METHOD FOR OPTIMIZING THE USABLE ENERGY OF A HIGH-VOLTAGE BATTERY

Abstract

Optimizing the usable energy for an electric vertical takeoff and landing (eVTOL) vehicle or other electric vehicle. Optimization may include charging a low-voltage (LV) power source to meet the energy requirements of LV systems and loads onboard the vehicle prior to performing a landing operation, thereby optimizing the vehicle's usable energy by enabling the landing operation to occur independently of a high-voltage (HV) power source that must simultaneously power the LV systems.

Description

INTRODUCTION

[0001] The present disclosure relates to a method for optimizing the usable energy of a high voltage battery of an electric vehicle, such as optimizing the usable energy available from a high voltage (HV) power source of an electric vertical takeoff and landing (eVTOL) vehicle.

[0002] For background information, reference is made at this point to the documents EP 4 043 344A1, EP 4 137 348 A1, DE 10 2018 116 167 A1, EP 4 246 757 A1, EP 4 122 753 A1, EP 4 035 928 A1 and JP 2024 - 30 603 A.

[0003] A wide range of electric vehicles may require a relatively significant amount of electrical energy to facilitate the powering of a propulsion system, and such electric vehicles generally operate in a manner whereby related power demands may fluctuate depending on the activities being performed. For example, in the case of an eVTOL vehicle, when performing takeoff or landing operations, power demands may increase significantly or approach maximum levels due to the accompanying requirements of an aircraft propulsion system to consume correspondingly proportional amounts of electrical energy from an electric energy storage system. Electric energy storage systems may be susceptible to power fluctuations due to the effects of slower diffusion, diffusion overload, and / or other influences resulting from power demand.The power fluctuations can be reflected by the amount by which the usable energy of the electric energy storage system deviates from its thermodynamic energy capacity. In the case of eVTOL vehicles or other electric vehicles, where range, speed, duration, and other performance-related parameters and capabilities may depend on the availability of a sufficient supply of electrical energy to support activities with relatively high power demands, it may be advantageous to optimize the usable energy so that the maximum amount of electrical energy and power can be achieved when needed. SUMMARY

[0004] One non-limiting aspect of the present disclosure relates to optimizing usable energy for an electric energy storage system. The optimization may include predicting demands expected for a relatively high-current activity and attempting to improve at least a portion of the predicted demands, such as by charging a low-voltage (LV) power source to meet the predicted demand for the LV systems before requesting a high-voltage (HV) power source to support the relatively high-current activity.In the case of an electric vertical takeoff and landing (eVTOL) vehicle, optimization may include predicting the LV power required for the LV systems when performing a landing operation and pre-charging the LV power source to meet the predicted LV power demand so that landing can occur regardless of the HV power source simultaneously powering the LV systems. The energy available from the LV power source can also be used to provide energy to support the HV power source during landing operations (or other high-current activities), as the LV power source can thus be used as a source to provide large amounts of power in a short period of time, e.g., ultracapacitance.

[0005] In particular, the invention provides a method for optimizing the usable energy of a high-voltage (HV) battery contained on board an electric vertical take-off and landing (eVTOL) vehicle to electrically power an aircraft propulsion system, the method being characterized by the features of claim 1.

[0006] The method may include performing a low-voltage (LV) energy prediction after the eVTOL vehicle has completed a takeoff operation to estimate an expected LV energy consumption that the LV systems onboard the eVTOL vehicle are expected to consume when performing a landing operation; determining whether the LV energy available from an LV battery onboard the eVTOL vehicle meets an LV landing threshold that indicates that the LV battery has LV energy suitable for supplying a total expected LV energy consumption; implementing an assist mode prior to commencing the landing operation in response to the LV energy not being able to supply the total expected LV energy consumption, wherein the assist mode optionally includes using the HV battery to facilitate charging the LV battery prior to commencing the landing operation;and implementing an unassisted mode of operation prior to the start of the landing operation in response to the LV energy being able to supply all of the expected LV energy consumption, wherein the unassisted mode of operation optionally includes powering the LV systems independently of the HV battery using the LV energy available from the LV battery, thereby optimizing the usable energy of the HV battery by enabling the landing operation to occur regardless of the HV battery having to power the LV systems at the same time.

[0007] The method may include implementing the assist mode of operation, which includes using the HV battery to charge the LV battery to a charge level sufficient to meet the LV landing threshold.

[0008] The method may include implementing the assist mode of operation that includes using the HV battery to power the LV systems while simultaneously charging the LV battery.

[0009] The method may include performing an HV energy prediction after the eVTOL vehicle completes the takeoff operation, wherein the HV energy prediction optionally estimates an expected HV energy consumption that the flight propulsion system is expected to consume when performing the landing operation.

[0010] The method may include determining whether the HV energy available from the HV battery meets an HV landing threshold that indicates that the HV battery has HV energy suitable for supplying a total expected HV energy consumption.

[0011] The method may include implementing the assist mode of operation including, in response to the HV power being able to supply all of the expected HV power consumption, charging the LV battery to a first charge level sufficient to meet the LV landing threshold, and, in response to the HV power not being able to supply all of the expected HV power consumption, implementing the assist mode of operation including charging the low voltage battery to a second charge level insufficient to meet the LV landing threshold.

[0012] The method may include selecting the second charge level to be proportional to a difference between the HV energy and the HV landing threshold.

[0013] The method may include implementing a warm-up mode prior to implementing the assist mode and the non-assist mode, wherein the warm-up mode optionally powers the LV systems using the HV energy provided by the HV battery to thereby optimize usable energy by warming up the HV battery more quickly than in a non-warm-up mode.

[0014] The method may include the no-warm-up mode of operation, which includes powering the LV systems using the LV energy provided by the LV battery regardless of the need for the HV battery to power the LV systems simultaneously.

[0015] The method may include limiting implementation of the warm-up mode to an initial portion of a cruise operation, wherein the initial portion optionally corresponds to a predetermined period of time that occurs after the takeoff operation after the eVTOL vehicle has reached a cruise altitude.

[0016] The method may include selecting the predetermined period based on an expected duration of a flight.

[0017] The method may include selecting the predetermined period of time so that it is proportional to a duration expected for a flight.

[0018] The method may include the HV battery including a plurality of battery cells having a lithium-ion construction, characterized in that the battery cells experience slower diffusion and slower decreases in usable energy when current demands are higher.

[0019] One non-limiting aspect of the present disclosure relates to a method for optimizing the usable energy of a high-voltage (HV) power source included onboard an electric vehicle to electrically power a propulsion system. The method may include determining whether the low-voltage (LV) energy available from an LV power source onboard the electric vehicle meets an LV landing threshold indicating that the LV power source has LV energy suitable for supplying a total expected LV energy consumption to perform a landing operation.The method may include implementing a support mode prior to commencing the landing operation in response to the LV power not being able to supply all of the expected LV power consumption, the support mode optionally including charging the LV power source using the high voltage power provided by the HV power source until the LV power source can supply all of the expected LV power consumption, thereby optimizing the usable energy of the HV power source by enabling the landing operation to occur regardless of the HV power source having to power the LV systems simultaneously.

[0020] The method may include determining whether the HV power available from the HV power source meets an HV landing threshold indicating that the HV power source has HV power suitable for supplying a total expected HV power consumption to perform the landing operation.

[0021] The method may include, in response to the HV power not being able to supply all of the expected HV power consumption, interrupting the assist mode to prevent further use of the HV power source in charging the LV power source.

[0022] The method may include the HV power source comprising a plurality of battery cells having a lithium-ion construction, characterized in that the battery cells experience diffusion fluctuations proportional to the current demands on them.

[0023] The method may include determining the expected HV power consumption based at least in part on an expected amount of diffusion predicted to occur at a terminal of the HV power source during performance of the landing operation.

[0024] Further described is a system for optimizing the usable energy of an electric vehicle. The electric vehicle may include an electric propulsion system configured to convert high-voltage (HV) energy into mechanical energy suitable for use in propelling the electric vehicle, and a low-voltage (LV) bus configured to distribute the LV energy to one or more LV systems onboard the electric vehicle. The system may include a rechargeable energy storage system (RESS) configured to provide the HV energy to the electric propulsion system and the LV energy to the LV bus, wherein the RESS includes a plurality of energy cells configured to store and deliver electrical energy, and a usable energy controller. The usable energy controller may be configured to determine whether the low-voltage (LV) energy,available from an LV power source connected to the LV bus corresponds to an LV landing threshold indicating that the LV power source has LV power suitable for supplying a total expected LV power consumption to perform a landing operation, implementing an assist mode prior to the start of the landing operation in response to the LV power not being able to supply the total expected LV power consumption, the assist mode optionally including charging the LV power source using the HV power provided by the RESS until the LV power source can supply the total expected LV power consumption, and implementing an unassisted mode prior to the start of the landing operation in response to the LV power being able to supply the total expected LV power consumption, the unassisted mode optionally including relying onthat the LV energy source supplies power to the LV systems independently of the RESS.

[0025] The usable energy controller may be configured to implement a warm-up mode prior to implementing the assist mode and the unassisted mode, wherein the warm-up mode optionally powers the LV systems using the HV energy provided by the RESS to thereby optimize usable energy by warming up an HV energy source of the RESS more quickly than if the LV systems were powered independently of the HV energy source.

[0026] The HV power source may contain multiple battery cells with a lithium-ion construction.

[0027] These features and advantages, along with other features and advantages of the present teachings, can be readily appreciated from the following detailed description of the modes for carrying out the present teachings when considered in conjunction with the accompanying drawings. It should be appreciated that, although the following figures and embodiments may be described separately, individual features thereof may be combined into additional embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which may be incorporated in and constitute a part of this specification, illustrate implementations of the disclosure and, together with the description, serve to explain the principles of the disclosure; in which: Fig. 1 is a schematic view of a vehicle configured to optimize usable energy according to a non-limiting aspect of the present disclosure; and Fig. 2 is a flowchart of a method for optimizing usable energy according to a non-limiting aspect of the present disclosure. DETAILED DESCRIPTION

[0029] Fig. 1 illustrates a schematic view of a vehicle 12 configured to optimize usable energy according to one non-limiting aspect of the present disclosure. The vehicle 12 is described primarily in terms of its configuration as a type of electric vertical takeoff and landing (eVTOL) vehicle 12 capable of flight. The vehicle 12 may include a propulsion system 14 configured to convert electrical energy into mechanical energy operable for the purposes of generating thrust, lift, or other forces sufficient to perform vertical takeoff and landing operations.The propulsion system 14, while not shown separately, may include an electric motor operable with a drivetrain or other mechanical system to generate thrust sufficient to lift the vehicle 12 off the ground as part of a takeoff operation, propel the vehicle 12 through the air as part of a cruise operation, and thereafter land the vehicle 12 on the ground as part of a landing operation. The vehicle 12, and in particular the propulsion system 14, may be configured to enable flights generally associated with drones, helicopters, airplanes, and / or other machines capable of flying in the air. The vehicle 12 is depicted, for example, as representative of a broad range of electric vehicles in which the power requirements of the propulsion system 14 may be reduced when performing certain activities, such as driving.During takeoff or landing operations, power consumption may increase significantly or approach maximum levels due to the accompanying need for the propulsion system 14 to consume correspondingly proportional amounts of electrical energy. This is done for a non-limiting purpose, as the present disclosure fully contemplates its use and application with other types of vehicles that may benefit from optimizing usable energy in the manner described herein, including electric trucks or electrical appliances that may utilize the propulsion system 14 for ground or non-airborne movement or for work.

[0030] The vehicle 12 may include a rechargeable energy storage system (RESS) 16 configured to store and deliver electrical energy. The RESS 16 may include various components configured to store and deliver electrical energy, which, according to the exemplary illustration, may include a first energy source 20 and a second energy source 22. The first energy source may be considered a high-voltage (HV) energy source operable to store and deliver HV energy, while the second energy source may be considered a separate low-voltage (LV) energy source operable to store and deliver LV energy. The HV and LV energy sources 20 and 22, respectively, may each include one or more battery cells (not shown), with the battery cells optionally arranged in one or more modules (not shown).The HV power source 20 may include more and / or taller battery cells and / or modules than the LV power source 22, with its battery cells / modules optionally connected in a special manner so that the HV power source 20 can store and deliver electrical energy at relatively higher levels than the LV power source 22. The battery cells may include a wide variety of components operable to store and deliver electrical power. For example, the battery cells may include a lithium-ion material or other material chemistry suitable for storing and delivering electrical power, with some of the battery cells optionally having a mixed or different chemistry than some of the other battery cells.However, the use of battery cells is presented for non-limiting purposes only, as the present disclosure fully contemplates that the battery cells are other types of energy cells that can store and / or supply electrical power, such as, but not necessarily limited to, energy cells that partially or entirely comprise capacitors, supercapacitors, fuel cells, and / or other types of components.

[0031] The RESS 16 may optionally include a converter 26 connected between the HV and LV power sources 20, 22, such as via an HV or main bus 28 connected to the HV power source 20 and the propulsion system 14, and an LV or auxiliary bus 30 connected to the LV power source 22 and one or more LV systems 32. The LV systems 32 may include a variety of different systems and, for non-limiting purposes, are shown as including an auxiliary power unit 34 operable to power accessories, heating, ventilation, air conditioning (HVAC), and / or other auxiliary systems 36. The converter 26 may be configured to convert electrical power for distribution between the HV and / or LV buses 28, 30. The converter 26 may, for example,a direct current (DC-DC) converter 26 or other suitable converter 26 operable to convert the HV power available from the HV power source 20 for use via the LV bus 30 and / or to convert the LV power available from the LV power source 22 for use via the HV bus 28. The converter 26 is illustrated, for non-limiting purposes, as representative of various systems that may be employed to facilitate managing the distribution of electrical power between multiple power sources onboard the vehicle 12. The vehicle 12 may include a controller 40 to facilitate monitoring, controlling, measuring, and otherwise directing the operation, performance, etc., onboard the vehicle 12, which may include taking measurements, taking readings, or otherwise collecting data to facilitate operations.The controller 40 may include additional controllers (not shown), the operations associated therewith optionally being performed according to one or more processors executing corresponding non-transitory instructions stored on one or more computer-readable storage media.

[0032] The RESS 16 may be susceptible to power fluctuations due to the effects of slower diffusion, diffusion overload, and / or other influences resulting from the current demands placed on the HV and LV power sources 20, 22 during operation of the vehicle 12. The diffusion may, for example, relate to a decreasing surface density of a terminal, e.g., an anode lithium surface, of the HV power source 20, such that a maximum possible terminal voltage thereon decreases accordingly, thereby limiting the available power. The resulting power fluctuations may be relatively more pronounced for the HV power source 20 than for the LV power source 22 due to the comparatively higher current demands of the propulsion system 14 with respect to the LV systems 32.For simplicity of illustration, the present disclosure will be described primarily in terms of optimizing the usable energy of the HV power source 20 to maximize its performance and / or to limit power fluctuations, which may be particularly advantageous in improving performance, flight range, longevity, efficiency, etc. for the propulsion system 14. The power fluctuations may be reflected in an amount by which the usable energy of the HV power source 20 deviates from its thermodynamic energy capacity at a given time. The thermodynamic energy capacity may be a representation of a maximum or theoretical amount of electrical energy available from the HV power source 20 under ideal or design conditions.The usable energy, on the other hand, may be a representation of an operational amount of electrical energy that is actually available from the HV energy source 20 in view of the currently occurring operating conditions, environment, etc.

[0033] In the case of eVTOL vehicles or other electric vehicles, where range, speed, duration, and other performance-related parameters and capabilities may depend on the availability of a sufficient supply of electrical energy to support activities requiring relatively high current, it may be advantageous to optimize the usable energy of the HV power source 20 so that the maximum amount of electrical energy and power can be achieved when needed. One non-limiting aspect of the present disclosure relates to the controller 40, which is or includes a usable energy controller 40 operable to optimize the usable energy for the HV power source 20.The related optimization may include predicting demands expected for a relatively high-current activity and attempting in advance to improve at least a portion of the predicted demands, such as by charging the LV power source 22 to meet the predicted demand for the LV systems 32 before the HV power source 20 is requested to support a relatively high-current activity. For example, in the case of an electric vertical takeoff and landing (eVTOL) vehicle 12, the optimization may include predicting the LV power required for the LV systems 32 when performing a landing operation and pre-charging the LV power source 22 to meet the predicted LV power demand so that the landing operation can occur regardless of the HV power source 20 needing to simultaneously power the LV systems 32.

[0034] Fig.2 illustrates a flowchart 44 of a method for optimizing usable energy according to one non-limiting aspect of the present disclosure. The method is primarily described with respect to optimizing usable energy for the HV energy source 20 contained within the vehicle 12, however, the contemplated optimization may be advantageous with other types of energy sources, including, but not necessarily limited to, non-HV energy sources and / or energy sources contained in other types of vehicles, as one of ordinary skill in the art will appreciate. The method may be implemented according to various systems, processes, controls, etc.be implemented and is described, for non-limiting purposes, with respect to the controller 40 being a usable energy controller 40 or including a usable energy controller 40 operable in accordance with one or more processors associated therewith executing a corresponding plurality of non-transitory instructions stored on one or more computer-readable storage media.

[0035] Block 50 refers to the controller 40 implementing a warm-up mode of operation after the vehicle 12 has completed a takeoff operation or is otherwise engaged in a suitable operational activity. The warm-up mode of operation may begin after the propulsion system 14 has consumed electrical energy from the HV power source 20 to lift the vehicle 12 off the ground and begin a cruise operation, during which it may be desirable for the vehicle 12 to perform a flight from one location to another, hover over a specific location, or otherwise engage in aerial operations. The warm-up mode of operation may include supplying power to the LV systems 32 using the power provided by the HV power source 20, i.e., via the converter 26, to optimize the usable energy by warming up the HV power source 20 more quickly than if the LV systems 32 were powered independently of the HV power source 20. The warm-up mode of operation can be contrasted with a no-warm-up mode of operation or a standard mode of operation in which the LV systems 32 are powered using LV power provided by the LV power source 22 independently of the HV power source 20, i.e., without requiring the converter 26 to convert HV power for use via the LV bus. The warm-up mode of operation can optionally be restricted to an initial portion of cruise operation corresponding to a predetermined period of time that occurs after the takeoff operation, after the vehicle 12 has reached a cruise altitude or other suitable condition.The predetermined time period may be based on a period expected for a flight and / or may be proportional to a period expected for the flight, so that the predetermined time period may be longer if the period is longer and shorter if the period is shorter.

[0036] Block 52 refers to the controller 40 making an LV energy prediction as part of an LV prediction process. For non-limiting purposes, the LV prediction process is shown to occur after the warm-up mode, as the warm-up mode may be omitted altogether, skipped if a flight is too short, or the warm-up process may occur concurrently with the LV prediction process. One non-limiting aspect of the present disclosure contemplates the LV prediction process as an iterative or ongoing process, where the controller 40 may repeatedly make the predictions considered herein during a flight to optimize the usable energy for the HV power source 20 before commencing a landing operation.The LV prediction process may include estimating an expected LV energy consumption that the LV systems 32 may be expected to consume while a landing operation is underway.

[0037] Block 54 relates to an LV evaluation process, where controller 40 may determine whether the LV energy currently available from LV energy source 22 is sufficient to meet an LV landing threshold, which indicates that LV energy source 22 has LV energy suitable for supplying a total expected LV energy consumption. LV energy source 22 may be considered to contain sufficient LV energy if it is operational to meet the demand without requiring the use of converter 26 to convert the HV energy provided by HV energy source 20. The LV landing threshold may be a variable that changes during flight and / or varies from one type of vehicle 12 to another. As such, the LV landing threshold may optionally be adjusted during flight in response to changes in wind conditions, altitude, humidity, etc.and / or increase or decrease depending on the capabilities of the vehicle 12 and / or the propulsion system 14. The LV landing threshold may optionally refer to a minimum amount of LV energy required to operate less than each of the LV systems 32, e.g., a minimum subset required to properly or desirably land the vehicle 12. The LV landing threshold may thereby correspond to a minimum amount of LV energy required at a particular point in flight or at a particular time should the vehicle 12 immediately or concurrently begin a landing operation.

[0038] Block 56 relates to implementing an unassisted mode of operation prior to the start of the landing operation in response to the LV power being able to supply all of the expected LV power consumption. The unassisted mode of operation may include powering the LV systems 32 independently of the HV battery using the LV power available from the LV battery. Restricting the use of LV power from the LV power source 22 during the unassisted mode of operation may accordingly optimize the usable HV battery power by allowing the landing operation to occur regardless of the HV battery simultaneously needing to power the LV systems 32.The ability to prevent the simultaneous use of the HV power source 20 to power the LV systems 32 during the landing operation can reduce the current demands placed on the HV power system, so that the amount of diffusion occurring at a terminal of the HV power source 20 during the landing operation can be reduced relative to those situations where the HV power system may be required to simultaneously power the LV systems 32 during landing. The feasibility of the unassisted mode of operation can be continuously reassessed during flight to continuously determine whether a sufficient amount of LV power is available from the LV power source 22 to meet the expected LV power consumption should the vehicle 12 subsequently begin a landing operation.

[0039] Block 58 refers to the controller 40 making an HV energy prediction as part of an HV prediction process. For non-limiting purposes, the prediction process is shown to occur after the LV prediction process, as the HV prediction process may be an ongoing process that may occur concurrently with the LV prediction. One non-limiting aspect of the present disclosure contemplates the HV prediction process as an iterative or ongoing process, wherein the controller 40 may repeatedly make the predictions considered herein during a flight to optimize the usable energy for the HV energy source 20 prior to commencing a landing operation. The HV prediction process may include estimating an expected HV energy consumption that the HV systems can be expected to consume when performing a landing operation, i.e., the HV energy that the propulsion system 14 or other HV-dependent systems may require to enable landing of the vehicle 12. The HV prediction process may include determining whether the HV energy currently available from the HV energy source 20 is sufficient to meet an HV landing threshold that indicates that the HV energy source 20 has HV energy suitable for supplying a total expected HV energy consumption. The HV landing threshold may optionally be based at least in part on an expected amount of diffusion predicted to occur at a port of the HV energy source 20 during performance of the landing operation. The HV landing threshold, like the LV threshold, may be a variable that changes during flight and / or that varies from one type of vehicle 12 to another.The HV landing threshold may correspond to a minimum amount of HV energy required at a given point in flight or at a given time if the vehicle 12 were to immediately or simultaneously begin a landing operation.

[0040] Block 60 relates to implementing an assist mode prior to the start of the landing operation in response to the LV power not being able to supply all of the expected LV power consumption. The assist mode may include using the HV battery to facilitate charging the LV battery prior to the start of the landing operation, which may include charging the LV battery to a first charge level sufficient to meet the LV landing threshold in response to the HV power being able to supply all of the expected HV power consumption, and charging the LV battery to a second charge level insufficient to meet the LV landing threshold in response to the HV power not being able to supply all of the expected HV power consumption. The second charge level may be selected to be proportional to a difference between the HV power and the HV landing threshold, i.e.,i.e., the second charge level may be greater when the difference is smaller and smaller when the difference is larger. In other words, the second charge level may correspond to a maximum at which the HV power source 20 can charge the LV power source 22 while maintaining the capabilities to land the vehicle 12 within the desired acceptable landing parameters or requirements. The support mode of operation may optionally include reducing the flight duration or otherwise taking corrective action so that the HV power source 20 can be used to fully charge the LV battery as much as is appropriate to match the expected LV power consumption for a landing operation.

[0041] Block 62 refers to a maintenance process in which charging of the LV power source 22 using the HV power source 20 may continue throughout the flight, i.e., it may be an ongoing process in which the HV power source 20 is used to periodically charge the LV power source 22 during the flight. Charging may be implemented iteratively by repeatedly using the HV power source to charge the LV power source each time the LV power source 22 falls below the LV landing threshold, while the HV power source 20 has sufficient reserves to meet the HV landing threshold.This charging of the LV power source 22 may optionally be supplemented by regenerative systems (not shown) included onboard the vehicle 12 that simultaneously generate electrical energy sufficient to provide additional energy to power the charging of the LV and / or HV power sources 20, 22. Charging may continue until the LV power source 22 is sufficiently charged to meet the LV landing threshold, or the HV power source 20 can no longer continue to charge the LV power source 22, while simultaneously requiring the landing operation to maintain acceptable energy reserves to power the propulsion system 14, which, for example, is shown to include returning to the unassisted mode in the block.This ability to charge the LV power source 22 prior to the onset of high current demands on the LV power source 22 can potentially reduce diffusion and thereby optimize usable energy during landing and other high current activities because the power demands on the HV power source 20 are reduced by allowing these activities to occur independently of the HV power source 20 having to simultaneously power the LV systems 32.

Claims

[1] A method for optimizing the usable energy of a high-voltage (HV) battery (20) contained on board an electric vertical take-off and landing (eVTOL) vehicle (12) to supply electrical power to an aircraft propulsion system (14), the method comprising: Performing a low voltage (LV) energy prediction after the eVTOL vehicle (12) has completed a takeoff operation, the LV energy prediction estimating an expected LV energy consumption that the LV systems (32) on board the eVTOL vehicle (12) are expected to consume when performing a landing operation; Determining whether the LV energy available from an LV battery (22) on board the eVTOL vehicle (12) meets an LV landing threshold indicating that the LV battery (22) has LV energy suitable for supplying a total expected LV energy consumption; Implementing a support mode prior to commencement of the landing operation in response to the LV power not being able to supply a total expected LV power consumption, the support mode including use of the HV battery (20) to facilitate charging of the LV battery (22) prior to commencement of the landing operation; and Implementing an unassisted mode of operation prior to commencement of the landing operation in response to the LV power being able to supply all of the expected LV power consumption, the unassisted mode of operation including powering the LV systems (32) independently of the HV battery (20) using the LV power available from the LV battery (22), thereby optimizing the usable energy of the HV battery (20) by allowing the landing operation to occur regardless of the HV battery (20) having to power the LV systems (32) simultaneously. [2] The method of claim 1, further comprising: Implementing the assist mode of operation including using the HV battery (20) to charge the LV battery (22) to a charge level sufficient to meet the LV landing threshold. [3] The method of claim 2, further comprising: Implementing the assist mode of operation including using the HV battery (20) to power the LV systems (32) while simultaneously charging the LV battery (22). [4] The method of claim 1, further comprising: Performing an HV energy prediction after the eVTOL vehicle (12) has completed the takeoff operation, wherein the HV energy prediction estimates an expected HV energy consumption that the flight propulsion system (14) is expected to consume when performing the landing. [5] The method of claim 4, further comprising: Determining whether the HV energy available from the HV battery (20) meets an HV landing threshold indicating that the HV battery (20) has HV energy suitable for supplying a total expected HV energy consumption. [6] The method of claim 5, further comprising: Implementing the assist mode of operation including charging the LV battery (22) to a first charge level sufficient to meet the LV landing threshold in response to the HV power being able to supply all of the expected HV power consumption; and Implementing the assist mode of operation including charging the LV battery (22) to a second charge level insufficient to meet the LV landing threshold in response to the HV power not being able to supply all of the expected HV power consumption. [7] The method of claim 6, further comprising: Selecting the second charge level proportional to a difference between the HV energy and the HV landing threshold. [8] The method of claim 1, further comprising: Implementing a warm-up mode prior to implementing the assist mode and the non-assist mode, wherein the warm-up mode powers the LV systems (32) using HV energy provided by the HV battery (20), thereby optimizing usable energy by warming up the HV battery (20) more quickly than in a non-warm-up mode. [9] The method of claim 8, further comprising: the no-warm-up mode of operation includes powering the LV systems (32) using LV energy provided by the LV battery (22), regardless of whether the HV battery (20) needs to power the LV systems (32) at the same time. [10] The method of claim 8, further comprising: Limiting implementation of the warm-up mode to an initial portion of a cruise operation, the initial portion corresponding to a predetermined period of time occurring after the takeoff operation after the eVTOL vehicle (12) has reached a cruise altitude.

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