U.S. patent application number 15/003932 was filed with the patent office on 2016-05-19 for battery pack chargers and charging methods.
This patent application is currently assigned to Black & Decker Inc.. The applicant listed for this patent is Black & Decker Inc.. Invention is credited to Rouse Roby Bailey, JR., Snehal S. Choksi, Nathan J. Cruise, Regina C. Cunanan, Geoffrey S. Howard, Alexis W. Johnson, Michelle L. Miller, Andrew E. Seman, Danh T. Trinh, Daniel J. White.
Application Number | 20160141902 15/003932 |
Document ID | / |
Family ID | 39789360 |
Filed Date | 2016-05-19 |
United States Patent
Application |
20160141902 |
Kind Code |
A1 |
Cruise; Nathan J. ; et
al. |
May 19, 2016 |
Battery Pack Chargers and Charging Methods
Abstract
A method of charging a battery pack is provided. The method
includes: providing a charger comprising a battery interface, a set
of terminals, and a power supply circuit for providing a charging
current scheme; providing a set of battery packs, each battery of
the set of battery packs comprising a charger interface having a
physical configuration to mate with the battery interface and a set
of terminals having a physical configuration to mate with the set
of charger terminals; and providing a charging scheme defined by a
relationship between the set of battery terminals and the set of
charger terminals.
Inventors: |
Cruise; Nathan J.; (Phoenix,
MD) ; Bailey, JR.; Rouse Roby; (New Park, PA)
; Choksi; Snehal S.; (Owings Mills, MD) ; Cunanan;
Regina C.; (Baltimore, MD) ; Howard; Geoffrey S.;
(Columbia, MD) ; Johnson; Alexis W.; (Warren,
PA) ; Seman; Andrew E.; (Pylesville, MD) ;
Trinh; Danh T.; (Towson, MD) ; White; Daniel J.;
(Baltimore, MD) ; Miller; Michelle L.;
(Westminster, MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Black & Decker Inc. |
New Britain |
CT |
US |
|
|
Assignee: |
Black & Decker Inc.
New Britain
CT
|
Family ID: |
39789360 |
Appl. No.: |
15/003932 |
Filed: |
January 22, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12213060 |
Jun 13, 2008 |
9281695 |
|
|
15003932 |
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|
60949603 |
Jul 13, 2007 |
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60945187 |
Jun 20, 2007 |
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Current U.S.
Class: |
320/113 |
Current CPC
Class: |
H01M 10/46 20130101;
H02J 7/00 20130101; H02J 7/0045 20130101; H01M 10/30 20130101; H01M
2220/30 20130101; Y02E 60/10 20130101; H02J 7/0021 20130101; H01M
10/441 20130101; H02J 7/007 20130101; H02J 7/00047 20200101; H02J
7/00038 20200101; H02J 7/00041 20200101; H01M 10/0525 20130101 |
International
Class: |
H02J 7/00 20060101
H02J007/00; H01M 10/30 20060101 H01M010/30; H01M 10/0525 20060101
H01M010/0525; H01M 10/46 20060101 H01M010/46; H01M 10/44 20060101
H01M010/44 |
Claims
1. A combination of a battery charger and a set of battery packs,
comprising: a charger comprising a battery interface, a set of
terminals, and a power supply circuit for providing a charging
current scheme; a set of battery packs, each battery of the set of
battery packs comprising a charger interface having a physical
configuration to mate with the battery interface and a set of
terminals having a physical configuration to mate with the set of
charger terminals; wherein the power supply circuit provided
charging scheme is defined by a relationship between the set of
battery terminals and the set of charger terminals.
2. The combination, as recited in claim 1, wherein the charging
scheme is defined by which of the battery terminals electrically
mate with which of the charger terminals when the battery pack is
physically mated with the charger.
3. The combination, as recited in claim 1, wherein the set of
charger terminals has a predefined configuration and each set of
battery terminals has a predetermined configuration and the
charging scheme is defined by a number of battery terminals that
electrically mate with the charger terminals.
4. The combination, as recited in claim 1, wherein the power supply
circuit provides a first charging scheme when a first charging path
is established between the battery charger and a first battery pack
of the set of battery packs and a second charging scheme when a
second charging path is established between the battery charger and
a second battery pack of the set of battery packs.
5. The combination, as recited in claim 1, wherein the power supply
circuit provides a first charging scheme for a first configuration
of the set of battery terminals and a second charging scheme for a
second configuration of the set of battery terminals.
6. The combination, as recited in claim 1, wherein the set of
charger terminals comprises a first subset of charger terminals and
a second subset of charger terminals and wherein the power supply
circuit provides a first charging scheme when a first set of
battery terminals electrically mates with the first subset of
charger terminals and a second charging scheme when a second set of
battery terminals electrically mates with the second subset of
charger terminals.
7. The combination, as recited in claim 1, wherein a first battery
pack has a first chemistry and a first set of battery terminals
having a first configuration and a second battery pack has a second
chemistry and a second set of battery terminals having a second
configuration and wherein the first set of battery terminals
electrically mates with a first subset of charger terminals when
the first battery pack is physically mated to the charger and the
second set of battery terminals electrically mates with a second
subset of charger terminals when the second battery pack is
physically mated to the charger.
8. The combination, as recited in claim 7, wherein the power supply
circuit provides a charging scheme defined by which subset of
charger terminals electrically mates with the set of battery
terminals.
9. A method of charging a battery pack, comprising the steps of:
providing a charger comprising a battery interface, a set of
terminals, and a power supply circuit for providing a charging
current scheme; providing a set of battery packs, each battery of
the set of battery packs comprising a charger interface having a
physical configuration to mate with the battery interface and a set
of terminals having a physical configuration to mate with the set
of charger terminals; and providing a charging scheme defined by a
relationship between the set of battery terminals and the set of
charger terminals.
10. The method of claim 9, wherein the charging scheme is defined
by which of the battery terminals electrically mate with which of
the charger terminals when the battery pack is physically mated
with the charger.
11. The method of claim 9, wherein the set of charger terminals has
a predefined configuration and each set of battery terminals has a
predetermined configuration and the charging scheme is defined by a
number of battery terminals that electrically mate with the charger
terminals.
12. The method of claim 9, wherein the power supply circuit
provides a first charging scheme when a first charging path is
established between the battery charger and a first battery pack of
the set of battery packs and a second charging scheme when a second
charging path is established between the battery charger and a
second battery pack of the set of battery packs.
13. The method of claim 9, wherein the power supply circuit
provides a first charging scheme for a first configuration of the
set of battery terminals and a second charging scheme for a second
configuration of the set of battery terminals.
14. The method of claim 9, wherein the set of charger terminals
comprises a first subset of charger terminals and a second subset
of charger terminals and wherein the power supply circuit provides
a first charging scheme when a first set of battery terminals
electrically mates with the first subset of charger terminals and a
second charging scheme when a second set of battery terminals
electrically mates with the second subset of charger terminals.
15. The method of claim 9, wherein a first battery pack has a first
chemistry and a first set of battery terminals having a first
configuration and a second battery pack has a second chemistry and
a second set of battery terminals having a second configuration and
wherein the first set of battery terminals electrically mates with
a first subset of charger terminals when the first battery pack is
physically mated to the charger and the second set of battery
terminals electrically mates with a second subset of charger
terminals when the second battery pack is physically mated to the
charger.
16. The method of claim 15, wherein the power supply circuit
provides a charging scheme defined by which subset of charger
terminals electrically mates with the set of battery terminals.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This continuing application derives priority to U.S.
non-provisional patent application Ser. No. 12/213,060 filed Jun.
13, 2008, which claims priority to U.S. provisional patent
application No. 60/945,187, titled "Battery Pack Charger" filed
Jun. 20, 2007 and 60/949,603, titled "Battery Pack Chargers and
Charging Methods" filed Jul. 13, 2007 the disclosures of which are
hereby incorporated by reference in their entirety.
BACKGROUND
[0002] 1. Field
[0003] Example embodiments relate in general to charging devices
and methods for charging and/or recharging battery packs, for
example, power tool battery packs having a variety of chemistries
and plug configurations.
[0004] 2. Description of Related Art
[0005] Portable power tools may rely on battery packs to supply
power when used in remote or otherwise inaccessible areas. Battery
packs for power tools may have a compact design to decrease overall
tool size and bulk and may have higher energy storage capacity to
facilitate longer remote tool use/discharge times. To achieve
higher power, energy storage, and recharging capacity with minimum
size and weight, conventional battery packs may include Lithium-Ion
(Li-Ion), Nickel-hydroxide/Cadmium (NiCad), and Nickel/Metal
hydride (NiMH) chemistries. Battery packs may include a variety of
other unique physical characteristics and shapes based upon their
intended use.
[0006] Similarly, conventional battery pack chargers exist to
recharge specific types of batteries with varying configurations
based on the battery-based application. Conventional battery pack
chargers are generally configured to be compatible with specific
conventional battery packs, which, as stated above, have varying
physical characteristics based upon their application. Conventional
battery pack chargers may charge only battery packs with specific
physical shape, chemistry, adaptor configuration, electronics,
and/or other battery pack characteristics. Conventional battery
pack chargers may not charge or may improperly charge battery packs
not meeting the specific criteria required for the individual
charger.
[0007] Accordingly, conventional battery pack chargers typically
have features matching a specific battery pack to be charged and
are incompatible with batteries not having these specific
characteristics, in order to both reduce cost and complexity. The
chargers may include only components capable of charging a specific
battery pack; for example, chargers may be capable of providing a
single electrical current type corresponding to the single type of
battery intended to be used in the charger. Further, conventional
battery packs may properly interact with only a single type of
battery; for example, chargers may be capable of determining
charge/recharge completion in only a single predetermined type of
battery.
[0008] Because conventional battery pack chargers are designed to
charge a single type of battery, undesirable results may occur if
inappropriate battery types are electrically connected to
conventional chargers. Thus conventional battery pack chargers
often include mechanisms to determine if the connected battery is
an appropriate type. If the battery pack does not have the specific
set of appropriate characteristics, conventional battery chargers
may not charge or otherwise interact with the inappropriate
battery.
[0009] Similar lockout mechanism for incompatible chargers and
batteries may be used with power tools, where multiple batteries
are used with multiple remote tools; however, it may also be
difficult to match multiple batteries having an exact set of
appropriate characteristics with the proper conventional battery
pack chargers.
SUMMARY
[0010] Example embodiments may include battery pack chargers and
methods capable of charging battery packs with varying physical
characteristics and chemistries, including Li-Ion batteries with
higher charge/weight ratios. Example battery pack chargers may
include mechanisms for determining the characteristics of a battery
pack to be charged and charging the battery pack based on those
characteristics. Example battery pack type determination mechanisms
include an electrical-characteristic sensor, specific terminal
engagement, and/or battery-charger mating components.
[0011] In accordance with one embodiment of the invention, a
battery charger is provided. The charger may include: a first
terminal for connecting to a battery pack; a second terminal for
connecting to a battery pack; a microprocessor operatively
connected to the terminals and configured to receive a signal from
at least one terminal regarding a battery pack connected to the
terminal and control the charger to select and apply a charging
scheme to the battery pack according to the signal.
[0012] In accordance with another embodiment of the invention, a
method of charging a battery is provided. The method may include:
applying a toggle signal to charging terminals; monitoring a
terminal voltage at the maximum and minimum of the toggle signal;
determining a difference in the terminal voltage at the maximum and
minimum of the toggle signal; comparing the difference in terminal
voltage to a predetermined threshold, if the difference in terminal
voltage is below the predetermined threshold, then; detecting a
type of battery pack connected to the terminals; and applying a
charging scheme according to the type of battery pack detected.
[0013] In accordance with yet another embodiment of the invention,
a method of charging a battery is provided. The method may include:
electronically connecting a battery pack to a charger; detecting
information regarding the battery pack; determining an appropriate
charging scheme based on the detected information; and applying the
charging scheme to the battery pack.
[0014] Example battery packs chargers may also include features to
prevent damage and wear when charging multiple types of battery
packs. Example damage-reducing features include voltage decay
sensors for determining battery presence.
[0015] The above and other features of example embodiments
including various and novel details of construction and
combinations of parts will now be more particularly described with
reference to the accompanying drawings. It will be understood that
the details of the example embodiments are shown by way of
illustration only and not as limitations of the example
embodiments. The principles and features of this invention may be
employed in varied and numerous embodiments without departing from
the spirit and scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIGS. 1 and 2 are isometric views of example embodiment
battery pack chargers.
[0017] FIG. 3 is an example battery pack using alternate terminals
to provide correct battery pack charging.
[0018] FIG. 4 is an example battery pack charger using alternate
terminals to provide correct battery pack charging.
[0019] FIG. 5 is a profile view of an example terminal engagement
with a first type of battery and example battery pack charger.
[0020] FIG. 6 is a profile view of an example terminal engagement
with a second type of battery and the example battery pack charger
of FIG. 5.
[0021] FIG. 6A is a profile view of an example alternative charging
terminal engagement with an alternate battery terminal.
[0022] FIG. 7 is an isometric view of an example dual terminal
engagement for utilizing alternate terminals.
[0023] FIG. 8 is a profile view of the example terminals of FIG.
7.
[0024] FIG. 9 is a plan view of example circuitry for determining
proper charging based on battery data.
[0025] FIG. 10 is a chart illustrating example types of voltage
ranges corresponding to different charging schemes.
[0026] FIG. 11 is a graph of example voltage ranges and voltage
decay waveforms in example chargers.
[0027] FIG. 12 is a flow chart of an example method for charging
battery packs.
[0028] FIG. 13 is an example waveform useable with example
methods.
DETAILED DESCRIPTION
[0029] The following description presents example embodiments and
is not intended to limit the present disclosure, in application or
use. It should be understood that throughout the drawings,
corresponding reference numerals indicate like or corresponding
parts and features.
[0030] As shown in FIGS. 1 and 2, an example embodiment battery
pack charger 1 may be configured to provide power to a battery pack
2 inserted therein or otherwise connected thereto. The charger 1
may include a power source and/or electrical connection 3 to
conventional power outlets from which power may be transferred to a
battery pack 2.
[0031] Multiple types and generations of battery packs 2 may be
present at a single location where portable power tools are being
used and charged, and multiple chargers 3 may exist for charging
the individual battery packs 2. Example embodiments described below
include features that allow multiple battery types and generations
to be charged with a single charger.
[0032] I. Example Embodiments Depicted in FIGS. 3-6:
[0033] FIGS. 3-5 illustrate a tower style example embodiment
battery pack and example embodiment charger including
battery-type-dependent charging paths. Other style chargers,
including rail style chargers, are useable as example embodiments,
and tower style batteries and chargers are shown merely as an
example of one such configuration.
[0034] As shown in FIG. 3, the example tower-style battery 100
includes a number of terminals 120 that electrically connect the
battery with example chargers. Terminals may be in a variety of
configurations, for example, positive and negative terminals 123
and 121 may provide electrical connection while a grounding
terminal 122 grounds the battery electronics, provides data
exchange, and/or otherwise connects the battery to the charger.
[0035] FIG. 4 shows an example tower-style charger into which the
battery pack of FIG. 3 may be inserted for charging. Because
example battery packs 100 may have varying chemical properties,
charging times, electrical requirements, and/or other physical
characteristics, example charger 200 may provide unique charging
current, voltage, charging time, and/or other charging
characteristics (hereinafter "charging scheme") based on the type
of battery inserted.
[0036] One way for example chargers to determine the proper
charging scheme for the battery inserted in the charger is to
provide different charging paths for different types of batteries.
Batteries with different chemistries, for example, Li-Ion batteries
and Ni/MH batteries, may have different body shape and/or terminal
configuration. An example charger 200 may thus provide different
terminals that match only a particular battery type and provide a
charging scheme matching that type.
[0037] As shown in FIG. 3, terminals 120 may be provided at one end
of a tower 125 of an example battery 100. The physical orientation
of the terminals 120 may be arranged on the battery for creating a
connection with the charger based on the particular battery being
charged. For example, the terminals 120 may have a particular
spacing or position on a defined area of the battery 100, each at
one end on the illustrated towers 125, that reflects the battery
type that forms a connection between a pack and a charger for a
particular battery type.
[0038] In particular, the terminals themselves may also be
configured for particular battery types. Further, terminals 120 of
the example battery 100 may be substantially different than
terminals of other battery types requiring different charging
schemes. Thus, example batteries can be screened by using a
terminal combination that establishes an electrical connection with
an appropriate battery.
[0039] While a tulip-style terminal arrangement is shown in the
example embodiments, other types of terminal configurations may be
used that are consistent with the invention.
[0040] As shown in FIG. 5, example chargers may discriminate among
various battery types by possessing sets of charging terminals 210
that will electrically connect with only a particular type of
battery. A charging scheme provided by terminals 210 may match only
the scheme required by other batteries that fully engage the
terminals as shown in FIG. 5. For example, voltage across terminals
210 may match only to a voltage required by other battery types
with terminals fully engaging terminals 210. Other scheme matching
characteristics, including for example charging time and maximum
current, may be provided to only terminals 210.
[0041] As shown in FIG. 5, the charger may contain a unique
charging terminal such as a tulip style arrangement. The other
battery terminals 123' and 121' may connect with the tulip-style
charging terminals 210 when the other battery is inserted into the
example charger 200. If however, example batteries 100 are inserted
into the example charger, instead of fully engaging the charging
terminals 210 like other battery types as shown in FIG. 5, positive
and negative terminals 121 and 123 may not connect with charging
terminals 210 as shown in FIG. 6.
[0042] FIG. 6A shows an alternate charging terminal 220 in the
example charger 200 that may be aligned with and engage alternate
battery terminal 130. The alternate charging terminal 220 may
provide a different charging scheme unique to example batteries 200
with alternate battery terminal 130 that engage alternate terminal
220. Other batteries having terminals 123' and 121' that fully
engage terminals 210 may not engage alternate terminal 220 in
example chargers and thus may not be electrically connected to
alternate charging terminal 220.
[0043] By these different terminals 210 and 220 in the same example
charger, different charging schemes may be provided to different
types of batteries, based on which terminals the battery contacts.
Thus batteries, even having a substantially similar overall shape,
with different terminal configurations may be charged differently
in the same example charger 200, based on the terminal shape and
configuration.
[0044] For example, a Li-Ion battery may have shorter terminals
than a Ni-Cad battery and an additional post terminal, but the two
batteries may have substantially similar shape and be useable in
the same tool. Example chargers may thus engage the Ni-Cad battery
through a first set of terminals and determine charge completion
based on typical Ni-Cad voltage variations at charge completion. A
Li-Ion battery may be inserted in the same charger yet engage a
different set of terminals and be charged in a different manner.
Thus, Li-Ion batteries, with charging requirements vastly different
than Ni-Cad batteries, may be successfully charged in the same
example charger without damaging the battery.
[0045] II. Example Embodiments Depicted in FIGS. 7-8:
[0046] Other example chargers may include co-located terminals that
provide alternate charging paths based on battery terminal length
alone, without relying on additional or alternately-located
terminals.
[0047] As shown in FIGS. 7 and 8, co-located terminals 311 and 312
may provide alternate charging paths based on the length of the
battery terminal inserted in those terminals. Negative terminal 310
may function as a shared negative terminal for all batteries
inserted in example chargers. Positive first terminal 311 may have
a length configured to engage types of tool terminals, and positive
second terminal 312 may engage only subsets of those types of tool
terminals. That is, shorter second terminals 312 may engage only
tools with longer terminals, while terminals 311 may engage tools
with both longer and shorter terminals.
[0048] Because co-located positive terminals 311 and 312 engage, in
combination, different types of tool terminals, terminals 311 and
312 may provide different charging schemes and thus differently
charge tools depending on terminal length. For example, if a tool
having terminals 123' and 121' as shown in FIG. 5 is inserted into
example terminals 311 and 312 in FIGS. 7 and 8, both positive
terminals 311 and 312 may engage the tool terminal. Alternatively,
if a tool having terminals 123 and 121 as shown in FIG. 6 is
inserted, only longer positive terminal 311 may engage the tool
terminal.
[0049] Longer and shorter co-located terminals 311 and 312 may
provide different charging schemes, and thus, different types of
charge may be delivered to tools based on their terminal length. As
previously stated, charging schemes may include voltage
characteristics, maximum current, charging time, resistance
detection, charge completion detection, and/or any other charging
characteristics of individual battery packs. If both terminals 311
and 312 are engaged by a long battery terminal (such as 121' in
FIG. 5), both terminals may provide charging such that their
combined charging provides a different charging scheme to the long
terminal battery. Alternately, example chargers may possess logical
or other known circuitry to allow only a single terminal of 311 and
312 to deliver an alternate charging scheme if both terminals 311
and 312 are engaged.
[0050] For example, only long positive terminal 311 may engage
Li-Ion batteries, because these types of batteries have shorter
terminals than NiCad or NiMH batteries. When only the long positive
terminal 311 is engaged, that terminal provides electric current,
voltage, and other charge characteristics required by only Li-Ion
batteries. Short terminal 312 may be engaged only to NiCad or NiMH
batteries. Thus, if both terminals 311 and 312 are engaged, they
provide, together or individually, charge characteristics required
by only NiCad or NiMH battery packs.
[0051] Several variations of the above example configurations are
possible while still achieving the same structural discrimination
in example chargers. For example, any number of alternate terminal
locations may be used to uniquely engage and charge any number of
batteries, each having a distinct charging requirement and terminal
configuration. Or, for example, some terminals may be shared among
all battery types, with non-shared terminals determining charge
scheme. For example, a common negative power terminal may be in
example chargers and accessible to all connected batteries, while
different positive terminals with alternate charging schemes may be
accessible only to particular batteries matching the positive
terminal's charging characteristics.
[0052] Similarly, any number of known variations may be used to
achieve alternate terminal engagement between different types of
batteries. For example, an example charger may have different
shaped openings or blocking parts that enable one type of battery
to engage one set of terminals but prevent other types of batteries
with other shapes from engaging the same terminals. Further, any
number of known terminal shapes and charging schemes may be used to
successfully electrically connect example chargers to example
batteries.
[0053] III. Example Embodiment Depicted in FIGS. 9-10
[0054] A second example charger mechanism for determining battery
pack configuration and applying a matching charging scheme may
include determining electrical properties of an inserted battery by
measuring electrical properties of the inserted battery. These
example structures may be useable with a universal terminal engaged
by all battery types, or with alternate terminals disclosed in
previous example embodiments.
[0055] Example batteries may include a non-charging terminal that
provides battery information that may be read by example chargers.
For example, terminal 122 in FIG. 3 may be a non-charging terminal
capable of providing battery-type information. From these
structures example chargers may discriminate among different
battery types and provide proper charging schemes to the inserted
batteries.
[0056] As shown in FIG. 9, one example mechanism for providing
battery information may involve a thermistor and/or resistor 510
electrically connected to a non-charging terminal in the battery.
Example resistors 510 provide a voltage range for a given current
that is unique to the battery type. Example battery pack chargers
may electrically connect with resistors 510 through connections
520, and the voltage may be read by a validation circuit 530. Based
on this reading, a microprocessor 540 may enable circuitry
corresponding to a proper charging scheme for batteries having the
measured voltage range. If no voltage or an unidentified voltage
range is measured, the microprocessor may discontinue charging as a
safety mechanism.
[0057] Through the example circuitry described in FIG. 9, different
charging schemes may be associated with particular resistances of
known battery types. For example, as shown in FIG. 10, a first
resistance may be associated with Li-Ion batteries that will
generate a known first voltage range 600 in example chargers
electrically connected to non-charging terminals of the battery.
Once example chargers detect the first voltage range 600, a
charging scheme corresponding to Li-Ion batteries is provided by
the charger. A second resistance may be associated with NiCad
batteries that will generate a known second voltage range 610 in
the same example chargers. When example chargers detect the second
voltage range 610, a charging scheme corresponding to NiCad
batteries is provided by the charger.
[0058] Although example embodiments in FIGS. 9-10 have been
described with regard to a characteristic resistance being
associated with particular batteries and charging schemes, several
other characteristics and measurements may be used to identify
battery type in example chargers. For example, a non-charging
terminal may provide digital signals that are readable by an
example charger microprocessor. The digital data may include a
battery type that is readable by the microprocessor and used to
determine a proper charging scheme. Known analog signals, voltages,
currents, and/or any other type of data transmission may be used to
convey battery type to example chargers and allow the charger to
select a proper charging scheme including, for example, maximum
current, charge time, charge completion indications, current and
voltage variations, and/or any other charging characteristic.
[0059] IV. Example Embodiment Depicted in FIG. 11
[0060] Example embodiments may further provide circuitry and
charging methods for preventing damage to example battery chargers
having low or no open circuit voltage. Example chargers may have no
open circuit voltage; that is, the voltage potential when no
battery pack is inserted is near zero between the charging
terminals. As shown in FIG. 11, V.sub.OC (open circuit voltage) may
be zero volts, whereas the voltage of battery terminals may be
measurably higher (V.sub.B). By use of a conventional voltage
measuring device, example chargers may begin charging only when a
non-zero voltage potential is detected between charging terminals.
For example, example chargers may begin charging shortly after time
T.sub.i when voltage increases and indicates battery insertion.
[0061] As also shown in FIG. 11, however, example chargers may not
jump between V.sub.OC and V.sub.B as a step-function; rather, the
voltage transition is a continuous exponential due to the presence
of capacitors in example batteries and chargers. Thus, when the
battery is withdrawn at time T.sub.W, the voltage potential does
not immediately near zero or V.sub.OC. If example chargers activate
at any voltage above V.sub.OC, then example chargers may continue
to deliver power after a battery is removed at T.sub.W, which may
damage components of example chargers.
[0062] In order to prevent stressing components of example
chargers, example chargers may include a further voltage detection
mechanism, such as a microprocessor or voltage microcontroller,
that senses voltage decrease instead of voltage at V.sub.OC.
Charging may be terminated by the microcontroller when voltage
first starts to decrease, shortly after T.sub.W, instead of near
T.sub.i2, which may be much later than T.sub.W.
[0063] For example, if a battery pack is charging in an example
charger and voltage across the charging terminals is V.sub.B, then
example chargers may continue delivering charging power while the
voltage remains at V.sub.B. When the battery pack is removed at
T.sub.W, voltage immediately begins decaying, and example chargers
sense this decay and terminate the charging power. Thus example
chargers may cease delivering charging power well before terminal
voltage reaches near zero and before battery components are
damaged.
[0064] V. Example Embodiment Depicted in FIGS. 12-13
[0065] As discussed above in earlier example embodiments, example
chargers may have no open circuit voltage; that is, the voltage
potential when no battery pack is inserted may be near zero between
the charging terminals.
[0066] Some battery types may have near-zero terminal voltage after
fully discharging. For example, a Ni-Cad battery may have a very
low voltage across its terminals after completely discharging, or a
Lithium Ion battery may have a very low voltage across its
terminals if damaged or in an inoperative state. Because of low
terminal voltage in both discharged battery packs and example
chargers, battery presence and charge scheme determination may
require another mechanism to determine low-voltage battery
presence.
[0067] Example chargers may include circuitry and associated
charging methods that determine battery presence even if an
inserted battery pack has low or no terminal voltage.
[0068] As shown in FIG. 12, example chargers may perform an example
method in order to determine battery presence. Example methods
include applying a toggle signal across the charger terminals at
step S100. The toggle signal may be a voltage or current pulse of
any magnitude sufficient to create an electrical response in
potentially-inserted battery packs without damaging those
packs.
[0069] For example, as shown in FIG. 13, the toggle signal may be a
square voltage pulse. The example pulse shown in FIG. 13 has a
maximum voltage of about 3 Volts and a minimum voltage of about 0
Volts. The example pulse in FIG. 13 is applied for about 0.5
seconds and then no voltage is applied for about 0.5 such that the
entire toggle signal cycles every second. The pulse used in example
methods need not be square as shown in FIG. 13, but may be a
variety of waveforms, including sawtooth and/or multi-stepped,
depending on the types of batteries to be identified.
[0070] As shown in FIGS. 12 and 13, after applying the toggle
signal at S100, the battery pack charger measures the terminal
voltage at the signal maximum and minimum at step S120. For
example, as shown in FIG. 13, the charger may measure the terminal
voltage at Tmax and Tmin in order to measure the voltage at the
signal maximum and minimum. If other pulse forms are used in
example methods, other measuring times may be used in order to
measure the signal maximum and minimum.
[0071] Example chargers may then determine the voltage difference
across the terminals at Tmax and Tmin in step S140. This difference
may then be compared against a no-pack threshold in step S150. The
no-pack threshold may be, for example, a threshold corresponding to
the voltage difference across the terminals when only air or a
different non-battery material is between the terminals while a
voltage pulse is applied from the charger across the charger
terminals. Such a threshold will generally be much higher compared
to voltage measured when a conductor or battery is connected
between the terminals, due to the differing resistance. The
threshold may be compared through any method known in the art,
including analog circuitry or digitally through a microprocessor in
example batteries.
[0072] If the voltage difference determined in step S140 is above
the no-pack threshold compared in step S150, the charger may
determine that no battery is present in step S160 and continue to
apply to toggle signal until a battery is detected. That is, steps
S100, S120, S140, S150, and S160 may be repeated as long as the
measured voltage is above the threshold, and thus, no battery is
detected.
[0073] If the voltage difference is below the no-pack voltage
threshold, then example chargers may determine that a battery pack
is present. Example methods may then include proceeding with
battery pack type detection in step S170. The battery pack type
detection may be performed by any example embodiment previously
discussed; that is, example embodiment charger structures for
discriminating based on pack type may be used in step S170. For
example, differing terminal placement, characteristic battery
resistance, and/or Hall sensor presence may be determined in step
170. Based on these determinations, the battery pack may be charged
or pre-charged in step S190 based on their type.
[0074] Additionally, the charger may display an error message based
on the results of step 150 and step S170 in step S190. For example,
if other battery type detection mechanisms determine that the
battery is a Lithium-Ion battery, but there is initially no voltage
across the Li-Ion terminals, the charger may display an error
message because correctly functioning Li-Ion chemistries may not
have zero-voltage states.
[0075] In addition to the previously described structures and
methods for determining pack type, step S175 illustrates another
method for determining pack type in a low-voltage situation. Once
the charger has proceeded through step S150 to determine that a
pack is present but in a low-voltage state, the example chargers
may apply a longer charging current to the battery in step S175.
This precharge may be of lesser duration and/or magnitude than a
full charge for specific pack types, but may be sufficient to power
electronics within an inserted battery. For example, example
chargers may apply full charging current to the battery for about 4
seconds and then stop for 6 seconds while determining a response
from the battery.
[0076] Batteries may include, for example, microchips
communicatively connected to example chargers. Such microchips may
not be able to communicate with example chargers while in a
low-voltage situation, and the precharge in step S175 may power
those microchips such that the charger may determine the type of
battery based on characteristics of the microchip. By the step
S175, example chargers may thus determine pack type and appropriate
charging scheme in packs in a low-voltage state before actual
charging commences.
[0077] Once the battery pack has been determined in steps S170
and/or S175, example chargers may apply an appropriate charge,
precharge, or error message based on the results of the battery
type detection and the voltage state of the battery. For example,
some types of batteries may be capable of being charged normally
while in a low-voltage state, while other batteries may have
special precharging schemes applicable to a low voltage state. The
example method shown in FIG. 12 allows example chargers to so
discriminate and apply appropriate charge schemes to batteries in a
low-voltage condition.
[0078] Each of the aforementioned embodiments may be used alone and
in combination for allowing battery packs having different charging
characteristics and requirements to be charged using the same
example charger.
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