Field of the art

The present disclosure refers to the field of energy storage devices and in detail concerns a battery unit, in particular for renewable energy in stationary and mobile applications.

Background art

Electric and electronic applications requiring batteries are widely known in several fields, both for consumer and for professional and/or industrial applications. In recent years, renewable energy systems have been developed for producing and/or storing, at least temporarily, electric energy for several future purposes; these applications may be referred to as stationary. Moreover, hybrid and fully electric vehicles exploit electric energy stored in batteries; these applications may be referred to as mobile applications.

In recent years, such battery units, both stationary and mobile, comprise a plurality of cells which typically contain Lithium.

The assembly of elements that include the batteries and their electronic control management are sometimes known as Energy Storage Systems (ESS).

Thermal management is critical for protecting and extending the life of these Energy Storage Systems (ESS), especially during charge and discharge or due to climatic conditions when utilized in outdoor applications. Typically using Lithium, these battery units show several limitations when at low temperatures. Bringing cells below certain temperature values leads to a reduction of the power or voltage that the battery is capable of storing and/or providing to an electric load.

Furthermore, over-heated cells result in reduction of the cell life and possibly result in a fire, known as a run-away effect. Heating may derive from a malfunction of any of the cells in the battery unit, from an intensive charge/discharge rate or following a localized overheated ambient temperature. It is in particular known that cells heat up in localized points, in particular at the contacts with the cables that connect the cells of the battery (localized resistance). A partial remedy to this drawback is to oversize the cables and/or the number of the cells in the battery, and/or the overall capacity of the battery in order to mitigate the risk of fire. This remedy is clearly not efficient.

Thus, there is a need for an improved battery unit that is capable of mitigating the known drawbacks of the known battery units.

It is an object of the present disclosure to provide a battery unit that is suitable to mitigate the drawbacks of the battery units known in the art.

In particular, it is an object of the present disclosure to provide a thermally stable battery unit that is configured to reduce the risk of overheating or over-cooling.

It is a further object of the present disclosure to provide a battery unit that shows a reduced fire risk.

It is a further object of the present disclosure to provide a battery unit that is capable of mitigating the thermal extremes developed in use by the plurality of cells with several stages of intervention and/or by means of several types of active or passive elements.

It is a further object of the present disclosure to provide a battery unit capable of uniformly dispersing the heat in use produced by the plurality of cells. In particular, it is an object of the present disclosure to provide a battery unit, which allows a substantially uniform heat dispersion for each of the cells therein contained.

It is a further object of the present disclosure to provide a battery unit capable of uniform thermal dispersion, in particular it is important that the temperatures of the top and bottom as well as the sides of the cell are managed uniformly.

It is a further object of the present disclosure to provide a battery unit that is capable of being coupled in a modular way with other battery units.

It is a further object of the present disclosure to provide a battery unit that is configured to generate alerting messages in case of malfunction. It is a further object of the present disclosure to provide a battery unit that allows a convenient substitution in case of malfunction and/or in case of an end-of-life condition.

These and further objects are achieved by the battery unit that is hereinafter presented in the summary and in the detailed description.

Some principal aspects of the battery of the present disclosure are hereinafter presented. Those aspects may be combined together and/or with parts of the detailed description and/or with the claims.

According to a first aspect, it is herewith disclosed a battery unit (1) for renewable energy, in particular in stationary and/or mobile applications, comprising:

- a plurality of cells (6) configured to store, in use, electric energy;

- a power connector, electrically connected with the plurality of cells (6), the power connector being configured at least to distribute electric energy withdrawn from the plurality of cells (6) to a load or to receive electric energy for recharging the plurality of cells (6);

- a case (4) defining a cavity within which the plurality of cells (6) is arranged in a predetermined spatial configuration;

- a body (5), comprising a cavity defining at least a cells storage portion (2) configured to house the case (4); wherein the cells storage portion (2) is configured to be sealed and to contain, in use, a thermal conductive fluid, in such a way that, in use, the fluid floods the cavity of said case (4) and comes into contact with the plurality of cells (6).

According to another independent aspect, it is herewith disclosed a battery unit (1) for renewable energy, in particular in stationary and/or mobile applications, comprising:

- a plurality of cells (6) configured to store, in use, electric energy; - a power connector, electrically connected with the plurality of cells (6), the power connector being configured at least to distribute electric energy withdrawn from the plurality of cells (6) to a load or to receive electric energy for recharging the plurality of cells

(6);

- a case (4) defining a cavity within which the plurality of cells (6) is arranged in a predetermined spatial configuration; wherein the battery unit (1) contains, in use, a thermal conductive fluid, in such a way that, in use, the fluid floods the cavity of said case (4) and comes into contact with the plurality of cells (6).

According to a further non-limiting aspect, the battery unit (1) comprises a body (5), comprising a cavity defining at least a cells storage portion (2) configured to house the case (4).

According to a further non-limiting aspect, the cells storage portion (2) is configured to be sealed and to contain, in use, said thermally conductive fluid.

According to a further non-limiting aspect, the body (5) comprises at least a first sealing panel or wall (5a) configured to seal the cells storage portion (2).

According to a further non-limiting aspect, the body (5) comprises a first sealing panel or wall (5a) and a second sealing panel or wall (5b), the first sealing panel or wall (5a) and the second sealing panel or wall (5b) being configured to seal the cells storage portion (2) respectively at a first end thereof and at a second end thereof, the first end and the second end of the cells storage portion (2) being opposite one with respect to the other.

According to a further non-limiting aspect, the first end and the second end of the cells storage portion (2) are opposite one with respect to the other.

According to a further non-limiting aspect, the body (5) and the case (4) have a common main direction of extension along a first axis (Y).

According to a further non-limiting aspect, the case (4) lays, in use, in a predefined spatial configuration with respect to the body (5). According to a further non-limiting aspect, the case (4) is configured to be removed from the cavity of the body (5).

According to a further non-limiting aspect, the case (4) comprises at least one contacting element (4c), optionally a rail.

According to a further non-limiting aspect, said contacting element (4c) extends mainly along said common main direction of extension along said first axis (Y).

According to a further non-limiting aspect, the body (5) comprises at least one guide element (5g), optionally a counter-rail, configured to house at least partially the contacting element (4c).

According to a further non-limiting aspect, the body (5) comprises at least one guide element (5g) configured to be at least partially housed in the contacting element (4c).

According to a further non-limiting aspect, the contacting element (4c) is arranged outside the cavity of the case (4) and/or in substantial correspondence of an outer wall of the case (4), the guide element (5g) is arranged and/or protrudes inside the cavity of the body (5), and the case (4) is configured to be removed from the cavity of the body (5) by means of a removal of the contacting element (4c) from the guide element (5g), in particular by means of a sliding, optionally an axial sliding, of the contacting element (4c) with respect to the guide element (5g).

According to a further non-limiting aspect, the sliding takes place along said first axis (Y).

According to a further non-limiting aspect, the case (4) comprises a top portion (4r) being at least partially domed and/or defining a concavity facing the cavity of the case (4).

According to a further non-limiting aspect, the top portion (4r) is configured to assist a fluid recirculation in said cavity of the case (4) due to thermal convection.

According to a further non-limiting aspect, the top portion (4r) is domed in correspondence of a central portion extending axially along said main direction of extension along said first axis (Y). According to a further non-limiting aspect, the top portion (4r) extends for the entire length of said cells storage portion (2).

According to a further non-limiting aspect, the contacting element (4c) is arranged at the top portion (4r) of the case (4).

According to a further non-limiting aspect, the guide element (5g) is arranged at the top portion of the body (5).

According to a further non-limiting aspect, the top portion (4r) extends at least partially, preferably substantially, along a main axial development of the battery unit (1).

According to a further non-limiting aspect, the body (5) comprises a first and a second lateral wall, substantially opposite one with respect to the other and/or parallel one with respect to the other; a top wall (5t) of the body (5) having respective left, right ends contacting substantially the top portions of the first and of the second lateral walls.

According to a further non-limiting aspect, the case (4) comprises a first and a second lateral wall, substantially opposite one with respect to the other and/or parallel one with respect to the other; the top portion (4r) having respective left, right ends contacting substantially the top portions of the first and of the second lateral walls.

According to a further non-limiting aspect, the power connector is configured to allow at least a partial recharge of the plurality of cells (6).

According to a further non-limiting aspect, the plurality of cells (6) comprises cylindrical cells.

According to a further non-limiting aspect, at least part of the plurality of cells, optionally the entire plurality of cells, is substantially oriented vertically.

According to a further non-limiting aspect, the cylindrical cells are oriented in such a way an axis thereof is arranged substantially in a vertical direction and/or along a direction (Z) substantially inclined, optionally orthogonal, with respect to a main direction of extension along a first axis (Y) of the body (5) and/or of the case (4).

According to a further non-limiting aspect, the plurality of cells (6) comprises cells arranged substantially in a honeycomb spatial configuration and/or wherein the plurality of cells (6) comprises at least two cells having at least a portion in substantial reciprocal contact.

According to a further non-limiting aspect, the axis of the cells is substantially orthogonal with respect to said main direction of extension along said first axis (Y).

According to a further non-limiting aspect, the cavity of the body (5) defines a crosssection whose shape at least partially matches, optionally substantially matches, with an outer shape of the case (4).

According to a further non-limiting aspect, the cavity of the case (4) has an overall height greater than a height of the plurality of cells (6), and leaves a free space (4f) above said plurality of cells (6).

According to a further non-limiting aspect, said free space is configured to allow a passage of the thermally conductive fluid above said plurality of cells (6).

According to a further non-limiting aspect, the case (4) comprises at least a top wall (4w) arranged within the cavity of the case (4) and a bottom wall (4b) supporting the plurality of cells (6).

According to a further non-limiting aspect, a distance between the top wall (4w) and the bottom wall (4b) is substantial equivalent to a height of the plurality of cells (6) and/or the bottom wall (4b) comprises a plurality of through-holes configured to allow a passage of the thermally conductive fluid below at least part of the plurality of cells (6).

According to a further non-limiting aspect, the free space (4f) extends at least partially in correspondence of the top portion (4r).

According to a further non-limiting aspect, the thermally conductive fluid substantially contacts at least one inner wall of the body (5).

According to a further non-limiting aspect, the thermally conductive fluid substantially contacts at least one external face of the case (4).

According to a further non-limiting aspect, the body (5) comprises a first heat exchanger (5d) configured to at least partially dissipate a heat coming from the plurality of cells (6). According to a further non-limiting aspect, the first heat exchanger (5d) is a passive heat exchanger (5d).

According to a further non-limiting aspect, the first heat exchanger (5d) is arranged substantially at a top portion of the body (5).

According to a further non-limiting aspect, the battery unit (1) comprises a thermal management system, configured to mitigate the temperature of the plurality of cells (6) by means of a sequential intervention of temperature management devices in accordance to the temperature of said plurality of cells (6) and/or of said thermally conductive fluid.

According to a further non-limiting aspect, the temperature management devices are configured to cause a heat transfer along at least a first direction and a second direction, the first direction being different from the second direction.

According to a further non-limiting aspect, at least one between said first direction and said second direction are substantially aligned with a main development direction of the battery unit (1).

According to a further non-limiting aspect, the temperature management devices comprise at least one passive heat exchanger (5d).

According to a further non-limiting aspect, the temperature management devices comprise at least one active heat exchanger.

According to a further non-limiting aspect, the battery unit (1) is configured to cause the intervention of the said at least one active heat exchanger after the intervention of said at least one passive heat exchanger (5d).

According to a further non-limiting aspect, said at least one passive heat exchanger (5d) comprises a first heat exchanger (5d) configured to at least partially dissipate a heat coming from the plurality of cells (6), arranged substantially at a top portion of the body (5).

According to a further non-limiting aspect, the first heat exchanger (5d) comprises a plurality of finned surfaces extending for at least part of an outer surface of the body (5). According to a further non-limiting aspect, the finned surfaces extend mainly along said first axis (Y).

According to a further non-limiting aspect, the body (5) comprises a control portion (3) comprising at least a heat exchanging unit (3p, 5k, 11, 12, 13) configured to provide and/or remove heat from the cells storage portion (2), the control portion (3) being optionally housed within said cavity.

According to a further non-limiting aspect, the body (5) comprises a control portion (3) housing at least part of the thermal management system.

According to a further non-limiting aspect, the control portion (3) is isolated with respect to the cells storage portion (2).

According to a further non-limiting aspect, the thermal management system comprises a heat exchanging unit (3p, 5k, 11, 12, 13) housing said at least one active heat exchanger.

According to a further non-limiting aspect, the heat exchanging unit (3p, 5k, 11, 12, 13) configured to provide and/or remove heat from the cells storage portion (2).

According to a further non-limiting aspect, the heat exchanging unit (3p, 5k, 11, 12, 13) comprises at least one fluid pump (3p) comprising an inlet and an outlet, said inlet and said outlet being connected to the cells storage portion (2) to force a recirculation of said thermally conductive fluid, in particular within the cells storage portion (2) and/or in the cavity of the case (4).

According to a further non-limiting aspect, the at least a first sealing panel or wall (5a) comprises a first fluid port (8) and a second fluid port (9) respectively connected to the inlet and to the outlet of the pump (3p) by means of respective conduits (10).

According to a further non-limiting aspect, the first fluid port (8) and the second fluid port (9) are respectively configured to cause a removal and an introduction of the thermally conductive fluid along a substantially horizontal direction (Y).

According to a further non-limiting aspect, the heat exchanging unit (3p, 5k, 11, 12, 13) comprises a thermoelectric device (11), in particular a solid-state thermoelectric device, specifically a Peltier cell, operatively coupled with said cells storage portion (2) and configured to cause a heating or a cooling of said thermally conductive fluid.

According to a further non-limiting aspect, the battery unit (1) comprises a data processing unit, or is connected to a data processing unit, the data processing unit being configured to receive at least one of the following signals: a temperature signal from a temperature sensor, a voltage signal; the data processing unit being configured to transmit at least an electronic signal or message in at least one condition following the reception of said temperature signal and/or voltage signal.

According to a further non-limiting aspect, the battery unit (1) comprises at least one temperature sensor configured to detect a cell temperature (Tc) and/or a thermal conductive fluid temperature (Tf).

According to a further non-limiting aspect, the data processing unit is configured to store a first minimum temperature threshold (Tl,min) and a first maximum temperature threshold (Tl,max) of a first range of temperatures ([Tl,min - Tl, max]) of active temperature mitigation.

According to a further non-limiting aspect, the data processing unit is configured to store a second minimum temperature threshold (T2,min) and a second maximum temperature threshold (T2,max) of a second range of temperatures ([T2,min -T2, max]) of active temperature mitigation.

According to a further non-limiting aspect, the first minimum temperature threshold (Tl,min) is lower than the second minimum temperature threshold (T2,min) and the first maximum temperature threshold (Tl,max) is higher than the second maximum temperature threshold (T2,max).

According to a further non-limiting aspect, the battery unit (1) is configured to keep the thermally conductive fluid in a liquid state during the use, optionally at least in the temperatures within the first range of temperatures ([Tl,min - Tl, max]) of active temperature mitigation.

According to a further non-limiting aspect, the temperature sensor is operatively connected to said data processing unit. According to a further non-limiting aspect, the data processing unit is configured to activate said thermoelectric device (11) in case the cell temperature (Tc) and/or the thermally conductive fluid temperature (Tf) exceeds a predetermined first maximum temperature threshold (Tl,max) or goes below a first minimum temperature threshold (Tl,min).

According to a further non-limiting aspect, the heat exchanging unit (3p, 5k, 11, 12, 13) comprises a radiator (12) operatively coupled with said fluid pump (3p) and configured to cause a cession of heat from the thermally conductive fluid or an absorption of heat to the thermally conductive fluid.

According to a further non-limiting aspect, the thermoelectric device (11) is coupled to the radiator (12) in such a way to cause, when activated, a removal of heat from the radiator (12) or a cession of heat to the radiator (12) to determine, in use, respectively a cooling or a heating of said thermally conductive fluid.

According to a further non-limiting aspect, the radiator (12) is a passive heat exchanger.

According to a further non-limiting aspect, the thermal management system is configured to cause:

- if at least one between a cell temperature (Tc) and/or a thermally conductive fluid temperature (Tf) is within a second temperature range [T2,min - T2,max], a passive temperature mitigation, in particular by means of a convective fluid circulation within the case (4) and/or by means of the first heat exchanger (5d);

- if at least one between a cell temperature (Tc) and/or a thermally conductive fluid temperature (Tf) is outside the second temperature range [T2,min - T2,max], and within a first temperature range [Tl,min - Tl,max] wider than said second temperature range [T2,min - T2,max], in particular above a maximum temperature (T2,max) of said second temperature range [T2,min - T2,max], an active temperature mitigation in combination with the passive temperature mitigation, in particular by means of an activation of the pump (3p) causing a forced circulation of the thermally conductive fluid, optionally up to the radiator (12), and of said ventilator (13); - if at least one between a cell temperature (Tc) and/or a thermally conductive fluid temperature (Tf) is outside the first temperature range [Tl,min - Tl,max], in particular above a maximum temperature (Tl,max) of said first temperature range [Tl,min-Tl,max], an active temperature mitigation in combination with the passive temperature mitigation, in particular by means of an activation of the pump (3 p) causing a forced circulation of the thermally conductive fluid, optionally up to the radiator (12), of said ventilator (13) and of said thermoelectric device (11).

According to a further non-limiting aspect, the thermal management system is operatively connected to said thermal sensor.

According to a further non-limiting aspect, the data processing unit is configured to cause:

- a cession of heat from the thermoelectric device (11) for heating said thermally conductive fluid when the cell temperature (Tc) or the thermal conductive fluid temperature (Tf) goes below the first minimum temperature threshold (Tl,min);

- a removal of heat for cooling of said thermally conductive fluid by means of the thermoelectric device (11), when the cell temperature (Tc) or a thermal conductive fluid temperature (Tf) exceeds the predetermined first maximum temperature threshold (Tl, max).

According to a further non-limiting aspect, the heat exchanging unit (3p, 5k, 11, 12, 13) comprises at least one ventilator (13) operatively coupled with said radiator (12) and configured to cause a removal of heat from the radiator (12) to determine a cooling of said thermally conductive fluid.

According to a further non-limiting aspect, the data processing unit is configured to cause an activation of the at least one ventilator (13) in case the cell temperature (Tc) or the thermal conductive fluid temperature (Tf) exceeds the second maximum temperature threshold (T2, max).

According to a further non-limiting aspect, the data processing unit is configured to cause, or to keep, a deactivation of the at least one ventilator (13) in case the cell temperature (Tc) or a thermal conductive fluid temperature (Tf) goes below, or is below, the first minimum temperature threshold (Tl, min) and/or goes below, or is below, the second minimum temperature threshold (T2,min).

According to a further non-limiting aspect, the at least one ventilator (13) is configured to cause an air flow directed outwards said control portion (3), optionally outside said body (5).

According to a further non-limiting aspect, the data processing unit is configured to deactivate, or to keep deactivated, the pump (3 p) in case the cell temperature (Tc) or the thermally conductive fluid temperature (Tf) goes below, or is below, the first minimum temperature threshold (Tl, min) and/or goes below, or is below, the second minimum temperature threshold (T2,min)

According to a further non-limiting aspect, the at least one ventilator (13) is configured to direct an airflow along a direction substantially parallel to the main direction of extension.

According to a further non-limiting aspect, the body (5) comprises at least one mounting element (5r) configured to be removably engaged with a supporting frame in such a way the battery unit (1) is kept, in use, in contact with said supporting frame.

According to a further non-limiting aspect, the mounting element (5r) comprises at least a first rail extending substantially for at least part of a longitudinal development of said body (5).

According to a further non-limiting aspect, the mounting element (5r) extends optionally along the common main direction of extension along a first axis (Y).

According to a further non-limiting aspect, said thermally conductive fluid is an electrically compatible oil and/or is an inert fluid and/or is a flame-retardant fluid and/or a fluid not suitable to generate oxygen when subjected to electric currents and/or fire and/or is a substantially non-conductive, dielectric, fluid.

According to a further non-limiting aspect, the battery unit (1) comprises a voltage sensor configured to detect the voltage of at least one of the cells of said plurality of cells (6), and configured to transmit the voltage signal, representing the voltage detected on at least one of the cells of said plurality of cells (6), to said data processing unit. According to a further non-limiting aspect, the data processing unit is configured to compare the voltage signal to a predetermined voltage threshold (Vthl, Vth2) and to cause the transmission of the electronic signal or message in case the voltage signal crosses said predetermined voltage threshold (Vthl, Vth2).

According to a further non-limiting aspect, the predetermined voltage threshold comprises a minimum voltage threshold (Vth2) and the data processing unit is in particular configured to compare the voltage signal to the minimum voltage threshold (Vth2) and to cause the transmission of the electronic signal or message in case the voltage signal is below said minimum voltage threshold (Vth2).

According to a further non-limiting aspect, the cells of said plurality of cells (6) are lithium cells, in particular Lithium Iron Phosphate cells.

According to a further non-limiting aspect, the battery unit (1) comprises at least one end panel (5e) configured to house an electrical connector (5c) for transferring the electric energy stored in said plurality of cells (6) to an outer load and/or for transferring electric energy from an outer source to the plurality of cells (6) for allowing a recharge thereof.

According to a further non-limiting aspect, the battery unit (1) is modular, and said mounting element (5r) is configured to cause a coupling and/or a juxtaposition of the battery unit (1) with at least one further battery unit (1).

According to a further non-limiting aspect, the mounting element (5r) and the electrical connector (5c) are configured in such a way to allow, through a sliding of the battery unit (1) along said supporting frame on said mounting element (5r), an electrical connection of the electrical connector (5c) to a corresponding socket.

According to a further non-limiting aspect, the power connector is electrically connected and/or is arranged in substantial correspondence with the electrical connector (5c). The following portion of the description discloses a preferred and non-limiting embodiment of the battery unit, which is disclosed with reference to the annexed figures. A brief description of the figures is hereinafter presented.

Figure 1 shows a perspective view of the battery unit according to the present disclosure.

Figure 2 shows a lateral view of the battery unit according to the present disclosure.

Figure 3 shows a top view of the battery unit of figure 2, without a protective case, thus leaving a plurality of cells exposed.

Figure 4 shows another perspective view of the battery unit according to the present disclosure.

Figure 5 shows a perspective view of a control portion of the battery unit according to the present disclosure.

Figure 6 shows a wiring diagram for the battery unit according to the present disclosure.

Detailed description

As shown in figure 1, with reference number 1 is indicated in its complex a battery unit. The battery unit 1 is configured to be used for renewable energy in stationary and/or mobile applications. Mobile applications may include, in a non-limiting way, vehicular applications, in particular automotive applications and more in particular propulsion. Vehicle applications, within the meaning of the present disclosure, shall be considered comprising any application for which the battery unit could be installed at least temporarily on a vehicle, in particular on a road vehicle, off-road vehicle, ship, boat, aircraft, for powering any auxiliary load that may be installed thereon.

The battery unit 1 comprises a body 5, which is preferably albeit in a non-limiting extent realized in aluminum or in another thermally conductive material, preferably but in a non-limiting extent metal, suitable to withstand the weight of the plurality of cells therein contained without substantial deformations. The body 5 has a substantially axial development, that lies along a first axis Y that identifies the length of the body 5. A second axis X, orthogonal to the first axis Y, identifies the width of the body 5. A third axis Z, orthogonal to the first axis Y and to the second axis X identifies the height of the body 5. In use, the first axis Y and the second axis X are horizontal; as it appears from the annexed figures, the body 5, and thus the battery unit 1, has a main development direction which is substantially horizontal.

The body 5 comprises a first and a second lateral wall, each one extending along a vertical plane, i.e. a plane parallel to the plane Y-Z, a bottom wall, preferably orthogonal with respect to the first and the second lateral walls and a top wall 5t. The bottom wall extends along a horizontal plane, i.e. a plane parallel to the plane X-Y. The body 5 may be realized in metal or in plastics; in an embodiment, the body 5 is realized in anodized aluminum, and may be coated by an electrically-insulating coating, e.g. an electrically insulating paint.

The body 5 comprises a couple of mounting elements 5r configured to be removably engaged with a supporting frame in such a way the battery unit 1 rests, in use, in contact with said supporting frame. The mounting elements 5r comprise each one a rail, which identifies a recess extending along the longitudinal development (i.e. along the first axis Y) of the body 5. As shown in figure 1, the mounting elements 5r are arranged substantially at an edge of the body 5 that connects the top portion of the first (or second) lateral wall with the top wall 5t. The recess is configured to house an axial connection rail of the supporting frame, and is open in correspondence of the front and rear end of the body 5 in such a way the removable engagement of the body 5 with respect to the supporting frame can be realized by means of an axial sliding ofthe mounting elements 5rwith respect to the axial connection rail along a direction substantially parallel to the direction identified by the first axis Y. It shall be noted that in an embodiment, not shown in the annexed figures, only one mounting element 5r is present. In this latter case, the mounting element 5r may be provided centrally on the top wall 5t.

As shown in figure 1 the top wall 5t may be provided with a passive first heat exchanger 5d, which preferably - albeit in a non-limiting extent - extends along the entire longitudinal development of the body 5. The first heat exchanger 5d is provided with a plurality of finned surfaces facing on the outer surface of the body and is configured to allow a passive dissipation of heat by a heat transfer with the air. Preferably, albeit in a non-limiting extent, the finned surfaces extend mainly along the first axis Y.

When seen from the cavity of the body 5, the top wall 5t is provided with a domed inner surface, defining a concavity directed towards the cavity of the body 5.

In the cavity, in particular in substantial correspondence of the edges that connect the top portions of the first and second lateral walls of the body 5 with the top wall 5t, the body 5 comprises a couple of guide elements 5g, one at the left edge and one at the right edge. The guide elements 5g are configured to guide a case 4 for the plurality of cells 6 that in use are introduced in the cavity of the body 5. In an embodiment, the guide elements 5g at least partially protrude into the cavity.

The guide elements 5g extend along a direction which is substantially parallel to the direction of the first axis Y, and in particular extend along at least part, preferably the entire, longitudinal development of the body 5. The guide elements 5g are arranged at the same height with respect to the bottom wall of the body 5.

A case 4 is arranged within the cavity of the body 5; the case 4 in turn defines a cavity within which a plurality of cells 6 is arranged in a predetermined spatial configuration. The case 4 comprises a first and a second lateral wall, each one extending along a vertical plane, i.e. a plane parallel to the plane Y-Z, a bottom wall, preferably orthogonal with respect to the first and the second lateral walls and a top portion 4r. The bottom wall extends along a horizontal plane, i.e. a plane parallel to the plane X-Y.

The case 4 may be realized in several materials; in a preferred, non-limiting, embodiment, the case 4 may be realized in a substantially rigid plastic material; this material is preferably an electrically non-conductive, thus insulating, material. Common plastics that could be used for this purpose are polyethylene, or polypropylene or polystyrene. This mitigates the risk of propagating the electric conductivity in case of a malfunction of any of the cells 6 therein contained.

The case 4 comprises a plurality of contacting elements 4c, optionally rails, arranged each one in substantial correspondence of an edge between the top of the first (or second) lateral wall and the top portion 4r, or arranged at a left and right end of the top portion 4r. The contacting elements extend along at least a part of the longitudinal development of the case 4, and preferably extend along the entire longitudinal development of the case 4. The contacting elements 4c are configured to match with the shape of the guide elements 5g, in particular with their recess, in such a way to allow a reciprocal motion between the body 5 and the case 4, which allows to extract the case 4 from the cavity of the body 5.

The above-referred motion is substantially axial, since - as it is apparent from the annexed figures - the case 4 has a principal direction of development which lays along the first axis Y. In particular, the reciprocal motion is an axial motion that takes place along the first axis Y.

In detail, as it is shown by the detailed part of figure 1, the guide elements 5g identify a concavity or recess and the contacting elements 4c identify a protrusion whose shape substantially matches the shape of said concavity or recess.

The top portion 4r is substantially domed and defines a concavity facing the cavity of the case 4. More in detail, the top portion 4r is domed in correspondence of a central portion, symmetrical if the case 4 is seen along a plane that develops along the first axis Y and along the third axis Z. In an embodiment, the extension of the domed portion along the first axis Y takes place for a length equivalent to the length of the cells storage portion 2. The radius or more in general the shape of the curve of the dome of the top portion 4r matches the shape of the curve of the dome of the inner surface of the top wall 5t of the body 5.

This feature, together with the precise coupling between the guide elements 5g and the contacting elements 4c allows obtaining a precise coupling between the case 4 and the body 5.

In a preferred, non-limiting, embodiment, the case 4 is realized in a polymeric material; as it will be apparent from the subsequent portion of the present description, such polymeric material is compatible with fluids, and is an electric insulator. In an embodiment, which shall not be considered limiting, the polymeric material is compatible with mineral oil. In a preferred, non-limiting embodiment, the case 4 is realized in a material compatible with the fluid used in the battery unit 1.

As already briefly anticipated, a plurality of cells 6 is arranged in the case 4. The plurality of cells comprises cylindrical cells, being oriented in such a way an axis thereof is arranged substantially in a vertical direction. The plurality of cells 6 comprises cells arranged substantially in a honeycomb spatial configuration. More in general, it could be inferred that two cells of the plurality of cells may have at least a portion in substantial reciprocal contact, and thus are not spaced apart one with respect to the other. This feature allows to have a particularly compacted and stable cells configuration, and further allows to have reciprocal contacts between adjacent cells ideally on a single, substantially vertical, line. This favors a proper heat dissipation, as there is a very limited contact surface between adjacent cells.

Albeit this shall not be considered limiting, the cells are Lithium Iron Phosphate cells; this reduces the risk of fire in case of overheating. Those cells have a lithium iron phosphate (LiFePO4) at the cathode, and a graphitic carbon electrode with a metallic backing at the anode. This material shows an increased safety. LiFePO4 is an intrinsically safer cathode material than e.g. LiCoO2 and manganese dioxide spinels through omission of the cobalt.

A power outlet is electrically connected with the plurality of cells 6 in such a way to allow the delivery of an electric power withdrawn from the plurality of cells to a load. It is herewith noted that a power outlet is further configured to allow recharging at least partially the plurality of cells 6. For such a reason, the aforementioned power outlet may be further used as a power inlet; thus the power outlet/inlet corresponds actually to a power connector.

The body 5 comprises a first sealing panel or wall 5a and a second sealing panel or wall 5b. The first and the second sealing panels or walls 5a, 5b have preferably the same shape, and are arranged at a front and at a rear end of the case 4. The shape of the sealing panels or walls 5a, 5b, seen along a direction substantially parallel to the first axis Y, matches with the overall cross-section of the case 4 and, in turn, with the overall crosssection of the cavity of the body 5. The first sealing panel or wall 5a and the second sealing panel or wall 5b are arranged on a plane which is substantially parallel to the X-Z plane.

The purpose of the sealing panels or walls 5a, 5b is to isolate a portion of the cavity of the body 5, in particular to seal a portion of the cavity of the body 5 including the entire case 4, in such a way to identify a cells storage portion 2 that is sealed from the outer environment. The cells storage portion 2 is configured to contain a thermally conductive fluid, in such a way that the fluid floods the cavity of the case 4 and contacts, and in particular submerses, the plurality of cells 6. As it will be appreciated by further reading the present disclosure, the thermally conductive fluid is also inert and dielectric. The sealing of the cells storage portion 2 is removable for allowing the replacement of the plurality of cells 6.

This feature optimizes the heat transfer from the cells to the body 5. Also thanks to the particular spatial configuration of the plurality of cells 6, the thermally conductive fluid contacts substantially the entire surface of the cells and therefore the area with which the heat can be transferred to the fluid is maximized. In particular, since all the cells are immersed in the thermally conductive fluid, all the cells 6 have a substantially similar capacity of thermal dispersion; this means that a risk that in use some cells may become significantly warmer than others is significantly mitigated.

Submersing the plurality of cells 6 in the fluid has a further advantage; should any of the cells of the plurality of cells 6 catch fire, such fire would be immediately extinguished by the fluid, and would not propagate in the case 4; in fact, the flooding does not leave space for any oxygen to burn. In addition, the electric currents that could spread from a damaged cell or from a burning cell would be limited by the limited electric conductivity of the fluid.

The Applicant has conceived a particular embodiment of the case 4 wherein the bottom wall 4b is provided with a plurality of through-holes; in a non-limiting embodiment, such through-holes have a circular cross-section. The size of the cross-section of the through-holes is lower than the size of each cell of the plurality of cells. This feature facilitates the passage of the thermally conductive fluid below the cells.

Furthermore, as it can be clearly seen from figure 1 (in particular and also in the magnified portion thereof) in a preferred, non-limiting, embodiment, the case 4 comprises at least a top wall 4w arranged within the cavity of the case 4; a distance between the top wall 4w and the bottom wall 4b is substantial equivalent to a height of the plurality of cells 6 (extension of the cells along the third axis Z). The top wall 4w is arranged on a plane which is substantially parallel to the horizontal plane X-Y. The top wall 4w lies below the top portion 4r of the case 4 and leaves a free space above the plurality of cells 6. The top wall 4w is not continuous, but is provided with a plurality of windows or openings. Thus the top wall 4w helps to achieve a proper confinement of the plurality of cells 6 within the case 4 and, at the same time, allows a passage of the thermally conductive fluid in a vertical direction.

Such free space, which despite the name is filled by the fluid, allows a particularly effective motion of the thermally conductive fluid due to convection. When the through- holes are present, the effect of the fluid circulation due to thermal convection is particularly effective, because fluid can naturally move from above the cells to below the cells.

In use, when the plurality of cells 6 heats up, the thermally conductive fluid moves from the bottom wall 4b to the top portion 4r by passing through the windows or openings of the top wall 4w. It is noted that even if the battery unit of the present disclosure is specifically albeit in a non-limiting extent conceived for operating substantially in a horizontal direction, the substantially complete filling of the case 4 with the aforementioned fluid allows to mitigate the risk that a change in the spatial orientation of the battery unit 1 may result in having a part of the cells 6 outside the fluid.

Albeit the invention is not limited in this sense, in an embodiment said thermally conductive fluid is an electrically compatible oil and/or is an inert fluid and/or is a flameretardant fluid and/or a fluid not suitable to generate oxygen when subjected to electric currents and/or fire. Preferably, care should be taken to keep compatibility between the thermally conductive fluid and the material used at least for producing the case 4. In a specific embodiment, the thermally conductive fluid is substantially non-conductive (dielectric).

The plurality of cells 6 can be substituted by simply opening the first or second sealing panels or walls 5a, 5b, extracting the thermally conductive fluid (should the case may be, this latter may be replaced with a fresh one), and by removing the case 4 from the body 5 by a simple axial sliding along the first axis Y.

The body 5 further defines a control portion identified by the reference number 3.

The control portion 3 is separate with respect to the cells storage portion 2, and in particular is isolated with respect to the cells storage portion 2 in order to avoid any contact with the aforementioned fluid. The control portion 3 is axially juxtaposed to the cells storage portion 2 along said first axis Y.

The control portion 3 comprises at least a heat-exchanging unit 3p, 5k, 11, 12, 13 configured to provide and/or remove heat from the cells storage portion 2. While the first heat exchanger 5d at the top of the body 5 is passive, the heat-exchanging unit is an active element, that contributes to cause a variation of temperature of the plurality of cells 6 in case such temperature goes beyond a predetermined range of allowable temperatures suitable to sustain the operative life of the plurality of cells 6 and further suitable to mitigate the risk of overheating.

The heat exchanging unit 3p, 5k, 11, 12, 13 comprises at least one fluid pump 3p comprising in turn an inlet and an outlet, said inlet and said outlet being connected to the cells storage portion 2 to force a recirculation of said thermally conductive fluid within the cells storage portion 2.

For the purposes of allowing a fluid communication of the cells storage portion 2 with the pump 3, one between the first or second sealing panels or walls 5a, 5b (in the figures, the second sealing panel or wall 5b lying between the cells storage portion 2 and the control portion 3) comprises a first fluid port 8 and a second fluid port 9 respectively connected to the inlet and to the outlet of the pump 3p by means of respective conduits 10. The first fluid port 8 is a fluid port that allows the extraction of the fluid from the cells storage portion 2 and the second fluid port 9 is a fluid port that allows the introduction of the fluid in the cells storage portion 2.

At the conduits 10, between the first fluid port 8 and the second fluid port 9, there is a thermal radiator 12 (that constitutes a second, passive, heat exchanger), which is configured to increase the heat exchange rate between the thermally conductive fluid contained in the conduits 10, and thus in the case 4, and the outside environment.

In particular, the first and the second fluid ports 8, 9 are arranged in such a way to cause, respectively, a removal and an introduction of the thermally conductive fluid along a substantially horizontal direction (first axis Y). Albeit in the annexed figures the first and the second fluid ports 8, 9 are depicted as simple through-holes practiced in the sealing panel or wall, in another embodiment, not shown in the annexed figures, such fluid ports may be actually nozzles protruding from the sealing panel or wall.

The first fluid port 8 is arranged at a height over the height at which the second fluid port 9 lays; in detail, the first fluid port 8 is arranged substantially at a top portion of the sealing panel or wall, in such a way to open in the portion of the cavity of the case 4 wherein there is a free space 4f above the top wall 4w. The free space is at least partially in correspondence of the top portion 4r. The second fluid port 9 is arranged substantially at a bottom portion of the sealing panel or wall, in such a way to be substantially close to the bottom wall 4b. In an embodiment, the second fluid port 9 is vertically aligned with the first fluid port 8. In an embodiment, which shall not be considered as limiting, at least one between the first fluid port 8 and the second fluid port 9 is provided with a plurality of through-holes. This feature cooperates with the natural convective motion of the thermally conductive fluid and helps a proper heat removal (or heat provision, should the cells be at a too low temperature) from the fluid within the cells storage portion 2. The arrangement of the first fluid port 8 and of the second fluid port 9 at different heights is particularly effective in case the battery unit 1 is arranged along a substantially horizontal direction.

In addition, the heat exchanging unit 3p, 5k, 11, 12, 13 comprises a thermoelectric device 11, in particular a Peltier cell, operatively coupled with said cells storage portion 2 and configured to cause an additional heating or a cooling of the thermally conductive fluid. The Peltier cell is a thermoelectric device 11 that acts as a solid-state heat pump, and is suitable, according to the specific way it is fed, to provide heat or to subtract heat. The thermoelectric device 11 may be provided with an own heat exchanger lie operatively coupled with the radiator 12.

The heat exchanging unit 3p, 5k, 11, 12, 13 comprises a radiator 12 operatively coupled with said pump 3p and configured to cause a cession of heat from the thermally conductive fluid or an absorption of heat to the thermally conductive fluid; the Peltier cell is operatively coupled with the radiator 12, and in particular lies in substantial contact with the radiator 12. In use, the activation of the pump 3p causes a circulation of the thermally conductive fluid in the radiator 12 before re-entering in the cells storage portion 2 through the second fluid port 9. The Peltier cell may be electrically fed to cool down the radiator 12, thus to cool down the thermally conductive fluid therein contained, or may be electrically fed to heat up the radiator 12, thus to transfer heat to the thermally conductive fluid therein contained. Such latter configuration is useful should the battery unit 1 operate at very low temperatures, as it helps keeping the plurality of cells 6 at a suitable operative temperature.

For the purposes of clearly explaining the operation of the battery unit 1 to mitigate the temperature of the plurality of cells 6, it is herewith identified a cell temperature Tc and a thermally conductive fluid temperature Tf. The battery unit 1 comprises at least one temperature sensor configured to detect the cell temperature Tc and/or the thermally conductive fluid temperature Tf. In the present description, the architecture of the sensor is not described, as any kind of sensor suitable for providing a temperature signal could be used in principle (thermocouple, RTD, thermistor, semiconductor-based ICs). Preferably, albeit in a non-limiting extent, a fast-responsive temperature sensor is used.

In the context of the present description a first temperatures range [Tl,min -Tl,max] of active temperature mitigation is disclosed. The range comprises a first maximum threshold temperature Tl,max and a first minimum threshold temperature Tl,min.

If the cell temperature Tc and/or the thermally conductive fluid temperature Tf exceeds the first maximum threshold temperature Tl,max, the thermoelectric device 11, in particular the Peltier cell, is fed in such a way to cool down the thermally conductive fluid that flows in the conduit 10 at the radiator 12. The conductive fluid temperature Tf limit, identified by the upper values of the above-disclosed ranges, is set at a proper value in order to avoid - unless in case of severe malfunction - any transformation of the thermally conductive fluid from the liquid state to gaseous and/or vapor state. This mitigates the risks of causing the pressurization of the cells storage portion 2; no specific need for an expansion valve is then present in the battery unit 1 of the present disclosure.

If the cell temperature Tc and/or the thermally conductive fluid temperature Tf goes below the first minimum threshold temperature, the Peltier cell is fed in such a way to heat up the radiator 12 and thus the thermally conductive fluid that is therein contained.

In other words, this means that the battery unit 1 of the present disclosure is provided with a thermal management stack that in detail operates as follows. Within a second range of temperatures, the pump 3p is left turned off, and thus no forced fluid circulation takes place between the first fluid port 8 and the second fluid port 9. The second range of temperatures is herewith defined as [T2,min - T2,max] and is referred also as a second range of active temperature mitigation. In such case, in the case 4 the only fluid circulation that may take place is the convective fluid circulation from the upper portions of the case 4 to the lower portions of the case 4 and vice versa.

Outside the second range of temperatures [T2,min - T2,max], in particular below or above the predetermined range of temperatures, the pump 3p is activated, in particular being automatically activated. With the activation of the pump 3p, also the ventilator 13 is activated, preferably simultaneously. This means that given certain conditions, the pump and the ventilator start respectively the circulation of the thermally conductive fluid between the first fluid port 8 and the second fluid port 9.

In an embodiment, the aforementioned first temperature range [Tl,min -Tl,max] is wider than the second range of temperatures. In other words, Tl,min < T2,min < T2,max < Tl,max. In the temperature range above the maximum value of the second range of temperatures [T2,min - T2,max] and below the first maximum threshold temperature Tl,max, the Peltier cell is kept off. Above the first maximum threshold temperature Tl,max, the Peltier cell is activated to increase the cooling of the thermally conductive fluid.

In an embodiment, in the temperature range below the minimum value (second minimum temperature threshold T2,min) of the second range of temperatures [T2,min - T2,max], and above the first minimum threshold temperature Tl,min, the Peltier cell is kept off. Below the first minimum threshold temperature Tl,min, the Peltier cell is activated to increase the temperature of the thermally conductive fluid, and preferably the ventilator 13 is turned off. In an embodiment, the ventilator 13 may be turned off also in the temperature range below the minimum value of the second range of temperatures [T2,min - T2,max], and above the first minimum threshold temperature Tl,min.

It is thus clear that the battery unit 1 comprises a thermal management system, configured to mitigate the temperature of the plurality of cells 6 by means of a sequential intervention of temperature management devices in accordance to the temperature of the plurality of cells 6 and/or of the thermally conductive fluid. At the first thermal mitigation, the first heat exchanger 5d operates a thermal transfer from the thermally conductive fluid even when the ventilator 13 and/or the thermoelectric device 11 are deactivated. The first thermal mitigation is purely passive. The thermal exchange takes place by means of the finned surfaces and by the convection process of the thermally conductive fluid. A second thermal mitigation is provided by the ventilator 13 and by the pump, which causes a forced circulation of the thermally conductive fluid that operates in association with the convection process that takes place within the case 4. A third thermal mitigation is provided by the thermoelectric device.

More schematically, in an embodiment:

- should Tc, Tf be within [T2,min - T2,max], only passive temperature mitigation takes place, principally by means of the convective fluid circulation within the case 4 and/or by the first heat exchanger 5d;

- should Tc, Tf be outside [T2,min - T2,max], in particular above T2,max, but within the wider range [Tl,min - Tl,max], an active temperature mitigation acts in combination with such passive temperature mitigation, and such active temperature mitigation is performed by means of a combined action of the pump 3p that forces a fluid circulation in the conduits up to the radiator 12, and of the ventilator 13 that helps to extract heat from the radiator 12;

- should Tc, Tf be outside [Tl,min - Tl,max], in addition to the steps above described, the active temperature mitigation is further improved by means of the thermoelectric device 11.

It is noted that the presence of the first heat exchanger 5d allows a fully operative and passive heat exchanging, providing the technical effect of allowing a proper heat exchange with the thermal conductive fluid and/or with the plurality of cells 6. It is further noted that the thermal management system allows for heat exchanges along at least two substantially different surfaces and/or directions; concerning the directions, one is substantially axial with the main development of the battery unit 1 (heat exchanging unit), another is substantially orthogonal to the first one (first heat exchanger 5d).

For such purposes, the battery unit 1 of the present disclosure may be provided with a data processing unit, or - preferably - may be operatively connected to a data processing unit. Such data processing unit is configured to receive at least one of the following signals: a temperature signal from a temperature sensor, a voltage signal.

In an embodiment, the data processing unit may be configured to transmit at least an electronic signal or message in at least one condition following the reception of said temperature signal and/or voltage signal, in particular should the voltage signal exceed a maximum voltage threshold Vthl or be equal, or under, a minimum voltage threshold Vth2. It is in particular noted that when the voltage of a Lithium cell falls below a predetermined voltage, the cell may undergo some unwanted chemical reactions that may lead to instability especially after a subsequent recharge.

In an embodiment, the data processing unit is configured to activate the, or to cause the activation of the, Peltier cell should the cell temperature Tc and/or the thermally conductive fluid temperature Tf raise above the first maximum temperature threshold Tl,max (cooling) or go below the first minimum temperature threshold Tl,min (heating). It is clear that the temperature sensor is thus operatively connected to the data processing unit. Such data processing unit may be configured to deactivate the ventilator 13 in case such temperature reaches a value below the first minimum threshold temperature Tl,min.

The data processing unit may be provided with one or more of the following types of processors: a general purpose processor, an application-specific type processor, an integrated circuit. The data processing unit may be further provided with an internal memory, or otherwise may be operatively connected to an external memory. In a specific, non-limiting, embodiment, the data processing unit may be an 8-Bit Microcontroller provided with an advanced RISC architecture.

The operative connection that takes place between the data processing unit and the temperature sensor may be such that the temperature signal transmitted is an electrical signal or an optical signal.

The heat exchanging unit 3p, 5k, 11, 12, 13 in addition comprises at least one ventilator 13 operatively coupled with the radiator 12 and configured to cause a removal of heat from the radiator 12 to determine a cooling of said thermally conductive fluid. Albeit in an embodiment the ventilator 13 is disclosed as present in the battery cell 1 in combination with the Peltier cell, this configuration shall not be intended as limiting. In 1 fact, according to a further embodiment, the heat exchanging unit 3p, 5k, 11, 12, 13 could be provided with said at least one ventilator without the Peltier cell.

In an embodiment, when the temperature sensor detects a temperature that exceeds the second maximum temperature threshold T2,max, through the data processing unit a control signal can be transmitted to cause the activation of the ventilator 13.

Resuming, according to the reciprocal level between the first and second maximum temperature thresholds Tl,max, T2,max, in an embodiment, when the cells temperature Tc and/or the thermally conductive fluid temperature Tf progressively rises, the Peltier cell may be activated before the ventilator 13, or - in contrast - the ventilator 13 may be activated before the Peltier cell. Should the first maximum temperature threshold Tl,max and the second maximum temperature threshold T2,max be equal, the Peltier cell and the ventilator 13 are activated together, simultaneously.

The ventilator 13 may be in principle any type of ventilator suitable to be electrically or electronically controlled. In a preferred, non-limiting, embodiment, the ventilator 13 is an axial ventilator and is configured to direct an airflow in a direction substantially coincident with the direction of maximum extension of the battery unit 1, i.e. the longitudinal direction thereof (first axis Y).

The ventilator 13 directs the airflow to an opening 5k that is realized in an end panel 5e of the body 5 of the battery unit 1. The end panel 5e is configured to house the opening 5k, which, as it can be seen in figure 4 is a thin-finned opening, and an electrical connector 5c. The electrical connector is configured to allow the electrical energy transfer from the plurality of battery cells 6 to the load. The aforementioned power connector is connected to, or is actually, the electrical connector 5c.

It is noted that the couple of mounting elements 5r is configured for allowing an automatic plugging of the electrical connector 5c with a corresponding socket, present in an adjacent battery unit 1 or at a connection point on the supporting frame. In use, thus, the operator may simply make the battery unit 1 slide on the mounting elements 5r with respect to the supporting frame in order to make the electrical connector 5c reach the corresponding socket. It is thus apparent that the battery unit 1 is substantially a modular unit that can be coupled with other batteries, in a series, parallel or series-parallel connection, in a very easy and effective way.

Finally, figure 6 discloses the electric diagram of the electrical connection for allowing the activation/deactivation of the pump 3p, of the Peltier cell and of the ventilator 13. In figure 6 are depicted a data processing unit 100, a thermistor 102 corresponding to the temperature sensor, the pump 3p, the ventilator 13 and the Peltier cell corresponding to the thermoelectric device 11. A first and a second relays 101, 102 are also present. The first and the second relays 101, 102 are useful for allowing a decoupling of the low-power controlling portion for the pump 3p, the ventilator 13 and for the Peltier cell, from the power control circuit actually used for feeding the pump 3p, the ventilator 13 and the Peltier cell.

In the non-limiting configuration of figure 6, the first relay 101 controls the activation of the pump 3p and of the ventilator 13, which are connected to an output controlling port 101'. The ventilator 13 is connected in series with the pump 3p; this means that with the feeding of the ventilator 13, automatically also the pump 3p is electrically fed and thus started to cause a forced flow of said thermally conductive fluid. The first relay 101 is excited by a first controlling signal sent by the data processing unit 100 on a first output controlling port 100'.

The second relay 102 is a bipolar relay configured to allow the feeding of the Peltier cell with a first polarity and with a second reversed polarity. The Peltier cell is connected to a second and a third output port 102', 102''. The second relay 102 is excited by a second controlling signal sent by the data processing unit 100 on a second and on a third controlling port 100", 100'".

The thermistor 103 is connected to a controlling input port 104 of the data processing unit, which is configured to receive the temperature signal corresponding to the cell temperature Tc or to the thermally conductive fluid temperature Tf.

In the wiring diagram of figure 6 further appears that the Peltier cell, the ventilator 13 and the pump 3p are fed with two different voltage sources; in detail the pump is fed by a first direct voltage at 5V; the same applies for the pump 3p. The Peltier cell is instead fed by a second direct voltage at 12V. It is further noted that the invention is not limited to the embodiments shown in the figures; therefore, the reference numbers in the claims, if present, are provided with the sole scope of increasing the intelligibility of the claims, and for any reason shall be considered limiting. It is finally clear that to the battery unit 1, additions or adaptations can be carried out without for this departing from the scope of protection provided by the annexed claims.