Note: Descriptions are shown in the official language in which they were submitted.
CA 02635338 2011-03-16
Title of the Invention
A Graphic State of Charge Indicator for a Battery Charging System and Method
of
Use
.Field of the Invention..
This invention relates to battery charging systems and more particularly to a
graphic state of charge indicator for such a system and method of use whereby
battery charging systems can be monitored for state of charge/discharge and
rate
of charge/discharge using a graphic indicator.
.Background of the Invention..
Advanced mobile power systems such as lithium based rechargeable battery packs
often include a capacity display of some sort. This capacity display is
generally
referred to as a State of Charge indicator and may be as complex as a
numerical
representation of the capacity of the battery, or as simple as a single
indicator light
for low battery conditions.
The conventional method for recharging these battery pack systems is to
provide a
plug-in charge connection through a direct household electrical connection,
through a vehicle power system, or through a computer power system such as a
USB (Universal Serial Bus) port.
Different rechargeable battery technologies require different charging
techniques. A
popular battery charging technology is called CCCV or Constant Current
Constant
Voltage charging. This charging technique uses a controlled current to
recharge the
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battery during the first phase of charging. As the battery nears fully charged
the
charger voltage reaches a point where it is limited and the current is allowed
to fall.
This method of charging is most commonly used in ion-exchange systems such as
Lithium Ion based batteries.
The state of charge system sometimes indicates if the system is charging by
flashing either the entire display or by flashing the highest capacity
indicator
element. This flashing is strictly binary in that it indicates either that the
battery is
charging or is not charging.
The state of charge indication devices commonly in use do not provide an
indication that the system they are monitoring is supplying a load.
Solar, hand-crank and fuel-based charging systems may be used to recharge a
portable power system. These chargers have the advantage of providing a
portable
recharging solution to accompany the portable power storage system. The
principle
disadvantage of these chargers is that it is difficult or impossible in most
applications to determine if the charger is putting out a significant amount
of
power, or if it is in an optimal configuration to provide power.
Further, there is not a good way to determine if these portable charging
solutions
are actually producing enough power to exceed the demand of the load which may
still be connected to the system.
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There exists a need for a graphic state of charge indicator for battery
charging
systems that provides state of charge indication but also provides more
information
with respect to recharge rate and discharge rate such that the battery charger
can
be optimally configured to provide the fastest recharge time possible. There
is also
a need for such indicator to be easy to read, to be similar in appearance to
existing
state of charge indicators and to be physically small to fit the natures of
these
complete portable solutions.
Summary of the Invention
In one embodiment of the invention there is provided a graphic state of charge
display for a battery charging system shaped like a battery for use on
conventional
battery operated equipment such as cellular phones and music players. In one
embodiment, the display contains a LCD display having between 3 and 10 but
generally 5 segments LCD which is coupled to a microcontroller that is
configured
1 5 to measure the state of charge of the battery. The microcontroller has
the ability to
measure the amount of current flowing into or out of the battery pack to an
external load and is able to provide this information to the user using the
same 5
segment LCD display in a way that is intuitive and easy to understand.
The actual form of the state of charge indicator, the battery pack and the
recharge
or discharge methods can be changed without detracting from the essence of the
invention which is to use the state of charge indicator as a state of load and
state of
recharge indicator. The display may be composed of a battery icon with the
segment indicators arranged beside the icon with each indicator segment a
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different size to indicate capacity, or the segments may be arranged around a
battery icon or be associated with printed numerical indicators to further
define the
capacity they represent.
Objects and Advantages of the Invention..
It is an object of the-invention to provide a state of charge indicator for a
battery
charging system that is similar in appearance to existing state of charge
indicators.
Another object of the invention is to provide a state of charge indicator that
can
also provide information to the user which is intuitive and easy to
understand.
Yet another object of the invention is to provide a state of charge indicator
that
conveys additional information with respect to the rate of load or the rate of
recharge.
It is a further object of the invention to permit users to better understand
how their
particular equipment works and to be able to optimize the use of such loads
and
recharge sources.
One advantage of the Invention is that it can be used to optimize a portable
photovoltaic (PV) battery charging system by displaying to a user how
orientation of
the PV array to the sun changes the voltage and current output of the array
and
therefore battery recharge power available.
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A further advantage of the invention is that the LCD display format is a
familiar to
the user and so data can be presented to the user in a less complicated
manner.
Yet another advantage of the invention is that the LCD display is small in
size and
so easy to implement from an electronics point of view.
Still another advantage of the invention is that the LCD display is less
expensive
than a system with more complicated display technology.
A further advantage of the invention is that multiple pieces of critical
information
may be combined in a single, simple display, to easily determine if a
rechargeable
system which is connected to both a load and a recharge source is actually
charging, that is, is the load drawing more power than the charging source is
capable of producing, resulting in a net-drain on the battery system.
.Descriotion of the Drawinos..
Figure 1 is a sketch of a battery state of charge indicator.
Figure 2 is a block diagram of a complete monitoring system.
Figure 3 is an illustration of the ripple effect of LCD enablement indicating
charging.
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Figure 4 is an illustration of the ripple effect of LCD enablement indicating
discharging.
Figure 5 is an illustration of another embodiment of the ripple effect of LCD
enablement.
Detailed Description..
Referring to Figure 1, a battery state of charge indicator (100) for a battery
charging
system is shown that is conventional in appearance and therefore easy to
understand by the user. The indicator has a graphic outline (101) designed to
look
like a battery. The battery outline contains between 3 and 10 and generally
five (as
illustrated) active LCD segments with the bottom segment (102) representing a
depleted battery and the top segment (106) representing a fully charged
battery.
Intermediate segments (103, 104, and 105) represent other intermediate charge
levels. The graphical representation of the battery can take any reasonable
format
and that the number, arrangement and order of the indicator segments could
take
any reasonable form. The indicator itself could be composed of a wide variety
of
Indicator technologies including but not limited to LCD, LED, organic LED, DLP
and
active matrix styles.
The battery state of charge indicator 100 of Figure 1 may have no indicator
segments enabled to indicate a completely discharged battery. It would enable
the
bottom segment (102) to indicate a battery that is nearly empty, perhaps 1 to
20%
capacity. Each subsequent indicator segment would indicate an additional 20%
(or
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other value as required by the application) such that the top segment (106)
would
be enabled for a battery with 80-100% capacity. The individual indicator
segments
may also flash to indicate when the battery is connected to a charger.
Referring to Figure 2, in the battery monitoring system 200 illustrated, a
microcontroller (201) is connected to the graphic state of charge indicator
(202).
The microcontroller (201) is also connected to a battery monitor (203) that
will
provide information on the current flowing into or out of the battery (204).
The
battery monitor (203) may also provide information with respect to battery
capacity
and state of health through temperature and voltage measurements that may be
displayed using some other display means. The battery (204) may be any
rechargeable type of battery and may be composed of any number or arrangement
of cells and could contain voltage translator circuitry that allows the
battery to
match the current and voltage requirements of the overall system.
The user may connect an at least one load (205) to the system. The load (205)
may
also contain circuitry to match the voltage and current requirements of the
load.
The battery (204) is recharged by at least one charge source (206) which may
be
composed of PV, fuel cell, mechanical or any other type or combination of
power
generating devices. The charge source (206) may contain other circuitry to
match
the current and voltage requirements of the battery (204) or load (205).
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The system is configurable such that the load (205) and charge source (206)
may be
removable and can be composed of multiple loads and multiple charge sources.
Where multiple charge sources and loads are used, the battery monitor will
display
the net effect on battery capacity, which may be a net charging or a net
discharging
effect depending on the types and configuration of all the sources and loads
in the
system. The battery monitor (203) may be configured to monitor multiple charge
and load sources from multiple batteries without departing from the intention
of
this invention.
When the microcontroller (201) detects that current is neither flowing into or
out of
the battery, the display (202) will show a static representation of the
battery state of
charge with an appropriate number of segments enabled.
Referring now to Figure 3, when the microcontroller (201) detects that current
is
flowing into the battery; this indicates that the system is gaining in overall
capacity.
The microcontroller will then periodically display a positive ripple effect on
the
display. The ripple effect shall be defined as activating the lowest indicator
(Figure
3a) segment followed by the next highest indicator segment (Figure 3b) and so
on
(Figure 3c to Figure 3e) until all segments from least to greatest are
activated in
sequence (Figure 3e). After the ripple effect is complete the display shall
revert to
displaying static battery capacity again (Figure 30.
The rate of the ripple effect, that is the rate that the LCD enablement moves
from
the least segment (Figure 3a) to the greatest segment (Figure 3e), is
proportional to
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the magnitude of charge flowing into the battery. The rate of the ripple
effect and
hence magnitude of charge flowing in to the battery can be illustrated to the
user
by adjusting the period between the ripple effect display. The more often the
ripple
effect is displayed to the user the greater the magnitude of charge. Another
method to illustrate magnitude of charge is by reducing the time period
between
each segment being activated so that the greater the magnitude of charge the
faster the display will go from bottom (Figure 3a) to top (Figure 3e), a
variable
ripple rate. In other examples of the invention both methods of display can be
used. In all cases it is expected that the period of time spent displaying the
static
battery capacity (Figure 30 shall exceed the time spent displaying the ripple
effect
so that the two types of information provided to the user, rate of charge and
state
of charge, can be distinguished.
The variable ripple rate is one advantage of this invention. In know displays,
a
battery charge can be indicated by a similar type of ripple effect on a 5
segment
LCD. However, the ripple rate of these types of known displays is constant and
the
information provided to the user is only that a charge is being provided to
the
battery, the presence of a load is not displayed. The magnitude of the charge
remains unknown. In my invention, the magnitude of the charge is displayed to
the
user by a variable ripple rate. The greater the ripple rate the greater the
magnitude
of charge. Using this innovative feature of my invention the proper
orientation of a
PV array towards the sun can be selected. The user can manipulate the
orientation
of the PV array while monitoring the ripple rate. The orientation where the
ripple
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rate is greatest is the=optimal orientation of the PV array because the
magnitude of
charge current will be greatest at that point.
in addition to displaying charge rate using a positive ripple effect display,
the
system is capab/e of displaying the rate of discharge using a negative ripple
effect
display. Referring to Figure 4, the negative ripple effect shall be defined as
activating all of the Indicator segments -(Figure 4a)1 then deactivating the
most
significant indicator segment followed (Figure 4b) by the second most
significant
segment and so on (Figure 4c - Figure 4e)
until all segments are inactive (Figure 40. The rate at which the
ripple effect occurs Is determined by the magnitude of charge flowing out of
the
battery. This can be done by either reducing the period between the ripple
displays,
by reducing the time period between each segment being deactivated, or both.
In
all cases it is expected that the period of time spent displaying the static
battery
capacity shall exceed the time spent displaying the riPPle effect. A user can
use the
information on the display to effect changes to the way they are using their
product, and to estimate the efficacy of those changes through, for example,
dimming a light, adjusting sound volume, or disabling features of the load
such
that the discharge rate Is reduced.
Referring now to Figure 5, the clescripUon of the ripple display effect
provided
above is only one example of a graphic display that is easy to understand and
intuitive to interpret. The graphic image of a battery icon emptying or
filling up.
and the rate at which it is doing so can be clearly interpreted by watching
the
display and the rate of the ripple in either a positive (charging) or a
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(discharging) direction. In my invention, other graphic display options are
possible
that will provide a similar informational function to the user. For example,
the
ripple effect can be modified so that only one LCD segment is active at any
time to
display state of charge (Figure Sa illustrating a half-charge or half-
discharge
situation). In this case, the ripple would originate at the active LCD (Figure
5a). In
the case of a positive ripple, only those segments above the activated LCD
segment
would enable (Figure 5a to Figure 5c). In the case of a negative ripple, only
those
segments below the activated segment would enable (Figure 5d to Figure 50.
In all examples of my invention there will be at least one battery status
display with
at least one multi-segment LCD indicator. The LCD indicator would be used to
display battery capacity, but would be manipulated in a way such that the
ripple
rate of the indicators and their ripple direction provide information on at
least three
battery parameters for the user: battery capacity (single enable segment),
capacity
usage rate (ripple rate in a negative direction when the battery is
discharging) and
capacity recovery rate (ripple rate in a possible direction when the battery
is
charging).
In Operation
A method of using a graphic state of battery charge indictor in a battery
charging
system comprising a source of charging power, a microcontroller and a battery
monitor connected to said microcontroller and adapted to provide a plurality
of
battery operating parameters for display on the graphic state of battery
charge
indicator wherein the graphic state of battery charge indicator comprises a
plurality
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of display segments including a top segment and a bottom segment adapted for
on
and off operation and arranged in the shape of a battery, the method
comprising
the following steps:
connecting the graphic state of battery charge indicator to the battery
charging
system;
adapting the battery monitor to detect and measure a plurality of battery
parameters including battery temperature, current direction and magnitude and
voltage flowing into and out of the battery;
sending the plurality of battery parameters to the microprocessor;
converting the plurality of battery parameters to on and off signals for the
display
segments; and,
sending the on and off signals as required to the graphic state of battery
charge
indicator in a predetermined sequence for visual display.
The method further comprising the steps of:
1 5 sending off signals to the plurality of display segments when the
battery is in a
depleted state;
sending an on signal to the bottom display segment when the battery is in its
lowest charge state;
sending an on signal to the top display segment when the battery is in its
fully
charged state;
sending an on signal to an intermediate display element disposed between the
top
display segment and the bottom display segment when the state of charge of the
battery is between the lowest charge state and said highest charge state
wherein
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the relative position of the intermediate display segment indicates a relative
state of
charge of the battery between its lowest charge state and its highest charge
state.
The method further comprising the steps of:
sending a positive ripple signal to the plurality of display segments when the
current flow is positive into the battery;
sending a negative ripple signal to the plurality of display segments when the
current flow is negative out of the battery; and,
modulating the rate of ripple so that a fast ripple indicates a high current
flow and
a slow ripple indicates a low current flow.
Although the description above contains much specificity, these should not be
construed as limiting the scope of the invention but as merely providing
illustrations of some of the presently preferred embodiments of this
invention.
Logic, analog detection and control means may be implemented using integrated
circuitry, microprocessor control, software and wireless control. Thus the
scope of
the invention should be determined by the appended claims and their legal
equivalents.
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