The present invention relates to a system for monitoring the health of a battery. Particularly,
the system for determining the health and performance of an electrochemical system by
measuring the temperature of a battery.
BACKGROUND OF INVENTION:
Over the last few decades, advances in electrochemical systems have expanded the capabilities
of these systems in a variety of fields including portable electronic devices, air and spacecraft
technologies, and automotive technologies. Many recent advances in electrochemical systems
are owing to the discovery and integration of new materials for battery components. Lithiumion battery technology has been at the forefront of this advancement. The research in advanced
electrode materials has significantly enhanced the energy capacities, energy densities,
discharge current rates and cycle life provided by these electrochemical cells, positioning
lithium-ion batteries to be the preferred technology for use in hybrid electric vehicles (HEV)
and electric vehicles (EV).
Electrochemical cells have two electrodes; an anode and a cathode, which are electrical
conductors, separated by a purely ionic conductor, the electrolyte. The capacity for positive
and negative ion exchanges at the electrodes with the electrolyte due to chemical reactions and
complementary physical processes results in the generation of electric current. The processes
simultaneously absorb or generate electrons to maintain the electrical neutrality of the whole
system. The potential of each electrode and the reaction rate affect the power density and
energy output of the cell. For rechargeable batteries, the extent of changes at the electrode
surface determine the life of the cell under specific thermodynamic and kinetic conditions like
temperature, voltage limits, current rates, etc.
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The understanding of the thermodynamics of the electrode reactions and the simultaneous
physical processes in a cell is a field that is continuously advancing. The gained knowledge is
crucial in determining and predicting the cell metrics that are required for the stability,
longevity and optimal performance of the cell. The health of an electrochemical system is one
such metric, which expresses the safety, longevity and usability of said system.
The health of an electrochemical system is expressed in the industry-accepted terminology of
State of Health, which is a metric that indicates the maximum capacity of the battery at that
instance, thereby also indicating the remaining life of the battery. Conventionally, the State of
Health (SOH) is defined in percentage terms as the maximum capacity of an electrochemical
system currently relative to the initial maximum capacity of the system. For automotive use,
the SOH of a system is expected to be greater than 70-80%. The SOH also encompasses other
characteristics of an electrochemical system like its safety and any physical damages. The
physical damages i.e. the deformations of the cell affect its capacity thus affecting the SOH.
Any electrochemical system generates heat broadly due to three reasons, which are the reaction
heat, the polarization heat and the ohmic heat.
The reaction heat is generated due to the electrochemical reaction that takes place that is the
source of the system’s energy. A side product of the reaction is heat. The polarization heat is
generated because of mechanical effects occurring at the interface between electrodes and
electrolyte. Accumulation of gases and development of concentration gradients of reagents at
such interfaces lead to polarization which in turn reduces the efficiency of the cell by
increasingly transforming energy desired for electrochemical potential into heat. Any
electrochemical system has an intrinsic property of an internal resistance, which is the cause
for the ohmic heat generation.
The internal resistance of a battery increases with age primarily due to the formation of a layer
at the anode of the cell. This layer is the solid electrolyte interphase (SEI) layer, the thickness
of which increases as the cell is used, inhibiting further electrolyte decomposition. This
inhibition is the primary cause for the ageing of the cell. The internal resistance of the cell
increases non linearly with the thickness of the SEI. With the increase in SEI thickness, the cell
ages and the internal resistance increases.
The above processes contribute to the heat generation in an electrochemical system.
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KR20180099668A discloses a battery and an electrical device including a battery management
system. The battery management system includes a controller in electrical communication with
a pressure sensor for monitoring a health condition of the battery. The controller uses a
mechanical signal of force measurements in combination with incremental capacity analysis to
estimate the capacity fading and other health indicators of the battery. The pressure sensor may
provide a force measurement signal to the controller, and the controller may determine which
incremental capacity curve to use based on the battery for the particular battery. The controller
then executes a program that utilizes stored incremental capacity curves based on data and
force from the pressure sensor to estimate the capacity fade and signal health status percentage
to the user. The main drawback of the invention is that the invention focusses on battery
expansion characteristics as an indication of battery health, which is not a very reliable metric.
Additionally, the invention cannot be scaled from a cell health determination to a battery pack
health determination reliably.
CN105301509B proposes the combined estimation methods of a kind of charge states of a
lithium-ion battery, health status and power rating, health status including On-line Estimation
battery: the recurrent least square method on-line identification open-circuit voltage with
forgetting factor and internal resistance are used, and according to the OCV-SOC
corresponding relationship indirect gain state-of-charge pre-established. The main drawback
of this invention is that the described processes are computationally intensive requiring a higher
grade of microcontroller involving higher costs. Additionally, the invention also uses complex
processes involving the determination of State of Charge and State of Health in parallel with
the internal resistance.
Therefore, there is a need for a device that has a simpler computation process and is based on
more reliable metrics than cell expansion characteristics. The present invention is a system that
uses a plurality of sensors such as temperature sensors and current sensors to collate
temperature data of the battery in real-time under the real-time current conditions, processes it
to determine the State of Health of the battery.
SUMMARY OF INVENTION:
In accordance with present aspect of invention, a system for monitoring the health of a battery
is disclosed, comprising: a plurality of sensors configured to sense data inputs from the said
battery; a device, comprising; a plurality of temperature monitoring integrated circuits; a
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plurality of current monitoring circuits; and a plurality of time measurement circuits, a
processor to process the said data inputs received from the said plurality of sensors; a display
module attached to the said device. In the present invention, the plurality of sensors are
configured at a plurality of strategic locations to sense the data inputs relating to an internal
resistance of the said battery, and the said data inputs relating to the internal resistance is sent
to the said device on a real time basis which is capable to receive and process the said data
inputs by means of the processor. A temperature at the plurality of strategic locations of the
said battery is analysed by the temperature monitoring integrated circuit and the said measured
temperature of the battery is displayed on the display module attached to the said device. The
current monitoring circuit further assist in determining the internal resistance of the said
battery, the time measurement circuits enables to determine the rate of change of temperature
with time and the said measured current and rate of change of temperature with time are
displayed on the display module attached to the said device.
Other objects and advantages of the present invention will become apparent from the following
description taken in connection with the accompanying drawings, wherein, by way of
illustration and example, the aspects of the present invention are disclosed.
BRIEF DESCRIPTION OF DRAWINGS:
The present invention will be better understood after reading the following detailed description
of the presently preferred aspects thereof with reference to the appended drawings, in which
the features, other aspects and advantages of certain exemplary embodiments of the invention
will be more apparent from the accompanying drawings in which:
Figure 1 is a table which refers the data collected from a battery with configuration 14 S 10 P,
where the independent variables are the internal resistance, the current drawn from the battery
and the ambient temperature. The internal resistance parameter of a cell is varied between {30
mΩ, 40 mΩ, 50 mΩ}. The current drawn parameter is varied between {17 A, 25 A, 30 A}
which correspondingly translate to (1.7 A, 2.5 A, 3 A) for a single cell as the battery has 10
cells in parallel. The ambient temperature has been varied between {25°C, 30°C, 35°C, 40°C}.
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Figure 2 is a graphical representation of the correlation between the maximum temperature and
the internal resistance of the cell against a variety of current drawn and the ambient
temperature.

Figure 3 is a graphical representation of the correlation between the minimum temperature and
the internal resistance of the cell against a variety of current drawn and the ambient
temperature.

Figure 4 is a battery pack temperature profile for current = 1.7A, internal resistance = 30 mΩ,
ambient temperature = 25 °C.
Figure 5 is battery pack temperature profile for current = 1.7A, internal resistance = 40 mΩ,
ambient temperature = 25 °C.

Figure 6 is a battery pack temperature profile for current = 1.7A, internal resistance = 50 mΩ,
ambient temperature = 25 °C.
Figure 7 is a battery pack temperature profile for current = 2.5 A, internal resistance = 30 mΩ,
ambient temperature = 25 °C.

Figure 8 is a battery pack temperature profile for current = 2.5A, internal resistance = 40 mΩ,
ambient temperature = 25 °C.
Figure 9 is a battery pack temperature profile for current = 2.5A, internal resistance = 50 mΩ,
ambient temperature = 25 °C.
DETAILED DESCRIPTION OF DRAWINGS:
The following description describes various features and functions of the disclosed device and
methods with reference to the accompanying figures. In the figures, similar symbols identify
similar components, unless context dictates otherwise. The illustrative aspects described herein
are not meant to be limiting. It may be readily understood that certain aspects of the disclosed
system, method and apparatus can be arranged and combined in a wide variety of different
configurations, all of which are contemplated herein.
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These and other features and advantages of the present invention may be incorporated into
certain embodiments of the invention and will become more fully apparent from the following
description and claims or may be learned by the practice of the invention as set forth
hereinafter.
Accordingly, those of ordinary skill in the art will recognize that various changes and
modifications of the embodiments described herein can be made without departing from the
scope of the invention. In addition, descriptions of well- known functions and constructions
are omitted for clarity and conciseness.
The terms and words used in the following description and claims are not limited to the
bibliographical meanings, but, are merely used to enable a clear and consistent understanding
of the invention. Accordingly, it should be apparent to those skilled in the art that the following
description of exemplary embodiments of the present invention are provided for illustration
purpose only and not for the purpose of limiting the invention.
It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless
the context clearly dictates otherwise.
It should be emphasized that the term “comprises/comprising” when used in this specification
is taken to specify the presence of stated features, integers, steps or components but does not
preclude the presence or addition of one or more other features, integers, steps, components or
groups thereof.
In accordance with present aspect of invention, a system for monitoring the health of a battery
is disclosed, comprising: a plurality of sensors configured to sense data inputs from the said
battery; a device, comprising; a plurality of temperature monitoring integrated circuits; a
plurality of current monitoring circuits; and a plurality of time measurement circuits, a
processor to process the said data inputs received from the said plurality of sensors; a display
module attached to the said device. In the present invention, the plurality of sensors are
configured at a plurality of strategic locations to sense the data inputs relating to an internal
resistance of the said battery, and the said data inputs relating to the internal resistance is sent
to the said device on a real time basis which is capable to receive and process the said data
inputs by means of the processor. A temperature at the plurality of strategic locations of the
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said battery is analysed by the temperature monitoring integrated circuit and the said measured
temperature of the battery is displayed on the display module attached to the said device. The
current monitoring circuit further assist in determining the internal resistance of the said
battery, the time measurement circuits enables to determine the rate of change of temperature
with time and the said measured current and rate of change of temperature with time are
displayed on the display module attached to the said device.
It is important to mention herein that as the temperature of the electrochemical system indicates
the heat generated in the system, the temperature measurements give an indication of the
internal resistance of the system. The temperature of the battery also depends on the reaction
heat, the polarization heat and the current being drawn from the battery, and therefore it is
imperative to understand the temperature in terms of both the internal resistance, polarization,
reaction kinetics and the current drawn from the system.
The rise in internal resistance of the electrochemical cell with the age of the cell is one of the
primary reasons for higher temperatures for the same current being drawn from the cell at a
later age. The present invention devises a reference point for the internal resistance of the
electrochemical system at its initial few cycles, to compare with as the basis during the life of
the electrochemical system.
On the basis of the above factors including internal resistance and overall heat generation, the
present invention then yields a State of Health metric for the electrochemical system in realtime. The algorithm in the invention accommodates for internal resistance variation with
ambient temperatures and the state of charge of the cell. The algorithm adjusts for the change
in resistance due to the temperature, if the operating conditions are not at optimal temperature.
It is also known that the internal resistance of a cell varies in a single charge or discharge cycle
as the state of charge of the cell varies. This variation is also accommodated for in the State of
Health determination algorithm.
As per Figure 1 which is a table, refers the data collected from a battery with configuration 14
S 10 P, where the independent variables are the internal resistance, the current drawn from the
battery and the ambient temperature. The internal resistance parameter of a cell is varied
between {30 mΩ, 40 mΩ, 50 mΩ}. The current drawn parameter is varied between {17 A, 25
A, 30 A} which correspondingly translate to (1.7 A, 2.5 A, 3 A) for a single cell as the battery
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has 10 cells in parallel. The ambient temperature has been varied between {25°C, 30°C, 35°C,
40°C}.
It is evident from the above data presented in Figure 1, as well as the corresponding graphs
Figure 2 and Figure 3, there is a marked rise in both minimum and maximum temperatures of
the cell with a rise in internal resistance. As predicted, the data shows results indicating a
dependence between internal resistance and the temperature.
Figures 4 to 10 of the present invention displays as how the internal resistance of the cells of a
battery pack affect the temperature. The trend of a rising temperature profile is visible with a
rise in internal resistance. This trend is similar for 2 different current values of 1.7A and 2.5A.
The data validates the hypothesis that the internal resistance of an electrochemical system is a
good indicator of the heat generated by the system. It further shows that the temperature
measurements can be used to determine the internal resistance of the system, which is one of
the primary reasons for the heat generation of the system, and thus can be used as a metric for
determining the state of health of system.

We Claim:

1. A system for monitoring the health of a battery, comprising:
a. a plurality of sensors configured to sense data inputs from the said battery;
b. a device, comprising;
i. a plurality of temperature monitoring integrated circuits;
ii. a plurality of current monitoring circuits; and
iii. a plurality of time measurement circuits,
c. a processor to process the said data inputs received from the said plurality of
sensors;
d. a display module attached to the said device;
wherein, the plurality of sensors are configured at a plurality of strategic locations
to sense the data inputs relating to an internal resistance of the said battery, and the said
data inputs relating to the internal resistance is sent to the said device on a real time
basis which is capable to receive and process the said data inputs by means of the
processor;
wherein, a temperature at the plurality of strategic locations of the said battery is
analysed by the temperature monitoring integrated circuit and the said measured
temperature of the battery is displayed on the display module attached to the said
device; and
wherein, the current monitoring circuit further assist in determining the internal
resistance of the said battery, the time measurement circuits enables to determine the
rate of change of temperature with time and the said measured current and rate of
change of temperature with time are displayed on the display module attached to the
said device.
2. The system as claimed in claim 1 wherein, the plurality of sensors are temperature
sensors.
3. The system as claimed in claim 1 wherein, the device may be mounted on a printed
circuit board or a flexible circuit board.
4. The system as claimed in claim 1 wherein, the device further comprising:
a. a plurality of resistors;
b. a plurality of capacitors; and
c. a plurality of inductors.
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5. The system as claimed in claim 4 wherein, the said plurality of resistors, capacitors and
inductors are positioned in electrical communication with one or more components of
the integrated circuits.
6. The system as claimed in claim 1 wherein, the said system for monitoring the health
can also be used in varied electrochemical devices and supercapacitors.