Field of the invention:
[0001] The present invention relates to a controller to determine characteristic parameter of a battery in vehicle and a method thereof.
Background of the invention:
[0002] Most methods to measure battery health are offline (remove the battery), time consuming and computationally complex. The online (without removing the battery) methods mentioned above use the coup-de-fouet phenomenon of the lead acid battery to determine the state of health of the battery. But these methods mandate that the battery be fully charged before testing and provide only an estimate of the capacity of the battery.
[0003] A patent literature WO06054066 discloses determining the state of health of a battery. A method and associated apparatus for determining the state of health of a battery, comprising the steps of discharging the battery through a known test load across the battery; measuring the voltage across the battery when the battery is discharging through the test load; and from the measured voltage determining at least one parameter relating to the state of health of the battery. Typically the method also models from the, or each, parameter relating to the state of health of the battery, the state of charge of the battery. The method is particularly suitable for monitoring the health of lead-acid batteries, and especially of those installed in vehicles. In one embodiment, the test load can be a pre-existing electric apparatus of a vehicle, such as a heated rear windscreen.
Brief description of the accompanying drawings:
[0004] An embodiment of the disclosure is described with reference to the
following accompanying drawing,
[0005] Fig. 1 illustrates a block diagram of a controller to determine characteristic
parameters of a battery in a vehicle, according to an embodiment of the present
invention;

[0006] Fig. 2 illustrates graphical representation of the voltage measured for determining characteristic parameters of the battery, according to the present invention, and
[0007] Fig. 3 illustrates a method for determining characteristic parameters of the battery of the vehicle, according to the present invention.
Detailed description of the embodiments:
[0008] Fig. 1 illustrates a block diagram of a controller to determine characteristic parameters of a battery in a vehicle, according to an embodiment of the present invention. The controller 110 adapted to energize at least one electrical load 120 connected to the battery 112 for a predetermined duration. The controller 110, characterized in that, further adapted to measure voltage of the battery 112 at multiple time instants during the predetermined duration, and determine the characteristic parameter in dependence of the measured voltages. The sequence of steps executed by the controller 110 is referred to as test phase, where the characteristic parameter of the battery 112 is determined/estimated. The voltage of the battery 112 is measured according to a coup-de-fouet phenomenon. The controller 110 determines the characteristic parameter by applying the measured voltages at respective time instants in a model stored in the memory element (not shown).
[0009] The controller 110 is connected to multiple sensors such as engine temperature sensor 102, engine speed sensor 104, throttle position sensor 106, Manifold Absolute Pressure (MAP) sensor, and the like. The controller 110 is an electronic device which comprises a Central Processing Unit (CPU) connected to various Input/ Output (I/O) interfaces, timers 108, memory elements such as Random Access Memory (RAM), Read Only Memory (ROM), and other components, all of which interconnected with address and data buses as known in

[0010] The vehicle 100 shown is a two-wheeler, but is also possible to be a three-wheeler such as an auto-rickshaw, a four-wheeler such as a car and other types of vehicles 100. Further, the at least one electrical load 120 is selected from but not limited to a headlight 114, at least one blinker, a horn 116, a spark plug, an infotainment unit, a sensor 118 and the like. The at least one electrical load 120 whose electrical characteristic is already known is selected for the test phase.
[0011] According to the present invention, before starting with the test phase, or before the controller 110 energizes the at least one electrical load 120, certain predetermined charging conditions of the battery 112 of the vehicle 100 are verified. The predetermined charging conditions are entry/enabling conditions to ensure that the battery 112 has undergone optimal charging and is at required capacity. The charging conditions comprises a value of a timer 108 above a threshold duration, the engine temperature above a threshold temperature and an open circuit voltage of the battery 112 is above a threshold level (or between an threshold range). Further, the controller 110 validates the charging conditions during post-drive cycle for maximum probability of the completion of the charging conditions. However, the charging conditions is possible to be checked in other drive cycles as well.
[0012] The value of the timer 108 of the controller 110 is dependent on the engine load and the engine speed. In other words, the timer 108 is activated upon detection of the engine load above a threshold limit and the engine speed above a threshold speed. The engine load is calculated from the signals received from the throttle position sensor 106 and the MAP sensor.
[0013] Fig. 2 illustrates graphical representation of the voltage measured for determining characteristic parameters of the battery, according to the present invention. A graph 200 shows two waveforms namely a first waveform 214 and a second waveform 216. The first waveform 214 represents measured voltage against time in respective and suitable units. Similarly, the second waveform 216 represents voltage gradient against time in respective and suitable units. The X-axis 220

represents time and Y-axis 210 represents voltage and change in voltage for the first waveform 214 and the second waveform 216 respectively. Now, using the graph 200, working of the controller 110 is explained.
[0014] Consider the predetermined charging conditions are completed and validated by the controller 110. The controller 110 detects the post-drive cycle and triggers the test phase. Just before a specific electrical load 120 is energized, the controller 110 measures the voltage, denoted by point 202. Consider, the headlight 114 of the vehicle 100 is selected as the electrical load 120. The controller 110 activates the headlight 114 for a predetermined duration (say few milliseconds) and monitors the voltage profile of the battery 112. Now, being a lead-acid battery 112, the voltage profile follows coup-de-fouet phenomenon. The voltage of the battery 112 is measured in at least four points, which comprises two saturation times at point 206 and at point 208. In the graph 200, the voltages are measured at point 202, 204, 206 and 208. The point 202 corresponds to an instant at which the voltage is measured just before the energization of the electrical load 120. The point 208 denotes the instant at which the voltage is measured at the lowermost point in the first waveform 214 after the energization of the electrical load 120. The point 206 denotes the instant at which the voltage is measured at the plateau of the second waveform 216. The point 208 denotes the instant at which the voltage is measured after the electrical load 120 is de-energized/deactivated. The second waveform 216 helps in ascertaining the points, specifically the point 206 and the point 208, i.e. by monitoring the rate of change of the curve is near zero.
[0015] The measured voltages are given as inputs to a model based on below.
�1-�2 ���� -�2 �1-�3 �1-�4
� = �1 ∗ �2∗ ∗ �4 ∗
�1 �1 �1 �1
�5 ∗ (�3 - �2) + �6 ∗ (�4 - �3) In simplified form
� = �1 ∗ �21� + �2 ∗ ����-1� + �3 ∗ �31� + �4 ∗ �41� + �5 ∗ �32 + �6 ∗ �34
Where,

�21� provides an indication of internal resistance
����-1� provides an indication of capacity fade
�31� provides an indication of capacitance
�41� provides an indication of resilience
�1 to �6 are weightage factor determined based on empirical analysis
[0016] Thus, with the above model, the controller 110 is enabled to determine different characteristic parameters of the battery 112. The characteristic parameters is at least one selected from a group comprising a State of Health (SOH), an internal resistance of said battery 112, a capacity fade of the battery 112, a capacitance of the battery 112, and a resilience of the battery 112.
[0017] The model based on the equation is corresponding to a general circuit model or an equivalent circuit (not shown) of the battery 112. The equivalent circuit comprises an open circuit Electro Motive Force (EMF) in series with an internal resistance, which is again in series with a parallel resistance Capacitance (RC) network. The parallel RC network signifies transient behavior of the battery 112. The parallel RC network is further connected in series to resistive load and a parasitic member of the circuit. An output terminal is connected across the resistive load and the parasitic member. This is just an example, and many electrical elements may be added or removed to make the equivalent circuit based on requirement, such as another RC network is possible to be added.
[0018] The term V21n corresponds to the internal resistance of the battery 112, i.e. higher the value of V21n, higher the internal resistance. The term Vref-1n corresponds to the capacity fade. As capacity fades the open circuit voltage reduces at 100% SOC. Thus, higher the Vref-1n drop, lower the capacity of the battery 112. The term V3n term corresponds to the parallel RC network, i.e. higher the V1-V3 drop, higher the capacitance value. A higher capacitance value indicates sulphation as the effective distance between the lead plates increases. The term V4n term refers to the resilience of the battery 112. The larger the V1-V4 drop, smaller the capacity and

higher parasitic losses. The terms are correlates to the respective characteristic parameters of the battery 112.
[0019] The value of A gives an indication of the SOH of the battery 112. The controller 110 compares the value of A against a list and determines the SOH of the battery 112.
[0020] The controller 110 is also adapted to monitor and compare the individual characteristic parameters with respective calibrated thresholds. The model associates each of the characteristic parameter with each point of the first waveform 214. Each of the characteristic parameter are given different weightages, pre¬determined while development based on empirical results. The weighted average of the factors are computed and converted to a score. The score is the indication of the battery health to the end-user.
[0021] A working of the present invention is elaborated with an example, and the same must not be understood in a limiting manner. Consider a driver/rider starts a vehicle 100. The controller 110 measures the engine temperature using the temperature sensor 102. The driver starts driving the vehicle 100 and during the drive, the controller 110 measures the engine load using the signals from the throttle position sensor 106 and the MAP sensor. When the engine load is detected above a threshold limit and the engine speed which is measured using the engine speed sensor 104 is detected above a threshold speed, the controller 110 starts/activates the timer 108. The engine speed is checked to be above the threshold speed to ensure that an alternator which is coupled with the engine, charges the battery 112 at the required rate and voltage level. Similarly, the engine load is checked to be above the respective threshold limit to ensure that the battery 112 undergoes charging in specific operating conditions. The timer 108 keeps working until the engine load and the engine speed are above respective thresholds. As soon as the engine load and/or the engine speed comes below the respective threshold value, the controller

110 stops the timer 108. Thus, during the drive cycle, the value of the timer 108 is accumulated and then checked with the threshold duration.
[0022] Assuming at the end of the drive cycle, the value of the timer 108 is above the threshold duration. The driver switches OFF the ignition and the same is detected by the controller 110. The controller 110 measures the engine temperature against the threshold temperature and the open circuit voltage above the threshold value. If the check is found favorable for the test phase, the controller 110 triggers the test phase and measures the voltage against the electrical load 120 of known load characteristics and determines the characteristic parameters of the battery 112.
[0023] Fig. 3 illustrates a method for determining for determining characteristic parameters of the battery in the vehicle, according to the present invention. The method comprises multiple steps, of which a step 306 comprises energizing the at least one electrical load 120 connected to the battery 112 for a predetermined duration. The method is characterized by a step 308 comprising measuring voltage of the battery 112 at multiple time instants during the predetermined duration. A step 310 comprises determining the characteristic parameter in dependence of the measured voltages.
[0024] The steps 306 to 310 is referred to test phase, which are triggered after specific predetermined charging conditions of the battery 112 of the vehicle 100 are completed. In other words, a step 300 comprising the parameters related to the charging conditions are measured. In a step 302, the result of the charging step 300 are checked for completeness. If yes, then the test phase is executed, otherwise not as represented by step 304.
[0025] The charging condition comprises monitoring the value of the timer 108 above the threshold duration, the engine temperature above the threshold temperature, and the open circuit voltage of the battery 112 above a threshold value (or within the threshold range). Further, the timer 108 is activated/started upon

detection of engine load above the threshold limit, and the engine speed above the threshold speed.
[0026] The characteristic parameters is at least one selected from the group comprising the State of Health (SOH) of the battery 112, the internal resistance of the battery 112, the capacity fade of the battery 112, the capacitance of the battery 112 and the resilience of the battery 112.
[0027] According to the present invention, the controller 110 and the method aims at developing a system for online monitoring of the health of the battery 112 to give the driver/rider warnings about the possible replacement of the battery 112. The invention uses the aspects of the coup-de-fouet phenomenon to draw additional insights about the battery 112. The controller 110 observes the voltage profile and draws insights from the model of the lead acid battery 112 and provides not only the SOH, but also indicates the mechanism responsible for the capacity fade. In simple words, the present invention provides a controller 110 and a method which computes the SOH of the automotive battery 112 by measuring the voltage profile and saturation times while actuating a controlled electrical load 120. In one embodiment, the test phase is triggered only once preconditioning or charging conditions is satisfactorily completed, and after engine is switched OFF (Post-Drive). The present invention is applicable for valve regulated lead acid battery 112, i.e. a VRLA battery112, but not limited thereto.
[0028] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.

We claim:
1. A controller (110) to determine characteristic parameters of a battery (112)
in vehicle (100), said controller (110) adapted to
energize at least one electrical load (120) connected to said battery
(112) for a predetermined duration, characterized by
measure voltage of said battery (112) at multiple time instants during
said predetermined duration, and
determine said characteristic parameters in dependence of the
measured voltages.
2. The controller (110) as claimed in claim 1, wherein said controller (110) energizes said at least one electrical load (120) after detection of predetermined charging conditions of said battery (112) of said vehicle (100).
3. The controller (110) as claimed in claim 2, wherein said charging condition comprises
a value of a timer (108) above a threshold duration,
an engine temperature above a threshold temperature, and
an open circuit voltage of said battery (112) above a threshold level.
4. The controller (110) as claimed in claim 3, wherein said timer (108) is
activated upon detection of
engine load above a threshold limit, and engine speed above a threshold speed.
5. The controller (110) as claimed in claim 1, wherein said characteristic
parameters is at least one selected from a group comprising a State of Health
(SOH), an internal resistance of said battery (112), a capacity fade of said
battery (112), a capacitance of said battery (112), and a resilience of said
battery (112).

6. A method for determining a characteristic parameter of a battery (112) in
vehicle (100), said method comprising the steps of:
energizing at least one electrical load (120) connected to said battery
(112) for a predetermined duration, characterized by
measuring voltage of said battery (112) at multiple time instants
during said predetermined duration, and
determining said characteristic parameter in dependence of the
measured voltages.
7. The method as claimed in claim 6, wherein steps of energizing, measuring and determining are triggered after detecting predetermined charging conditions of said battery (112) of said vehicle (100).
8. The method as claimed in claim 7, wherein said charging condition comprises monitoring
a value of a timer (108) above a threshold duration,
an engine temperature above a threshold temperature, and
an open circuit voltage of said battery (112) above a threshold value.
9. The method as claimed in claim 8, wherein said timer (108) is activated
upon detection of
engine load above a threshold limit, and engine speed above a threshold speed.
10. The method as claimed in claim 6, wherein said characteristic parameters is
at least one selected from a group comprising a State of Health (SOH), an
internal resistance of said battery (112), a capacity fade of said battery (112),
a capacitance of said battery (112), and a resilience of said battery (112).