit, the owner of the battery
is not penalized with an increased count.
[0018] Referring now to FIG. 2, there is shown a charging diagram
200 of voltage and current verses time for a normal charge mode and
an enhanced charge mode, in accordance with an embodiment of the
invention. The vertical axis 202 indicates voltage and current
magnitude, generally. The horizontal axis 204 indicates charging
time. The voltage line 206 indicates the battery voltage while the
battery is charging, while the current line 208 indicates the
charging current as the battery is charged. The battery is first
charged using a constant current regime until the battery voltage
reaches the normal charge voltage limit 210 at a first time T.sub.n
214. If the enhanced charging mode is not enabled, the battery
voltage is maintained at the normal charge voltage limit, and the
charge current will diminish as indicated by curve charge current
218.
[0019] If the enhanced charge mode is enabled, however, the charge
current continues at the constant current regime level until the
battery voltage reaches the enhanced voltage limit 212 at a
subsequent time T.sub.e. The charging may continue by maintaining
the battery voltage at the enhanced charge voltage limit, and the
charge current falls away much faster, as indicated by charge
current curve 220. Using the enhanced charging mode, the battery is
recharged to a higher capacity in less time than that resulting
from charging using the normal charging mode. Alternatively, if
after the battery voltage reaches the enhanced charge voltage
limit, and the charging is continued at the normal charge voltage
limit, the current will follow curve similar to charge current
curve 222. In that case, the capacity is not substantially
enhanced, but the charge time is reduced.
[0020] Referring now to FIG. 3, there is shown a communication
system 300 for enabling an enhanced charging mode in a mobile
communication device, in accordance with an embodiment of the
invention. The communication system 300 includes a base station
302. The base station includes an antenna for transmitting signals
to mobile communication devices in the vicinity of the base
station. The geographic region serviced by the base station is
known as a serving area or cell. The base station may further
receive signals from devices located within its serving area.
According to a present embodiment of the invention, the base
station is used to broadcast an enhanced charging mode command 304
to mobile communication devices in the serving area such as mobile
communication device 306. The broadcast command may be broadcast to
specific, addressable or otherwise select call receivers or mobile
communication devices, such as those used by emergency services
personnel. The broadcast command causes all designated devices
receiving the command to recharge their associated battery using
the enhanced charging mode for increased battery capacity. The
command may be issued upon the occurrence of an emergency
situation. Upon connecting the device 306 to a power supply 308,
electric power will be supplied to the device over a power link
310. The electric power is used to both power the device and charge
the battery of the device. The device may have an integral charge
controller, as shown in FIG. 1, or the external power supply may
contain the charge control function, and the device then indicates
enablement of the enhanced charging mode over a communication link
312. The communication link may simply read a bit field in the
battery memory that has been adjusted by the device to indicate
enablement of the enhanced mode.
[0021] Referring now to FIG. 4, there is shown a flow chart diagram
400 of a method of charging a lithium ion battery to achieve an
enhanced capacity, in accordance with an embodiment of the
invention. At the start 402 of the method, the battery is coupled
to a charging entity, such as an external charger, or a charge
controller in a portable device to which the battery is coupled.
According to the present embodiment, the charging entity commences
charging of the battery (404) by application of a constant or
substantially constant current. While the constant current is
applied to the battery, the charging entity observes or sampled the
battery voltage to determine if the battery voltage has reached a
nominal or normal voltage limit (406). Once the normal charging
voltage limit is reached, the charging entity determines if the
enhanced mode is enabled (408). Alternatively, the determination of
whether the enhanced mode is enabled may be made before the battery
voltage reaches the normal charge limit, even prior to commencement
of charging. If, upon the battery voltage reaching the normal
charging voltage limit, the enhanced mode is not enabled, the
charging entity changes to a constant voltage charge regime (410),
and the charging continues normally until the battery is fully
recharged (412) to its normal capacity.
[0022] However, if upon the battery voltage reaching the normal
charge voltage limit, the charging entity has determined that the
enhanced charging mode is enabled, the charging entity continues
applying the constant current charge regime, allowing the battery
voltage to exceed and continue rising above the normal charge
voltage limit (414). While continuing to apply the constant current
charge regime, then, the charging entity checks to see if the
battery voltage has reached an enhanced charging voltage limit
(416). Once the enhanced voltage limit is reached, the charging
entity commences a constant voltage charge regime holding the
battery voltage at the enhanced voltage limit (420). The charging
entity may update warranty information in a battery memory (418),
either after the battery voltage has reached the enhanced voltage
limit, or after the battery voltage exceeds the normal voltage
limit, such as before box 414. While the constant voltage charge
regime is applied, the current diminishes until the battery is
fully charged (412). The battery is considered fully recharged when
the charging current decreases to a predefined level while
maintaining the charging voltage at the selected level.
[0023] Thus, method and apparatus for charging provides in one
embodiment a method of charging a lithium ion battery to provide
enhanced capacity. The enhanced capacity resulting in greater
energy storage compared to a normal capacity of the battery
obtained by using a normal charge more. The method commences by
selecting an enhanced capacity charge mode at a charging entity
used to control charging of the battery. The charging entity may be
a charge controller of a portable device such as a mobile
communication device, or it may be a stand alone charger. The
charging entity commences applying a charge current to the battery.
The charge current is held constant or substantially constant. The
charging entity monitors a charge voltage of the battery while
applying the charge current to the battery. Since the enhanced
charging mode is selected, the battery voltage will rise above the
normal voltage limit. Upon the charge voltage of the battery
passing a normal charge voltage limit and reaching the enhanced
capacity voltage level, the charging entity continues to charge the
battery at a constant charging voltage level substantially equal to
the enhanced capacity charging voltage level. Selecting the
enhanced capacity charge may be performed by a user of a portable
device, to which the battery is coupled, via a user interface of
the portable device. The user interface may be a graphical user
interface, providing visual information to the user and accepting
input from the user.
[0024] Alternatively, selecting the enhanced capacity charge may be
performed in response to a portable device, to which the battery is
coupled, receiving a broadcast command. The broadcast command may
be an emergency notification. Where the portable device is a mobile
communication device, receiving the emergency notification may be
received from a fixed equipment network or base station with which
the mobile communication device is wirelessly connected. If the
device receives a broadcast command, the device may alert the user
of the portable device upon receipt of the broadcast command. The
device may record the instance of the charge voltage of the battery
passing the normal voltage limit in a memory associated with the
battery, which may be used to modify a warranty or warranty
condition of the battery.
[0025] The method and apparatus for charging further provides in an
alternative embodiment a portable device system including a
portable device and a battery coupled to the portable device. The
battery having a battery voltage. Furthermore, the portable device
includes a charging entity such as a charge controller disposed in
the portable device. The charge controller charges the battery
according to either a normal charge regime or an enhanced charge
regime. The portable device provides a means for selecting either
the normal charge regime or the enhanced charge regime. The normal
charge regime comprises charging the battery with a charging
current until the battery voltage reaches a normal voltage limit,
and then charging the battery at a constant voltage substantially
equal to the normal charge voltage level.
[0026] The enhanced charge regime comprises charging the battery
with a charging current until the battery voltage reaches an
enhanced voltage limit that is higher than the normal voltage
limit, and then charging the battery at a constant voltage
substantially equal to the enhanced voltage limit. The battery may
be removeably coupled to the portable device and include a
writeable memory in which each instance of the battery voltage
exceeding the normal voltage limit is recorded. The means for
selecting the enhanced mode may be provided via a user interface of
the portable device, such as a graphical user interface.
Alternatively, the means for selecting the enhanced mode may
include a receiver for receiving a broadcast command. The device
may therefore include a means for alerting the user of the mobile
communication device upon receipt of the broadcast command.
[0027] While the preferred embodiments of the invention have been
illustrated and described, it will be clear that the invention is
not so limited. Numerous modifications, changes, variations,
substitutions and equivalents will occur to those skilled in the
art without departing from the spirit and scope of the present
invention as defined by the appended claims.
* * * * *