FIELD OF THE INVENTION

Aspects and embodiments relate to battery control methods, computer program products operable to perform those battery control methods, a controller and a battery module including a controller.

BACKGROUND

It is known that batteries of electrical energy cells can provide electrical energy to devices when, for example, a grid or generator power supply is unavailable. Such batteries may be rechargeable or single-use, depending upon cell chemistry.

Batteries may be provided to supply energy in various contexts, ranging from consumer electronics to industrial power supply back-ups. In typical battery deployments, comprising one or more batteries of cells, batteries are passive components. Failure of one or more cells in a battery, or one or more battery modules together forming a single battery, may cause consequent failure of a system which the battery, or cluster of batteries, is operating. Aspects and embodiments aim to address some issues associated with typical battery deployments.

SUMMARY

A first aspect provides a battery control method, the battery being configured to operate as a unitary energy source comprising a plurality of connectable battery modules from which stored energy may be used by a load concurrently, each battery module comprising a plurality of cells; the control method comprising: determining a configuration of the battery modules within the battery and an action to be taken in relation to at least one battery module within the battery; generating a control signal for the plurality of connectable battery modules in dependence upon the determined action to be taken in relation to the at least one battery module and the battery module configuration, the control signal relating to an action to be taken by one or more of the plurality of connectable battery modules to protect operation of the plurality of battery modules as a unitary energy source comprising a plurality of connectable battery modules from which stored energy may be used by a load concurrently; and

outputting the control signal to the plurality of connectable battery modules. The first aspect recognises that battery operation can be an important component in a given electrical system and that poor battery performance can limit the extent to which that system is able to operate efficiently or reliably. In particular, the first aspect recognises that whilst a degree of autonomous control within a battery module may be beneficial, for example, if a battery determines that it is not operating correctly, it may take unilateral actions to shut itself down, such behaviour might also prove detrimental to operation of a battery formed from a plurality of battery modules within which that battery module is operating. For example, if one battery module connected in series with other battery modules provided within a battery shuts itself down as an act of self- preservation, the whole string of battery modules within the battery may be

incapacitated. The first aspect recognises that there may be advantages associated with providing a control method which takes a holistic approach to the management of a cluster of battery modules forming a battery. Aspects and embodiments recognise that allowing a controller within a battery to determine characteristics of the configuration of a cluster of battery modules, together with determination of an action which is to occur in relation to at least one of the battery modules, it may be possible for the controller to determine possible consequences of a unilateral action taken by, for example, a single battery module, upon the remaining battery modules within the battery and issue appropriate control signalling to mitigate any possible detrimental effects upon the battery as a whole.

Some aspects recognise that it is possible to equip one or more battery modules from which the battery is formed to perform the battery control method. Such aspects recognise that it is possible to allow a typically "passive" battery module to

communicate or issue signals outside itself, thereby allowing for provision of a so-called "smart" battery module which may operate to control the battery or system into which it is connected.

Further aspects may provide for a distributed control system or self-organising control system in which the control method of the first aspect is performed by one or more smart battery modules provided within the battery.

Further aspects may provide for a battery control method and apparatus to perform a method in which control of a power supply system, a load supplied by the battery, and/ or energy source used by the battery for recharging purposes, or overall apparatus into which a battery module may be placed may be provided. Whilst the first aspect is explained in the context of a battery providing energy to a load, it will be understood that the general principles explained are particularly applicable in an arrangement in which one or more of the battery modules which form the battery are rechargeable batteries. In such a scenario it will be understood that the first aspect may also provide a battery control method, the battery being configured to operate as a unitary energy store comprising a plurality of connectable battery modules to which energy may be transferred by an energy source concurrently, each battery module comprising a plurality of cells; the control method comprising: determining a configuration of the battery modules within the battery and an action to be taken in relation to at least one battery module within the battery; generating a control signal for the plurality of connectable battery modules in dependence upon the determined action to be taken in relation to the at least one battery module and the battery module configuration, the control signal relating to an action to be taken by one or more of the plurality of connectable battery modules to protect operation of the plurality of battery modules as a unitary energy store comprising a plurality of connectable battery modules to which energy may be transferred by an energy source concurrently; and outputting the control signal to the plurality of connectable battery modules.

That is to say, the first aspect may provide a mechanism to try to improve the holistic performance of a battery within a system, particularly when the battery comprises a rechargeable battery within a system where there may be concurrent charging from an energy source and discharge to a load occurring.

The first aspect may provide a battery control method. That is to say, a method may be provided which controls the operation of a battery within a system. The battery may comprise a rechargeable battery.

The battery may be configured to operate as a unitary energy source. That is to say, although the battery may comprise one or more separable, removably connectable, or removably insertable individual battery modules, a load may see those modules as a single energy source. Indeed, energy requirements of a load may only be satisfied by an appropriately configured cluster of battery modules arranged to form an energy source having an appropriate voltage or current for a particular application. Similarly, an energy source may to provide those modules, where rechargeable, with energy, via power source adjustment circuitry, as if they are a single energy store. The battery may comprise a plurality of connectable battery modules. Those battery modules may comprise one or more removably connectable battery modules, one or more fixed battery modules, or similar. The connections between the battery modules may be reconfigurable.

The battery modules may be configured within the battery such that stored energy from more than one battery module may be used by a load concurrently. That is to say, the battery modules are not typically used consecutively by a load. Together at least two battery modules within the battery may provide a load with electrical energy of the appropriate voltage and/ or current.

Each battery module may comprise a plurality of cells. The plurality of cells may comprise cells of the same chemistry, or cells of different chemistries, the cells forming the battery may have the same, or different, electrical properties. That is to say, the cells may have the same or different voltage or capacitive properties.

The control method may comprise: determining a configuration of said battery modules within said battery. The determination may comprise being told, on commissioning, manufacture or installation of battery modules forming a battery, of the physical and/ or electrical configuration of the battery modules forming the battery. The determination may comprise the interrogation or testing of one or more battery modules forming a battery, or of the battery as a whole, for example, by appropriate control of connections between battery modules, or similar, to determine the physical and/ or electrical configuration of the battery modules forming the battery.

The control method may comprise: determining an action to be taken in relation to least one a battery module within said battery. That is to say, the method may determine by interrogation of one or more battery modules or by reception of a signal generated by one or more battery modules, or by calculations performed in relation to the operating parameters of one or more battery modules, that an action needs to be taken in relation to one or more battery modules. That action may comprise an action which needs to be taken for safety or maintenance reasons, such as disconnection of the battery module, or may comprise an action such as a need to charge a rechargeable battery module. That action may comprise an action which maintains continuity of operation of the battery modules as a battery as a useful and/ or efficient energy source and/ or energy store within a system. The control method may comprise: generating a control signal for said plurality of connectable battery modules in dependence upon said determined action to be taken in relation to said at least one battery module and said battery module configuration. Once an action to be taken in relation to one or more battery modules has been determined, the method may operate to try to protect overall operation of the battery in the event that the determined action takes place and issue appropriate control signals to all, or some, battery modules forming the battery. The method may, for example, operate to maintain continuity of operation of the battery modules as a battery. The control signal may be generated in relation to one, more than one, a sub-set or all of the plurality of connectable battery modules.

The first aspect may provide a holistic approach to overall battery management: for example, a unilateral decision taken by a battery module on the basis of module - internal management circuitry may no longer cause catastrophic damage to other battery modules in the battery provided some indication of the unilateral action to be taken is provided or determined prior to that action being performed. The method of the first aspect may provide a mechanism by which the consequences which flow through the battery system as a result of an action are considered and ameliorative or holistic actions are taken to try to disrupt overall operation of the battery system as appropriate.

It will be also appreciated that the appropriate action to be taken may depend upon the physical or electrical configuration of the battery modules (and cells forming those battery modules) within the battery and thus the control signal generated will need to depend upon that configuration.

The control signal may relate to an action to be taken by one or more of said plurality of connectable battery modules to protect operation of said plurality of battery modules as a unitary energy source or store. The battery control method may operate reactively, that is to say, a battery module may decide that it is going to take and action and the method may respond to that action. Alternatively, the battery control method may operate predictively, for example, based on information about a battery module or modules, to determine that an action should be taken in relation to one or more battery modules can be taken. In either instance, an action or set of actions may be taken to protect overall operation of the battery, and/ or mitigate the chance of damage to battery modules and/ or other components of the battery, to enable it to serve a load or act as an energy store, if and as required.

The control method may comprise: outputting said control signal to said plurality of connectable battery modules. Accordingly, a direct instruction may be sent to one or more of the battery modules.

According to one embodiment, the determined configuration comprises: determination of a number of battery modules forming the battery. Accordingly, the method may comprise determining the number of battery modules forming the battery. The method may comprise determining the voltage, current and/ or capacity required to be supplied to a load by the battery. The determined configuration may comprise an indication of the type of cells forming at least one battery module. The determined configuration may comprise the voltage, current and/ or capacity of at least one battery module. The determined configuration may comprise the state of charge of at least one battery module, where rechargeable battery modules form part of the battery.

According to one embodiment, determining a configuration of the battery modules comprises: communicating with at least one of the battery modules forming the battery. The communication may comprise: receiving a signal which is broadcast or available on request from a battery module. The communication may comprise: requesting transmission of an indication of an operational parameter from at least one battery module. The communication may comprise electrical or logical testing of the battery modules forming part of the battery to determine their configuration.

According to one embodiment, determining an action to be taken in relation to at least one battery module within the battery comprises: communicating with at least one battery module forming the battery. The action may comprise a unilateral action which a battery module has identified as being necessary or may comprise an action which, having regard to all battery modules within the battery, is determined to be necessary in relation to a battery module.

According to one embodiment, the communicating comprises: transmission or reception of signals via network signal cabling. According to one embodiment, the communicating comprises: transmission or reception of signals via electrical power cabling. According to one embodiment, the communicating comprises : transmission or reception of signals via near field communication techniques. According to one embodiment, the communicating comprises: transmission or reception of signals via wireless communication techniques. Communication with could take place by various means including, for example: wired connections, wired network connections, wireless communication techniques including: blue tooth/ ZigBee/ Wi-Fi/ near field

communication.

According to one embodiment, communicating comprises: requesting an indication of an operational characteristic of one or more of the battery modules. Accordingly, that operational characteristic may comprise one or more of: reported state of charge, nominal voltage, instantaneous voltage, battery chemistry, an indication of a unique battery identifier, battery age, a charge profile and/ or similar operational factors.

According to one embodiment, communicating comprises: requesting an indication of an electrical configuration of one or more of the battery modules within the battery. Accordingly, it may be possible to determine how the battery modules are connected, ie: in parallel or in series, within the battery. Furthermore the status of electrical connections between battery modules may be determined. The location of connection breaks or switches within the battery between battery modules may be determined as appropriate.

According to one embodiment, determining a configuration of the battery modules forming the battery comprises: receiving an indication of a physical configuration of at least one battery module in relation to at least one further battery module forming the battery. Accordingly, in a battery formed from a number of battery modules, for example forming an array or housed in a battery cabinet, knowing the physical location, for example, second battery module from the left, may assist when locating a battery module for replacement.

According to one embodiment, determining the action to be taken in relation to at least one battery module within the battery comprises: one or more of: determining that the battery module is to disconnect from the battery; determining that the battery module is to connect to the battery; determining that the battery module is at a different state of charge compared to at least one other battery module within the battery and requires charging from an energy source or discharging to a load and/ or similar actions.

According to one embodiment, generating a control signal for the plurality of connectable battery modules comprises: generation of a control signal for each battery module within the battery in dependence upon the determined action to be taken in relation to least one a battery module within the battery. That is to say every battery module may receive a control signal, even if the control signal indicates no change. In some embodiments, only those battery modules which are required to take action or change some operational characteristic may be issued with a control signal.

According to one embodiment, the control signal comprises: one or more of: an instruction to turn off; an instruction to alter one or more operational parameters of the battery modules; an instruction to operate as a slave to a master battery module in a cluster of the one or more battery modules within the battery; an instruction to disconnect from the battery; an instruction to perform an action at an instructed time or when an appropriate threshold value of an operational parameter is reached and/ or similar battery module actions. According to one embodiment, at least one battery module comprises: a rechargeable battery module and the battery control method comprises managing charging of the battery module in dependence upon the determined action to be taken in relation to the at least one battery module and the battery module configuration. Accordingly, charging of the battery modules may be controlled according to a charge profile for each battery module. It may be possible to adjust the energy source characteristics to match the requirements of a battery module charge requirement. In some

embodiments, sequential fast charging methods may be implemented across the battery modules, such that "even" and rapid charging is achieved for all battery modules within the battery.

According to one embodiment, at least one battery module comprises: a rechargeable battery module and the battery control method comprises managing discharge of the battery module in dependence upon the determined action to be taken in relation to the at least one battery module and the battery module configuration. According to one embodiment, the method comprises: receiving an indication of at least one operating characteristic of an energy source configured to charge at least one rechargeable battery module within the battery; and generating the control signal in dependence upon the received indication of at least one operating characteristic of the energy source. According to one embodiment, the method comprises: receiving an indication of at least one operating characteristic of a load supplied by the battery; and generating the control signal in dependence upon the received indication of at least one operating characteristic of the energy source.

According to one embodiment, the method comprises: generating a control signal for the energy source or the load in dependence upon the determined action to be taken in relation to the at least one battery module and the battery module configuration in conjunction with the received characteristic of the energy source and the received characteristic of the load. According to one embodiment, the method may include: determining a pattern in an operational characteristic of a charging energy source or a load, and generating a control signal in response to a detected characteristic of the battery, system, energy source or system load, together with the determined pattern ; and outputting the control signal to one or more of the battery modules, or a component of system external to the battery, for example, the energy source or load.

According to one embodiment, the method may operate to allow for the introduction of one or more rechargeable battery modules at a different state of charge to other battery modules within the battery. If it is determined that a battery module is at a different state of charge to others within a battery, the method may operate to prevent full connection of that battery module into the battery until an appropriate stage in the battery charge and discharge cycle at which the battery modules are all at

approximately the same state of charge. At the point such matching occurs, the battery module which was at a different state of charge may be brought on-line and connected to other battery modules within the battery. In such circumstances, for example, the battery module state of charge and full on-line connection to the other batteries within battery are the parameters which may require holistic action in accordance with the battery control method of the first aspect. The control signal output to the modules relates to the point at which the battery modules which were at a different state of charge "pick up" the other battery module.

According to one embodiment, the method may operate to allow for the introduction of one or more rechargeable battery modules at a different state of charge to other battery modules within the battery. If it is determined that a battery module is at a different state of charge to others within a battery but it is determined that the battery module could be "pre charged" within a relatively short period to more matched state of charge, the method may operate implement full connection of that battery module into the battery with an appropriate electrical resistance to limit current, and leave that resistance in electrical connection until an appropriate stage at which the battery module is charged to approximately the same state of charge as the other battery modules.

According to one embodiment, the method may allow for the presence of one or more configurable battery modules within the battery. Where this is the case the method determines the presence of the one or more configurable battery modules within the battery and generates a control signal for transmission to said configurable battery module, said control signal indicating a configuration of the battery module in the form of an output voltage and/ or capacity of the battery module.

A configurable battery module comprises a plurality of cells and switching circuity for selectively connecting at least one of a subset of the plurality of cells in at least one of series and parallel to provide at least one of a plurality of output voltages and output capacities. One of these plurality of output voltages and/ or capacities can be selected by the control method as being appropriate for the battery and a control signal generated and output to the battery module indicating the required voltage and/ or capacity.

Having a configurable battery module in such a battery system allows for greater granularity in the control of the battery system allowing for control of both the operation of whole modules and control of the configuration of certain configurable modules.

A second aspect provides a battery controller, the battery being configured to operate as a unitary energy source comprising a plurality of connectable battery modules from which stored energy may be used by a load concurrently, each battery module comprising a plurality of cells; the controller comprising: connection logic configured to determine a configuration of the battery modules within the battery and an action to be taken in relation to least one a battery module within the battery; control logic configured to generate a control signal for the plurality of connectable battery modules in dependence upon the determined action to be taken in relation to the at least one battery module and the battery module configuration, the control signal relating to an action to be taken by one or more of the plurality of connectable battery modules to protect operation of the plurality of battery modules as a unitary energy source comprising a plurality of connectable battery modules from which stored energy may be used by a load concurrently; and output logic configured to output the control signal to the plurality of connectable battery modules.

According to one embodiment, the determined configuration comprises: determination of a number of battery modules forming the battery.

According to one embodiment, determining a configuration of the battery modules comprises: communicating with at least one of the battery modules forming the battery. According to one embodiment, determining an action to be taken in relation to least one a battery module within the battery comprises: communicating with at least one battery module forming the battery.

According to one embodiment, the communicating comprises : transmission or reception of signals via near field communication techniques.

According to one embodiment, communicating comprises: requesting an indication of an operational characteristic of one or more of the battery modules. According to one embodiment, communicating comprises: requesting an indication of an electrical configuration of one or more of the battery modules within the battery.

According to one embodiment, determining a configuration of the battery modules forming the battery comprises: receiving an indication of a physical configuration of at least one battery module in relation to at least one further battery module forming the battery.

According to one embodiment, determining the action to be taken in relation to at least one battery module within the battery comprises: one or more of: determining that the battery module is to disconnect from the battery; determining that the battery module is to connect to the battery; determining that the battery module is at a different state of charge compared to at least one other battery module within the battery and requires charging from an energy source or discharging to a load. According to one embodiment, generating a control signal for the plurality of connectable battery modules comprises: generation of a control signal for each battery module within the battery in dependence upon the determined action to be taken in relation to least one a battery module within the battery.

According to one embodiment, the control signal comprises: one or more of: an instruction to turn off; an instruction to alter one or more operational parameters of the battery modules; an instruction to operate as a slave to a master battery module in a cluster of the one or more battery modules within the battery; an instruction to disconnect from the battery; an instruction to perform an action at an instructed time. According to one embodiment, at least one battery module comprises: a rechargeable battery module and the battery control method comprises managing charging of the battery module in dependence upon the determined action to be taken in relation to the at least one battery module and the battery module configuration. According to one embodiment, at least one battery module comprises: a rechargeable battery module and the battery control method comprises managing discharge of the battery module in dependence upon the determined action to be taken in relation to the at least one battery module and the battery module configuration. According to one embodiment, the controller comprises: reception logic operable to receive an indication of at least one operating characteristic of an energy source configured to charge at least one rechargeable battery module within the battery; and generate the control signal in dependence upon the received indication of at least one operating characteristic of the energy source.

According to one embodiment, the controller comprises: reception logic operable to receive an indication of at least one operating characteristic of a load supplied by the battery; and generate the control signal in dependence upon the received indication of at least one operating characteristic of the energy source.

According to one embodiment, the controller comprises: component control logic configured to generate a control signal for the energy source or the load in dependence upon the determined action to be taken in relation to the at least one battery module and the battery module configuration in conjunction with the received characteristic of the energy source and the received characteristic of the load. A third aspect provides a battery module removably insertable into a battery being configured to operate as a unitary energy source, the battery comprising a plurality of connectable battery modules from which stored energy may be used by a load concurrently, the battery module comprising: a plurality of cells; and a controller according to the second aspect.

In some embodiments the battery module comprises a configurable battery module with switching circuitry for selectively connecting at least a subset of said plurality of cells in at least one of series and parallel, the controller being operable to select at least one of a plurality of output voltages and capacities and to configure said battery module by controlling said switching circuitry.

Where there are other configurable battery modules within the battery the controller may also generate control signals indicating at least one of a plurality of output voltages and capacities for at least a subset of these and output these to the relevant battery module(s). In this way, some form of central control of the battery is provided at the battery module level, where a controller in one battery module acts as a master to the battery as a whole and transmits control signals to control other battery module's function and/ or configurations.

A fourth aspect provides a control method performed by a battery module comprising a plurality of cells, the battery module being removably insertable into a battery being configured to operate as a unitary energy source comprising a plurality of connectable battery modules from which stored energy may be used by a load concurrently; the control method comprising: determining a configuration of the battery modules within the battery and an action to be taken in relation to least one a battery module within the battery; generating a control signal for the plurality of connectable battery modules in dependence upon the determined action to be taken in relation to the at least one battery module and the battery module configuration ; and outputting the control signal to the plurality of connectable battery modules.

A fifth aspect provides a computer program product operable, when executed on a computer to perform the method of any one of the first aspect or the fourth aspect. A further aspect may provide a battery module removably insertable into a power supply system, the battery module comprising: at least one cell; battery management circuitry configured to generate a control signal in response to a detected characteristic of the power supply system; and an output configured to output the control signal to a component of the power supply system external to the battery module.

Further aspects provide a secure battery module and battery module security method.

An aspect provides a secure battery module removably insertable into a power supply, the battery module comprising: input logic configured to receive an identifier associated with that battery module; and security logic configured to require entry of the unique identifier to enable operation of that battery module. Accordingly, a battery module may only be used by a system or user who is in possession of the identifier. The identifier may comprise a unique identifier such as a personal identification number (PIN), or similar. The PIN may be encrypted and, for example, a system using the battery module may be equipped to do the necessary encryption and decryption in relation to valid use of the battery module. For example, appropriate encryption techniques may be implemented, such as public key cryptography or similar. Such a battery module may mitigate battery module theft and successful reinstallation into a different battery module deployment.

In some embodiments, the security logic may be configured to prevent operation of the battery module if an incorrect identifier is entered.

In some embodiments, the security logic may require periodic entry of the unique identifier to enable continued operation of that battery module. An aspect provides a security method for a battery module removably insertable into a power supply, the security method comprising: associating an identifier with a battery module; and requiring provision of the unique identifier to the battery module to enable operation of that battery module. A computer program product operable, when executed on a computer, to perform that method may also be provided.

Furthermore, in an arrangement where a secure battery module is provided, a battery control method may comprise: determining the presence of a secure battery module within a battery, the secure battery module comprising input logic configured to receive an identifier associated with that battery module; and security logic configured to require entry of the unique identifier to enable operation of that battery module; acquiring said identifier associated with said secure battery module; and

communicating the identifier to the secure battery module to allow that battery module to function within the battery. Accordingly, a controller may operate to allow operation of a secure battery module within a battery. Acquisition of the identifier may comprise being specifically informed of the identifier on commissioning of a system, or being informed of an appropriate public encryption key or similar. A controller may be configured to periodically repeat provision of an appropriate unique identifier to a secure battery module.

Aspects and embodiments may provide a method and apparatus such that a battery controller is configured to communicate with each of the plurality of connectable battery modules to obtain one or more of the various operational parameters indicated below.

Communication between the controller and battery module(s) may be configured to occur regularly, or periodically. The period of regular communication may depend upon the particular application envisaged for an installation. In many

implementations, regular communication may occur on a time scale of the order of seconds, for example, every 0.5 to 10 seconds. For example, in one possible

implementation, such communication to obtain operational parameters may occur every few seconds. Periodic communication having a period of the order of seconds may represent a practical operational limit based on the number of battery modules and speed of communication buses used within a particular system implementation.

The communication method implemented between a controller and the plurality of battery modules may be such that communication with each battery module occurs according to a "round robin" (sequential) approach. According to some aspects and embodiments a method and apparatus are configured to implement an alternative system of substantially continuous parallel communication to a portion of, or all, of the connectable battery modules. It will be appreciated that, during charging and discharging, manyof the operational parameters of each battery module may only vary slowly (for example, a change of approximately 2% per minute) under normal operating conditions. It will be appreciated that if a battery module is disconnected or on float, the operational parameters of each battery module may vary even more slowly. The slow variance during charging and discharging is likely only to change in circumstances such as, for example: a battery module disconnection and/ or a similar step change occurs, for example: a load being applied to the system or a charger being switched on or reconnected. As a result, monitoring periodically (for example, in the order of seconds, as referred to above) may offer an accurate enough assessment of th e operational parameters of each battery module.

Operational characteristics and parameters which may be monitored may comprise one or more of: voltage across a battery module and/ or across a cell, this value may, for one possible 48 v battery formed from lithium-ion calls, comprise 14 values: one for each cell bank in series; voltage max across a cell; voltage max across a cell; battery current which is typically signed, with a negative value indicating battery discharge and a positive value indicating battery charging; current maximum; current minimum;

operational temperature, which may be monitored by appropriate sensors which can be provided to supply an indication to the controller of: a system temperature, and/ or battery module temperature, and/ or cell temperature and/ or cell bank temperature; state of charge computed and reported by each battery module; state of health computed and reported by each battery module; charge current limit, for example, as computed by a battery module based on present conditions; discharge current limit, for example, as computed by a battery module based on present conditions; a battery module request to disconnect from the unitary energy source; and/ or a battery module warning of imminent disconnect from the unitary energy source.

Aspects and embodiments may provide a method and controller which operate to analyse operational characteristic information obtained in relation to each battery module. The analysis may also use, for example, known characteristics associated with that battery module obtained via a look-up table; and/ or from detailed information obtained from a battery module manufacturer; battery module information stored in the controller, and/ or available to be read from each battery module.

The analysis performed according to some methods and controllers may allow for determination of how close a battery module may be to any limit(s) that may cause that battery module to, for example, request a change in operation. Such a change in operation may for example, comprise one or more of: a lower or higher charging current, and/ or likelihood of autonomous switch off of a charging or discharging mode, and/ or likelihood of autonomous disconnect from the unitary energy source. In some implementations, if the analysis performed indicates that a battery module is likely to request an imminent change in battery module operation, the method and controller may be configured to calculate, for the unitary energy source (ie the system as a whole) what the impact will be on other battery modules. That is to say, the method and controller according to some aspects and embodiments may be configured to perform an analysis of battery module characteristics to make a prediction about likely future behaviour of that battery module. That prediction may, in turn, be used to predict the impact of the predicted behaviour of one or more battery module(s) on the unitary energy source. A method and controller may, in some aspects and

embodiments, then be able to initiate action by the unitary system or by one or more battery modules within the unitary system to protect ongoing operation of the unitary system or protect ongoing operation of one or more battery modules within the unitary system. For example, a prediction of an action to be taken by one or more battery modules may result in system charge ( or discharge ) current being shared between the modules on the DC bus (though not necessarily completely equally). In particular, a battery module disconnecting is likely to increase the current through other modules which may then, in turn, cause those modules to disconnect. The method and controller may be able to take action, such as reducing charge or discharge current, to protect operation of the unitary source. In a further example, the method and controller may be configured to recognise that seeing the temperature of the battery modules increase over time may enable prediction of when the battery modules are likely to reach a temperature threshold at which the battery module(s) are configured to disconnect from the unitary energy source. The controller may be configured to implement a method in which, if such an event were predicted, an instruction to increase battery module cooling may be issued. In a further example, a method and controller may be configured to communicate with a battery module before it is connected to the unitary energy source. In such an arrangement, the controller may be configured to receive an indication of battery module voltage before connection to the bus by that module.

In some aspects and embodiments, the method and controller may be implemented such that, the battery controller communicates with, and/ or has information from all of the battery modules forming the unitary energy source; and/ or may have an ability to control unitary energy source load(s) and unitary energy source charging source(s).

In some aspects and embodiments, the method and controller may be implemented such that, the battery controller communicates with, and/ or has information relating to the system in which the unitary energy source is operating. In other words, the controller may "know" about the application it is operating within and may be configured to factor that application into its scenario prediction and planning and take appropriate holistic system action. For example, a controller may implement a method which recognises that the battery modules forming the unitary energy source are increasing in temperature, but the controller may also be aware that it is operating in a system in which one of the charge sources is solar energy. If the controller determines that it is coming to the end of the day when solar charging is likely to cease and the ambient temperature will fall anyway, it may be configured to determine that no action need be taken. In a further example, the controller may be aware that a system load may follow a defined profile, and factor that defined load profile into analysis and prediction before identifying an appropriate action which may be taken to protect ongoing operation of the unitary energy source. In general, some aspects and embodiments may implement a method and controller in which the controller is configured to take action and/ or instruct action to ensure safe operation and, if possible, continuity of operation of the unitary energy source within a system. Continuity of operation may comprise continued power to a load whilst the battery modules forming the unitary energy source remain in good state of heath .

The method and controller of some aspects and embodiments may be such that the controller is configured to take one or more actions which may, for example, keep the battery modules within a preferred operating region to extend battery module life; or may keep the unitary energy source in a position to provide energy to a load, even if the energy supplied is of a lover voltage or current, but within load safe operating parameters. It will be appreciated that appropriate actions to be taken by a controller may be determined by a particular application or by desired system characteristics.

Actions which a controller may be configured to take in response to analysis of battery module operational characteristics and a resulting prediction of battery module behaviour, may, in various implementations include one or more of the following: reducing charging current from charging source, that charging source may comprise a rectifier, generator, solar source, wind turbine or similar, or may comprise a combination of sources; ceasing charging completely, for example, in the case where no battery module can accept charge current; reducing load current ; remove load completely, for example, in the case where no module can accept discharge current or load cannot be reduced appropriately; isolating all battery modules from a DC bus simultaneously, which may prevent a cascade of disconnects of any remaining battery modules on bus, for example at end of discharge; switching on external (and/ or internal) battery heating or cooling mechanisms; instructing battery modules or a system to "switch in" a series resistor to limit current, which may, for example, be configurable on a battery module by battery module basis; instructing battery modules not to disconnect until one or more action(s) listed above have been completed;

instructing one or more battery module(s) not to connect until their voltage "matches" (or is within defined limits of) the battery bus; and/ or permitting or instructing (by direct control) one or more battery module to disconnect when system conditions are appropriate. It will be appreciated that in the specific case of "end of discharge" the controller may act to prevent damage to the battery modules since the "last remaining" battery module connected to the bus may otherwise be left carrying the whole load current which may cause its fuse to blow or otherwise damage the battery module. **********

Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.

Where an apparatus feature is described as being operable to provide a function, it will be appreciated that this includes an apparatus feature which provides that function or which is adapted or configured to provide that function.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described further, with reference to the accompanying drawings, in which :

Figure la illustrates schematically one possible generalised system in which a battery module according to at least one aspect may be configured to operate;

Figure lb illustrates schematically a power source supply arrangement;

Figure 2a illustrates schematically a rechargeable battery formed from a cluster of battery modules;

Figure 2b illustrates schematically a battery module;

Figure 3 illustrates schematically a system in which a controller is provided external to a battery module;

Figure 4 schematically shows a configurable battery module; and Figure 5 schematically shows a cluster of configurable battery modules. DESCRIPTION OF THE EMBODIMENTS

Before describing features of particular arrangements in more detail, a general overview is provided:

As previously mentioned, battery operation can be an important factor in any given electrical system and poor battery performance can limit the extent to which an electrical system is able to operate efficiently or reliably.

Battery packs may be used in a wide range of applications. Such applications may include: electric or hybrid vehicles, local energy storage, or industrial back-up power supplies. Battery packs or modules may typically comprise a plurality of cells. The cells in a battery module may all be of the same general chemistry. In some cases, the cells in a battery module may comprise substantially the same cell type of the same chemistry. In some cases, the cells in a battery module may comprise different cell types of the same chemistry. In some cases, a hybrid battery may be provided. A hybrid battery may comprise a battery module formed from at least two different battery cell chemistries. The battery module may comprise a single-use battery, but more typically will be of more use if the battery comprises at least one rechargeable cell. Such rechargeable cells may, for example, comprise lithium ion cells or lead acid cells.

Battery modules typically comprise a plurality of cells. Those cells may comprise one or more string of cells connected in series, and those one or more strings of cells may be arranged in one or more banks of cell strings connected in parallel. Appropriate choice of cell arrangement within a battery module typically sets the voltage and capacity provided by a battery module. Charging and discharging such multi cell battery modules to try to maximise operation of a battery formed from such modules, each comprising a plurality of cells arranged in series and in parallel may become a complex problem.

Some aspects and embodiments provide a battery including a battery module having a degree of configurability as described further below. Some aspects and embodiments therefore provide a battery control method in which the control signal to a battery module may comprise an instruction to configure or reconfigure such a configurable battery module. In a typical power supply system, a battery formed from a plurality of battery modules may be provided. If a cell in a battery module fails to operate as intended, a whole battery module may be considered to be faulty. Similarly, if one of a plurality of battery modules fails to operate as intended, the entire power supply system may not perform as hoped. Typical battery modules may have a degree of autonomous control and be operable to perform internal monitoring steps and/ or provide information to, for example, an external battery module controller. As such, a battery module may be self- aware and take an action which preserves itself. That action may negatively impact upon the overall operation of the power supply system. If, for example, a battery determines that it is not operating correctly, it may take unilateral actions to shut itself down, such behaviour might also prove detrimental to operation of a power supply in which that battery module is operating. For example, if one battery module connected in series with other battery modules provided within a power supply shuts itself down as an act of self-preservation, the whole string of battery modules within the power supply may be incapacitated. Similar problems may arise in relation to events in which, for example, a battery module at a different state of charge is inserted into a battery formed from other battery modules at a different state of charge, or a system overcurrent scenario which may occur if some battery modules within a battery have unilaterally chosen to disconnect.

According to some arrangements, an external overall power supply system controller may operate to monitor all battery modules within a power supply and issue control commands to those monitored battery modules. Central control may require explicit configuration on commissioning a system to inform the central controller of the parameters of the power supply system and the system within which the power supply system is working, or may require interrogation of components forming the battery and power supply.

Some aspects and embodiments recognise that provision of a "smart battery module" configured to determine at least one characteristic of the power supply system within which it has been placed, may allow for improved battery module operation within that power supply system, but also may allow for a battery module to operate as an intelligent, or more active, component in a power supply system or overall system. Some aspects and embodiments thus recognise that a battery module may be configured to operate as a so-called smart "node" within a battery forming part of a power supply system. If more than one smart battery module is provided within a battery, those smart nodes may be configured to self-optimise and form a distributed smart battery control system.

Some aspects and embodiments recognise that there may be advantages associated with allowing a battery module within a power supply to operate as a controller and determine characteristics of the power supply system into which it has been placed. A general battery module arrangement may comprise a battery module which is removably insertable into a battery forming part of a power supply system. The cell chemistry, voltage, capacity and physical size of a battery module may be selected in dependence upon envisaged application. The battery module may comprise at least one cell. The battery module may comprise battery management circuitry. That battery management circuitry may be configured to generate a control signal in response to a detected characteristic of the power supply system. The battery module may also comprise an output configured to output the control signal to a component of the power supply system external to itself.

In some embodiments, both in relation to an external controller and a controller provided within a battery module, one or more battery modules may be provided with a sensor configured to provide an indication of an operating parameter associated with that battery module. For example, such a sensor may comprise a temperature sensor, a voltmeter, an ammeter, a charge cycle counter, a proximity sensor or similar.

In some embodiments, the electrical connections between battery modules may be adjustable. That is to say, the electrical configuration of the battery modules within the battery may be altered.

In some embodiments, the connection of a battery module into the battery may be activated by the controller. That is to say, whether a battery module forms a part of the battery providing a unitary energy source or energy store may be controlled by the controller.

Figure la illustrates schematically one possible generalised system 1 in which a battery module according to at least one aspect may be configured to operate. In the arrangement shown, an energy source 10 is provided which supplies a load 20 with power via a power supply 30. The energy source may comprise a grid power supply, a generator power supply, a renewable power energy source, such as a wind turbine or solar cells and similar. The energy source may comprise a combination of such energy sources. The energy generated by those sources is passed via a connection 40 to the power supply system 30. The power supply system 30 receives the energy, adjusts that energy as appropriate to make it suitable for the load 20 and passes it, as appropriate to the load 20 via a connection 50.

Figure lb illustrates schematically a power source supply arrangement. The power source supply 30 receives energy from the energy source 10 and passes it to the load 20. In the arrangement shown in Figure la, the power supply system 30 comprises power source adjustment circuitry 60 and a rechargeable battery cluster 70. As shown in Figure lb the power source adjustment circuitry may be configured to receive energy from the source 10 and adjust the characteristics of the supplied energy to meet the needs of the load 20 and supply such adjusted energy directly to the load 20. The power source adjustment circuitry 60 may also be configured to supply the

rechargeable battery cluster 70 with appropriately adjusted energy. In the event that the primary energy source 10 is unavailable, energy stored in the rechargeable battery cluster 70 may be supplied to the load 20.

Figure 2a illustrates schematically a rechargeable battery cluster. The rechargeable battery cluster 70 shown in Figure 2a comprises a plurality of battery modules 80a to 80e. The battery modules 80a to 80e may be nominally identical or may be different. Figure 2b illustrates schematically a battery module. The battery module 80 illustrated in Figure 2a comprises a plurality of cells 90 , battery management circuitry 80 and an input 110 and output 120.

It will be appreciated that the general configuration described in relation to Figures la to 2b may be applicable to a number of particular deployments.

In one possible deployment, battery modules 80a to 80e may comprise lithium ion cell battery modules. It will be understood that, if overcharged, lithium ion batteries may overheat and cause fire. Typical lithium ion cells forming a battery module therefore comprise battery management circuitry which is configured to ensure charging of the lithium ion cells occurs in a manner which is unlikely to cause overcharging.

Accordingly, such circuitry may operate within a single battery module to connect and disconnect appropriate combinations of resistors to strings, banks or individual cells to ensure "even" balanced charging of the lithium ion cells and avoid overcharging of any cell. That is to say, typical Lithium Ion cell battery management circuitry may be provided within a battery module to provide a safety protection system.

Aspects recognise that no such safety protection system may exist between a cluster of battery modules. Accordingly, an arrangement in accordance with an aspect may provide battery management circuitry configured to generate a control signal in response to a detected characteristic of the power supply system 30 and the battery module 80 may comprise an output 120 configured to output the control signal generated by the battery management circuitry to a component of the power supply system external to the battery module. In one example, a smart battery module 80 may be operable, when inserted into a rechargeable battery cluster, before providing any connection between the lithium ion cells 90 within itself to the rest of the rechargeable battery cluster, to determine at least one characteristic of, for example, the battery cluster into which it has been inserted, and then based on the determined characteristic or characteristics, generate a control signal to send to, for example, the power source adjustment circuitry so that its insertion into the cluster and actual connection to that cluster need not cause a failure in operation of the entire battery cluster.

Alternatively or additionally, a battery module in accordance with an aspect may understand the system it is has been placed within and be configured to interact with the power supply system into which it has been placed to optimise its own, and/ or the overall power supply system operation. For example, a battery module may comprise a lithium ion cell battery module or a lead acid cell battery module. A charging profile (that is to say, how each rechargeable cell within a battery module may be charged to achieve a greater state of charge) of cells by a source may be dependent upon the ambient temperature of the cells. By determining the temperature of the cells, the battery management circuitry 100 may be configured to then instruct, by issuing an appropriate control signal via the output 120 to appropriate power source adjustment circuitry comprising, for example, a rectifier or DC-DC converter with configurable voltage and current to adjust the voltage or current (or both CI-CV) of the energy supplied to the battery module. Alternatively or additionally, a battery module in accordance with an aspect may be configured to determine, for example, by interrogation of components of, the system it is has been placed within and be configured to interact with the power supply system into which it has been placed to optimise its own, and/ or the overall power supply system operation. For example, in order to protect rechargeable battery modules 80 forming part of a rechargeable battery cluster, a "low voltage disconnect" may be implemented. It will be understood that if one or more battery modules take action to disconnect in the event of detection of a low voltage event, the entire load may be connected to only the remaining connected battery modules and such a situation may cause damage to the remaining battery modules. One arrangement may provide that the battery management circuitry may be configured to determine that a low voltage event is likely to occur, given for example, availability of energy from the power source adjustment circuitry and/ or operation of the load and then a control signal may be generated instructing all battery modules 80 to disconnect or shutdown

simultaneously, thus avoiding an overload scenario. It will be understood that, in such a scenario, battery management circuitry 80 may be configured to determine characteristics of components of a system 1 outside the power supply system 30 , namely, for example, characteristics of the energy source 10 and/ or load 20.

In general, the battery module 80 may be configured to detect various characteristics of a power supply system 30 or general system 1. The detected characteristic within the power supply system 30 may be, for example, the presence of one or more further battery modules 80 forming part of the power supply system 30. The battery module and the further battery modules may be rechargeable battery modules or otherwise. The circuitry 100 may be configured to determine that characteristic about the further battery modules. The determined characteristic may relate to other power supply 30 characteristics including environmental characteristics such as ambient temperature, or electrical characteristics such as general voltage and/ or capacity requirements of the battery module and similar.

In order to detect characteristics, the battery management circuitry 100 may comprise connections with other components or sensors provided within the power supply system 30. The battery management circuitry may comprise communication circuitry configured to communicate with one or more further battery modules forming part of the power supply system. The battery management circuitry may comprise

communication circuitry configured to communicate with one or more sensors provided as part of the power supply system. The battery management circuitry may comprise communication circuitry configured to communicate with other components of the power supply system, such as: the power source adjustment circuitry, for example a rectifier provided as part of the power source adjustment circuitry, the load 20 and/ or the energy source 10.

The communication circuitry provided may be configured to receive a signal indicative of an operational characteristic of the one or more further battery modules or actively interrogate or request an indication of an operational characteristic of the one or more further battery modules. The communication may take the form of wired connections or may comprise various wireless communication devices or signals received from a probe or probes or sensor(s) provided throughout a power supply system 30 or general system 1. The detected characteristic may comprise a signal indicative of a

characteristic, for example, an electrical signal indicative of a temperature.

Communication with battery management circuitry could take place by various means including, for example: wired connections, wired network connections, wireless communication techniques including: blue tooth/ ZigBee/ Wi-Fi/ near field

communication.

In some arrangements, the detected characteristic of the power supply system may comprise an indication of an electrical configuration of the battery module 80 within the power supply 30. The detected characteristic of the power supply system 30 may comprise an indication of the electrical configuration of any further battery modules 80 forming part of the power supply 30. That is to say, the battery module 80 may be able to detect whether it is connected in parallel or in series with other battery modules 80. The battery module 80 may be able to determine its position within a set of battery modules connected in series or in parallel. Such determining may occur as a result of appropriate measurement of voltage and/ or current and/ or interrogation of adjacent further battery modules.

The detected characteristic of the power supply system may comprise: an indication of a physical configuration of the battery module 80 within the power supply 30. Often battery modules 80 are provided within a battery cabinet or battery cluster housing. Being able to determine the physical position of a battery module 80 within a cluster may allow for ease of replacement of a battery within a cabinet. Such determining may occur as a result of, for example, interrogation of neighbour battery modules via wireless techniques or similar. Such a determination may also allow the battery module to determine an indication of a physical configuration of further battery modules 80 forming part of the power supply 30. The battery management circuitry 100 may be configured to issue various control signals. The control signal may comprise: a control signal to one or more further battery modules forming part of the power supply system. For example, the control signal to further battery modules may comprise one or more of: an instruction to turn off; an instruction to alter one or more operational parameters of the one or more further battery modules; an instruction to operate as a slave to the battery module in a cluster of the one or more further battery modules; an instruction to disconnect from the power supply system; and/ or an instruction to perform an action at an instructed time.

In the event that battery module 80 forms part of a cluster of similar battery modules, each with battery management circuitry provided, the battery management circuitry 100 may be configured to receive a control message from a further battery module forming part of the power supply system 30 and alter its own operation in dependence upon that control signal.

In some arrangements, the battery control circuitry 100 may be configured to control the charging and/ or discharging of a rechargeable battery module cluster 70. The battery management circuitry 100 can then be configured to manage charging and/ or discharging of the battery module 80 or battery modules 80 in response to a detected characteristic of the power supply system 30. The charging and/ or discharging may be managed in dependence upon determined parameters associated with the energy source 10 , for example power availability over time. The charging and/ or discharging may be managed in dependence upon determined parameters associated with the load 20 , for example, likely load over time.

Figure 3 illustrates schematically a system 200 in which a controller 300 is provided external to the battery modules 80. Figure 3 illustrates an arrangement which may be provided as a power supply to support operation of a load comprising, for example, a mobile telecommunications base station (BTS) 220. As shown in Figure 3, a system

200 may be provided to deliver energy from an energy source 210 to the BTS 220. The energy sources shown in Figure3 comprise a diesel generator (DG) 210a, and renewable energy sources or direct connection to a grid source 210b. The system shown in Figure 3 comprises a rechargeable battery cluster 270 formed from thirty battery modules 80. An external controller 300 is provided and is configured to communicate with various components within the system 200 including the battery 270 formed from battery modules 80 and power source adjustment circuitry 260. The controller may be configured to determine the overall configuration of the system. In particular, the controller may be directly programmed with that information, or may be operable to interrogate a system to determine the configuration of the system. The controller may determine, either by appropriate commissioning steps during set-up of the system, or via system interrogation techniques, the operational parameters of the various components of the system, including, for example, the demands of load 220 , the capabilities of the energy source 210 , the capability and operational parameters of the battery and the battery modules 80 forming the battery 270.

The controller may be configured to control charge and discharge of the battery 270. The controller may be configured to control charge and discharge of each battery module 80 forming the battery 270. The controller may be configured to control energy flow from the energy source 210 to the battery 270. The controller may be configured to control operational parameters of the load 220 so that energy flow from the battery to the load may be controlled.

In the arrangement shown in Figure 3 , each battery module may include internal battery module management circuitry which determines the status of the cells forming that battery module 80. If a battery module 80 determines, via the internal battery module management circuitry, that it needs to shut itself down, (for example, detection of over temperature, under temperature, over voltage, under voltage, over current) it is operable to transmit an indication that it is going to shut down to the controller 300. The controller 300 may be configured, if it receives such an indication, to consider the impact of that battery module shutdown upon the other battery modules 80 forming the battery. Various actions may be possible in response to such a battery module shut down event, for example: further battery modules may be safely shut down in order to avoid damage to one or more battery modules. Alternatively, one or more connections between battery modules may be changed such that the electrical configuration of the battery modules supports the shutdown of one or more battery modules.

The controller 300 in the arrangement of Figure 3 may also be configured to take action in relation to other components of the system 200 based upon a determined status of the battery. For example, the controller may instruct initiation of the diesel generator 210a in the event that no grid power or other alternative energy source 210b is available and the state of charge of the battery has fallen beneath a predetermined value, for example 20 % or 50 %. Furthermore, for example, the controller may be configured to alter, via adjustment circuitry 260 , voltage and current being fed to the battery from the energy source 210. Similarly, the controller 300 may be configured to implement a low voltage disconnect or similar. For example, the controller 300 may be configured to disconnect a load 220 from the system in the event the battery state of charge is determined to have fallen below a selected threshold. That threshold may, for example, be a state of charge of in the region of 10 %. Similarly, a battery disconnect may be provided which the controller may activate in the event that the controller determines that there is a need to prevent battery over-discharge.

In addition to the above, aspects and embodiments recognise that provision of a configurable battery module that is able to adapt in response to at least one

characteristic of the power supply system within which it has been placed, may allow not only for more universal application of such a module but also for improved battery module operation within that power supply system, allowing for a battery module to operate as an intelligent, or more active, component in a power supply system or overall system and allowing its configuration to be changed to compensate for changes in load for example. Embodiments recognise that a battery module may be configured to operate in conjunction with other battery modules and or a central control hub, to adapt to changes in themselves or in other battery modules or in the requirements of the system and to self-optimise and form a distributed battery control system. Aspects and embodiments recognise that there may be advantages associated with allowing a battery module within a power supply to determine characteristics of the power supply into which it has been placed. Furthermore, embodiments recognise that by allowing a battery module to communicate or issue signals outside of itself, it may be possible to more effectively manage that battery module within the power supply and/ or more effectively manage the power supply system into which the battery module may be placed.

A general battery module arrangement may comprise a battery module which is removably insertable into a power supply system. The cell chemistry and physical size of a battery module may be selected in dependence upon envisaged application. The voltage and capacity may also depend on the application but in some embodiments at least a subset of the battery modules are able to configure themselves or be configured to supply different voltages and/ or capacities. The battery module comprises a controller or battery management circuitry that is configured to generate a control signal in response to a detected characteristic of a circuit to which it is connected or a characteristic of the battery module itself. The battery module may also comprise an output configured to output said control signal to a component of said power supply system external to itself. Alternatively it may simply comprise an input operable to receive a configuration control signal.

Figure 4 shows an example of a configurable battery unit 710 according to one embodiment. Battery unit 10 has positive and negative terminals 712, 714 respectively between which multiple banks of cells, CI to C4 are arranged, the banks of cells CI to C4 being interconnected by switches 720 which are controlled by battery management circuitry 735 to provide either serial or parallel connections between the banks of cells. Battery unit 710 also comprises an isolating switch 722 for connecting or isolating the banks of cells from the terminal 712 via in this embodiment a sensor 730. The battery module can operate in a self- configurable mode where sensor 730 that is a current and voltage sensor senses the voltage at terminal 712 when switch 722 is open, and this provides the module with information on the voltage level required by the circuit (not shown) to which it is connected. Sensor 730 can also sense the current that is supplied by the battery module 710 to the circuit when switch 722 is closed and the battery is supplying power to the circuit. It can also sense current flowing in the other direction during a charging cycle. Sensor 730 outputs the information that it has sensed to battery management circuitry 735 which in this embodiment comprises a microprocessor. Battery management circuitry 735 determines from the information received the required voltage and/ or capacity of the battery module and transmits control signals to the switches 720 such that they connect the cells in such a way so as to provide the required output voltage and/ or capacity. In an alternative embodiment the configuration control signals are received from a central controller via input 750 and this control signal is transmitted to microprocessor 735 which transmits control signals to the switches 720.

Following configuration of the battery module, battery management circuitry 735 controls isolating switch 722 to connect the cells to the terminal 712. In this way the battery module supplies the required voltage to the system to which it is connected. During operation sensor 730 may continue to monitor the voltage and current at the terminal 712 and may control switches 720 to rearrange the configuration as required. In this regard, it may be that one of the cells within a banks of cell is failing and where the banks of cells are not currently all arranged in series, then the bank of cells with the failing cell can be isolated from the other cells and from the terminal 712, while the module can be reconfigured to still output the desired voltage.

Figure 5 shows an alternative embodiment where the backup power supply 775 is formed of a plurality of battery modules, which each have sensors 730 , controllers 735 and communication circuitry 750 operable to communicate wirelessly with other battery modules. Battery module 710 is a configurable battery module and is in this embodiment the master battery module within the system and port 760 is both an input and output port, outputting control signals to control other battery modules 770 and 780 within the cluster. Port 760 is also configured to receive signals from these battery modules. These signals may be indicative of an operational characteristic of the further battery modules and the communication circuitry 750 may simply receive these signals or it may actively interrogate the further battery modules 770 , 780. These received signals may provide information on the current charge status of the modules and also in some cases on their potential failure.

Controller 735 within master battery module 710 analyses the signals received from the other modules 770 , 780 along with signals received from its own sensor 730 and determines a preferred configuration of each module within the system and from this analysis generates control signals. These control signals are transmitted from master battery module 710 to battery modules 770 and 780 and to its own switching circuitry 720. The signals output to other battery modules may indicate a change in the configuration of the battery module or they may indicate that that module should be isolated from the system. The configuration of the battery modules 770 and 780 may be performed in response to signals detected by its own sensors and/ or in response to the signals received at their input ports from the master battery module 710. In this regard sensors 730 within each battery module may detect the voltage levels supplied by individual cells or banks of cells within the battery module and determine cells that are failing. Controllers 735 within the module may reconfigure to remove failing cells from the power supply, while still configuring the module to supply a voltage level indicated by a control signal received from the master battery module 710. In this embodiment the battery modules communicate with each other wirelessly, while in other embodiments they may have hardwired connections or communicate in some other manner. In the embodiment described above battery module 710 acted as a master battery module. In other embodiments there may be an external power management system (not shown) which provides central control of the charging and loading of the battery modules. In this embodiment the battery modules are connected to the charging and load circuits by switching circuitry 790 , which can be controlled by signals from the power management system to connect individual modules to the load and charging circuits as required. The power management system also transmits control signals to the battery modules which indicate desired configurations of the individual battery modules. These signals are received by communication circuitry 750 and transmitted to controller 735 which controls switching circuitry 720 and isolating switches 722 accordingly. Thus, in this embodiment rather than receiving external control signals from a master battery module they are received from a central power management system.

Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiment and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.