GB2556881A

GB2556881A - A method of adaptively controlling an electrical system having a lithium-ion battery

Info

Publication number: GB2556881A
Application number: GB1619769.1A
Authority: GB
Inventors: Naidu Ashish; George Brittle Peter; Alimario Allan; Pandey Neeraj
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2016-11-23
Filing date: 2016-11-23
Publication date: 2018-06-13
Also published as: GB201619769D0

Abstract

A method of adaptively controlling an electrical system having a lithium-ion battery comprising cells (118a-c, Figures 5a and 5b) by setting upper and lower temperature thresholds for the Li-ion battery based on power requirements, checking the current temperature of the battery and if the temperature is outside the required range using a thermo-electric control apparatus to adjust the temperature by cooling or heating. A relationship between temperature and power output may be used to set the required temperature range based on a required power output. A current state of charge of the Li-ion battery may additionally be used to set the upper and lower temperature thresholds. The setting of the desired temperature range may further comprise using a state of health of the Li-ion battery. If the state of charge is below a level where the required output can be obtained by adjustment of temperature the method may include increasing the state of charge of the battery. The thermo-electric temperature control apparatus may comprise at least one module having a peltier device (153, Figures 5a and 5b) interposed between two heat transfer plates (154 and 155, Figures 5a and 5b), one such plate being thermally connected to the battery.

Description

(71) Applicant(s):

Ford Global Technologies, LLC (Incorporated in USA - Delaware)

Suite 800, Fairlane Plaza South,

330 Town Center Drive, Dearborn, Michigan 48126, (56) Documents Cited:

EP 2506359 A2 JP 2015147499 A US 20160016485 A1 US 20080311466 A1

WO 2014/110524 A1 JP 2007097359 A US 20100291414 A1

United States of America (72) Inventor(s):

Ashish Naidu

Peter George Brittle Allan Alimario

Neeraj Pandey (58) Field of Search:

INT CL B60L, H01M Other: WPI, EPODOC (74) Agent and/or Address for Service:

Ivan Rogers

Room 1/445 Eagle Way, Warley, BRENTWOOD, Essex, CM13 3BW, United Kingdom (54) Title ofthe Invention: A method of adaptively controlling an electrical system having a lithium-ion battery Abstract Title: Thermo-electric temperature control of a Li-ion battery (57) A method of adaptively controlling an electrical system having a lithium-ion battery comprising cells (118a-c, Figures 5a and 5b) by setting upper and lower temperature thresholds for the Li-ion battery based on power requirements, checking the current temperature of the battery and if the temperature is outside the required range using a thermo-electric control apparatus to adjust the temperature by cooling or heating. A relationship between temperature and power output may be used to set the required temperature range based on a required power output. A current state of charge of the Li-ion battery may additionally be used to set the upper and lower temperature thresholds. The setting of the desired temperature range may further comprise using a state of health of the Li-ion battery. If the state of charge is below a level where the required output can be obtained by adjustment of temperature the method may include increasing the state of charge of the battery. The thermoelectric temperature control apparatus may comprise at least one module having a peltier device (153, Figures 5a and 5b) interposed between two heat transfer plates (154 and 155, Figures 5a and 5b), one such plate being thermally connected to the battery.

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A Method of Adaptively Controlling an Electrical System having a Lithium-Ion Battery

This invention relates to the control of an electrical system having a Lithium-Ion battery and, in particular, to a method of adaptively controlling an electrical system of a motor vehicle having a Lithium-Ion battery.

It is well known to provide a motor vehicle with a low voltage (for example 12 volt) electrical system having a low voltage battery to operate various components of the motor vehicle such as, for example, a starter motor used to start an internal combustion engine of the motor vehicle

It is further known to provide a motor vehicle with a high voltage (for example 48 volt) electrical system having a Lithium-Ion (Li-Ion) battery and an electrical machine such as a belt integrated starter generator (BISG) driveably connected to a crankshaft of the engine by a drive belt to either be driven by the engine to generate electrical power for charging the Li-Ion battery, or driving the engine to provide torque assist to the engine or for starting the engine in the case of micro-hybrid (stop-start vehicles), mild hybrid and full hybrid vehicles.

It is a problem with the use of Li-Ion batteries that the Li-Ion cells used to form the battery are sensitive to operating temperature and outside a particular operating temperature range may be unable to provide sufficient power to meet a current requirement for electrical power.

In the case of a motor vehicle where the engine of the motor vehicle is automatically stopped and started in order to save fuel and reduce emissions, this inability to provide sufficient power can have the negative effect by preventing the use of automated stopping and starting following a cold start in a low ambient conditions thereby reducing the reduction in overall emissions and increasing fuel usage.

In order to overcome this problem it has been previously proposed to flow hot air from the engine past the Li-Ion battery in order to increase the temperature of the Li-Ion battery.

However, the inventors have realised that if the temperature of the Li-Ion battery could be better regulated then technical benefits can be obtained compared to a simple battery heating approach.

It is an object of the invention to provide a method of adaptively controlling an electrical system having a Li-Ion battery to improve the operating performance of the Li-Ion battery.

According to a first aspect of the invention there is provided a method of adaptively controlling an electrical system having a Lithium-Ion battery wherein, when there is one of a current requirement and an expected requirement for power from the Lithium-Ion battery, setting upper and lower temperature thresholds for the Lithium-Ion battery based upon the requirement for power, checking whether the current temperature of the Lithium-Ion battery is within a desired temperature range bounded by the upper and lower temperature thresholds and, if the current temperature of the LithiumIon battery is not within the desired temperature range, using a thermo-electric temperature control apparatus to adjust the temperature of the Lithium-Ion battery to bring the temperature of the Lithium-Ion battery within the desired temperature range.

If the current temperature of the Lithium-Ion is higher than the upper temperature threshold, the thermo-electric temperature control apparatus may be used to cool the

Lithium-Ion battery to bring the temperature of the LithiumIon battery within the desired temperature range.

Alternatively, if the current temperature of the Lithium-Ion is lower than the lower temperature threshold, the thermo-electric temperature control apparatus may be used to bring the temperature of the Lithium-Ion battery within the desired temperature range.

Setting the desired temperature range may comprise using the requirement for power from the Lithium-Ion battery and a relationship between temperature and power output for the Lithium-Ion battery.

Setting the desired temperature range may further comprise using a current state of charge of the Lithium-Ion battery to set the upper and lower temperature thresholds.

Setting the desired temperature range may further comprise using a state of health of the Lithium-Ion battery, the current state of charge of the Lithium-Ion battery and one of the current requirement for power and the expected requirement for power to set the upper and lower temperature thresholds .

If a state of charge of the Lithium-Ion battery is below a state of charge level that an adjustment of temperature of the Lithium-Ion battery alone will be unable to meet one of the current requirement for power and the expected requirement for power from the Lithium-Ion battery, the method may further comprise increasing the state of charge of the Lithium-Ion battery to a level where an adjustment of temperature of the Lithium-Ion battery will be able to meet the requirement for power from the Lithium-Ion battery.

The thermo-electric temperature control apparatus may comprise at least one thermo-electric control module having a Peltier device interposed between two heat transfer plates, one of the heat transfer plates being thermally connected to the Lithium-Ion battery.

Convection may be used to thermally connect said one heat transfer plate to the Lithium-Ion battery. Conduction may be used to thermally connect said one heat transfer plate to the Lithium-Ion battery.

According to a second aspect of the invention there is provided an electrical system having a Lithium-Ion battery, an electronic controller and a thermo-electric temperature control apparatus wherein, when there is one of a current requirement for power and an expected requirement for power from the Lithium-Ion battery, the electronic controller is arranged to set upper and lower temperature thresholds for the Lithium-Ion battery based upon the requirement for power, check whether the current temperature of the LithiumIon battery is within a desired temperature range bounded by the upper and lower temperature thresholds and, if the current temperature of the Lithium-Ion battery is not within the desired temperature range, using the thermo-electric temperature control apparatus to adjust the temperature of the Lithium-Ion battery to bring the temperature of the Lithium-Ion battery within the desired temperature range.

If the current temperature of the Lithium-Ion is higher than the upper temperature threshold, the electronic controller is arranged to use the thermo-electric temperature control apparatus to cool the Lithium-Ion battery to bring the temperature of the Lithium-Ion battery within the desired temperature range.

Alternatively, if the current temperature of the Lithium-Ion is lower than the lower temperature threshold, the electronic controller is arranged to use the thermoelectric temperature control apparatus to heat the LithiumIon battery to bring the temperature of the Lithium-Ion battery within the desired temperature range.

The Lithium-Ion battery may have a number of cells connected together to provide a desired power output and the temperature of the battery may be the temperature of at least one of the cells of the Lithium-Ion battery.

The electrical system may include one or more temperature sensors operatively connected to the electronic controller arranged to measure the temperature of the Lithium-Ion battery.

The electronic controller may be arranged to set the desired temperature range using the requirement for power from the Lithium-Ion battery and a relationship between temperature and power output for the Lithium-Ion battery.

The electronic controller may be further operable to set the upper and lower temperature thresholds of the desired temperature range by using a current state of charge of the Lithium-Ion battery and the requirement for power.

- 6 The electronic controller may be further arranged to set the upper and lower thresholds of the desired temperature range by using a state of health of the LithiumIon battery, the current state of charge of the Lithium-Ion battery and the requirement for power to set the upper and lower temperature thresholds.

If the state of charge of the Lithium-Ion battery is below a level where an adjustment of temperature of the Lithium-Ion battery alone will be unable to meet the requirement for power from the Lithium-Ion battery, the electronic controller may be further operable to use an electric generator to increase the state of charge of the Lithium-Ion battery to a level where an adjustment of temperature of the Lithium-Ion battery will be able to meet the requirement for power from the Lithium-Ion battery.

The electrical system may include a navigation system and the navigation system may be used to enable the temperature of the Li-Ion battery to be adjusted to a temperature within the desired temperature range in preparation for meeting a predicted future demand for electrical power from the Li-Ion battery.

According to a third aspect of the invention there is provided a motor vehicle having an internal combustion engine and an electrical system wherein the electrical system is constructed in accordance with said second aspect of the invention.

The motor vehicle may have an electric generator and the electric generator may be drivingly connected to the internal combustion engine of the motor vehicle.

The motor vehicle may be a mild hybrid vehicle and the electric generator is a belt integrated starter-generator.

The invention will now be described by way of example with reference to the accompanying drawing of which:Fig.la is a flow chart of a first part of a method of adaptively controlling an electrical system having a LiIon battery in accordance with a first aspect of the invention;

Fig.lb is a flow chart of a second part of the method of adaptively controlling an electrical system having a Li-Ion battery in accordance with a first aspect of the invention;

Fig.lc is a high level flow chart of a method of adaptively controlling an electrical system having a Lithium-Ion battery in accordance with a first aspect of the invention;

Fig.2a is a chart referencing temperature against time for a Li-Ion battery show a desired operating temperature range;

Fig.2b is a graph showing the effect of temperature on a power limit of a typical Lithium-Ion battery;

Fig.3 is a block diagram of a motor vehicle according to a third aspect of the invention having an electrical system in accordance with a second aspect of the invention;

Fig.4a is a schematic diagram of a first embodiment of a thermo-electric temperature control apparatus forming part of the electrical system of Fig.3 showing the apparatus in a temperature increasing mode of operation;

- 8 Fig.4b is a schematic diagram similar to Fig.4a but showing the apparatus in a temperature reducing mode of operation;

Fig.5a is a schematic diagram of a second embodiment of a thermo-electric temperature control apparatus for use in an electrical system such as the electrical system of Fig.3 showing the apparatus in a temperature increasing mode of operation;

Fig.5b is a schematic diagram similar to Fig.5a but showing the apparatus in a temperature reducing mode of operation; and

Fig.6 is a schematic diagram of a third embodiment of a thermo-electric temperature control apparatus for use in an electrical system such as the electrical system of Fig.3 showing the apparatus in a temperature reducing mode of operation.

With particular reference to Fig.la there is shown a high level flow chart of a method 1000 for controlling the temperature of a Li-Ion battery forming part of a method of adaptively controlling an electrical system such as the method 3000 shown in Fig.lc.

The method 1000 starts in box 1100 which is a motor vehicle key-on event (an engine start event) and then advances to box 1120 in which it is checked whether there is a requirement for power from the Li-Ion battery. If there is no requirement then the method loops around box 1120 because temperature control of the Li-Ion battery is only active when required so as to save electrical power and thereby increase fuel economy.

However, if when checked in box 1120 there is a requirement either current or predicted for power from the Li-Ion battery then the method advances to box 1150.

In box 1150 the current temperature, state of charge and state of health of the Li-Ion battery are assessed.

This can be by direct measurement or by any other means such as calculation or modelling based upon usage of the Li-Ion battery. Based upon the outcome of the assessment upper and lower temperature limits T_Upper and T_Lower are set for the LiIon battery. These limits are shown graphically in Figs.2a and 2b and it is these limits that are used to control a thermo-electric temperature control apparatus including at least one Thermo-electric temperature control module (TEC Module) as will be described hereinafter. It will be appreciated that if the temperature of the Lithium battery is lower than the lower temperature limit T_Lower then the electrochemistry of the Lithium battery will be compromised that is to say it will be less reactive and that above upper temperature threshold Tu_PPer the power limit is reduced to reduce internal heating and degradation of the cells making up the Lithium battery.

After box 1150 the method advances to box 1200 where the current temperature T_BAT of the Li-Ion battery or to be more precise the temperature of the cells making up the LiIon battery is compared with the upper and lower temperature limits T_UpPer and T_Lower set in box 1150. It will be appreciated that only a single cell temperature could be used for the comparison or a normalised value for the temperature of a number of the cells and in some cases all of the cells of the Li-Ion battery is used for comparison purposes .

That is to say the check in box 1200 comprises a test such as : 10

Is Tupper > Teat > TLower?

If the answer is 'Yes' then the method advances to box 1500 where a thermo-electric temperature control module (TEC module is switched 'off' if it is 'on' or is left 'off' if it is already 'off'. This is because temperature adjustment is not currently required and so electrical energy is not wasted operating the TEC module(s).

The method then advances to box 1550 where any battery inhibitors are cancelled and then on to box 1600 where it ends the temperature control mode of operation havening been completed. So long as a key-on state remains key steps of the method 1000 will then be repeated so that from box 1600 the method will return to box 1120 as indicated by the broken line on Fig.la.

Returning to box 1200 if the result of the check in box 1200 is 'No' then the method advances to box 1250 where one or more battery usage inhibitors are set preventing the use of the Li-Ion battery for certain purposes such as, for example, starting an engine of the motor vehicle or providing a torque boost to the engine of the motor vehicle.

The method then advances to box 1300 where the polarity of the TEC module is adjusted to provide the required effect.

For example, from the check in box 1200 it will be known whether the temperature of the Li-Ion battery is above or below the desired operating range as defined by the upper and lower temperature thresholds T_Upper and T_Lower and therefore whether heating or cooling of the Li-Ion battery is required.

Therefore if T_BAT is greater than the upper temperature threshold Tu_PPer the polarity of the TEC module will be set to promote cooling of the Li-Ion battery and if T_BAT is less than the lower temperature threshold T_Lower the polarity of the TEC module is set to promote heating of the Li-Ion battery.

From box 1300 the method returns to box 1150 to recheck the temperature of the Li-Ion battery (T_BAT) and then on to box 1200 and will cycle around boxes 1150, 1200, 1250 and 1300 until eventually after a short period of time the temperature adjustment produced by the use of the TEC module will result in the check in box 1200 being past at which point the method branches to box 1500 and the steps 1500 through 1600 are then repeated as described previously.

It will be appreciated that depending upon the arrangement of the thermo-electric temperature control apparatus in some embodiments the cancelling of the temperature controlling effect can be temporarily delayed in order to ensure that the battery temperature T_BAT has reached a temperature well within the desired operating range as defined by the upper and lower temperature thresholds T_Upper and T_Lower rather than cancelling the temperature controlling effect of the TEC module as soon as one of the temperature thresholds T_Upper and T_Lower is crossed and in other embodiments the TEC module is turned off as soon as the relevant temperature threshold T_Upper or T_Lower is crossed.

With particular reference to Fig.lb there is shown a high level flow chart of a method 2000 for controlling the temperature of a Li-Ion battery based upon a current or predicted power requirement which forms part of the method of adaptively controlling an electrical system having a LiIon battery as shown in Fig.lc.

The method 2000 starts in box 2100 which is a determination of a current or a predicted requirement for power from the Li-Ion battery. The current or predicate requirement can be, for example, a requirement to provide sufficient power for automatic stop-start operation of an engine of the motor vehicle, that is to say, a requirement to provide sufficient power from the Li-Ion battery for restarting the engine after it has been automatically stopped or it could be, for example, a requirement to provide a torque assist to the engine.

In a particularly advantageous arrangement a navigation system can be used to predict a requirement for power from the Li-Ion battery such as a predicted requirement for torque assist and/or the likelihood of stop-start operation being used. That is to say the navigation system is used to enable the temperature of the Li-Ion battery to be adjusted in preparation for meeting a predicted future demand for electrical power from the Li-Ion battery.

Therefore, after evaluating the requirement for power in box 2100 the method advances to box 2200 where the current Li-Ion battery power limit is checked against the expected or predicted requirement for electrical power from the Li-Ion battery.

If the current state of the Li-Ion battery is such that the required power can be supplied then no action is required and the method advances to box 2500 where a Thermoelectric temperature control module (TEC module) is turned 'off' if it is 'on' and is otherwise left in an off state and then advances to box 2600 where the power requirement satisfying mode of operation is complete. So long as a keyon state remains the key steps of the method 2000 will then be repeated so that from box 2600 the method will return to box 2100 as indicated by the broken line on Fig.lb.

Returning to box 2200 if the Li-Ion battery is unable to meet the power required from it then the method advances to box 2300 where the temperature of the Li-Ion battery or to be more precise the temperature of one or more cells making up the Li-Ion battery is checked to see whether it is within a desired operating range and based upon the outcome of the check in box 2300 the polarity of the TEC module is adjusted or kept the same in order to bring the temperature of the Li-Ion battery within the desired temperature range as described with reference to Fig.la.

The method then returns to box 2200 to recheck whether the current power capacity limit of the battery is greater than the requirement for power from the Li-Ion battery. It will be appreciated that if the Li-Ion battery is too hot or too cold the amount of power that it can provide will be less than if it within an optimum temperature range that is to say the desired temperature range.

It will be appreciated that setting the desired temperature range can comprise using a state of health of the Lithium-Ion battery, the current state of charge of the Lithium-Ion battery and the expected requirement for power to set the upper and lower temperature thresholds.

The method will then loop around the boxes 2200, 2300 and 2400 until eventually the check in box 2200 is passed at which point the method branches to box 2500 and the boxes 2500 and 2600 are executed as described previously.

Referring now to Fig.lc there is shown in a high level form a method of adaptively controlling an electrical system having a Li-Ion battery of a motor vehicle in accordance with the invention.

The method 3000 starts in box 3100 which is motor vehicle key on event and then advances to box 3200 where an estimate for a requirement for power from the Li-Ion battery. As before this can be a current knowledge based estimate such as knowing that stop-start is active and so restarting of an engine of the motor vehicle will likely be required or can be a predictive estimate based upon a number of vehicle operating factors in combination with information received from a navigation system of the motor vehicle.

From box 3200 the method advances to box 3300 where the current state of the Li-Ion battery is checked to see if it can meet the expected requirement for power.

This check will take into account the current temperature of the Li-Ion battery, the current state of charge of the Li-Ion battery and in some embodiments the aged state (State of Health) of the Li-Ion battery. It will be appreciated that all of these factors will have an effect on whether the Li-Ion battery can meet the requirement for power .

If the result of the check in box 3300 is that the LiIon battery can meet the requirement for power (a 'Yes' result) the method returns to box 3200 via box 3250 in which any TEC modules are turned 'off' or maintained 'off' and will continue to loop around these two boxes so long as the Li-Ion battery continues to be able to meet the requirement for power and no Key-off event has occurred, that is to say, so long as no action is required.

However, if the result of the check in box 3300 is that the Li-Ion battery cannot meet the requirement for power (a 'No' result), the method advances to box 3400 where it is checked whether adjusting the temperature of the Li-Ion battery alone will enable the Li-Ion battery to meet the requirement. That is to say, can an adjustment to the temperature of the Li-Ion battery be used to improve its performance sufficiently to enable it to meet the requirement for power?

If the result of the check in box 3400 is 'Yes' that is to say a temperature adjustment will enable the Li-Ion battery to meet the requirement for power then the method advances to box 3500 where the temperature of the Li-Ion battery is adjusted by using one or more TEC modules with the correct polarity to either produce heating or cooling of the Li-Ion battery as previously described with reference to Fig. la .

The method then returns to box 3300 where the Li-Ion battery will now be able to meet the requirement for power.

Returning to box 3400, if the result is 'No', that is to say, a temperature adjustment will not enable the Li-Ion battery to meet the requirement for power then the method advances to box 3600.

In box 3600 the state of charge (SOC) of the Li-Ion battery is increased by charging the Li-Ion battery to a level where temperature adjustment can then be used to provide sufficient power from the Li-Ion battery. For example if the current SOC is 20% and at the current temperature a SOC of 50% is required to meet the requirement for power but if the temperature of the Li-Ion battery is increased by 10°C then a SOC of 35% would be sufficient to meet the requirement for power then the SOC is increased to 35% and then the temperature of the Li-Ion battery is increased. Note that whenever possible temperature adjustment is used in preference to SOC adjustment because this has the least negative effect on overall operating efficiency of the motor vehicle. Therefore the SOC is only increased to a level where temperature adjustment can then be used to meet the power requirement.

From box 3600 the method returns to box 3400 with the SOC increased and then advances to box 3500 to increase the temperature of the Li-Ion battery. The method then continues as previously discussed. It will be appreciated that if the temperature of the Li-Ion battery is too high a similar approach is used but in that case the temperature adjustment is one of Li-Ion battery cooling.

Therefore preferably only adjustment of the temperature of the Li-Ion battery is used unless the SOC of the Li-Ion battery is so low that even with adjustment of the temperature it will be unable to meet the power requirement.

With reference to Fig.3 there is shown a motor vehicle which in the case of this example is a mild hybrid vehicle 5 having an engine system including an engine 11 drivingly connected to a gearbox 12 and an electrical system 1 including a starting apparatus for starting the engine 11. One or more exhaust gas aftertreatment devices 6 are arranged to receive exhaust gas from the engine 11 as is well known in the art.

The electrical system 1 comprises an electronic controller in the form of a control unit 10, a low voltage starter system including a starter motor 13, a low voltage battery 17 and a low voltage battery management system 15 and a high voltage starter system including a belt integrated starter-generator 14, a high voltage battery in the form of a Li-Ion battery 18 and a high voltage battery management system 16.

The electrical system 1 further comprises a DC to DC voltage converter for selectively connecting the high voltage Li-Ion battery 18 to the low voltage battery 17 for the purpose of recharging the low voltage battery 17 and a number of inputs 20 for providing information to the electronic controller 10.

A 'mild hybrid vehicle' is a vehicle having an electric motor/generator (starter-generator) driveably connected to an engine of the vehicle to:a/ assist the engine of the vehicle by producing mechanical torque using electricity stored in a high voltage Li-Ion battery (torque assist);

b/ capture energy from the vehicle with no fuel penalty;

c/ store captured energy as electricity in the high voltage Li-Ion battery;

d/ start the combustion engine of the vehicle; and e/ provide electrical energy to users of the vehicle.

The electric machine is not used on its own in a mild hybrid vehicle to drive the vehicle it is only used to start the engine or assist the engine in driving the vehicle so as to reduce the instantaneous fuel consumption of the engine.

Therefore the BISG 14 can operate in two modes, in the first mode it is driven by the engine 11 to produce electrical power for storage in the high voltage Li-Ion battery 18 (HV battery) and in the second mode is produces torque to either supplement the torque produced by the engine 11 or for use in starting the engine 11.

The electronic controller is described in this case as being a single control unit 10 operable to control not only the general operation of the engine 11 but also the low and high voltage starter systems. It will however be appreciated that the electronic controller could comprise of a number of interlinked electronic units or controllers providing in combination the same functionality.

In the case of the example shown in Fig.3 the inputs to the electronic controller 10 include at least one input from which the temperature of the engine 11 can be deduced such as, for example, one or more of coolant temperature;

cylinder head temperature and engine cylinder block temperature and at least one input indicative of engine speed and further inputs providing information regarding the temperature of the high voltage Li-Ion battery 18, the state of charge of the high voltage Li-Ion battery 18, the state of charge of the low voltage battery 17 and any other input required to effect adaptive control of the operation of the high voltage Li-Ion battery 18.

An input to the electronic controller 10 is also received from a navigation system 60 forming part of the electrical system 1 that is used by the electronic controller 10 to predict a future demand for electrical power from the high voltage Li-Ion battery 18. That is to say, the navigation system 60 can be used to enable the temperature of the Li-Ion battery 18 to be adjusted to a temperature within a desired temperature range set for good operation of the Li-Ion battery 18 in preparation for meeting a predicted future demand for electrical power from the Li-Ion battery 18.

The high voltage Li-Ion battery 18 is operatively connected via the DC to DC converter 19 to the low voltage battery 17 so that the low voltage battery 17 can be recharged by the BISG 14 via the DC to DC converter 19 when required.

The electronic controller 10 is operatively connected to the DC to DC converter 19, to the high and low voltage battery management systems 16 and 15, the starter motor 13 and BISG 14 and various other devices and sensors associated with the engine 11.

In the case of this example the electronic controller 10 also includes an engine stop-start controller for the motor vehicle 5 and the inputs 20 also include inputs for use in determining when the engine 11 should be automatically stopped in order to save fuel. Any suitable combination of stop and start triggers can be used in accordance with this invention. An automatic engine stop or Έ-stop' is one where the engine 11 is temporarily stopped to save fuel and reduce emissions by the electronic controller 10 in response to one or more conditions based upon driver actions.

In addition to the foregoing and in accordance with this invention the electrical system 1 further includes a thermo-electric temperature control apparatus 50. The function of the thermo-electric temperature control apparatus is to regulate the temperature of the Li-Ion battery 18 as will be described in greater detail hereinafter .

The thermo-electric temperature control apparatus in a first embodiment includes a thermo-electric temperature control module 50 and a fan 45 that receive a supply of electricity from the low voltage battery management system 15 in response to control commands or signals from the electronic controller 10.

With particular reference to Figs.4a and 4b there is shown in more detail the first embodiment of a thermoelectric temperature control apparatus in the form of the 'convection' thermo-electric temperature control apparatus.

The convection thermo-electric temperature control apparatus includes the thermo-electric temperature control module 50 (TEC module 50), the fan and a casing defining an air flow passage from the fan 45 to the Li-Ion battery 18.

The TEC module 50 comprises a Peltier device 53 having a first electrical input end 53-1 and a second electrical input end 53-2 interposed between a pair of heat transfer plates 54, 55. The heat transfer plates 54, 55 are made from a material such as aluminium alloy have a high thermal conductivity so as to effectively transfer thermal energy away from the Peltier device 53.

A first heat transfer plate 54 is located in the air flow passage 42 defined by the casing 40 for the Li-Ion battery 18 and then electric fan 45 is arranged to cause air to flow in the direction of the arrow 'f' through the air flow passage 42 so that it flows over the first heat transfer plate 54 before reaching the Li-Ion battery 18. It will be appreciated that the first heat transfer plate 54 can include a number of fins or projections (not shown) extending into the air flow through the air flow passage 42 and extending in the direction of the air flow through the air flow passage 42 in order to increase the rate of heat transfer from the first heat transfer plate 54 to the air flowing through the air flow passage 42.

The battery 18 is spaced away from the casing 40 so as to define air flow paths 18f between the Li-Ion battery 18 and the casing 40.

In Fig.4a the TEC module 50 is shown in a Li-Ion battery heating mode. In this mode of operation the first electrical input end 53-1 is connected to a negative electrical supply (-ve) and the second electrical input end 53-2 is connected to a positive electrical supply (+ve).

In Fig.4b the TEC module 50 is shown in a Li-Ion battery cooling mode. In this mode of operation the first electrical input end 53-1 is connected to a positive electrical supply (+ve) and the second electrical input end 53-2 is connected to a negative electrical supply (-ve).

The electrical supply to the Peltier device 53 of the TEC module 50 is in the case of this example provide from a polarity switching device 15P formed as part of the low voltage battery management system 15 but it will be appreciated that the supply of electricity to the TEC module 50 could be from any suitable source. The polarity switching device 15P receives a supply of electrical energy from the low voltage side of the electrical system 1 and either transfers the electricity to the Peltier device 53 with no change of polarity or switches the polarity of the supply to the Peltier device 53 depending upon whether heating or cooling of the Li-Ion battery 18 is required as determined by the electronic controller 10. It will be appreciated that although not shown the supply of electricity to the polarity switching device is also controlled so that the supply of electricity to the Peltier device 53 of the TEC module 50 can be switched on or switched 'off'.

It will be appreciated that the Li-Ion battery 18 includes a number of Li-Ion cells that are connected together to provide the required nominal output voltage and that one or more temperature sensors are embedded within the Li-Ion battery 18 in order to provide an indication of the temperature of the Li-Ion battery 18 during use. In some cases the temperatures of a number of the cells in the LiIon battery 18 are sensed and combined to provide an indication of the temperature of the Li-Ion battery 18 and in other arrangements the temperature in only one chosen location is sensed. Irrespective of the temperature sensing arrangement an input indicative of the temperature of the Li-Ion battery 18 is provided to the electronic controller 10 as one of the inputs 20.

The electronic controller 10 is arranged to use the input it receives regarding the temperature of the Li-Ion battery 18 with other inputs such as, for example, sensed ambient temperature, state of charge of the Li-Ion battery 18, state of charge of the low voltage battery 17, state of health of the Li-Ion battery (battery ageing) in order to determine whether Li-Ion battery heating, Li-Ion battery cooling or no temperature control is required (TEC module off) .

As previously referred to, the performance of a Li-Ion battery is dependent upon a number of parameters including the temperature of the Li-Ion battery, the state of charge of the Li-Ion battery and the state of health of the Li-Ion battery 18.

The electronic controller 10 is arranged to set upper and lower temperature thresholds for the Li-Ion battery 50 based upon these parameters.

In general terms there is a lower temperature threshold below which heating of the Li-Ion battery 18 is required and an upper temperature threshold above which cooling of the Li-Ion battery 18 is required. In one non-limiting embodiment the upper temperature was set to 35°C and the lower limit was set to 20°C.

Therefore if the temperature of the Li-Ion battery 18 is sensed to be greater than 35°C such as, for example 45°C, the electronic controller 10 is arranged to set the polarity of the electrical supply to the TEC module 50 as shown in Fig.4b such that the first end 53-1 of the Peltier device 53 receives a positive polarity input and the second end 53-2 of the Peltier device 53 receives a negative input.

This will have the effect of causing the first heat transfer plate 54 to be cooled by the Peltier device 53 and the second heat transfer plate 55 to be heated by the Peltier device 53 and the TEC module is said to be in a 'battery cooling' mode of operation because the air is flowing the cold heat transfer plate 54 of the TEC module 50 .

In addition to controlling the polarity switching device 15P to provide the required polarity for the Peltier device 53 the electronic controller 10 is further arranged to activate the fan 45 thereby causing air to flow across the cooled first heat transfer plate 54 to the Li-Ion battery 18 thereby cooling the Li-Ion battery 18.

The temperature of the Li-Ion battery 18 is continuously monitored by the electronic controller 10 and when the temperature of the Li-Ion battery 18 falls below the upper temperature threshold the electronic controller 10 is arranged to switch off the TEC module 50 and the fan 45. It will be appreciated that the electronic controller can be arranged to delay switching off of the TEC module 50 and the fan 45 until the temperature of the Li-Ion battery 18 is well within the temperature range bounded by the upper and lower temperature thresholds.

Similarly, if the temperature of the Li-Ion battery 18 is sensed to be less than 20°C such as, for example 5°C, the electronic controller 10 is arranged to set the polarity of the electrical supply to the TEC module 50 as shown in Fig.4a such that the first end 53-1 of the Peltier device 53 receives a negative polarity input and the second end 53-2 of the Peltier device 53 receives a positive input.

This will have the effect of causing the first heat transfer plate 54 to be heated by the Peltier device 53 and the second heat transfer device 55 to be cooled by the Peltier device 53 and the TEC module is said to be in a 'battery heating' mode of operation because the air is flowing the hot heat transfer plate 54 of the TEC module 50.

In addition to controlling the polarity switching device 15P to provide the required polarity for the Peltier device 53 the electronic controller 10 is further arranged to activate the fan 45 thereby causing air to flow across the heated first heat transfer plate 54 to the Li-Ion battery 18 thereby cooling the Li-Ion battery 18.

The temperature of the Li-Ion battery 18 is continuously monitored by the electronic controller 10 and when the temperature of the Li-Ion battery 18 exceeds the lower temperature threshold the electronic controller 10 is arranged to switch off the TEC module 50 and the fan 45. It will be appreciated that the electronic controller is normally arranged to delay switching off of the TEC module 50 and the fan 45 until the temperature of the Li-Ion battery 18 is well within the temperature range bounded by the upper and lower temperature thresholds.

The setting of the temperature range is adapted to take into account the state of charge of the Li-Ion battery 18 and preferably the state of health of the Li-Ion battery 18. This can be done in several ways but in the case of this example a series of look-up tables referenced by state of health are used. Each of the look-up tables references state of charge against temperature to produce a power output value for the Li-Ion battery 18. This power output value can then be used to define the upper and lower temperature thresholds based upon a predicated power delivery requirement for the Li-Ion battery 18.

The look up table used is selected upon the age of the Li-Ion battery 18. It will be appreciated that as a Li-Ion battery ages the performance of the Li-Ion battery deteriorates and, in particular, its power limit at high and low temperatures deteriorates.

For example, if the current temperature of the Li-Ion battery 18 is 5°C and the current state of charge is 25% and an expected power demand requires an output of 5kW then it may be required to set the lower temperature threshold at 20°C in order to achieve the required power delivery.

However, if the state of charge of the Li-Ion battery 18 is 50% then a lower temperature threshold of 15°C may be sufficient to provide the required power delivery.

In one particularly advantageous embodiment the navigation system 60 is used by the electronic controller 10 to predict a future power requirement for the Li-Ion battery 18 by using information regarding the route the motor vehicle 5 is following. For example if the motor vehicle 5 will be required to ascend a hill in the near future thereby requiring the BISG 14 to provide torque assist to the engine 11 then a power requirement for this activity is estimated and the Li-Ion battery 18 is readied for this demand by adjusting its temperature to fall within an optimum temperature range and in some cases charging the Li-Ion battery 18 if the current state of charge is such that temperature adjustment alone will not be sufficient to provide the required power delivery. It will be appreciated that charging of the Li-Ion battery 18 will be avoided whenever possible because it will increase fuel consumption and emissions unless it can be done in a regenerative manner when, for example, the motor vehicle 5 has to be retarded.

In a similar manner, the navigation system 60 may provide information to the electronic controller 10 indicating that the motor vehicle 5 will likely encounter standing traffic in 3km thereby requiring the use of stopstart operation in order to reduce fuel consumption and emissions. The expected power requirement for the stopstart operation can then be predicted and the Li-Ion battery 18 be readied by controlling its temperature and, if required, the state of charge of the Li-Ion battery 18 to provide the required power for using the BISG 14 to start the engine 11 during the period of stop-start operation.

Therefore in summary, the electronic controller 10 is arranged to control the temperature of the Li-Ion battery 18 either to increase it or to decrease it using the TEC module 50 in order to adjust the temperature of the Li-Ion battery 18 so that it falls within a temperature range where it can provide the required power output to meet current and predicted future demands.

With particular reference to Figs.5a and 5b there is shown a second embodiment of a thermo-electric temperature control apparatus in the form of the 'conduction' thermoelectric temperature control apparatus as applied to a LiIon battery 118 (not shown in full) only three cells 118a, 118b and 118c of the battery 118 are shown in Figs.5a and 5b. It will be appreciated that the Li-Ion battery 118 will include more than the three cells 118a, 118b, 118c shown in Figs.5a and 5b and that the same approach is applied to the temperature control of all the cells making up the Li-Ion battery. The battery 118 is intended to be a direct replacement for the battery 18 shown in Fig.3.

The convection thermo-electric temperature control apparatus shown includes six a thermo-electric temperature control modules 150 (TEC modules 150) each of which comprises a Peltier device 153 having a first electrical input end 153-1 and a second electrical input end 153-2 interposed between first and second heat transfer plates 154, 155.

The first and second heat transfer plates 154 and 155 are, as before, made from a material such as aluminium alloy having a high thermal conductivity so as to effectively transfer thermal energy away from the Peltier device 153.

In Fig.5a the TEC modules 150 are shown in a Li-Ion battery heating mode. In this mode of operation the first electrical input ends 153-1 of the Peltier devices 153 are connected to a negative electrical supply (-ve) and the second electrical input ends 153-2 are connected to a positive electrical supply (+ve). It will be noted that between adjacent cells 118a, 118b, 118c there is always interposed two TEC modules 150. That is to say, there are two TEC modules 150 between the cells 118a and 118b, two TEC modules 150 between the cells 118a and 118b and two TEC modules 150 between the cells 118b and 118c. Although not shown this arrangement of TEC modules 150 is repeated throughout the Li-Ion battery.

The two adjacent TEC modules 150 are orientated so that the first heat transfer plate 154 of each of the TEC modules 150 is in contact with the adjacent cell 118a, 118b, 118c and the second heat transfer plate 155 of each of the TEC modules 150 is in contact with the second heat transfer plate 155 of the adjacent TEC module 150. With this arrangement the first heat transfer plates 154 will get hot thereby heating the adjacent cell 118, 118b, 118c and the two adjacent second heat transfer plates 155 will get cold when the electrical supply is connected to the Peltier devices 153 with the polarity shown in Fig.5a and as referred to above.

In Fig.5b the TEC module 150 is shown in a Li-Ion battery cooling mode. In this mode of operation the arrangement of the TEC modules 150 is the same as that shown in Fig.5a and the only difference is that the polarity of the supply has been reversed so that the first electrical input ends 153-1 of the Peltier devices 153 are connected to a positive electrical supply (+ve) and the second electrical input ends 153-2 are connected to a negative electrical supply (-ve). With this arrangement the first heat transfer plates 154 will get cold thereby cooling the adjacent cell 118a, 118b, 118c and the two adjacent second heat transfer plates 155 will get hot when an electrical supply is connected to the Peltier devices 153.

It will be appreciated that the ends of the second heat transfer plates 155 can extend outwardly from the adjacent cells 118a, 118b, 118c so that heat or cold can be transferred away by, for example, flowing air past the exposed ends of the second transfer plates 155.

The electrical supply to the Peltier devices 153 of the TEC modules 150 is provided in the case of this example from a polarity switching device (not shown) forming part of a low voltage battery management system such as the low voltage battery management system 15 shown in Fig.3 but it will be appreciated that the supply of electricity to the TEC module 150 could be from any suitable source.

The polarity of the supply to the Peltier devices 153 depends upon whether heating or cooling of the Li-Ion battery is required as determined by an electronic controller such as the electronic controller 10. It will be appreciated that the supply of electricity to the Peltier devices 153 of the TEC modules 150 can be switched on or switched 'off' by the electronic controller 10.

It will be further appreciated that the Li-Ion battery will normally include a number of Li-Ion cells such as the cells 118a to 118c that are connected together to provide the required nominal output voltage and that one or more temperature sensors can be embedded within the Li-Ion battery in order to provide an indication of the temperature of the Li-Ion battery during use. In some cases the temperature of every cell in the Li-Ion battery is sensed and combined to provide an indication of the overall temperature of the Li-Ion battery and in other arrangements the temperature in only one chosen location is sensed. Irrespective of the temperature sensing arrangement an input indicative of the temperature of the Li-Ion battery is provided to the electronic controller 10 as one of the inputs 20.

The electronic controller 10 is arranged to use the input it receives regarding the temperature of the Li-Ion battery 118 with other inputs such as, for example, sensed ambient temperature, state of charge of the Li-Ion battery 118, state of charge of the low voltage battery 17, state of health of the Li-Ion battery 118(battery ageing state) in order to determine whether Li-Ion battery heating, Li-Ion battery cooling or no temperature control is required (TEC module off) .

As previously referred to the performance of a Li-Ion battery is dependent upon a number of parameters including the temperature of the Li-Ion battery, the state of charge of the Li-Ion battery and the state of health of the Li-Ion battery and, as before, the electronic controller 10 is arranged to set upper and lower temperature thresholds for the Li-Ion battery that includes the cells 118a, 118b, 118c based upon these parameters.

As before, the lower temperature threshold is a temperature threshold below which heating of the Li-Ion battery or more accurately the cells making up the battery is required and the upper temperature threshold is a temperature threshold above which cooling of the Li-Ion battery 18 is required.

Therefore if the temperature of the Li-Ion battery is sensed to be greater than the upper temperature threshold the electronic controller 10 is arranged to set the polarity of the electrical supply to the TEC module 150 as shown in Fig.5b such that the first end 153-1 of the Peltier devices 153 receive a positive polarity input and the second ends 153-2 of the Peltier devices 153 receive a negative input.

This will have the effect of causing the first heat transfer plates 154 to be cooled by the Peltier device 153 and the second heat transfer plates 155 to be heated by the Peltier device 153 and the TEC modules are said to be in a 'battery cooling' mode of operation.

The temperature of the Li-Ion battery is continuously monitored by the electronic controller 10 and if the temperature of the Li-Ion battery falls within the upper an lower temperature thresholds the electronic controller 10 is arranged to switch off the TEC modules 150.

Similarly, if the temperature of the Li-Ion battery is sensed to be below the lower temperature threshold then the electronic controller 10 is arranged to set the polarity of the electrical supply to the TEC module 150 as shown in Fig.5a such that the first ends 153-1 of the Peltier devices 153 receive a negative polarity input and the second ends 153-2 of the Peltier devices 153 receive a positive input.

This will have the effect of causing the first heat transfer plates 154 to be heated by the Peltier devices 153 and the second heat transfer plates 155 to be cooled by the Peltier devices 153 and the TEC modules 150 are said to be in a 'battery heating' mode of operation and the cells 118a, 118b, 118c will be heated.

The temperature of the Li-Ion battery is continuously monitored by the electronic controller 10 and when the temperature of the Li-Ion battery 18 exceeds the lower temperature threshold the electronic controller 10 is arranged to switch off the TEC modules 150. It will be appreciated that the electronic controller 10 can be arranged to delay switching off of the TEC modules 150 until the temperature of the Li-Ion battery is well within the temperature range bounded by the upper and lower temperature thresholds .

As before the setting of the temperature range is adapted to take into account the state of charge of the LiIon battery that is to say the state of charge of the cells making up the Li-Ion battery and preferably the state of health of the Li-Ion battery 18. This can be done in several ways but in the case of this example a series of look-up tables referenced by state of health stored in a memory of the electronic controller 10 are used. Each of the look-up tables references state of charge against temperature to produce a power output value for the Li-Ion battery. This power output value can then be used to define the upper and lower temperature thresholds based upon a predicated power delivery requirement for the Li-Ion battery.

The look up table used is selected upon the aged state of the Li-Ion battery. It will be appreciated that as a LiIon battery ages the performance of the Li-Ion battery deteriorates and, in particular, its performance at high and low temperatures deteriorates.

As before, in a particularly advantageous embodiment, a navigation system such as the navigation system 60 is used by the electronic controller 10 to predict a future power delivery requirement for the Li-Ion battery by using information regarding the route the motor vehicle 5 is following.

Therefore in summary the electronic controller 10 is, as before, arranged to control the temperature of the Li-Ion battery including the cells 118a, 118b and 118c either to increase the temperature of the cells 118a, 118b and 118c or to decrease cell temperatures using the TEC modules 150 so that the temperature falls within a temperature range where the Li-Ion battery can provide the required power output to meet current and predicted future demands.

With particular reference to Fig.6 there is shown a third embodiment of a thermo-electric temperature control apparatus in the form of the 'conduction' thermo-electric temperature control apparatus as applied to a Li-Ion battery 218 (not shown in full) of which only five cells 218a, 218b, 218c, 218d and 218e are shown in Fig.6. It will be appreciated that the Li-Ion battery 218 will include more than the five cells 218a to 218e shown in Fig.6 and that the same approach is applied to the temperature control of all the cells making up the Li-Ion battery.

In the case of this embodiment first and second thermoelectric temperature control modules 250a and 250b (TEC modules 250a and 250b) are used to control the temperature of the cells 218a to 218e.

The two TEC modules 250a and 250b are controlled by an electronic controller such as the electronic controller 10 shown in Fig.3 and the same control methodology is used to control the temperature of the cells 218a to 218e as previously described.

The first TEC module 250a has a Peltier device 253a interposed between a first heat transfer plate 254a and a second heat transfer plate 255a. The first heat transfer plate 254a has a number of upstanding fins 260a in the case of this example over which air can be flowed as indicated by the arrow Έ'. However in other embodiments not shown such fins are not used. The second heat transfer plate 255a has a number of spaced apart upstanding fins 255a-f. The fins 255a-f are positioned on each side of the cells 218a-218e so that each of the cells 218a to 218e is interposed at one end between a pair of the fins 255a-f of the second heat transfer plate 255a.

The second TEC module 250b has a Peltier device 253b interposed between a first heat transfer plate 254b and a second heat transfer plate 255b. The first transfer plate 254b has a number of upstanding fins 260b in the case of this example over which air can be flowed as indicated by the arrow Έ'. However in other embodiments not shown such fins are not used. The second heat transfer plate 255b has a number of spaced apart upstanding fins 255b-f. The fins 255b-f are positioned on each side of the cells 218a-218e so that each of the cells 218a to 218e is interposed at a second end between a pair of the fins 255b-f of the second heat transfer plate 255b.

Therefore the cells 218a to 218e are enclosed between the upstanding fins 255a-f, 255b-f of the second heat transfer plates 255a, 255b of the first and second TEC modules 250a and 250b.

In Fig.6 respective first ends 253-la, 253-lb of the two Peltier devices 253a, 253b are connected to a negative (-ve) electrical supply and respective second ends 253-2a, 253-2b of the two Peltier devices 253a, 253b are connected to a positive (+ve) electrical supply and with this polarity arrangement the cells 218a to 218e will be cooled by the first and second TEC modules 250a and 250b due to conduction from the fins 255a-f, 255b-f of the second heat transfer plates 255a, 255b that will be cooled by their respective Peltier device 253a, 253b with this polarity arrangement.

If heating of the cells 218a to 218e is required then the polarity of the TEC modules 250a and 250b is reversed so that the first ends 253-la, 253-lb of the two Peltier devices 253a, 253b are connected to a positive (+ve) electrical supply and respective second ends 253-2a, 253-2b of the two Peltier devices 253a, 253b are connected to a negative (-ve) electrical supply.

The control of the polarity and when each polarity is chosen is controlled as before by the electronic controller

10.

Although in the case of the examples described herein 'low voltage' is a voltage of circa 12 volts and 'high voltage' is a voltage of circa 48 volts. It will be appreciated that the invention is not limited to the use of these voltages and other voltages could be used. However, io the use of 12/48 volts is advantageous in that equipment utilising such voltages is readily available.

It will be appreciated by those skilled in the art that although the invention has been described by way of example with reference to one or more embodiments it is not limited to the disclosed embodiments and that alternative embodiments could be constructed without departing from the scope of the invention as defined by the appended claims.

Claims

1. A method of adaptively controlling an electrical system having a Lithium-Ion battery wherein, when there is one of a current requirement and an expected requirement for power from the Lithium-Ion battery, setting upper and lower temperature thresholds for the Lithium-Ion battery based upon the requirement for power, checking whether the current temperature of the Lithium-Ion battery is within a desired temperature range bounded by the upper and lower temperature thresholds and, if the current temperature of the LithiumIon battery is not within the desired temperature range, using a thermo-electric temperature control apparatus to adjust the temperature of the Lithium-Ion battery to bring the temperature of the Lithium-Ion battery within the desired temperature range.

2. A method as claimed in claim 1 wherein, if the current temperature of the Lithium-Ion is higher than the upper temperature threshold, the thermo-electric temperature control apparatus is used to cool the Lithium-Ion battery to bring the temperature of the Lithium-Ion battery within the desired temperature range.

3. A method as claimed in claim 1 wherein, if the current temperature of the Lithium-Ion is lower than the lower temperature threshold, the thermo-electric temperature control apparatus is used to bring the temperature of the Lithium-Ion battery within the desired temperature range.

4. A method as claimed in any of claims 1 to 3 wherein setting the desired temperature range comprises using the requirement for power from the Lithium-Ion battery and a relationship between temperature and power output for the Lithium-Ion battery.

5. A method as claimed in claim 4 wherein setting the desired temperature range further comprises using a current state of charge of the Lithium-Ion battery to set the upper and lower temperature thresholds.

6. A method as claimed in claim 5 wherein setting the desired temperature range further comprises using a state of health of the Lithium-Ion battery, the current state of charge of the Lithium-Ion battery and one of the current requirement for power and the expected requirement for power to set the upper and lower temperature thresholds.

7. A method as claimed in any of claims 1 to 4 wherein, if a state of charge of the Lithium-Ion battery is below a state of charge level that an adjustment of temperature of the Lithium-Ion battery alone will be unable to meet one of the current requirement for power and the expected requirement for power from the Lithium-Ion battery, the method further comprises increasing the state of charge of the Lithium-Ion battery to a level where an adjustment of temperature of the Lithium-Ion battery will be able to meet the requirement for power from the Lithium-Ion battery.

8. A method as claimed in any of claims 1 to 7 wherein the thermo-electric temperature control apparatus comprises at least one thermo-electric control module having a Peltier device interposed between two heat transfer plates, one of the heat transfer plates being thermally connected to the Lithium-Ion battery.

9. A method as claimed in claim 8 wherein convection is used to thermally connect said one heat transfer plate to the Lithium-Ion battery.

10. A method as claimed in claim 8 wherein conduction is used to thermally connect said one heat transfer plate to the Lithium-Ion battery.

11. An electrical system having a Lithium-Ion battery, an electronic controller and a thermo-electric temperature control apparatus wherein, when there is one of a current requirement for power and an expected requirement for power from the Lithium-Ion battery, the electronic controller is arranged to set upper and lower temperature thresholds for the Lithium-Ion battery based upon the requirement for power, check whether the current temperature of the LithiumIon battery is within a desired temperature range bounded by the upper and lower temperature thresholds and, if the current temperature of the Lithium-Ion battery is not within the desired temperature range, using the thermo-electric temperature control apparatus to adjust the temperature of the Lithium-Ion battery to bring the temperature of the Lithium-Ion battery within the desired temperature range.

12. An electrical system as claimed in claim 11 wherein, if the current temperature of the Lithium-Ion is higher than the upper temperature threshold, the electronic controller is arranged to use the thermo-electric temperature control apparatus to cool the Lithium-Ion battery to bring the temperature of the Lithium-Ion battery within the desired temperature range.

13. An electrical system as claimed in claim 11 wherein, if the current temperature of the Lithium-Ion is lower than the lower temperature threshold, the electronic controller is arranged to use the thermo-electric temperature control apparatus to heat the Lithium-Ion battery to bring the temperature of the Lithium-Ion battery within the desired temperature range.

14. An electrical system as claimed in any of claims 11 to 13 wherein the thermo-electric temperature control apparatus comprises at least one thermo-electric control module having a Peltier device interposed between two heat transfer plates and one of the heat transfer plates is thermally connected to the Lithium-Ion battery.

15. An electrical system as claimed in claim 14 wherein convection is used to thermally connect said one heat transfer plate to the Lithium-Ion battery.

16. An electrical system as claimed in claim 14 wherein conduction is used to thermally connect said one heat transfer plate to the Lithium-Ion battery.

17. An electrical system as claimed in any of claims 11 to 16 wherein the Lithium-Ion battery has a number of cells connected together to provide a desired power output and the temperature of the battery is the temperature of at least one of the cells of the Lithium-Ion battery.

18. An electrical system as claimed in any of claims 11 to 17 wherein the electrical system includes one or more temperature sensors operatively connected to the electronic controller arranged to measure the temperature of the Lithium-Ion battery.

19. An electrical system as claimed in any of claims 11 to 18 wherein the electronic controller is arranged to set the desired temperature range using the requirement for power from the Lithium-Ion battery and a relationship between temperature and power output for the Lithium-Ion battery.

20. An electrical system as claimed in claim 19 wherein the electronic controller is further operable to set the upper and lower temperature thresholds of the desired temperature range by using a current state of charge of the Lithium-Ion battery and the requirement for power.

21. An electrical system as claimed in claim 20 wherein the electronic controller is further arranged to set the upper and lower thresholds of the desired temperature range by using a state of health of the Lithium-Ion battery, the current state of charge of the Lithium-Ion battery and the requirement for power to set the upper and lower temperature thresholds.

22. An electrical system as claimed in any of claims 11 to 19 wherein, if the state of charge of the Lithium-Ion battery is below a level where an adjustment of temperature of the Lithium-Ion battery alone will be unable to meet the requirement for power from the Lithium-Ion battery, the electronic controller is further operable to use an electric generator to increase the state of charge of the Lithium-Ion battery to a level where an adjustment of temperature of the Lithium-Ion battery will be able to meet the requirement for power from the Lithium-Ion battery.

23. An electrical system as claimed in any of claims 11 to 22 wherein the electrical system includes a navigation system and the navigation system is used to enable the temperature of the Li-Ion battery to be adjusted to a temperature within the desired temperature range in preparation for meeting a predicted future demand for electrical power from the Li-Ion battery.

24. A motor vehicle having an internal combustion engine and an electrical system wherein the electrical system is an electrical system as claimed in any of claims 11 to 23.

25. A motor vehicle as claimed in claim 24 when dependent upon claim 22 wherein the electric generator is drivingly connected to the internal combustion engine of the motor vehicle.

26. A motor vehicle as claimed in claim 25 wherein the motor vehicle is a mild hybrid vehicle and the electric generator is a belt integrated starter-generator.

Intellectual

Property

Office

Application No: GB 1619769.1