Battery management system, electric vehicle, method and control unit

Abstract

A battery management system for an electric vehicle is provided. The battery management system includes a first load connector, a second load connector, a first switch, a first battery connector, a second battery connector, and a control unit. The first load connector is connectable to a first group. The second load connector is connectable to a second group. The first battery connector is connectable to a first battery. The second battery connector is connectable to a second battery. The battery management system is adapted to transfer electrical energy from the first battery to the first group and the second group via the first switch. The battery management system is adapted to connect the second battery to the second group. The control unit is configured to receive a signal indicating a dangerous situation for the first battery. In response to the signal, the control unit is configured to switch the first switch to disconnect the first battery from the first group and the second group and start transferring electrical energy from the second battery to the second group.

Description

[Technical field]

[0001] The present invention relates to a battery management system for an electric vehicle. The present invention further relates to an electric vehicle including a battery management system. The present invention further relates to a method for transferring electric energy. Furthermore, the present invention relates to a control unit for use in a battery management system. [Background technology]

[0002] An electric vehicle, such as an electric car, has a battery for storing electric energy. The electric vehicle has various loads that consume electric energy. A load is a device or system in the electric vehicle that requires electric energy to operate. The larger the electrical capacity of the battery, the longer the load can be operated without needing to recharge the battery. However, the larger the electrical capacity of the battery, the larger and heavier the battery will be. Therefore, the selection of a certain electrical capacity for an electric vehicle is a trade-off based on the desired electrical capacity, the volume available within the electric vehicle, and the mass of the battery.

[0003] Some types of batteries have a higher electrical capacity per unit volume and per unit mass than other types of batteries. For example, lead-acid batteries have been commonly used in the automotive industry for several decades. Lead-acid batteries typically have a specific energy value of about 30 Wh / kg (watt-hours per kilogram) and an energy density of about 70 Wh / L (watt-hours per liter). A newer type of battery is the lithium-based battery, such as the lithium-ion battery. Lithium-based batteries are rechargeable batteries with a specific energy value of about 135 Wh / kg and an energy density of about 195 Wh / L. Thus, lithium-based batteries have about 4 to 5 times the electrical capacity of a lead-acid battery of the same weight. Lithium-based batteries have about 2.8 times the electrical capacity of a lead-acid battery of the same weight.

[0004] Due to the improved electrical capacity, many electric vehicles are equipped with lithium-based batteries. However, lithium-based batteries have the disadvantage that the lithium-based batteries may cause fires or may produce toxic gases upon damage or electrical failure. Therefore, safety regulations require that electric vehicles have a safety system that can disconnect the lithium-based battery. By disconnecting the lithium-based battery in a timely manner, fires or toxic gases can be prevented. To ensure that the electric vehicle can be operated for a sufficient amount of time after the lithium-based battery is disconnected, the electric vehicle is equipped with a lead-acid battery. Since the lead-acid battery is inherently safe, the lead-acid battery can provide electrical energy when the lithium-based battery is disconnected. However, since both the lithium-based battery and the lead-acid battery are required to provide energy to operate the vehicle, a large volume and a large mass are required for energy storage. Summary of the Invention [Problem to be solved by the invention]

[0005] It is an object of the present invention to provide a battery management system for electric vehicles that is less affected by the above-mentioned disadvantages, or to provide at least an alternative battery management system. [Means for solving the problem]

[0006] The object of the present invention is achieved by a battery management system for an electric vehicle. The battery management system includes a first load connector, a second load connector, a first switch, a first battery connector, a second battery connector, and a control unit. The first load connector is connectable to a first group of at least one first load. The second load connector is connectable to a second group of at least one second load. The second group is different from the first group. The first battery connector is connectable to a first battery. The second battery connector is connectable to a second battery. The battery management system is adapted to transfer electric energy from the first battery to the first group and the second group via the first switch. The battery management system is adapted to connect the second battery to the second group. The control unit is configured to receive a signal indicative of a dangerous situation for the first battery. Within the meaning of the present invention, the dangerous situation for the first battery may refer to an ambient environment of the battery management system and / or may refer to one or more internal characteristics related to the first battery. The dangerous situation related to the surrounding environment of the battery management system is, for example, an emergency occurring outside the battery management system. An example of when the dangerous situation is related to the surrounding environment of the battery management system is that the vehicle is in a crash, accident, or crush state. Alternatively, the dangerous situation is related to one or more internal characteristics related to the first battery. The one or more internal characteristics related to the first battery are, for example, a temperature, a voltage, or a state of charge (SOC) of the first battery. For example, the dangerous situation may occur when the temperature of the first battery becomes unacceptably high. The control unit is configured to switch the first switch to disconnect the first battery from the first group and the second group and start transferring electric energy from the second battery to the second group in response to the signal.

[0007] When no dangerous situation exists for the first battery, the battery management system transfers electric energy from the first battery to the first group and the second group of the vehicle. In this way, the vehicle is operated in a normal mode. When a dangerous situation occurs for the first battery, the control unit receives a signal. In response to the signal, the control unit switches a first switch. By switching the first switch, the first battery is disconnected from the first group and the second group, preventing the first battery from transferring energy to the first group and the second group. By disconnecting the first battery from the first group and the second group, the risk of the first battery resulting in fire or toxic gas is reduced or completely eliminated. By starting to transfer electric energy from the second battery to the second group, some loads of the electric vehicle are supplied with electric energy from the second group. The loads in the first group are allowed to stop in the safety mode, while the loads in the second group are selected as critical loads to remain operable in the safety mode. As a result of supplying electrical energy to the second group instead of the first group, the electrical capacity of the second battery may be less than the electrical capacity of the first battery, but still supply electrical energy to the second group for a sufficient amount of time. In this way, the battery management system creates a safe situation when the first battery is at risk, without requiring a large volume or mass of energy storage.

[0008] The battery management system may include, for example, a single circuit or may be a combination of multiple circuits integrated together. For example, the battery management system may include a DC circuit, an AC circuit, or a combination of a DC circuit and an AC circuit. The battery management system may include various electrical components, for example, circuit breakers, converters, resistors, capacitors, inductors, etc. The battery management system may include, for example, electrical wires for transmitting electrical energy. For example, the battery management system may be adapted to use the body of an electric vehicle to conduct electrical current.

[0009] The electric vehicle is, for example, a car or a truck or a bus. For example, the electric vehicle is a bicycle or a motorbike. For example, the electric vehicle is a plane or a watercraft such as a boat.

[0010] The first load connector is a connector suitable for connecting to at least one load of the first group. For example, the first load connector is a single connector for connecting to a single wire of the first group. The single wire of the first group is, for example, split into multiple wires, each for a different load in the first group. For example, the first load connector includes multiple connectors for connecting to multiple loads of the first group in parallel. The first load connector includes a removable connector, for example, a plug or jack or a screw terminal or a blade connector. The first load connector is adapted to permanently connect to the first group, for example, by welding or gluing or soldering.

[0011] The second load connector is a connector suitable for connecting to at least one load of the second group. For example, the second load connector is a single connector for connecting to a single wire of the second group. The single wire of the second group is, for example, split into multiple wires, each for a different load in the second group. For example, the second load connector includes multiple connectors for connecting in parallel to multiple loads of the second group. The second load connector includes a removable connector, for example, a plug or jack or a screw terminal or a blade connector. The second load connector is adapted to permanently connect to the second group, for example, by welding or gluing or soldering, etc. The first load connector and the second load connector include, for example, the same type of connector or different types of connectors.

[0012] The first group has at least one first load. The first group has only one load or has multiple loads. The first group has loads that are used in normal mode and not in safety mode. For example, the loads from the first group are related to comfort for people in the cabin of the vehicle. For example, the first group includes a seat heater and / or a motor for adjusting a seat. For example, the first group includes a power outlet in the cabin. For example, the first group includes a radio for listening to music. It may be inconvenient that the loads in the first group do not function in safety mode. However, this does not or is unlikely to lead to an unsafe situation.

[0013] The second group has at least one second load. The second group has only one load or has multiple loads. The loads in the second group are different from the loads in the first group. There is no load that is in both the first group and the second group. The second group has loads that are used in the normal mode and also in the safety mode. For example, the loads in the second group are directly related to the operation of the vehicle. For example, the second group includes a system for controlling the steering of the vehicle and / or a system for controlling the braking of the vehicle. In this way, the driver of the vehicle can safely drive and stop the vehicle in the appropriate place in the safety mode. For example, the second group includes a lighting system for providing light. The lighting system includes, for example, at least one front headlight. The front headlight illuminates the road in front of the vehicle to enable the driver to safely drive the vehicle to the appropriate place in the safety mode, especially at night. The lighting system includes, for example, lights arranged to show the outline of the vehicle. This allows other traffic to clearly see the electric vehicle when the vehicle is parked in the safety mode. The lighting system may, for example, include hazard lights or indicators to notify other traffic that the electric vehicle has a malfunction and to be careful.

[0014] The first battery connector is any connector suitable for connecting to the first battery. For example, the first battery connector includes two terminals, each of which is connected to a pole of the first battery. For example, the first battery connector includes an SAE Post type connector or a JIS type connector or an L terminal. The first battery connector includes, for example, one or more threaded posts.

[0015] The second battery connector is any connector suitable for connecting to the second battery. For example, the second battery connector includes two terminals, each of which is connected to a pole of the second battery. For example, the second battery connector includes an SAE Post type connector or a JIS type connector or an L terminal. The second battery connector includes, for example, one or more threaded posts.

[0016] The battery management system is adapted to connect a first battery to the first switch via the first battery connector and from the first switch to the first group via the first load connector. The battery management system is adapted to connect the first battery to the first switch via the first battery connector and from the first switch to the second group via the second load connector. The battery management system is adapted to connect a second battery to the second load connector via the second battery connector and to the second group via the second load connector.

[0017] The first switch can connect the first battery to the first group and the second group in a normal mode, and can disconnect the first battery from the first group and the second group in a safety mode. The first switch is a single switch or is formed by multiple switches. For example, the first switch includes one or more switches for connecting the first battery to all the loads of the first group. For example, the first switch includes one or more switches for connecting the first battery to all the loads of the second group. For example, the first switch includes a relay switch. For example, the first switch includes a transistor. For example, the first switch includes an electronic switch such as a DC contactor or a MOSFET.

[0018] The first battery is, for example, a lithium-based battery. For example, the first battery has a large electrical capacity that can supply the loads in the first group and the second group for a long period of time, such as at least one hour or several hours. The first battery is a single battery or is formed by a plurality of batteries connected to each other. The plurality of batteries are, for example, connected to each other in series or in parallel. In one example, the first battery has some batteries arranged in series and some batteries arranged in parallel to each other. The first battery is, for example, a rechargeable battery.

[0019] The second battery is, for example, a safer battery than the first battery. The second battery is, for example, a lead-acid battery. The second battery is, for example, an LTO battery or a solid-state battery or a supercapacitor. For example, the second battery has a small electrical capacity that can supply the loads in the second group for a short period of time, such as a few minutes or half an hour. For example, the second battery has an electrical capacity that can supply the loads in the second group for a long period of time, such as many minutes or hours. To obtain a long period of time, for example, only a few loads are present in the second group and / or the loads in the second group require only a small amount of power. The second battery is a single battery or is formed by multiple batteries connected to each other. The multiple batteries are, for example, connected to each other in series or in parallel. In one example, the second battery has several batteries arranged in series and several batteries arranged in parallel to each other. The second battery is, for example, a rechargeable battery.

[0020] In one embodiment, the second battery is the same type of battery as the first battery. For example, both the first battery and the second battery are lithium-based batteries. If a dangerous situation occurs for one of the lithium-based batteries, the other lithium battery takes over. For example, one of the lithium-based batteries has a dangerously high temperature, while the other battery has an acceptable temperature. Safety regulations may require that the second battery be connected to the second group through a switch similar to the first switch. In this embodiment, both lithium-based batteries may need to be disconnected from the second group at the same time. This may occur if a dangerous situation occurs for both lithium-based batteries. However, depending on the application, the risk of this occurring may be acceptably low. This risk may be acceptable, for example, when the electric vehicle is designed to operate at low speeds, such as less than 25 km / h or less than 10 km / h, or when the electric vehicle operates only within a non-public environment, such as a factory site.

[0021] The control unit receives a signal indicative of a dangerous situation for the first battery. The signal is provided, for example, by a sensor. The sensor is adapted to provide a signal indicative of a dangerous situation for the first battery. For example, the sensor is a temperature sensor for sensing a temperature of the first battery. In a situation where the temperature exceeds a threshold value, the first battery may be damaged. When the temperature exceeds the threshold value, the sensor provides a signal. For example, the sensor is a current sensor for sensing a current through the first battery. In a situation where the current exceeds a maximum value, the first battery may be damaged. When the current exceeds the maximum value, the sensor provides a signal. For example, the sensor is an acceleration sensor for sensing an acceleration of the electric vehicle. In a situation where the vehicle has crashed, the vehicle experiences an acceleration. For example, the acceleration is greater than a maximum deceleration that can result in braking. For example, the acceleration is in a direction different from the direction of motion of the vehicle. For example, the vehicle accelerates without using a brake and / or a propulsion unit to achieve that acceleration. During the crash, the first battery may be damaged. The sensor determines that a crash has occurred based on the acceleration of the electric vehicle and provides a signal accordingly. Another dangerous situation is, for example, the electric vehicle accidentally entering water, such as a pond or a river. For example, the sensor is adapted to provide a signal when the electric vehicle is in water. In this situation, people inside the vehicle may be electrocuted by the first battery through the water. To improve safety, the control unit disconnects the first battery.

[0022] In one example, the signal is provided by a safety switch. For example, when an operator of the vehicle visually perceives a dangerous situation, the operator presses a safety switch. In response, the safety switch provides a signal. For example, the safety switch is a forced stop switch. In one example, the safety switch is a deadman switch. The deadman switch provides a signal if the operator of the vehicle leaves or is disabled from the vehicle.

[0023] The control unit receives a signal. For example, the control unit has terminals for receiving a signal from a sensor or from a safety switch. For example, the control unit receives a signal via a wire. For example, the control unit receives a signal via wireless communication. The control unit receives a single signal, for example, from a single sensor. In another example, the control unit receives signals from multiple sensors. For example, the control unit performs signal processing to determine whether to switch the first switch. For example, the control unit may only open the first switch when the sensor provides a signal for a certain amount of time. For example, the control unit is configured to open the first switch based on one or more other parameters of the vehicle. The control unit includes, for example, a microprocessor. For example, the control unit includes a memory for storing software.

[0024] The control unit is configured to switch the first switch to disconnect the first battery, for example by providing a control signal to the first switch, in response to the control signal the first switch switches and disconnects the first battery from the first group and the second group.

[0025] The control unit is configured to start transferring electrical energy from the second battery to the second group. For example, the control unit is configured to switch a switch between the second battery and the second group to connect the second battery and the second group to each other. For example, the control unit causes the second battery to transfer electrical energy to the second group by stopping the transfer of energy from the first battery to the second group. By stopping the transfer of energy from the first battery, the voltage of the second group is reduced due to the first battery. This causes the voltage of the second battery to generate a current to the second group. As a result, electrical energy is transferred from the second battery to the second group. In another example, the control unit is configured to control the second battery to start transferring electrical energy.

[0026] In one embodiment, the control unit is adapted to receive a signal while the battery management system transfers electrical energy from the first battery to the first group and the second group.

[0027] According to this embodiment, the first battery is in the process of supplying electrical energy to the first group and the second group when the control unit receives a signal. For example, the electric vehicle is driving and the first battery is transferring electrical energy to the loads in the first group and the second group. While the electric vehicle is driving, a dangerous situation for the first battery occurs. The control unit receives a signal indicating the dangerous situation. The control unit then disconnects the first battery from the first group and the second group. The second battery provides electrical energy to the second group to enable the loads in the second group to help safely stop the vehicle.

[0028] In one embodiment, the control unit is configured to, in response to the signal, initiate the transfer of electrical energy from the second battery to only the second group.

[0029] According to this embodiment, the second battery begins transmitting electrical energy only to the second group and not to loads outside the second group, and the second group does not receive any electrical energy from batteries other than the second battery in the safe mode.

[0030] In one embodiment, the battery management system includes a charge controller connectable to the second battery, the charge controller configured to maintain the second battery in a fully charged state at least while the battery management system transfers electrical energy from the first battery to the first group and the second group.

[0031] According to this embodiment, in order to ensure that the electric vehicle can remain operable in the safety mode for as long as possible, the charge controller maintains the second battery in a fully charged state. When the vehicle is operated in the normal mode, the battery management system transfers electric energy from the first battery to the first group and the second group. At least during the normal mode, the charge controller keeps the second battery fully charged. Optionally, the charge controller also maintains the second battery in a fully charged state when the vehicle is not in the normal mode. For example, the charge controller also maintains the second battery in a fully charged state when the vehicle is not operating, such as when parked or charging the battery. For example, the charge controller is adapted to receive electric energy from the first battery to maintain the second battery in a fully charged state. For example, the charge controller cannot maintain the second battery in a fully charged state in the safety mode.

[0032] In one embodiment, the battery management system includes a first electrical component and a second electrical component. The battery management system is adapted to connect the first group and the second group to each other via the first electrical component. The battery management system is adapted to connect a second battery to the second group via the second electrical component. The first electrical component is adapted to prevent transfer of electrical energy from the second battery to the first group. The second electrical component is adapted to prevent transfer of electrical energy from the first battery to the second battery.

[0033] According to this embodiment, the first group and the second group are electrically connected to each other via the first electrical component. For example, during normal mode, electrical energy from the first battery is transferred to the second group via the first electrical component in parallel with the first group via a portion of the first group. The first electrical component allows a current to pass to transfer electrical energy from the first battery to the second group. However, the first electrical component blocks the passage of a current transferring electrical energy from the second group to the first group or from the second battery to the first group. This prevents problems in the safety mode, since the loads in the first group are prevented from receiving electrical energy from the second battery.

[0034] The second electrical component prevents the transfer of energy from the first battery to the second battery. This prevents the second battery from being recharged during the normal mode in an uncontrolled manner. Many battery types have improved life spans if uncontrolled recharging is prevented. The second electrical component helps the second battery to conserve electrical energy in the normal mode. In this way, the electrical energy of the second battery is conserved for the safety mode.

[0035] In one embodiment, at least one of the first electrical component and the second electrical component includes a diode.

[0036] According to this embodiment, the first electrical component includes a diode, the second electrical component includes a diode, or each of the first electrical component and the second electrical component includes a diode. If the first electrical component includes a diode, the diode is arranged to block current from the second group to the first group while allowing current to flow from the first group to the second group. If the first electrical component includes a diode, the diode is arranged to block current from the second battery to the first group. If the second electrical component includes a diode, the diode is arranged to block current from the first battery to the second battery while allowing current to flow from the second battery to the second group. In this case, the voltage of the second battery is, for example, slightly lower than the voltage of the first battery. The voltage of the second battery is high enough to apply a sufficient voltage to the second group in the safety mode. For example, the voltage of the second battery is 0.1V or 0.2V or 1V lower than the voltage of the first battery. This small difference in voltage causes the diode of the second electrical component to block current from the second battery to the second group in normal mode, while allowing current to pass from the second battery to the second group in safety mode.

[0037] In one embodiment, at least one of the first electrical component and the second electrical component includes a further switch, and the control unit is configured to operate the further switch in response to the signal.

[0038] According to this embodiment, the first electrical component includes a further switch, the second electrical component includes a further switch, or each of the first electrical component and the second electrical component includes a further switch. If the first electrical component includes a further switch, the further switch is set by the control unit to connect the first group and the second group to each other in the normal mode. When the control unit receives a signal, the control unit switches the further switch to disconnect the first group and the second group from each other. If the second electrical component includes a further switch, the further switch is set by the control unit to disconnect the second battery and the second group from each other in the normal mode. When the control unit receives a signal, the control unit switches the further switch to connect the second battery and the second group to each other.

[0039] In one embodiment, an electric vehicle is provided that includes a battery management system according to any of the embodiments disclosed above, a first group, a second group, a first battery, a second battery, and a sensor adapted to provide a signal indicative of a dangerous situation for the first battery.

[0040] In one embodiment, the second battery has a smaller energy capacity than the first battery.

[0041] According to this embodiment, the second battery may have a small weight and / or volume because the energy capacity of the second battery is smaller than the energy capacity of the first battery. For example, the energy capacity of the first battery is larger than 400Wh, or larger than 1000Wh, or larger than 2000Wh, or larger than 3000Wh. For example, the energy capacity of the second battery is smaller than 300Wh, or smaller than 200Wh, or smaller than 100Wh. Since the second battery only needs to supply electric energy to the second group and not to the first group, the small capacity of the second battery is sufficient to supply electric energy to the second group for a sufficiently long time. As a result, the second battery has a reduced weight and a reduced volume.

[0042] In one embodiment, the first battery includes a lithium ion battery and the second battery includes a lead acid battery.

[0043] According to this embodiment, the first battery includes a lithium-ion battery having a very high energy capacity per unit mass and per unit volume. In a normal mode, the large lithium-ion battery is used to supply electrical energy to the loads in the first and second groups for a long time between recharges. In a safe mode, the lead-acid battery provides a safe energy source for the loads in the second group. Since the lead-acid battery does not need to supply electrical energy to the first group, a small size lead-acid battery is sufficient. For a small size lead-acid battery, it is acceptable for the lead-acid battery to have less energy capacity per unit mass and per unit volume than the lithium-ion battery.

[0044] In one embodiment, the sensor is adapted to provide a signal based on a temperature and / or a voltage of the first battery.

[0045] According to this embodiment, a dangerous situation for the first battery occurs when the temperature of the first battery exceeds a certain threshold or when the voltage of the first battery exceeds a certain threshold. In particular, lithium-ion batteries are susceptible to high temperatures and overvoltage. By adapting the sensor to provide a signal based on temperature or voltage, important dangerous situations can be detected. When the sensor detects a dangerous situation and provides a signal, the control unit reacts accordingly.

[0046] In one embodiment, the electric vehicle includes an electric propulsion system for propelling the electric vehicle, and a third battery connected to the electric propulsion system via a battery management system to supply electric energy to the electric propulsion system, the voltage of the third battery being higher than the voltage of the first battery and the voltage of the second battery.

[0047] According to this embodiment, the electric vehicle is propelled by an electric propulsion system, such as an electric motor or an electric turbine or an electric propeller. For example, the electric motor is a motor for driving the wheels, such as an in-wheel motor or a hub motor. Since the electric propulsion system can convert a large amount of electric energy into kinetic energy, the third battery supplies electric energy to the propulsion system at a high voltage, such as greater than 200V, or greater than 300V, or greater than 400V. The electric propulsion system is not a load in the first group or the second group. The load in the first group or the second group converts less electric energy compared to the propulsion system in this embodiment. To improve the safety and efficiency of the vehicle, the voltage of the first battery and the second battery is a low voltage, such as less than 50V, for example 48V, or 24V, or 12V. In one example, the propulsion system is adapted to remain operable in the safety mode. In another example, the propulsion system is adapted to not remain operable in the safety mode.

[0048] In one embodiment, the battery management system includes a second switch. The third battery is connected to the electric propulsion system via the second switch to supply electric energy to the electric propulsion system. The control unit is configured to switch the second switch in response to the signal to disconnect the third battery from the electric propulsion system to cause the third battery to stop transferring electric energy to the electric propulsion system.

[0049] According to this embodiment, the third battery is connected to the electric propulsion system via the second switch. The control unit receives a signal if a dangerous situation exists for the first battery. The dangerous situation for the first battery may also be a dangerous situation related to the third battery. Therefore, in response to receiving the signal, the control unit switches the second switch to disconnect the third battery from the electric propulsion system. This helps to create a safe situation in the event of a collision. In the event of a collision, the electric propulsion system may be damaged. By disconnecting the third battery from the electric propulsion system, the risk of a short circuit in a damaged electric propulsion system is reduced. Also, the risk of electric shock due to a damaged electric propulsion system is reduced or eliminated.

[0050] Alternatively, the third battery remains connected in the safety mode. For example, the battery management system is arranged to transfer electrical energy from the third battery to the second group in the safety mode. For example, a power converter is part of the second group that allows electrical energy from the third battery to be converted and transferred to the second group in the safety mode.

[0051] In one embodiment, the second group includes safety systems of the vehicle.

[0052] According to this embodiment, the second group includes one or more systems related to safety. The electric vehicle may be in operation when the control unit receives a signal indicating a dangerous situation. It is therefore desirable that the electric vehicle can be safely stopped while the second battery supplies electric energy to the second group. The second group therefore includes at least one safety system.

[0053] The safety systems relate to, for example, the motion of the vehicle, for example, the safety systems include steering systems, such as power steering, or braking systems for braking electric vehicles, such as a power braking system, an anti-lock braking system (ABS), or a dynamic stability control system (DSC system).

[0054] For example, the safety system includes a lighting system for providing light. For example, the lighting system provides light ahead of the vehicle, enabling the driver of the electric vehicle to guide the electric vehicle to a suitable place to stop the electric vehicle in a safety mode, especially at night or during bad weather. For example, the lighting system is adapted to activate hazard indicators to warn other traffic that the electric vehicle is in a malfunction. For example, the lighting system is adapted to activate emergency lights inside the vehicle, enabling people to easily find a way out of the electric vehicle, especially at night. Such emergency lights are particularly beneficial when the vehicle is a bus or a train or a passenger ship.

[0055] For example, the safety system includes a telecommunication system for providing remote communication with an emergency service. For example, the telecommunication system is configured to transmit a communication signal to the emergency service when the second battery supplies electric energy to the second group. The communication signal includes information about a current location of the electric vehicle, such as, for example, GPS coordinates. The emergency service is, for example, a service for requesting assistance from the police, fire brigade, or medical services. The emergency service is, for example, a service of a manufacturer or dealer of the electric vehicle. The telecommunication system is, for example, a one-way system adapted only for transmitting communication signals. The telecommunication system is, for example, a two-way system adapted for transmitting and receiving communication signals. For example, the two-way system is a telephone system or a chat message system or a video conferencing system or a two-way radio system.

[0056] For example, the safety system includes an unlocking system for unlocking the doors and / or windows of the vehicle. Many vehicles, particularly automobiles, have a central locking system for locking the doors of the vehicle. For example, the central locking system automatically locks the doors when the vehicle starts. However, the central locking system requires electrical energy to unlock the doors. Therefore, in the safety mode, the second battery supplies electrical energy to the unlocking system to unlock the doors. Additionally or alternatively, the unlocking system unlocks one or more windows of the vehicle. For example, the unlocking system opens one or more windows. By including the unlocking system in the second group, people in the vehicle can safely exit the vehicle in the safety mode.

[0057] In one embodiment, the safety system includes at least one of a lighting system for providing light, a remote communication system for providing remote communication with emergency services, an unlocking system for unlocking doors and / or windows of the vehicle, and a braking system for braking the vehicle.

[0058] In one embodiment, the first group includes at least one of an HVAC system adapted to provide heating, ventilation and / or air conditioning for the vehicle, seat heaters arranged to provide heating for seats within the vehicle, and an entertainment system for providing audio or video.

[0059] According to this embodiment, the first group includes systems that provide comfort to people inside the vehicle. However, such systems may require a large amount of power. By placing these systems in the first group, the second battery can supply electrical energy to the second group for a longer period of time.

[0060] The HVAC system includes, for example, a heater for supplying a heated air flow to a cabin in an electric vehicle. The HVAC system includes, for example, a fan for supplying a fresh air flow from outside the vehicle into the cabin. The HVAC system includes, for example, an air conditioning system for removing heat from the cabin. Although it may be inconvenient for people in the cabin of the vehicle that the HVAC system is not operating in a safety mode, this is unlikely to result in an unsafe situation. In one example, the HVAC system has some loads that receive electrical energy from a first battery, while the HVAC system has other loads that receive electrical energy from a third battery. For example, the HVAC system includes a climate system that receives electrical energy from the first battery. In the safety mode, the first switch disconnects the first battery from the loads of the HVAC system that are connected to the first battery in the normal mode.

[0061] The seat heater provides seat heating in normal mode, which provides comfort to the occupants, especially when the seat is leather covered, but since the seat heater does not contribute to safety, the seat heater is placed in the first group.

[0062] Entertainment systems provide audio, such as music, or video, such as movies. Entertainment systems are placed in the first group because they do not contribute to safety.

[0063] In one embodiment, the electric vehicle includes an airbag system, and the sensor is adapted to provide a signal upon activation of the airbag system.

[0064] According to this embodiment, the control unit receives a signal when the airbag system is activated. The airbag system is an example of a safety system. The airbag system is typically activated in case of a crash, so that activation indicates a dangerous situation for the first battery. The sensor is, for example, configured to perform a measurement of whether the airbag system is activated. For example, the sensor is part of the airbag system. For example, the sensor is configured to generate an activation signal for activating the airbag system in case of a crash. The sensor transmits the activation signal to an actuator in the airbag system. The sensor also transmits the activation signal to the control unit as a signal indicating a dangerous situation for the first battery.

[0065] In one embodiment, the electric vehicle includes an autonomous emergency braking system for autonomously braking the vehicle in an emergency, the sensor being adapted to provide a signal upon activation of the autonomous emergency braking system.

[0066] According to this embodiment, the autonomous emergency braking system is a system adapted to predict whether the electric vehicle is about to crash. When the impending crash is detected, the autonomous emergency braking system activates the brakes in an attempt to avoid the crash or to reduce the impact of the crash. The autonomous emergency braking system is activated in the event of an impending crash, so that a dangerous situation for the first battery occurs. Therefore, the sensor provides a signal based on the activation of the autonomous emergency braking system. For example, the sensor is configured to measure whether the autonomous emergency braking system is activated. For example, the sensor is part of the autonomous emergency braking system. For example, the sensor is configured to generate an activation signal for activating the autonomous emergency braking system in the event of an impending crash. The sensor transmits the activation signal to an actuator in the brake system. The sensor also transmits the activation signal to a control unit as a signal indicating a dangerous situation for the first battery.

[0067] In one embodiment, the electric vehicle includes a solar panel for generating electric energy based on solar energy. The solar panel is connected to the first battery via a first switch for transferring the electric energy to the first battery. The control unit is configured to switch the first switch in response to a signal to disconnect the solar panel from the first battery.

[0068] According to this embodiment, the solar panel supplies electrical energy to the first battery in normal mode, and in safety mode, the first battery is disconnected from the solar panel, which helps prevent overvoltage of the first battery.

[0069] In one embodiment, the electric vehicle includes a connector for connecting the first battery to an external power source, the connector is positioned to transfer electrical energy from the external power source to the first battery, and the control unit is configured to disconnect the first battery from the external power source in response to a signal.

[0070] According to this embodiment, the electric vehicle is chargeable by connecting the electric vehicle to an external power source via the connector. The external power source is, for example, a power grid or a charging station or a generator or an external solar panel. The external power source is called "external" because it does not form part of the electric vehicle. The external power source does not, for example, move with the vehicle. If the control unit receives a signal while the connector is connected to the external power source, the control unit disconnects the first battery from the external power source. For example, the control unit toggles a switch arranged between the first battery and the connector. The connector is adapted to directly or indirectly connect the first battery to the external power source. For example, the connector is adapted to indirectly connect the first battery to the external power source via a third battery and / or via a power converter. In response to the signal, the control unit will, for example, disconnect the third battery from the connector and / or the connector from the power converter and / or the third battery from the first battery.

[0071] In a further aspect of the present invention, there is provided a method for transmitting electrical energy, the method comprising: connecting the first battery to a first group and a second group to enable the first battery to transfer electrical energy to the first group and the second group, the first group including at least one first load and the second group including at least one second load, the second group being different from the first group; receiving a signal indicating a hazardous condition for a first battery; after receiving the signal, disconnecting the first battery from the first group and the second group; and after receiving the signal, connecting the second battery to the second group to enable the second battery to transfer electrical energy to the second group.

[0072] According to a further aspect of the invention, the first battery can supply electrical energy to the first group and the second group when there is no dangerous situation for the first battery. When a signal is received that there is a dangerous situation for the first battery, the first battery is disconnected from the first group and the second group. This improves the safety associated with the first battery. By connecting the second battery to the second group, the second group continues to be supplied with electrical energy. Because the second battery supplies electrical energy to the second group and not to the first group, the second battery can supply electrical energy to the second group for an extended period of time.

[0073] In one embodiment, the method comprises: transferring electrical energy from a first battery to the first group and to the second group; after receiving the signal, stopping transmitting electrical energy from the first battery to the first group and the second group; and after receiving the signal, starting to transfer electrical energy from the second battery to the second group.

[0074] According to this embodiment, a process of transferring electrical energy from the first battery to the first group and the second group is ongoing. After a signal is received, the process is stopped. After a signal is received, the transfer of electrical energy from the second battery to the second group is initiated.

[0075] In one embodiment, connecting the second battery to the second group includes connecting the second battery to only the second group.

[0076] According to this embodiment, the second battery is connected only to the second group in the safety mode and is not connected to any load outside the second group, and the second group does not receive any electrical energy from any battery other than the second battery in the safety mode.

[0077] In one embodiment, the method includes maintaining a second battery in a fully charged state while the first battery transfers electrical energy from the first battery to the first group and to the second group.

[0078] While maintaining the second battery in a fully charged state, it is ensured that the second battery is able to supply electrical energy to the second group in a safe mode for as long as possible.

[0079] In one embodiment, receiving a signal includes receiving a signal indicative of a temperature and / or a voltage of the first battery.

[0080] In a further aspect of the present invention, there is provided a control unit for use in a battery management system according to any one of the above-mentioned embodiments or in an electric vehicle according to any one of the above-mentioned embodiments.

[0081] The invention is explained in more detail below with reference to the drawings, in which exemplary embodiments of the invention are shown. [Brief description of the drawings]

[0082] [Figure 1] FIG. 1 is a diagram of a battery management system according to a first embodiment. [Diagram 2] FIG. 2 is a detailed diagram of the battery management system according to the first embodiment in normal mode. [Diagram 3] FIG. 2 is a detailed diagram of the battery management system according to the first embodiment in a safe mode. [Figure 4] FIG. 1 is a diagram of a battery management system according to a second embodiment. [Diagram 5] FIG. 13 is a diagram of a battery management system according to a third embodiment. [Figure 6] 1 is a diagram of a vehicle according to one embodiment of the present invention; [Figure 7]1 is a flowchart of a method for transferring electrical energy according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0083] 1-3 show a battery management system 100 for an electric vehicle. The battery management system 100 is further referred to as BMS 100. The BMS 100 includes a first load connector 101, a second load connector 102, a first switch 201, a first battery connector 111, a second battery connector 112, and a control unit 103. The first load connector 101 is connectable to a first group 131 of three first loads 131a-131c. The second load connector 102 is connectable to a second group 132 of three second loads 132a-132c. In practice, the first group 131 and the second group 132 may include many further loads. The second group 132 is different from the first group 131. The first battery connector 111 is connectable to a first battery 121. The second battery connector 112 is connectable to the second battery 122. The BMS 100 is adapted to transfer electrical energy from the first battery 121 to the first group 131 and the second group 132 via the first switch 201. The BMS 100 is adapted to connect the second battery 122 to the second group 132. The control unit 103 is configured to receive a signal 105 indicating a dangerous situation for the first battery 121. In response to the signal 105, the control unit 103 is configured to switch the first switch 201 to disconnect the first battery 121 from the first group 131 and the second group 132 and start transferring electrical energy from the second battery 122 to the second group 132.

[0084] The BMS 100 includes a solar connector 114 that is connectable to a solar panel 104. The solar panel 104 is for generating electrical energy based on solar energy.

[0085] The BMS 100 includes a second switch 202, a third switch 203, and a fourth switch 204. The second switch 202 connects the solar panel 104 to the first battery 121. The third switch 203 connects the second group 132 to the first battery 121. The fourth switch 204 connects the second battery 122 to the second group 132.

[0086] FIG. 2 shows the first embodiment in normal mode. In normal mode, no dangerous situation is detected for the first battery 121. In normal mode, the first switch 201 is in an ON state and connects the first battery 121 to the first group 131 via the first switch 201. The second switch 202 is in an ON state and connects the solar panel 104 to the first battery 121 and the first group 131. The solar energy from the solar panel 104 is used to charge the first battery 121 and / or the solar panel 104 directly supplies solar energy to the first group 131 and the second group 132. The third switch 203 is in an ON state and connects the first battery 121 to the second group 132 via the first switch 201 and the third switch 203. The third switch 203 is in an ON state, connecting the solar panel 104 to the second group 132 via the second switch 202 and the third switch 203. The fourth switch 204 is in an OFF state, disconnecting the second battery 122 from the first battery 121, the first group 131 and the second group 132. The fourth switch 204 is in an OFF state, disconnecting the second battery 122 from the solar panel 104.

[0087] In normal mode, electrical energy is transferred from the first battery 121 to the first group 131 and from the first battery 121 to the second group 132. Electrical energy is transferred from the solar panel 104 to the first battery 121 and / or the first group 131 and the second group 132. The transfer of electrical energy is indicated by arrows.

[0088] 3 shows the first embodiment in a safety mode. While the BMS 100 transfers electrical energy from the first battery 121 to the first group 131 and the second group 132 in a normal mode, a dangerous situation is detected for the first battery 121. The control unit 103 receives a signal 105 indicating the dangerous situation. Upon receiving the signal 105, the control unit 103 switches the first switch 201 to an OFF state to disconnect the first battery 121 from the first group 131, the second group 132, and the solar panel 104. The control unit 103 switches the second switch 202 to an OFF state to disconnect the solar panel 104 from the first group 131. The control unit 103 switches the fourth switch 204 to an ON state to connect the second battery 122 to the second group 132. To prevent the second battery 122 from being connected to the first group 131 via the fourth switch 204, the control unit 103 switches the third switch 203 to the OFF state.

[0089] In the safe mode, electrical energy is only transferred from the second battery 122 to the second group 132, as indicated by the arrows. No electrical energy is transferred from the first battery 121 or the solar panel 104 to the first group 131 or the second group 132.

[0090] 4 shows a BMS 100 according to a second embodiment. The second embodiment has the same elements as the first embodiment, except for the following items:

[0091] Instead of the third switch 203 and the fourth switch 204, the second embodiment has two different electrical components. The third switch 203 is replaced by a first diode 401. The fourth switch 204 is replaced by a second diode 402. Since the control signals for the third switch 203 and the fourth switch 204 are omitted, the control unit 103 has fewer outputs than the first embodiment to send control signals.

[0092] In the normal mode, the first battery 121 supplies electrical energy to the first group 131 and the second group 132. The first battery 121 supplies current through the second load connector 102 and applies a voltage to the second load connector 102. This voltage is called the first battery voltage. The first diode 401 allows the current to pass from the first battery 121 to the second load connector 102. The second diode 402 blocks the current from passing towards the second battery 122. The voltage of the second battery 122 is further called the second battery voltage and is 0.2V lower than the first battery voltage. Since the second battery voltage is 0.2V lower than the first battery voltage, no current flows from the second battery 122 to the second load connector 102 through the second diode 402 in the normal mode.

[0093] In the safety mode, the control unit 103 switches the first switch 201 to the OFF state and switches the second switch 202 to the OFF state. As a result, the first battery voltage is no longer applied to the second load connector 102. As a result of the second battery voltage, a current flows through the second diode 402. The current is prevented by the first diode 401 from flowing towards the first battery 121. The current from the second battery 122 flows towards the second load connector 102 to transfer electrical energy to the second group 132. The second group 132 can operate with the second battery voltage, albeit slightly lower than the first battery voltage.

[0094] 5 shows a BMS 100 according to a third embodiment of the present invention. The third embodiment includes the same elements and / or the same embodiments as the first embodiment, except for the following items:

[0095] The BMS 100 includes a charge controller 500 connectable to the second battery 122. The charge controller 500 is configured to maintain the second battery 122 in a fully charged state at least while the BMS 100 transfers electrical energy from the first battery 121 to the first group 131 and the second group 132. The charge controller 500 receives electrical energy from the first battery 121. The charge controller 500 is configured to detect a charging state of the second battery 122. For example, when the second battery 122 loses electrical energy in a normal mode as a result of energy leakage, the charge controller 500 supplies electrical energy to the second battery 122 to keep the second battery 122 in a fully charged state. By being in a fully charged state, the second battery 122 can supply most of the electrical energy in a safe mode. For example, the charge controller 500 is one of the loads in the first group 131. In the safe mode, the charge controller 500 is no longer powered.

[0096] In a third embodiment, the BMS 100 is connectable to a third battery 503 and a third group 533 of at least one load. The third battery 503 is arranged to supply electric energy to the third group 533. A voltage of the third battery 503 is higher than a voltage of the first battery 121 and a voltage of the second battery 122. The voltage of the third battery 503 is referred to as a third battery voltage. One of the loads in the first group 131 includes a power converter 501. The power converter 501 is connected to the first battery 121 and to the third battery 503. The power converter 501 is adapted to transfer electric energy from the first battery 121 to the third battery 503 and / or vice versa. The power converter 501 is adapted to convert electric energy from the first battery voltage to the third battery voltage and / or vice versa.

[0097] The third battery 503 is connected to the third group 533 via a fifth switch 505. The power converter 501 is connected to the third battery 503 and the third group 533 via a sixth switch 506. The control unit 103 is configured to switch the fifth switch 505 to an OFF state in response to the signal 105 to disconnect the third battery 503 from the third group 533. In this way, electrical energy is not supplied to the third group 533 in case of a dangerous situation for the first battery 121. The control unit 103 is configured to switch the sixth switch 506 to an OFF state in response to the signal 105 to disconnect the power converter 501 from the third battery 503. In this way, electrical energy is not transferred from the third battery 503 via the power converter 501 to the other parts of the first group 131 in a dangerous situation for the first battery 121.

[0098] 6 shows a vehicle 600 according to an embodiment of the present invention. The vehicle 600 may, for example, include one of the embodiments described above, or any combination thereof. The vehicle 600 is shown diagrammatically as a top view.

[0099] The vehicle 600 is an electric vehicle having four wheels 601. Each wheel 601 has an in-wheel motor 602 for driving the corresponding wheel 601. Each wheel 601 is provided with a brake 611, for example a disc brake. The vehicle 600 has a brake system 610 for controlling the brake 611.

[0100] The vehicle 600 has several systems that are considered safety systems. The safety systems include a lighting system 620 that includes lights for providing light, and a braking system 610. The safety systems are loads in the second group 132.

[0101] The electric vehicle 600 has an HVAC system 630 adapted to provide heating, ventilation, and / or air conditioning for the vehicle 600. The electric vehicle 600 has an entertainment system 640 for providing audio or video. These systems are shown diagrammatically in Figure 6. The HVAC system 630 and the entertainment system 640 are not considered safety systems and are loads in the first group 131.

[0102] The electric vehicle 600 has a first battery 121 and a second battery 122. The second battery 122 has a smaller energy capacity than the first battery 121. The first battery 121 includes a lithium-ion battery. The second battery 122 includes a lead-acid battery. The first battery 121 and the second battery 122 are at a low voltage of less than 50V.

[0103] The electric vehicle 600 includes a third battery 503 and an electric propulsion system. The electric propulsion system includes an in-wheel motor 602 and an inverter 603. The inverter 603 receives electric energy from the third battery 503, inverts the electric energy, and supplies the inverted electric energy to the in-wheel motor 602. The in-wheel motor 602 converts the inverted electric energy into motion to propel the electric vehicle 600. The third battery 503 has a large capacity to store electric energy. The third battery 503 is at a voltage greater than 100V, for example 400V. The third battery 503 is at a voltage higher than the voltages of the first battery 121 and the second battery 122.

[0104] The electric vehicle 600 includes two sensors. A temperature sensor 651 is provided for sensing the temperature of the first battery 121. The electric vehicle 600 includes an airbag system, not shown in the figures. The electric vehicle 600 includes an airbag sensor 650 adapted to sense activation of the airbag.

[0105] If the temperature of the first battery 121 exceeds a threshold, a dangerous situation occurs for the first battery 121. A signal from the temperature sensor 651 indicates a temperature exceeding a threshold. The signal indicates a dangerous situation. If the airbag sensor 650 senses that the airbag system has been activated, it is assumed that the vehicle 600 has crashed. A crash is a dangerous situation for the first battery 121. A signal from the airbag sensor 650 indicating activation of the airbag indicates a dangerous situation.

[0106] In the normal mode, the first switch 201 is in an ON state and connects the first battery 121 to the brake system 610, the lighting system 620, the HVAC system 630, and the entertainment system 640. The fifth switch 505 is in an ON state and connects the third battery 503 to the inverter 603 to supply electrical energy to the in-wheel motors 602.

[0107] If the control unit 103 receives a signal 105 from the temperature sensor 651 and / or the airbag sensor 650, the control unit 103 switches to a safety mode. Upon receiving the signal 105, the control unit 103 switches the first switch 201 to an OFF state to disconnect the first battery 121 from the brake system 610, the lighting system 620, the HVAC system 630, and the entertainment system 640. The control unit 103 switches the fourth switch 204 to an ON state to connect the second battery 122 to the brake system 610 and the lighting system 620. To prevent the second battery 122 from being connected to the HVAC system 630 and the entertainment system 640 via the fourth switch 204, the control unit 103 switches the third switch 203 to an OFF state. In response to the signal 105, the control unit 103 switches the fifth switch 505 to an OFF state to disconnect the third battery 503 from the inverter 603 and stop the third battery 503 from transferring electrical energy to the electric propulsion system.

[0108] In the safety mode, electrical energy is transferred from the second battery 122 only to the braking system 610 and the lighting system 620, and not to the HVAC system 630 and the entertainment system 640. Optionally, in the safety mode, electrical energy is not transferred from the third battery 503 to the propulsion system.

[0109] Optionally, the electric vehicle 600 includes a connector for connecting the first battery 121 to an external power source. The connector is arranged to transfer electric energy from the external power source to the first battery 121. The control unit 103 is configured to disconnect the first battery 121 from the external power source in response to the signal 105.

[0110] FIG. 7 illustrates a method for transferring electrical energy according to one embodiment of the present invention.

[0111] The method includes the following steps: Step 700 connects the first battery 121 to the first group 131 and the second group 132 to enable the first battery 121 to transfer electric energy to the first group 131 and the second group 132. The first group 131 includes at least one first load 131a-131c. The second group 132 includes at least one second load 132a-132c. The second group 132 is different from the first group 131.

[0112] Step 701 is a step of receiving a signal 105 indicating a dangerous situation for the first battery 121. Step 702 is a step of disconnecting the first battery 121 from the first group 131 and the second group 132 after receiving the signal 105. Step 703 is a step of connecting the second battery 122 to the second group 132 after receiving the signal 105 to enable the second battery 122 to transfer electrical energy to the second group 132.

[0113] Optionally, the method includes a step of transferring electrical energy from the first battery 121 to the first group 131 and the second group 132, and stopping the transfer of electrical energy from the first battery 121 to the first group 131 and the second group 132 after receiving the signal 105, and starting the transfer of electrical energy from the second battery 122 to the second group 132 after receiving the signal 105.

[0114] Optionally, the step 703 of connecting the second battery 122 to the second group 132 includes connecting the second battery 122 to only the second group 132 .

[0115] Optionally, the method includes maintaining the second battery 122 in a fully charged state while the first battery 121 transfers electrical energy from the first battery 121 to the first group 131 and the second group 132.

[0116] Optionally, receiving 701 a signal 105 includes receiving a signal 105 indicative of a temperature and / or a voltage of the first battery 121 .

[0117] This specification describes detailed embodiments of the present invention, however, it is to be understood that the disclosed embodiments serve only as examples and that the present invention may be embodied in other forms. [Explanation of symbols]

[0118] 100 Battery Management System 101 First load connector 102 Second Load Connector 103 Control Unit 104 Solar Panel 105 Signal 111 1st Battery Connector 112 Second Battery Connector 114 Solar Connector 121 First Battery 122 Second Battery 131 First Group 131a First Load 131b First Load 131c First Load 132 Second Group 132a Second Load 132b Second Load 132c Second Load 201 First Switch 202 Second Switch 203 Third Switch 204 The Fourth Switch 401 First Diode 402 Second Diode 500 charge controller 501 Power Converter 503 Third Battery 505 The 5th Switch 506 6th Switch 533 Third Group 600 vehicles 601 Wheels 602 In-wheel motor 603 Inverter 610 Brake System 611 Brake 620 Lighting System 630 HVAC System 640 Entertainment System 650 Airbag Sensor 651 Temperature Sensor

Claims

1. A battery management system (100) for an electric vehicle (600), comprising: a first load connector (101) connectable to a first group (131) of at least one first load (131a-131c); a second load connector (102) connectable to a second group (132) of at least one second load (132a-132c), said second group (132) being different from said first group (131); a first switch (201); a first battery connector (111) connectable to a first battery (121); a second battery connector (112) connectable to a second battery (122); a control unit (103); Including, the battery management system (100) is adapted to transfer electrical energy from the first battery (121) to the first group (131) and the second group (132) via the first switch (201); the battery management system (100) is adapted to connect the second battery (122) to the second group (132); the control unit (103) is configured to receive a signal (105) indicative of a critical situation for the first battery (121), the critical situation being related to an ambient environment of the battery management system and / or related to one or more internal characteristics associated with the first battery; The battery management system (100) is configured such that, in response to the signal (105), the control unit (103) switches the first switch (201) to disconnect the first battery (121) from the first group (131) and the second group (132) and start transferring electrical energy from the second battery (122) to the second group (132).

2. 2. The battery management system (100) of claim 1, wherein the control unit (103) is adapted to receive the signal (105) while the battery management system (100) transfers electrical energy from the first battery (121) to the first group (131) and the second group (132).

3. 2. The battery management system (100) of claim 1, wherein the control unit (103) is configured to initiate the transfer of electrical energy from the second battery (122) to only the second group (132) in response to the signal (105).

4. a charge controller (500) connectable to the second battery (122); 2. The battery management system (100) of claim 1, wherein the charge controller (500) is configured to maintain the second battery (122) in a fully charged state at least while the battery management system (100) transfers electrical energy from the first battery (121) to the first group (131) and the second group (132).

5. a first electrical component (203, 401) and a second electrical component (204, 402); the battery management system (100) is adapted to connect the first group (131) and the second group (132) to each other via the first electrical component (203, 401); the battery management system (100) is adapted to connect the second battery (122) to the second group (132) via the second electrical component (204, 402); the first electrical component (203, 401) is adapted to block the transmission of electrical energy from the second battery (122) to the first group (131); 2. The battery management system (100) of claim 1, wherein the second electrical component (204, 402) is adapted to prevent transfer of electrical energy from the first battery (121) to the second battery (122).

6. 6. The battery management system (100) of claim 5, wherein at least one of the first electrical component (203, 401) and the second electrical component (204, 402) includes a diode (401, 402).

7. 6. The battery management system (100) of claim 5, wherein at least one of the first electrical component (203, 401) and the second electrical component (204, 402) includes a further switch (203, 204), and the control unit (103) is configured to operate the further switch (203, 204) in response to the signal (105).

8. The battery management system (100) of claim 1, wherein the signal (105) is based on activation of an airbag system.

9. The battery management system (100) of claim 1, wherein the signal (105) is based on activation of an autonomous emergency braking system.

10. The battery management system (100) of claim 1; the first group (131); the second group (132); the first battery (121); the second battery (122); a sensor (650, 651) adapted to provide said signal (105) indicative of a dangerous situation for said first battery (121); Including, The electric vehicle (600), wherein the unsafe condition is related to an ambient environment of the battery management system and / or related to one or more internal characteristics associated with the first battery.

11. 11. The electric vehicle (600) of claim 10, wherein the second battery (122) has a smaller energy capacity than the first battery (121).

12. 11. The electric vehicle (600) of claim 10, wherein the first battery (121) comprises a lithium ion battery and the second battery (122) comprises a lead acid battery.

13. The electric vehicle (600) of claim 10, wherein the sensor (651) is adapted to provide the signal (105) based on a temperature and / or a voltage of the first battery (121).

14. an electric propulsion system for propelling the electric vehicle (600); a third battery (503) connected to the electric propulsion system via the battery management system (100) for supplying electric energy to the electric propulsion system; Including, 14. The electric vehicle (600) of claim 13, wherein the voltage of the third battery (503) is higher than the voltage of the first battery (121) and the voltage of the second battery (122).

15. the battery management system (100) includes a second switch (505); the third battery (503) is connected to the electric propulsion system via the second switch (505) to supply electric energy to the electric propulsion system; 15. The electric vehicle (600) of claim 14, wherein the control unit (103) is configured to switch the second switch (505) in response to the signal (105) to disconnect the third battery (503) from the electric propulsion system and stop the third battery (503) from transmitting electric energy to the electric propulsion system.

16. The electric vehicle (600) of claim 10, wherein the second group (132) includes a safety system of the vehicle (600).

17. The safety system comprises: an illumination system (620) for providing light; a telecommunications system for providing remote communication with emergency services; an unlocking system for unlocking the doors and / or windows of said vehicle (600); a braking system (610) for braking the vehicle (600); 17. The electric vehicle (600) of claim 16, comprising at least one of:

18. The first group (131) comprises: an HVAC system (630) adapted to provide heating, ventilation, and / or air conditioning for the vehicle (600); a seat heater adapted to provide heating for a seat within said vehicle (600); an entertainment system (640) for providing audio or video; The electric vehicle (600) of claim 10, comprising at least one of:

19. The electric vehicle (600) of claim 10, including an airbag system, wherein the sensor (650) is adapted to provide the signal (105) based on activation of the airbag system.

20. 11. The electric vehicle (600) of claim 10, including an autonomous emergency braking system for autonomously braking the vehicle (600) in an emergency, the sensor being adapted to provide the signal (105) based on activation of the autonomous emergency braking system.

21. a solar panel (104) for generating electrical energy based on solar energy; the solar panel (104) is connected to the first battery (121) via the first switch (201) to transfer electrical energy to the first battery (121); 11. The electric vehicle (600) of claim 10, wherein the control unit (103) is configured to switch the first switch (201) in response to the signal (105) to disconnect the solar panel (104) from the first battery (121).

22. a connector for connecting the first battery (121) to an external power source; the connector is arranged to transfer electrical energy from the external power source to the first battery (121); 11. The electric vehicle (600) of claim 10, wherein the control unit (103) is configured to disconnect the first battery (121) from the external power source in response to the signal (105).

23. 1. A method for transmitting electrical energy, comprising: connecting a first battery (121) to a first group (131) and a second group (132) to enable the first battery (121) to transfer electrical energy to the first group (131) and the second group (132), wherein the first group (131) includes at least one first load (131a-131c) and the second group (132) includes at least one second load (132a-132c), the second group (132) being different from the first group (131); receiving a signal (105) indicative of a critical condition for the first battery (121), the critical condition being related to an ambient environment of the battery management system and / or related to one or more internal characteristics associated with the first battery; disconnecting the first battery (121) from the first group (131) and the second group (132) after receiving the signal (105); after receiving the signal (105), connecting the second battery (122) to the second group (132) to enable the second battery (122) to transfer electrical energy to the second group (132); A method comprising:

24. transferring electrical energy from the first battery (121) to the first group (131) and the second group (132); after receiving the signal (105), stopping the transfer of electrical energy from the first battery (121) to the first group (131) and the second group (132); after receiving the signal (105), starting to transfer electrical energy from the second battery (122) to the second group (132); 24. The method of claim 23, comprising:

25. 24. The method of claim 23, wherein the step of connecting the second battery (122) to the second group (132) comprises connecting the second battery (122) only to the second group (132).

26. 24. The method of claim 23, comprising maintaining the second battery (122) in a fully charged state while the first battery (121) transfers electrical energy from the first battery (121) to the first group (131) and the second group (132).

27. 24. The method of claim 23, wherein the receiving the signal (105) comprises receiving the signal (105) indicative of a temperature and / or a voltage of the first battery (121).

28. 24. The method of claim 23, wherein receiving the signal (105) comprises receiving the signal (105) based on activation of an airbag system.

29. 24. The method of claim 23, wherein receiving the signal (105) comprises receiving the signal (105) based on activation of an autonomous emergency braking system.

30. A control unit (103) for use in the battery management system (100) of claim 1 or in the electric vehicle (600) of claim 10, comprising: the control unit (103) is configured to receive the signal (105) indicative of the critical situation for the first battery (121), the critical situation being related to an ambient environment of the battery management system and / or related to one or more internal characteristics associated with the first battery; The control unit (103) is configured to switch the first switch (201) in response to the signal (105) to disconnect the first battery (121) from the first group (131) and the second group (132) and start transferring electrical energy from the second battery (122) to the second group (132).

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