GB2573279A

GB2573279A - A method and a controller for controlling a battery of a vehicle

Info

Publication number: GB2573279A
Application number: GB1806754.6A
Authority: GB
Inventors: Ghataore Balraj
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2018-04-25
Filing date: 2018-04-25
Publication date: 2019-11-06
Anticipated expiration: 2038-04-25
Also published as: GB201806754D0; GB2573279B; GB2593001B; GB202010906D0; GB2593001A

Abstract

A method for preheating a vehicle battery 104 comprises warming the battery by controlling an electrical loading of a battery before an anticipated start time when the temperature of the battery is indicated to be below a threshold temperature. The electrical loading may comprise a time-varying electrical load such as a plurality of pulses. The anticipated start time may be dependent on a user setting; detection of a user approaching or entering the vehicle; or machine learning which could for example be based on data on previous use of the vehicle. Controlling the electrical loading may comprise activating a dummy load 110. A controller 108 is adapted to control electrical loading of the battery based on a received temperature parameter and an anticipated start time. The controller may include an electronic processor 116 comprising electrical inputs. The controller may also comprise an electronic memory 112 for storing computer programmable instructions 114 which can be executed in order to control the electrical loading based on the temperature parameter and start time.

Description

The present disclosure relates to a method and a controller for controlling a battery of a vehicle. In particular, but not exclusively it relates to a method and a controller for controlling a battery of a vehicle to improve engine starting performance and charge acceptance in cold temperatures.

Aspects of the invention relate to a method, a controller, a vehicle and a computer program.

BACKGROUND

Vehicles are known to comprise one or more batteries. A vehicle equipped with an internal combustion engine may comprise a 12V starting-lighting-ignition (SLI) battery for a 12V starter motor. A hybrid-electric or fully electric vehicle may comprise a traction battery.

A hybrid-electric or fully electric vehicle may comprise a traction battery. For example, a mild hybrid electric vehicle (MHEV) with a parallel hybrid powertrain may comprise an integrated starter-generator or the like which requires the traction battery to output a higher voltage than an SLI battery, for example 48V.

A fully electric vehicle with a series hybrid powertrain may comprise an electric traction motor which requires a higher voltage battery in the order of hundreds of volts.

Many vehicle batteries, particularly of the Lithium-ion (Li-ion) type, perform poorly at low temperatures. This is because the internal resistance of the battery is temperaturedependent, increasing with falling temperature. High internal resistance results in reduced power output at low temperatures. In SLI batteries this can result in poor or failed engine cranking when attempting to turn the engine on. In traction batteries this can result in limited torque for accelerating the vehicle. High internal resistance can also result in a greater voltage drop under load, which can cause damage to vehicle components or trigger a damage-preventing interruption by a supervising controller.

It is known for SLI batteries and traction batteries to be implemented as secondary batteries. Charging a Li-ion battery at low temperatures can result in Lithium plating which can cause internal short circuits in the battery.

External battery heaters, such as heating mats or liquid heating systems, are known. An external heater is typically placed on the outer casing of the battery, and its heat is gradually conducted to the battery cells via the outer casing.

It is an aim of the present invention to address disadvantages of the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a method, a controller, a vehicle and a computer program as claimed in the appended claims.

According to an aspect of the invention there is provided a method for a vehicle, the method comprising:

receiving a parameter indicative of a temperature of a battery of the vehicle; anticipating a start time of the vehicle; and controlling an electrical loading of the battery before the anticipated start time to warm the battery, in dependence on the anticipated start time and on the parameter being indicative of a below-threshold temperature.

This provides the advantage that the battery is automatically heated internally to improve cold temperature performance. Specifically, the battery cells are directly heated by l²R heating, where I is (electrical) current and R is the internal resistance of the battery.

In some examples, the electrical loading comprises a time-varying electrical load.

This provides the advantage of reducing hot-spot formation and therefore improving battery durability.

In some examples, the time-varying electrical load comprises an increase in electrical load followed by a decrease in electrical load. In some examples, the decrease in electrical load comprises a decrease to zero electrical load.

This provides the advantage of reduced energy consumption because peaks of higher current can be more efficient than a sustained lower current.

In some examples, the time-varying electrical load comprises a plurality of pulses of electrical load, the pulses having the same maximum load as each other or a different maximum load from each other.

This provides the advantage of further reducing energy consumption and further reducing hot-spot formation.

In some examples, the duration of a relatively higher electrical load of the time-varying electrical load is shorter than the duration of a relatively lower electrical load of the timevarying electrical load.

This provides the advantage of further reducing hot-spot formation. The short pulses may be sufficiently short that only move surface charge is moved.

In some examples, the time-varying electrical load comprises a step and/or ramp from a first above-zero electrical load to a second above-zero electrical load higher than the first electrical load.

This provides the advantage that battery warm-up can be integrated with a staged procedure for activating and/or warming up vehicle systems other than the battery. For example, the electrical load may operate an engine heater first, then both engine and cabin heaters concurrently, then engine, cabin and windscreen heaters concurrently.

In some examples, the method comprises ceasing the electrical loading once a threshold cranking voltage condition and/or a threshold cranking current condition is met during the electrical loading.

In some examples, the method comprises ceasing the electrical loading once a indicative of cranking is experienced e.g. we may use a lower load to predict battery temperature and therefore an engines ability to crank and engine.

This provides the advantage of assuring a successful engine start.

In some examples, the parameter is an indirect measure of battery cell temperature.

This provides the advantage that a temperature sensor elsewhere on the vehicle than inside the battery casing itself can be utilized.

In some examples, the threshold is no higher than 263 Kelvin.

This provides the advantage that battery performance (at the expense of some energy consumption) is improved only in sub-freezing conditions when it is most beneficial to heat the battery.

In some examples, anticipating the start time is dependent on at least one of: a user setting; detection of a user approaching or entering the vehicle; or machine learning. In some examples, the method comprises commencing the electrical loading a threshold time before the anticipated start time.

This provides the advantage of minimizing or avoiding having to maintain the battery in a warmed state.

In some examples, performing the controlling an electrical loading comprises controlling activation of at least one of a dummy load or one or more vehicle accessories. The dummy load may electrically connect to the battery terminals.

This provides the advantage that the energy discharged from the battery can be employed for useful purposes such as engine, cabin or windscreen heating, or can be returned to the battery.

In some examples, the battery has a nominal voltage from the range 5V to 30V. An SLI battery is an example of such a battery. In one example, the nominal voltage is 12V.

In some examples, the battery has a nominal voltage from the range 30V to 60V. A traction battery for a parallel hybrid powertrain of a mild hybrid electric vehicle (MHEV) is an example of such a battery. In one example, the nominal voltage of such an MHEV battery is 48V.

In some examples, the battery has a nominal voltage from the range 100V to 500V. A traction battery for a series hybrid or fully electric powertrain is an example of such a battery. In some examples, the nominal voltage is from the range 130V to 400V.

According to another aspect of the invention there is provided a controller for a vehicle, the controller comprising:

means to receive a parameter indicative of a temperature of a battery of the vehicle;

means to anticipate a start time of the vehicle; and means to control an electrical loading of the battery before the anticipated start time to warm the battery, in dependence on the anticipated start time and on the parameter being indicative of a below-threshold temperature. In some examples, the controller may comprise means to cause any one or more of the methods as described herein to be performed.

According to a further aspect of the invention there is provided a controller as described above, wherein:

said means to receive a parameter indicative of a temperature of a battery of the vehicle and said means to anticipate a start time of the vehicle comprises an electronic processor having one or more electrical inputs for receiving said parameter indicative of a temperature of a battery of the vehicle and for receiving a parameter indicative of a start time of the vehicle; and an electronic memory device electrically coupled to the electronic processor and having computer program instructions stored therein; and said means to control an electrical loading of the battery before the anticipated start time to warm the battery, in dependence on the anticipated start time and on the parameter being indicative of a below-threshold temperature, comprises the processor being configured to access the memory device and execute the instructions stored therein such that it is operable to control an electrical loading of the battery before the anticipated start time to warm the battery, in dependence on the anticipated start time and on the parameter being indicative of a below-threshold temperature. Therefore, the controller ‘means’ as described herein may equate to at least one electronic processor; and at least one electronic memory device electrically coupled to the electronic processor and having instructions stored therein.

According to a further aspect of the invention there is provided a system or controller comprising means for causing any one or more of the methods as described herein to be performed.

The system comprises a controller and may further comprise hardware such as the battery, and the dummy load (if included).

According to a further aspect of the invention there is provided a controller operable to control an electrical loading of a battery of a vehicle, the controller comprising at least one electronic processor, and at least one electronic memory device having computer program instructions stored therein, wherein the at least one electronic memory device and the computer program instructions are configured to, with the at least one electronic processor, cause the controller to perform:

receiving a parameter indicative of a temperature of the battery;

anticipating a start time of the vehicle; and controlling an electrical loading of the battery before the anticipated start time to warm the battery, in dependence on the anticipated start time and on the parameter being indicative of a below-threshold temperature.

According to a further aspect of the invention there is provided a non-transitory tangible physical entity embodying a computer program comprising computer program instructions that, when executed by at least one electronic processor, enable a controller at least to perform:

receiving a parameter indicative of a temperature of a battery of a vehicle; anticipating a start time of the vehicle; and controlling an electrical loading of the battery before the anticipated start time to warm the battery, in dependence on the anticipated start time and on the parameter being indicative of a below-threshold temperature.

According to a further aspect of the invention there is provided a computer program that, when run on at least one electronic processor, causes a controller to perform one or more of the methods described herein.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig 1 illustrates an example of a vehicle;

Fig 2A illustrates an example of a controller and Fig 2B illustrates an example of a computer readable storage medium;

Fig 3 illustrates an example of a method; and

Fig 4A to 4C illustrate three examples of time-varying electrical preloads that can be applied to a battery.

DETAILED DESCRIPTION

Fig 1 illustrates an example of a vehicle 100 in which embodiments of the invention can be implemented. In some, but not necessarily all examples, the vehicle 100 is a passenger vehicle, also referred to as a passenger car or as an automobile. Passenger vehicles generally have kerb weights of less than 5000 kg. In other examples, embodiments of the invention can be implemented for other applications, such as industrial vehicles, air or marine vehicles.

The vehicle 100 of Fig 1 comprises an engine 106 defining, at least in part, the powertrain of the vehicle 100. The engine 106 may be a reciprocating internal combustion engine or a variant therefrom.

The engine 106 may be a diesel or gasoline (petrol) engine. Certain embodiments of the present invention are particularly advantageous for diesel engines which require higher starting current than gasoline engines.

The vehicle 100 comprises a battery 104. In some, but not necessarily all examples the battery 104 is a secondary battery. In some examples, the battery 104 is a Li-ion battery. In other examples, the battery 104 may be a lead acid battery.

The battery 104 may be responsible for supplying energy to a starter motor 107 to start the engine 106, as part of an ignition process. The nominal voltage of the battery 104 may be that required for starting. Depending on implementation, the nominal voltage is from the range 5-60V, with 12V or 48V being common implementations. The battery 104 may optionally be responsible for supplying charge for other purposes such as vehicle external lighting and other ignition related loads.

In a hybrid electric powertrain, the battery 104 may additionally or alternatively be configured to operate as a traction battery. In a fully electric vehicle powertrain (not shown in Fig 1), the vehicle 100 comprises no engine and the battery 104 is solely a traction battery. If the vehicle 100 comprises a plurality of batteries such as an SLI battery and a traction battery, aspects of the present invention may be embodied in more than one of the batteries.

Fig 1 also illustrates a component 110 which functions as a vehicle accessory or a dummy load for loading the battery 104 by consuming the energy stored in the battery 104. Although only one component 110 is shown in Fig 1, several components could be provided in other examples.

Fig 1 also illustrates a system 102 having at least one electronic controller 108 (abbreviated to ‘controller’ herein). The illustrated system 102 is a dashed line drawn around the controller 108. Therefore, the illustrated system 102 purely consists of a control system for controlling implementation of various embodiments of the invention. In other examples, the system 102 may further comprise the hardware to be controlled, such as the battery 104 and/or the component 110.

The controller 108 may have some supervisory control over the electrical loading of the battery 104. For example, the controller 108 may be operable to activate and deactivate certain loads. Certain embodiments of the present invention warm the battery 104 to reduce the likelihood of an excessive voltage drop or failure to meet a current required for engine starting.

Fig 2A illustrates an example implementation of the controller 108 of Fig 1. The controller 108 comprises at least one electronic processor 116, and at least one electronic memory device 112 having computer program instructions 114 (abbreviated to ‘computer program’) stored therein.

In some examples, the controller 108 could be an engine control unit (ECU), which is known. In other examples, the controller 108 could be another known type of controller such as a battery management system (BMS) or be implemented in a separate controller. The controller functionality could be implemented in a plurality of distinct control units in some examples.

Inputs to and outputs from the controller 108 are also shown. The controller 108 comprises one or more electrical inputs for receiving the parameter indicative of a temperature of the battery 104, and for receiving the parameter indicative of a start time of the vehicle 100. The controller 108 also comprises one or more electrical outputs for controlling the electrical loading of the battery 104. In some, but not necessarily all examples the electrical loading is controlled by controlling actuation of a switch 118 or relay associated with the component 110 to be controlled. The switch 118 or relay could be operably coupled to the controller 108 via a wire and/or a communication bus such as a CAN (Controller Area Network) or LIN (Local Interconnect Network) bus.

Fig 2B illustrates an example of a computer-readable storage medium 201 storing the computer program 114. The computer program 114 can be loaded into the controller 108, for example, during a software update of the vehicle 100.

Fig 3 illustrates a method 300, more specifically a battery preheating method, to be performed by the system 102, in accordance with an aspect of the present invention. The computer program 114 may be configured to cause the system 102 to implement the method 300, when run on the at least one electronic processor 116.

At block 302, the method 300 comprises receiving a parameter indicative of a temperature of the battery 104 of the vehicle 100. This provides useful information about whether the battery 104 needs warming. The parameter may be detected by any suitable sensing means (sensor(s)) and received by the controller from the sensing means.

The parameter may be a direct or an indirect measure of battery cell temperature. A direct measure could be dependent on a measurement by a temperature sensor such as a thermistor or thermocouple.

An indirect measure could be dependent on a measurement by a non-temperature sensor. An example of an indirect measure could be the internal resistance of the battery cells which correlates to temperature. The correlation could be stored in a map in the controller 108. Internal resistance could be measured or estimated with reference to a known or measured voltage, current, resistance, impedance, state of charge, or a combination thereof.

The parameter could be indicative of the temperature inside or outside the battery casing. For example, a temperature sensor for sensing an ambient temperature external to the vehicle 100 could be employed, or a sensor of a temperature of another vehicle subsystem (e.g. coolant temperature sensor) could be employed, to provide an approximation of battery cell temperature. In another example, the parameter could be obtained from an internet weather forecasting service via a communication interface that provides connectivity to the internet.

The parameter could be received periodically while the vehicle 100 is key-off. Alternatively, the parameter could be received in response to a trigger event such as reaching a threshold time before an anticipated start time of the vehicle 100 (in which case block 302 could be implemented after block 304). Alternatively, the parameter could have been received during previous operation of the vehicle 100 and not updated since.

In Fig 3 the method 300 proceeds from block 302 to block 304. In other examples, the method 300 starts at block 304 and then proceeds to block 302.

At block 304, the method 300 comprises anticipating a start time of the vehicle 100.

In some, but not necessarily all examples vehicle start is defined as a transition from key-off to key-on. If the vehicle 100 has an engine 106 and the preheating method 300 is in preparation for engine start, block 304 may relate to anticipating a start time of the engine 106, i.e. when the starter motor 107 will be operated.

It is useful to anticipate the start time of the vehicle 100 and control battery preheating accordingly so that preheating is performed when needed (e.g. 10 minutes before start) and not continuously while the vehicle 100 is key-off. The preheating may need to commence a threshold time before the anticipated start time. For example, the threshold time may be from the range 5-30 minutes, optimally around 10 minutes.

In some, but not necessarily all examples anticipation of the start time can be dependent on a user setting. The user setting may relate to a time, for example a time of day at which the user has decided preheating is needed such as 7:45am. The user setting could specify when the preheating should begin, or could specify the start time of the vehicle 100 from which a preheating start time is automatically determined by the controller 108, or a combination thereof.

Additionally or alternatively, anticipation of the start time can be dependent on detection of a user approaching or entering the vehicle 100. In some examples, the detection may relate to detected use of a key fob for the vehicle 100, for example to unlock the vehicle 100. Additionally or alternatively, the detection may relate to detected proximity of a personal mobile electronic device registered to the vehicle 100 and/or user. An example of such a device is a smartphone. In some, but not necessarily all examples the proximity of such a device could be detected by detection of a connection or availability to connect the device or vehicle 100 to a wireless personal area network or wireless local area network hosted by the other of the device or vehicle 100.

Detection of a user approaching or entering the vehicle 100 could provide little advance warning to enable the battery 104 to be fully preheated by the time the vehicle 100 is started. A more aggressive (higher current load) preheating strategy could be used in such a situation, and/or the controller 108 may enforce delayed vehicle start until battery preheating has occurred for a sufficient period of time, or a notification may be output to the user suggesting delaying vehicle start.

Additionally or alternatively, anticipation of the start time can be dependent on machine learning. Machine learning relates to any procedure or algorithm that enables a ‘routine’ of past start times of the vehicle 100 to be established from past recorded start times of the vehicle 100. The machine learning routine information can then be interrogated based on current context information with a certain granularity such as whether the current day is a weekday or a weekend (coarse), or event what is the specific day of the week (fine). If recent past data exists for a similar historic context such as a weekend, the expected vehicle start time can be predicted with a good degree of confidence. In some examples, a weighting factor may favour recent recorded use data over older recorded use data. If several start times have been recorded for a given context, a representative vehicle start time may be determined, for example by averaging the start times.

The method 300 then progresses to blocks 306 and 308. At blocks 306 and 308, the method 300 comprises controlling an electrical loading of the battery 104 (preheating the battery 104) before the anticipated start time to warm the battery 104, in dependence on the anticipated start time and on the parameter being indicative of a below-threshold temperature.

Block 306 is a decision block for deciding whether and when to start preheating. If the outcome of block 306 is positive, the method 300 progresses to block 308 which preheats the battery 104. If the outcome of block 306 is negative, the method 300 terminates or loops to an earlier block.

Block 306 determines whether the temperature is below the threshold. If the temperature is below the threshold, the outcome is positive. If the temperature is above the threshold, the outcome is negative. In some examples, the threshold is a threshold for ‘sub-freezing’ temperatures. The threshold could be from the range 233 Kelvin (-40 Celsius) to 263 Kelvin (-10 Celsius). An optimal value is approximately 253 Kelvin (-20 Celsius).

In some, but not necessarily all examples the threshold temperature is a factory pre-set. However, in other examples the threshold could be set by a user.

Block 306 also determines whether the current time is within the threshold time before the anticipated start time. If the current time is later than the threshold, the outcome is positive. If the current time is earlier than the threshold, the outcome is negative.

In some, but not necessarily all examples the threshold time is a factory pre-set. However, in other examples the threshold could be set by a user.

Therefore, in Fig 3, but not necessarily in all examples, preheating is only performed if the temperature is below a threshold and only commences from a certain time before the anticipated start time.

Although one decision block 306 is shown for both the temperature and time criteria, the criteria could be checked in separate decision blocks and at different times.

Various implementations for preheating the battery 104 at block 308 will now be described, with reference to Figs 4A to 4C.

In some, but not necessarily all examples, block 308 comprises controlling activation of at least one of the above-described component(s) 110 (dummy load or vehicle accessory). As described above, the activation could be controlled by closing an electrical circuit containing the component 110 and the battery 104 to enable the component(s) 110 to discharge the battery 104. As a result, current flows through the battery cells resulting in a preheating effect.

The component(s) 110 could comprise any vehicle subsystem other than the subsystem that turns the vehicle 100 on, e.g. the starter motor 107 for the engine 106.

The component(s) 110 could be configured to be operated at a nominal current which is no less than 5A, and less than cranking current (e.g. less than 300A). In some, but not necessarily all examples, the battery temperature rise only needs to be a few degrees so a suitable component 110 is configured to be operated at a nominal current less than 100A.

In some, but not necessarily all examples at least one of the component(s) 110 may provide no function other than for battery preheating, i.e. the component is a dummy load. The dummy load may advantageously comprise energy storage means to store the charge, then return the charge to the battery 104.

In some, but not necessarily all examples the component 110 could be an accessory of the vehicle 100. Advantageously, the accessory could be a heater of another vehicle subsystem, such as an engine preheater, a cabin heater, a windscreen heater. An example of an engine preheater is a fuel fired heater that requires some battery energy to operate. The windscreen heater could be a front or rear windscreen heater. The cabin heater could provide heat to the cabin via one or more vents.

At least one of the component(s) 110 may be user settable to turn on to provide a function independent of battery preheating while the vehicle 100 is key off and the user is outside the vehicle 100, such as an engine preheater or cabin heater that can be timed to operate in advance of user use of the vehicle 100.

By contrast, one or more other components 110 may not be user settable to turn on to provide a function independent of battery preheating while the vehicle 100 is key off and the user is outside the vehicle 100, such as a windscreen heater which is normally only settable by a user inside the vehicle 100, or a dummy load.

In some, but not necessarily all examples the electrical loading is performed intelligently to reduce hot spot formation in the battery cells, and to reduce energy consumption. For example, the electrical loading may comprise a time-varying electrical load (time-varying electrical current).

With reference to the current-time graphs of Figs 4A and 4B, the time-varying electrical load may comprise an increase in electrical load followed by a decrease in electrical load, as opposed to the series of increases shown in the current-time graph of Fig 4C. The decrease in electrical load may comprise a decrease to zero electrical load. The increases and decreases may be step changes as shown in Figs 4A and 4B, or gradual changes of current. The time-varying electrical load may comprise a plurality of pulses 402, 404, 406, 412, 414, 416 of electrical load. The pulses could be separated by periods of zero electrical load as shown in Figs 4A and 4B.

With each successive pulse, the battery 104 gets warmer which will result in a smaller voltage drop when starting the vehicle 100. Therefore, the preheating at block 308 may stop when it is detected that the battery 104 is ‘warm enough’ for a reliable engine start/vehicle start.

Fig 4A shows a pulse train with three pulses 402, 404, 406. Different numbers of pulses could be provided depending on implementation. Fig 4A represents a control strategy in which at least some, optionally all the pulses 402, 404, 406 have the same maximum load as each other. The maximum load may be set at a predefined value which is the current required for cranking, e.g. a value from the range 300-600A, and the voltage drop during a pulse is measured. As the battery 104 warms with each successive pulse, the voltage drop for a given current reduces, resulting in each voltage drop being smaller than the last. The fixed-magnitude current pulses may continue until a threshold cranking voltage condition is satisfied by the measured voltage drop (e.g. once voltage drops to no less than a threshold voltage such as around 7-8V, e.g. 7.5V). Once satisfied, block 308 ceases because the battery 104 is warm enough to support engine cranking. In another embodiment an indicative load of circa 100A could be used with a voltage threshold of circa 10V as an indicator of the battery being warm enough to support engine cranking. Other currents and voltages may be used.

Fig 4B shows another pulse train with three pulses 412, 414, 416. Different numbers of pulses could be provided depending on implementation. Fig 4B represents a control strategy in which at least some, optionally all the pulses 412, 414, 416 have a different maximum load from each other. The voltage drop during a pulse may be set at a predefined value which could be the threshold cranking voltage (e.g. 7.5V), and once that voltage is reached the current climbs no further. As the battery 104 warms with each successive pulse, the maximum current for a given voltage drop increases, resulting in the maximum current of each pulse being greater than the last. The variable-maximum pulses may continue until a threshold cranking current condition is satisfied (e.g. current for a voltage drop to the threshold voltage has reached a minimum amount for successful engine start such as around 300-500A, e.g. 400A). Then the battery 104 is warm enough to support engine cranking.

In some, but not necessarily all examples some low-level battery preheating may continue until the actual start time of the vehicle 100 or until a timeout expires, to preserve the battery temperature.

In Figs 4A and 4B, but not necessarily in all examples the duration of a relatively higher electrical load of the time-varying electrical load (load period) is shorter than the duration of a relatively lower electrical load of the time-varying electrical load (rest period). The relatively lower load could be OA in an example. In some examples, the duration of the load period could from the range twice to ten times the duration of the rest period. In an example implementation, the load period could be from the range 1-2 seconds and the rest period could be from the range 5-15 seconds.

Fig 4C shows a preheating strategy which does not necessarily rely on increases followed by decreases of current such as pulses. Fig 4C shows three levels of progressively higher load (three steps), associated with progressive activation of three components 110. In other examples, more or fewer levels could be provided. In some examples, the load may be ramped rather than stepped.

The first level represents a first load by a first component 110. The first component could be an accessory such as a fuel fired heater. The second level represents the sum of the first load with a second load by a second component. The second component could be a cabin heater. The third level represents the sum of the first and second loads with a third load by a third component. The third component could be a windscreen heater.

The first load could correspond to a 6A current or some other value from the range 5-1 OA. The second load could correspond to a 9A current or some other value from the range 515A. The third load could correspond to a 25A current or some other value from the range 10-50A. In this example, but not necessarily all examples each subsequent load is greater than the previous load. Each load in this example corresponds to a substantially constant current, but the current could vary with respect to time in other examples.

The duration of each load in Fig 4C could be the same or could vary. The first (earliest) load could have the longest duration. In some examples, the last (latest) load before vehicle start could have the shortest duration because it corresponds to the highest current. In some examples, the duration of the load could be inversely proportional to the magnitude of the current, to reduce energy consumption.

For purposes of this disclosure, it is to be understood that the controller(s) 108 described herein can each comprise a control unit or computational device having one or more electronic processors 116. A vehicle 100 and/or a system 102 thereof may comprise a single control unit or electronic controller or alternatively different functions of the controller(s) may 16 be embodied in, or hosted in, different control units or controllers. A set of instructions could be provided which, when executed, cause said controller(s) or control unit(s) to implement the control techniques described herein (including the described method(s) 300). The set of instructions may be embedded in one or more electronic processors, or alternatively, the set of instructions could be provided as software to be executed by one or more electronic processor(s). For example, a first controller may be implemented in software run on one or more electronic processors, and one or more other controllers may also be implemented in software run on or more electronic processors, optionally the same one or more processors as the first controller. It will be appreciated, however, that other arrangements are also useful, and therefore, the present disclosure is not intended to be limited to any particular arrangement. In any event, the set of instructions described above may be embedded in a computer-readable storage medium 201 (e.g., a non-transitory computer-readable storage medium) that may comprise any mechanism for storing information in a form readable by a machine or electronic processors/computational device, including, without limitation: a magnetic storage medium (e.g., floppy diskette); optical storage medium (e.g., CD-ROM); magneto optical storage medium; read only memory (ROM); random access memory (RAM); erasable programmable memory (e.g., EPROM ad EEPROM); flash memory; or electrical or other types of medium for storing such information/instructions.

The blocks illustrated in Fig 3 may represent steps in a method and/or sections of code in the computer program 114. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some steps to be omitted.

The terms ‘key off’ and ‘key on’ have well recognized meanings for vehicles, regardless of whether the vehicle 100 has an internal combustion, hybrid or full electric powertrain. For the absence of doubt, some explanation is provided below. In some, but not necessarily all examples, when the vehicle 100 is key-off the powertrain is unable to produce tractive force. When the vehicle 100 is ‘key-on’, the powertrain is able to produce tractive force in response to a torque demand. In some, but not necessarily all examples, whether the vehicle 100 is key-off or key-on depends on driver action. For example, whether the vehicle 100 is key-off or key-on depends on the actuation state of a user control such as a start button or ignition switch - the vehicle 100 transitioning to key-on following actuation of the button or switch. In some, but not necessarily all examples, the vehicle 100 could be remotely controllable so that whether the vehicle 100 is key-off or key-on depends on user operation of or automatic detection of a user key fob or personal mobile electronic device (e.g. smartphone) - the vehicle 100 being key-on if a signal is received from the key fob or personal mobile electronic device. In some examples, every step of the method 300 is performed before the user has entered the vehicle 100. Further, the term ‘preload’ as used herein refers to applying a load while the vehicle 100 is ‘key off’. In some examples, the battery preheating method 300 disclosed herein is no longer performed while the vehicle 100 is key-on, for example the method 300 is terminated upon commencement of an ignition process in which a starter motor 107 for an engine 106 is operated.

The term ‘current’ as used herein refers to electrical current. The term ‘resistance’ as used herein refers to electrical resistance, and if appropriate, electrical impedance. The term ‘voltage’ as used herein refers to a nominal voltage. The actual measured voltage of a battery made according to the present invention can vary from the nominal voltages described herein within a range that permits satisfactory operation of equipment. The term ‘coupled’ as used herein is intended to mean operably coupled. A coupling may be entirely galvanic, or in other examples could include a capacitive or inductive separation or other separation of the coupled components.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed. For example, the method 300 could be triggered solely based on manual user operation, without receiving a parameter indicative of a temperature of a battery 104 of the vehicle 100 and without anticipating a start time of the vehicle 100.

Features described in the preceding description may be used in combinations other than the combinations explicitly described.

Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis 5 has been placed thereon.

Claims

1. A method for a vehicle, the method comprising:

receiving a parameter indicative of a temperature of a battery of the vehicle;

2. The method as claimed in any preceding claim, wherein the electrical loading comprises a time-varying electrical load.

3. The method as claimed in claim 2, wherein the time-varying electrical load comprises an increase in electrical load followed by a decrease in electrical load.

4. The method as claimed in claim 3, wherein the decrease in electrical load comprises a decrease to zero electrical load.

5. The method as claimed in claim 3 or 4, wherein the time-varying electrical load comprises a plurality of pulses of electrical load, the pulses having the same maximum load as each other or a different maximum load from each other.

6. The method as claimed in any one of claims 2 to 5, wherein the duration of a relatively higher electrical load of the time-varying electrical load is shorter than the duration of a relatively lower electrical load of the time-varying electrical load.

7. The method as claimed in any one of claims 2 to 6, wherein the time-varying electrical load comprises a step and/or ramp from a first above-zero electrical load to a second abovezero electrical load higher than the first electrical load.

8. The method as claimed in any preceding claim, comprising ceasing the electrical loading once a threshold cranking voltage condition and/or a threshold cranking current condition is met during the electrical loading.

9. The method as claimed in any preceding claim, wherein the parameter is an indirect measure of battery cell temperature.

10. The method as claimed in any preceding claim, wherein anticipating the start time is dependent on at least one of: a user setting; detection of a user approaching or entering the vehicle; or machine learning.

11. The method as claimed in any preceding claim, comprising commencing the electrical loading a threshold time before the anticipated start time.

12. The method as claimed in any preceding claim, wherein performing the controlling an electrical loading comprises controlling activation of at least one of a dummy load or one or more vehicle accessories.

13. The method as claimed in any preceding claim, wherein the battery has a nominal voltage from the range 5V to 30V, or wherein the battery has a nominal voltage from the range 30V to 60V, or wherein the battery has a nominal voltage from the range 100V to 500V.

14. A controller for a vehicle, the controller comprising:

means to anticipate a start time of the vehicle; and means to control an electrical loading of the battery before the anticipated start time to warm the battery, in dependence on the anticipated start time and on the parameter being indicative of a below-threshold temperature.

15. The controller as claimed in claim 14, wherein:

said means to receive a parameter indicative of a temperature of a battery of the vehicle and said means to anticipate a start time of the vehicle comprises an electronic processor having one or more electrical inputs for receiving said parameter indicative of a temperature of a battery of the vehicle and for receiving a parameter indicative of a start time of the vehicle; and an electronic memory device electrically coupled to the electronic processor and having computer program instructions stored therein, said means to control an electrical loading of the battery before the anticipated start time to warm the battery, in dependence on the anticipated start time and on the parameter being indicative of a below-threshold temperature, comprises the processor being configured to access the memory device and execute the instructions stored therein such that it is operable to control an electrical loading of the battery before the anticipated start time to warm the battery, in dependence on the anticipated start time and on the parameter being indicative of a below-threshold temperature.

16. The controller as claimed in any one of claims 14 or 15, wherein the electrical loading comprises a time-varying electrical load.

17. The controller as claimed in claim 16, wherein the time-varying electrical load comprises an increase in electrical load followed by a decrease in electrical load.

18. The controller as claimed in claim 17, wherein the decrease in electrical load comprises a decrease to zero electrical load.

19. The controller as claimed in claim 17 or 18, wherein the time-varying electrical load comprises a plurality of pulses of electrical load, the pulses having the same maximum load as each other or a different maximum load from each other.

20. The controller as claimed in any one of claims 16 to 19, wherein the duration of a relatively higher electrical load of the time-varying electrical load is shorter than the duration of a relatively lower electrical load of the time-varying electrical load.

21. The controller as claimed in any one of claims 16 to 20, wherein the time-varying electrical load comprises a step and/or ramp from a first above-zero electrical load to a second above-zero electrical load higher than the first electrical load.

22. The controller as claimed in any one of claims 14 to 21, wherein the parameter is an indirect measure of battery cell temperature.

23. The controller as claimed in any one of claims 14 to 22, comprising means to commence the electrical loading a threshold time before the anticipated start time.

24. The controller as claimed in any one of claims 14 to 23, wherein performing the controlling an electrical loading comprises controlling activation of at least one of a dummy load or one or more vehicle accessories.

5

25. A vehicle comprising the controller of any one or more of claims 14 to 24.

26. A computer program that, when run on at least one electronic processor, causes a controller to perform the method as claimed in any one or more of claims 1 to 13.