EP4736292A1 - A driver arranged to be connected to a battery management system, bms, as well as a corresponding method - Google Patents

Abstract

A driver arranged to be connected to a Battery Management System, BMS, said BMS comprising a battery, wherein the driver comprises a voltage control unit arranged to control a voltage provided to said BMS for charging said battery, wherein said voltage provided to said BMS gradually increases to a charging voltage and a current control unit arranged to control a current provided to said BMS wherein said current provided to said battery is set at a safety current value during a time that said voltage gradually increases and is then increased to a nominal current value once said charging voltage has been reached.

Description

A DRIVER ARRANGED TO BE CONNECTED TO A BATTERY MANAGEMENT

SYSTEM, BMS, AS WELL AS A CORRESPONDING METHOD

FIELD OF THE INVENTION

The present disclosure generally relates to the field of Emergency lighting systems comprising a Battery Management System, BMS, and, more specifically, to a driver to be connected to such a BMS.

BACKGROUND OF THE INVENTION

Emergency lighting systems incorporate a battery, typically utilizing various technologies, including lithium-ion, Li-ion, batteries. These Li-ion battery packs are equipped with a Battery Management System, BMS, responsible for safeguarding against unsafe situations and optimizing battery lifespan. The BMS may act as a switch, thereby disconnecting the battery pack in the event of hazardous occurrences such as a short-circuit within a cell or load, excessively deep discharge, or overcharge.

When a completely safe too-deep-discharge condition arises, the BMS promptly disconnects the battery pack from the charger in the emergency driver, ensuring protection. However, an inherently dangerous condition, such as a bulging or short-circuited cell, triggers the same response - disconnection of the battery pack by the BMS.

The charger in the emergency driver cannot differentiate between these safe and potentially unsafe conditions. Consequently, some emergency drivers available in the market adopt a simplistic approach by automatically resetting the BMS whenever the mains voltage is switched on. This reset is accomplished by applying a higher voltage to the battery than the voltage release threshold, while limiting the current to its maximum value.

This procedure is acceptable when the BMS disconnects the battery pack due to a safe condition, such as a too-deep-discharge. However, when the battery pack is disconnected due to an unsafe condition like a short-circuited or bulging cell, this resetting mechanism poses a concern.

Each time the charger is restarted, the hot-spot within the battery pack becomes energized. Consequently, with every activation of the hot spot, the condition worsens, potentially escalating the risk. Given the relatively small size of the hot spot and the presence of multiple cells within a battery pack, detecting this failure mode with absolute certainty using a simple Negative Temperature Coefficient, NTC, sensor located on a single cell is not feasible.

Therefore, it may be of importance to consider more advanced detection and protection mechanisms for emergency lighting systems. These could involve incorporating sophisticated sensors capable of identifying hazardous conditions accurately. By implementing an advanced monitoring system that can assess the overall health of the battery pack, including the status of individual cells, it would be possible to mitigate risks effectively.

While battery packs in emergency lighting systems are equipped with a BMS to ensure safety, distinguishing between safe and potentially unsafe conditions solely based on charger behaviour is challenging. Relying on simplistic resetting methods may exacerbate the risks associated with unsafe conditions. Hence, exploring advanced detection and protection strategies, such as comprehensive monitoring systems, becomes imperative to enhance the safety and reliability of emergency lighting systems using Li-ion batteries.

SUMMARY OF THE INVENTION

It would be advantageous to obtain a driver that is to be connected to a Battery Management System, BMS, wherein the driver is adapted to prevent unsafe situations at the BMS side.

It would further be advantageous to obtain a corresponding method and a computer program product.

In a first aspect of the present disclosure, there is provided a driver arranged to be connected to a Battery Management System, BMS, said BMS comprising a battery, wherein the driver comprises: a voltage control unit arranged to control a voltage provided to said BMS for charging said battery, wherein said voltage provided to said BMS gradually increases to a charging voltage; a current control unit arranged to control a current provided to said BMS wherein said current provided to said battery is set at a safety current value during a time that said voltage gradually increases and is then increased to a nominal current value once said charging voltage has been reached.

The present disclosure is directed to a system comprising a driver, for example an emergency driver, and a battery pack. The battery pack comprises a Battery Management System, BMS, arranged for managing and optimizing the performance of a battery. It may perform all kinds of operations to ensure the safe and efficient operation of the battery.

The driver in accordance with the present disclosure may be an emergency driver. An emergency driver is a component of a system designed to provide emergency lighting in situations where the primary power source fails. It is typically used in buildings, such as commercial spaces, offices, or residential complexes, to ensure that there is sufficient illumination during power outages or emergencies.

The emergency driver is responsible for supplying power to emergency lighting fixtures, such as exit signs or emergency lights. It is specifically designed to operate with a battery system, which stores electrical energy to be used in case of a power failure.

When the primary power source is functioning normally, the emergency driver may charge the battery, ensuring that it remains in a ready state to provide power during an emergency. It monitors the battery's charge level and ensures that it is maintained at a particular level for quick response and extended runtime when needed.

In the event of a power outage, the emergency driver may detect the loss of the main power supply and automatically switches to battery mode. It activates the emergency lighting fixtures connected to it, allowing them to remain illuminated. The emergency driver may regulate the power output to the fixtures, ensuring that they receive a steady and reliable power supply for the duration of the emergency.

Typically, the BMS is connected to the driver using a + and - connection. Sometimes an additional input is provided to the driver in the form of a Negative Temperature Coefficient, NTC, resistor. The BMS does not have a separate communication line to the driver for communication purposes. There is typically no intelligence available at the BMS to inform the driver on whether a particular situation that has arisen is safe or unsafe.

In prior art solutions, typically, the full charger voltage is provided to the BMS upon connection of the battery.

The present disclosure aims at a different approach. Instead of directly switching the full release voltage on the BMS with no current limiter, it is proposed to provide a gradually increasing voltage to the BMS. The BMS is arranged to connect said battery once said voltage reaches the full release voltage.

During the above-described period of time in which the voltage is gradually increasing, the current may be set at a safety current value and is then increased to a nominal current value once said charging voltage has been reached The safety current value is, of course, lower compared to the nominal current value.

One of the advantages of the present disclosure, in view of the prior art solution, is that the maximum charge current is no longer pushed into the battery without checking the charger/battery voltage. This prevents unsafe conditions to occur at the battery side.

It is noted that the terminology Battery Management System is used throughout this particular disclosure. It is explicitly noted that a Protection Circuit Module is encompassed by this particular wording. The Protection Circuit Module, PCM, is typically an electronic circuit often incorporated into batteries to provide various safety features and protection mechanisms. The PCM may help to prevent overcharging, over-discharging, and excessive current flow, which may be harmful to the battery and the devices it powers.

The driver in accordance with the present disclosure is described as having a voltage control unit and a current control unit. It is noted that such a driver may encompass any type of Switched Mode Power Supply, SMPS. The SMPS may have a controller, like a micro-controller, to control the corresponding SMPS. The particular functions of the voltage control unit and the current control unit may be embodied in such a controller.

The voltage control unit and the current control unit may thus be implemented as a logical framework that is executed by the controller, for example in the form of software, flow charts and/or algorithms.

In an example, the voltage control unit is arranged to gradually increase said charging voltage by stepwise increments.

This means that the voltage is incremented or raised in discrete steps or increments, rather than changing continuously or smoothly.

In a stepwise voltage increase, the voltage level is increased in specific predefined intervals or steps, rather than having a gradual or continuous change. Each step may represent a distinct voltage level.

For example, consider a scenario where the voltage is stepwise increased by 1 volt every second. Initially, the voltage might be at 0 volts. After the first second, it increases to 1 volt. After the 2^nd second, it further increases to 2 volts, and so on. The voltage changes abruptly from one step to the next, without any gradual transition.

In a further example, the current control unit is arranged to gradually increase said current from said safety current value to said nominal current value once said charging voltage has been reached. This entails that the current is maintained at the safety current value during the time that the voltage is gradually increase. Once the voltage reaches it charging voltage, the current is gradually increased. The current is increased until a maximum charging current has been reached.

In an example, the current control unit is arranged to gradually increase said current from said safety current value to said nominal current value once said charging voltage has been reached, by stepwise increments.

In another example, the driver comprises: a processing unit arranged for keeping track of a number of times said battery is disconnected within a predefined time window and for stopping said providing said voltage and said current to said BMS when said number of times exceed a predefined reset counter.

The processing unit may, for example, be a microcontroller, a Field Programmable Gate Array, FPGA, an Application Specific Integrated Circuit, ASIC, an Integrated Circuit, IC, or anything alike.

The inventors have found that it may be beneficial to stop trying to charge the battery once it is clear that the BMS has been reset a couple of times within a predefined time window. This would be superfluous as it may be clear that an erroneous situation may be applicable. This would prevent any possible unsafe condition at the battery side.

In another example, the driver further comprises: a processing unit arranged for keeping track of a time required for said battery to charge to a battery voltage and for stopping said providing said voltage and said current to said BMS when said tracked time exceeds of predefined time period.

In a further example, the voltage control unit is arranged for determining that a voltage over said battery is above a predefined safety threshold, and for triggering said current control unit to start with gradually increasing said current provided to said battery.

In a second aspect of the present disclosure, there is provided a method for managing a driver in accordance with any of the previous examples, wherein said driver is arranged for driving a Battery Management System, BMS, wherein said BMS comprises a battery, wherein said method comprises the steps of: controlling, by said voltage control unit, a voltage provided to said BMS for charging said battery, wherein said voltage provided to said BMS gradually increases to a charging voltage; controlling, by a current control unit, a current provided to said BMS, wherein said current provided to said BMS is set at a safety current value during a time that said voltage gradually increases and is then increased to a nominal current value once said charging voltage has been reached.

It is noted that the advantages as explained with respect to the first aspect of the present disclosure, being the driver, are also applicable for the second aspect of the present disclosure, being the method for managing the driver.

In an example, the step of controlling said voltage comprises: gradually increasing said charging voltage by stepwise increments.

In a further example, the step of controlling said current comprises: gradually increasing said current from said safety current value to said nominal current value once said charging voltage has been reached.

In another example, the step of gradually increasing comprises: gradually increasing said current from said safety current value to said nominal current value once said charging voltage has been reached, by stepwise increments.

In an example, the driver further comprises a processing unit, and wherein said method comprises the step of: keeping track, by said processing unit, of a number of times said battery is disconnected within a predefined time window and for stopping said providing said voltage and said current to said BMS when said number of times exceed a predefined reset counter.

In an example, the driver comprises a processing unit, and wherein said method comprises the step of: keeping track, by said processing unit, of a time required for said battery to charge to a battery voltage and for stopping said providing said voltage and said current to said BMS when said tracked time exceeds of predefined time period.

In a further example, the method comprises the step of: determining, by said voltage control unit, that a voltage over said battery is above a predefined safety threshold, and for triggering said current control unit to start with gradually increasing said current provided to said battery.

In a third aspect of the present disclosure, there is provided a computer program product comprising a computer readable medium having instructions stored thereon which, when executed by a driver, cause said driver to implement a method in accordance with any of the examples provided above.

In the appended figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

The above and other aspects of the disclosure will be apparent from and elucidated with reference to the examples described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 discloses waveforms related to a too-deep discharge condition of the battery;

Fig. 2 discloses waveforms related to a short-circuit cell condition of the battery;

Fig. 3 discloses an example of a Battery Management System, BMS;

Fig. 4 discloses further waveforms related to a short-circuit cell condition of the battery;

Fig. 5 discloses an example of a driver connected to a Battery Management System, BMS.

DETAILED DESCRIPTION OF THE EMBODIMENTS

It is noted that in the description of the figures, same reference numerals refer to the same or similar components performing a same or essentially similar function.

A more detailed description is made with reference to particular examples, some of which are illustrated in the appended drawings, such that the manner in which the features of the present disclosure may be understood in more detail. It is noted that the drawings only illustrate typical examples and are therefore not to be considered to limit the scope of the subject matter of the claims. The drawings are incorporated for facilitating an understanding of the disclosure and are thus not necessarily drawn to scale. Advantages of the subject matter as claimed will become apparent to those skilled in the art upon reading the description in conjunction with the accompanying drawings. The ensuing description above provides preferred exemplary embodiment(s) only, and is not intended to limit the scope, applicability or configuration of the disclosure. Rather, the ensuing description of the preferred exemplary embodiment(s) will provide those skilled in the art with an enabling description for implementing a preferred exemplary embodiment of the disclosure, it being understood that various changes may be made in the function and arrangement of elements, including combinations of features from different embodiments, without departing from the scope of the disclosure.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." As used herein, the terms "connected," "coupled," or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, electromagnetic, or a combination thereof. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word "or," in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

These and other changes can be made to the technology in light of the following detailed description. While the description describes certain examples of the technology, and describes the best mode contemplated, no matter how detailed the description appears, the technology can be practiced in many ways. Details of the system may vary considerably in its specific implementation, while still being encompassed by the technology disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the technology should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the technology with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the technology to the specific examples disclosed in the specification, unless the Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the technology encompasses not only the disclosed examples, but also all equivalent ways of practicing or implementing the technology under the claims. Fig. 1 discloses waveforms 1 related to atoo-deep discharge condition of the battery.

At the left hand side 2a, waveforms 2b, 2c, 2d, 2e, 2f are shown that relate to the prior art. At the right hand side 3a, waveforms 3b, 3c, 3d, 3e, 3f are shown that relate to the driver, and Battery Management System, BMS, in accordance with the present disclosure.

The scenario that is depicted relates to a too-deep discharge condition of the battery.

This refers to a situation where a battery is discharged to a very low voltage or depleted to a level that may be considered harmful or detrimental to its overall health and performance.

Batteries may have a specific voltage range within which they operate optimally. If a battery is discharged beyond its recommended depth of discharge, it can lead to several negative consequences, including reduced capacity, decreased lifespan, and potential damage to the battery.

When a battery is discharged, its voltage gradually drops as energy is consumed. Each type of battery chemistry has a specific lower voltage limit beyond which it should not be discharged. Discharging a battery beyond this limit can cause irreversible chemical reactions within the battery cells, resulting in loss of capacity and potentially rendering the battery unusable.

For example, in the case of a lithium-ion battery, discharging it below a certain voltage, typically between 2.0 to 2.7 volts per cell, can lead to deep discharge. Deep discharge can cause the formation of lithium plating on the battery's electrodes, which can lead to reduced capacity, increased internal resistance, and even safety hazards such as cell rupture or thermal runaway.

The waveforms as indicated with reference numeral 2a are split into multiple phases 4, 5, 6.

In phase 4, the internal voltage of the battery decreases to a particular low voltage level. This low voltage level is, in this case, 7.5V. Below this particular value, it is assumed that the battery in in a too-deep discharge condition.

The external voltage, i.e. the voltage at the pins of the battery pack, as indicated with reference numeral 2c, follows the same trajectory as indicated in phase 4. Once the particular low voltage level is reached, the BMS comes into play.

The BMS has connected the battery to the outside world in the phase 4, but disconnects the battery in phase 5, as the battery is in a too-deep discharge condition. This is clear from the waveform shown in figure 2c, as the external voltage drops to zero volt - the battery is not connected.

The internal voltage of the battery, i.e. 2b, will see a small increase in voltage as the battery is disconnected such that no load is connected.

The phase 6 is initiated by the driver providing 2e a voltage, and a current 2f, to the BMS. The BMS will then connect 2d the battery such that the charger voltage as well as the charger current is provided to the battery.

The waveforms as indicated with reference numeral 3a are split into multiple phases 7, 8, 9, 10, 11. These waveforms correspond to the operation of the driver in accordance with the present disclosure.

In this particular case, phase 7 is the same as phase 4. The BMS has connected the battery to the outside world in phase 7 but disconnects the battery in phase 8 as the battery is in a too-deep discharge condition.

As shown in the waveform 2e, the charger voltage is fully applied to the BMS in prior art solutions. The present disclosure aims at gradually increasing the voltage provided to the BMS, as shown in waveform 3e. During this period of time, the charger current is kept relatively low, i.e. to a safety current value.

Once the charger voltage has reached a particular limit, the BMS connects the battery back to the outside world as indicated in phase 10. In phase 10, the charger current is then ramped up to the nominal charging level, for example a maximum charging current. Phase 11 is again comparable to phase 6 of the prior art solution.

Fig. 2 discloses waveforms related to a short-circuit cell condition of the battery.

At the left hand side 52a, waveforms 52b, 52c, 52d, 52e, 52f are shown that relate to the prior art. At the right hand side 53a, waveforms 53a, 53b, 53c, 53d, 53e, 53f are shown that relate to the driver, and Battery Management System, BMS, in accordance with the present disclosure.

The scenario that is depicted relates to a short-circuit cell condition. This may, for example, be caused by a low resistance path within the particular cell. This may consume the energy and the corresponding cell may appear to be faulty or discharged.

Reference is first made to the figure indicated with reference numeral 52b. Here, it is shown that the internal voltage of the battery starts to drop. After a while, the voltage may suddenly drop to below a particular low voltage level. In this example, the particular low voltage level is set at 7.5V. As mentioned, in this particular case, the voltage drops due to a short circuit cell condition.

In the prior art, the BMS will connect the battery from the outside world such that the external voltage of the battery drops to 0V. This is shown in figures as indicated with reference numerals 52c and 52d.

After a particular time period has passed, the BMS will try to connect the battery again to the corresponding load. As such, the charger voltage is instantly increased to about 12V and the charger current is instantly increase to the maximum charging current. This is shown in figures having reference numerals 52d, 52e and 52f

At the right hand side, the waveforms 53a are shown that correspond to the method in accordance with the present disclosure. The waveforms are indicated with reference numerals 53b, 53c, 53d, 53e and 53f

The difference is that there is a build-up of the charging voltage as indicated with reference numeral 53e. The charging voltage is gradually increased, while the current is fixed at a certain small amount.

Because there is a faulty condition at the battery side, the process will also repeat itself. However, in this particular scenario, no hazardous situation may occur given that the current is relatively low.

Fig. 3 discloses an example of a Battery Management System, BMS 101.

As mentioned in the previous paragraphs, there is a difference between the external battery voltage 102 and the internal battery voltage 103. The external battery voltage is provided to the “outside world”, and is thus present on the connecting terminals of the battery. The internal voltage is the voltage over the cells of the battery internally.

The BMS may be equipped with a series connection of a P-channel and an N- channel switch, for example Metal Oxide Semiconductor, MOS, Field Effect Transistor, FET.

Typically, the charging FET 104 is enabled when the battery is to be charged. The discharging FET 105 is enabled when the battery may be discharged.

In the case that a BMS is equipped with such a connection of a P-channel and N-channel MOSFET, it may become more complex as charging with a current limited charger may still be possible as long as the overcurrent protection is not triggered. This is indicated with the arrow having reference numeral 106.

The result is that the BMS may not switch off the battery (pack) and thus that unsafe conditions may occur. Fig. 4 discloses further waveforms related to a short-circuit cell condition of the battery in this particular situation.

At the left hand side, again the waveforms are shown that relate to the prior art when such a BMS resets after short-circuit in the cell of the battery. The waveforms are indicated with reference numerals 202b, 202c, 202d, 202e and 202f.

What is apparent here is that the charger current 202f may still flow towards the battery even when the BMS has disconnected the battery 202d. This may cause an undesired situation at the battery side.

The waveforms as indicated with reference numerals 203b, 203c, 203d, 203e and 203f relate to the present disclosure when such a BMS resets after a short-circuit in the cell of the battery.

In this particular case, the charger voltage again slowly ramps up, and the charger current is fixed at a certain minimum. A protection time-out mechanism may be implemented. In the prior art, the driver may continue to push the maximum current into the battery without checking the battery voltage. The present disclosure describes that the battery voltage may be checked and, if the battery voltage does not seem to change withing a predefined time window, the charging may be cancelled. This is indicated in the waveforms 203e and 203f.

Fig. 5 discloses an example 301 of a driver 302 connected to a Battery Management System, BMS 304. The BMS 304 comprising a battery. The BMS 304 is connected to the driver 302 using two supply lines, a +line and a -line. Optionally an NTC connection 305 may be established between the driver 302 and the BMS 304.

To reduce the number of claims, certain aspects of the technology are presented below in certain claim forms, but the applicant contemplates the various aspects of the technology in any number of claim forms. For example, while some aspect of the technology may be recited as a computer-readable medium claim, other aspects may likewise be embodied as a computer-readable medium claim, or in other forms, such as being embodied in a means-plus-function claim.

In the description above, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of implementations of the disclosed technology. It will be apparent, however, to one skilled in the art that embodiments of the disclosed technology may be practiced without some of these specific details.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope thereof.

Claims

1. A driver (302) arranged to be connected to a Battery Management System, BMS (304), said BMS (304) comprising a battery, wherein the driver (302) comprises: a voltage control unit arranged to control a voltage (3e, 53e) provided to said BMS (304) for charging said battery, wherein said voltage (3e, 53e) provided to said BMS (304) gradually increases to a charging voltage; a current control unit arranged to control a current (3f, 531) provided to said BMS (304) wherein said current (3f, 531) provided to said battery is set at a safety current value during a time that said voltage gradually increases and is then increased to a nominal current value once said charging voltage has been reached, a processing unit arranged for: keeping track of a number of times said battery is disconnected within a predefined time window and for stopping said providing said voltage and said current to said BMS (304) when said number of times exceed a predefined reset counter; and/or keeping track of a time required for said battery to charge to a battery voltage and for stopping said providing said voltage and said current to said BMS (304) when said tracked time exceeds of predefined time period.

2. A driver (302) in accordance with claim 1, wherein said voltage control unit is arranged to gradually increase said charging voltage by stepwise increments.

3. A driver (302) in accordance with any of the previous claims, wherein said current control unit is arranged to gradually increase said current from said safety current value to said nominal current value once said charging voltage has been reached.

4. A driver (302) in accordance with claim 3, wherein said current control unit is arranged to gradually increase said current from said safety current value to said nominal current value once said charging voltage has been reached, by stepwise increments.

5. A driver (302) in accordance with any of the previous claims, wherein said voltage control unit is arranged for determining that a voltage over said battery is above a predefined safety threshold, and for triggering said current control unit to start with gradually increasing said current provided to said battery.

6. A method for managing a driver (302) in accordance with any of the previous claims, wherein said driver (302) is arranged for driving a Battery Management System, BMS (304), wherein said BMS (304) comprises a battery, wherein said method comprises the steps of: controlling, by said voltage control unit, a voltage provided to said BMS (304) for charging said battery, wherein said voltage provided to said BMS (304) gradually increases to a charging voltage; controlling, by a current control unit, a current provided to said BMS (304), wherein said current provided to said BMS (304) is set at a safety current value during a time that said voltage gradually increases and is then increased to a nominal current value once said charging voltage has been reached.

7. A method in accordance with claim 6, wherein said step of controlling said voltage comprises: gradually increasing said charging voltage by stepwise increments.

8. A method in accordance with any of the claims 6 - 7, wherein said step of controlling said current comprises: gradually increasing said current from said safety current value to said nominal current value once said charging voltage has been reached.

9. A method in accordance with claim 8, wherein said step of gradually increasing comprises: gradually increasing said current from said safety current value to said nominal current value once said charging voltage has been reached, by stepwise increments.

10. A method in accordance with any of the claims 6 - 9, wherein said driver (302) further comprises a processing unit, and wherein said method comprises the step of: keeping track, by said processing unit, of a number of times said battery is disconnected within a predefined time window and for stopping said providing said voltage and said current to said BMS (304) when said number of times exceed a predefined reset counter.

11. A method in accordance with any of the claims 6 - 10, wherein said driver (302) comprises a processing unit, and wherein said method comprises the step of: keeping track, by said processing unit, of a time required for said battery to charge to a battery voltage and for stopping said providing said voltage and said current to said BMS (304) when said tracked time exceeds of predefined time period.

12. A method in accordance with any of the claims 6 - 11, wherein said method comprises the step of: determining, by said voltage control unit, that a voltage over said battery is above a predefined safety threshold, and for triggering said current control unit to start with gradually increasing said current provided to said battery.

13. A computer program product comprising a computer readable medium having instructions stored thereon which, when executed by a driver (302), cause said driver (302) to implement a method in accordance with any of the claims 6 - 12.