A method to monitor battery health of a vehicle

Complete Specification:

The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed.

Field of the invention

[0001] The present invention relates to a method to monitor battery health of a vehicle and an Electronic Control Unit (ECU) thereof.

Background of the invention

[0002] Modern day vehicles, both automotive and electric, include a battery. The battery is used to power the electrical system when the engine is not running. Additionally, the engine is used to charge the battery. The engine is also used to power electrical components of the vehicle when the engine is running. State of health of a battery defines the performance of a battery relative to its original condition. Conventional methods for determining battery state of health typically involve discharging batteries at constant current to predefined voltages. Such methods are not only expensive and time consuming, but also require the batteries under test to be out of service for long periods of time. There are no in- vehicle prognostic methods to detect degradation or predict an imminent failure of a vehicle battery. Accordingly, there is a need for a simple and robust method to monitor battery health in a vehicle.

[0003] Patent application WO2009158224A2 titled “Method for battery state-of- health monitoring using battery voltage during vehicle starting” discloses a method for determining a battery's state-of -health. An initial battery voltage is measured after a first voltage drop during an initiation of an engine cranking phase. A battery voltage is monitored during the remainder of the engine cranking phase. A lowest battery voltage is determined during the remainder of the engine cranking phase. A determination is made if a voltage difference between the lowest battery voltage and the initial battery voltage at the initiation of the engine cranking phase is less than a voltage threshold. A low battery state-of-health is identified in response to the voltage difference being less than the voltage threshold.

Brief description of the accompanying drawings

[0004] An embodiment of the invention is described with reference to the following accompanying drawings:

[0005] Figure 1 depicts a vehicle battery (102) in a vehicle in accordance with one of the embodiments of this invention;

[0006] Figure 2 illustrates method steps (200) to monitor battery health of a vehicle in accordance with this invention;

[0007] Figure 3 is a graphical representation of battery voltage with respect time for a new and old battery; and

[0008] Figure 4 is a graphical representation of area under curve in a battery voltage vs time graph for a new and old battery.

Detailed description of the drawings

[0009] Figure 1 depicts a vehicle battery (102) in a vehicle in accordance with one of the embodiments of this invention. The battery (102) is in communication with a control unit (101) in the vehicle. The battery (102) is also connected to other vehicle loads (104) such as a starter motor, lamps, air conditioner and the like. In an embodiment of this invention, a voltage sensor (103) configured to measure voltage across the battery (102) is connected to the battery (102). The voltage sensor (103) is also in communication with the control unit (101). In another embodiment of the invention, the voltage sensor is dispensable and the control unit (101) itself can read the voltage across the battery (102).

[0010] The control unit (101) comprises a processing means, a communicating means and at least a memory. The communicating means is capable of connecting to a cloud or a server. In one embodiment of this invention the control unit (101) is implemented as a combination of hardware and software i.e. some building blocks are hardcoded onto a microprocessor chip while other building block are implemented in a software which may either reside in a microprocessor chip or on a cloud (105). A plurality of mobile devices (107) such as a mobile phones, tablets, computers and the like having a user interface can be connected to the cloud (105) and retrieve information from it. In another embodiment of this invention the control unit (101) is connected to onboard lamps (106) for indicating the health of the battery (102).

[0011] Figure 2 illustrates method steps to monitor battery health of a vehicle in accordance with this invention. A person skilled in the art will appreciate that the components described above in accordance with figure 1 are used to perform the method steps. The method step 201 comprises cranking the vehicle at least two times within a duration of minute. The main idea of using multiple consecutive cranks is to ensure that the battery (102) charge is depleted.

[0012] The control unit (101) is adapted to monitor health of the battery (102). The control unit (101) monitors health of the battery (102) in a test case. When the test case mode is switched on and once it detects cranking of the vehicle at least two times within a duration of minute, the control unit is activated. Method step 202, comprises recording a real time value of battery voltage with respect to time measured by the battery (102) voltage sensor (103) by the control unit (101). This recording of real time values includes keeping the vehicle in no load or a constant load condition for least 10 seconds after the last crank.

[0013] Method step 203, comprises comparing the said recorded value with a stored reference value. The stored reference value refers to a pre-determined values of battery voltage with respect to time. These values are determined based on experimental value and data recorded for a different states of health of a battery (102) after at least two cranks within a duration of one minute. In an embodiment of the present invention the comparison take place inside the processor of the control unit (101). In another embodiment of the present invention, the control unit (101) merely acts a telematics device that records and communicates the data to a cloud (105) or a server.

[0014] Method step 204, comprises indicating the health of the battery (102) based on the said comparison. Indicating the health of the battery (102) comprises an audio or visual means of indication. In an embodiment of present invention, the audio-visual means of indication can be in the form of an onboard diagnostics lamp on the vehicle. In another embodiment of the present invention the audio-visual means of indication are present on a mobile device having access to the cloud (105).

[0015] The main idea of using multiple consecutive cranks is to ensure that the battery (102) charge is depleted. After this charge depletion, battery tries to stabilize and reach certain voltage (at no load or constant load condition). The difference between initial voltage immediately after cranking and the stabilized voltage will give insight on the battery (102) status. For a new battery the difference will be very less compared to old battery. This is illustrated in figure 4. Time Period “T” indicates the time period for wherein the vehicle is kept in no load or a constant load condition for recording the real time values. This time period as described earlier is at least 10 seconds and varies according to the vehicle and the type of starter motor is use. [0016] Figure 5 is a graphical representation of area under curve in a battery (102) voltage vs time graph for a new and old battery. Area under the curve of the battery (102) voltage vs time is one of the ways of capturing the essence of the data conveyed by the battery (102) voltage vs time graph. The greater area under this curve corresponds to more time needed by the battery (102) voltage to stabilize after the last cranking, thereby corresponding to a relatively more degraded state of the battery (102). In another mode of performing the method steps disclosed by this invention, equation and slope comparison or any statistical techniques also can be used for data analysis and result derivation.

[0017] This idea to develop a method to monitor battery health of a vehicle and a control unit (101) thereof provides a simple and robust technique to detect health of the vehicle battery (102) that is independent of state of charge (SOC) level of battery. The method can be implemented independent of vehicle/ variant/ user/region/type of data logger used as long as battery voltage data is available for analysis. Further the method doesn’t need any usage of external power sources, sensors or any measurement devices other than an control unit (101) for data logging, processing or an control unit (101) capable of data logging and communicating with a cloud (105) or server.

[0018] Further the disclosed method has benefits over the conventional method used. Conventional methods measure only open circuit voltage will not be sufficient for indicating whether the battery (102) is new or old. This idea will not accurately indicate the battery (102) state based on data evaluation post cranking, but also help fleet manager of vehicles and service centers I dealers will not know if the replaced battery is new or refurbished.

[0019] It must be understood that the embodiments explained in the above detailed description are only illustrative and do not limit the scope of this invention. Any modification to the method to monitor battery health of a vehicle are envisaged and form a part of this invention. The scope of this invention is limited only by the claims.