Method and device for trickle charging of battery of vehicle

Abstract

The invention relates to a method for trickle charging a battery (40) of a vehicle (10), in which a current pulse (50) from a power source (12) is supplied to the battery (40) for a predetermined time interval (54) for a predetermined duration (52) until a voltage of the battery (40) is at least equal to a voltage of the power source (12). A duration (52) of the current pulses (50) and a time interval (54) between the current pulses (50) are selected such that an on-board electrical system of the vehicle (10) remains in a passive mode. The invention also relates to a device (100) for trickle charging of a battery (40) of a vehicle (10) using such a method.

Description

[0001] The present invention relates to a method and a device for trickle charging a battery of a vehicle.

[0002] Vehicle batteries, especially starter batteries, due to the battery chemistry, undergo natural self-discharge. If the vehicle remains stationary for a long time, this self-discharge can progress to the point where the vehicle cannot be started. Therefore, the battery is usually continuously charged with a normal charging current shortly before restarting or with a significantly lower current during parking. In the latter case, this is referred to as trickle charging of the battery.

[0003] EP 3 459 155 B1 describes a method for charging a battery. The method includes selecting a pulse period. In this case, a charging pulse is provided to the battery. For this purpose, at the start of the conduction period of the charging pulse, a charging current is provided to the battery from a current source. The current flowing through the battery is determined, and the change in the current flowing through the battery is detected. Based on when the change in the current flowing through the battery is detected relative to the application of the charging current to the battery, the duration of the conduction period of the charging pulse is determined. The charging current from the power source to the battery is interrupted at the end of the conduction period of the charging pulse. Then the duration of the off period of the charging pulse is determined. In this case, the difference between the selected pulse period and the conduction period of the charging pulse is calculated. It is the duration of the off period of the delayed charging pulse. Then another pulse period is selected. These steps are repeated using the selected pulse period.

[0004] US 4661758 discloses a solar power supply and battery charging system having a solar power supply that, when exposed to sunlight, supplies a consumption current to a load and a charging current to a secondary battery. The secondary battery is connected in series with the solar power supply and is charged by the current provided by the solar power supply. A control circuit is connected to the battery to determine the state of charge of the battery and to sequentially control the operation of a variable pulse width generator. The output pulse of the pulse width generator is applied to a short-circuit resistance switch connected to the terminals of the connected power supply to periodically open the short-circuit switch at different time intervals determined by the state of charge of the secondary battery.

[0005] In solar regulators, mainly two methods are used to input energy into the electrical energy storage, namely the so-called pulse width modulation (PWM) and the so-called maximum power point tracking (MPPT).

[0006] In pulse width modulation, a square wave signal is set to oscillate between two different voltage levels. In this case, in particular, the voltage level can also be zero, such that in principle the signal can also be a rapid sequence of on and off states. Pulse width modulation has a wide range of applications in electronics.

[0007] In electrical engineering, especially in the field of photovoltaics, the term maximum power point tracking refers to a method in which the electrical load of a solar cell, a solar module, or several solar modules connected in series is adjusted so that the maximum possible power can be obtained from the cell. In the case of a solar cell, the optimal operating point is not constant but depends on, among other things, the radiation intensity, the temperature at the solar module, and the type of solar cell.

[0008] An object of the present invention is to provide an improved method for trickle charging a battery of a vehicle.

[0009] Another object of the present invention is to provide a device for trickle charging a battery of a vehicle using such an improved method.

[0010] The above objects are achieved by the features of the independent claims.

[0011] Advantageous designs and advantages of the present invention result from the further claims, the description, and the drawings.

[0012] According to one aspect of the present invention, a method for trickle charging a battery of a vehicle is proposed, wherein current pulses from a power source are supplied to the battery for a predetermined duration in a predetermined time interval until the voltage of the battery is at least equal to the voltage of the power source. In this case, the duration of the current pulses and the time interval of the current pulses are selected such that the on-board electrical system of the vehicle remains in a passive mode.

[0013] The on-board electrical systems of modern motor vehicles always have a low static current, which causes the battery to discharge. Therefore, an improved charging method for trickle charging a battery is advantageously proposed, which can charge the battery at low power, for example, by means of a solar module, while the active on-board electrical system of the vehicle does not consume more energy than the solar module can provide.

[0014] In order to be able to permanently charge the battery at low power to maintain the charge state, it is possible to avoid the undesired activation of the on-board electrical system that would occur in the case of a trickle charging current. Therefore, it is proposed to supply only pulsed charging current to the battery. In this case, the current pulses are selected to be so short that the electronics of the on-board electrical system are not activated and remain in a passive mode or a stationary mode, in which the next current pulse also occurs only after a specific duration that allows the system to remain in the stationary mode. In this case, the current pulses are selected to be so short and to occur at such large time intervals that the fault suppression that may exist in the on-board electrical system is suppressed as irrelevant, and the vehicle or its electrical consumers are not activated or "awakened".

[0015] The pulsation can be advantageously set according to the corresponding in-vehicle electronic devices used in the vehicle. The pulse length can be correspondingly selected to be short enough, and the charging current can be correspondingly selected to be small enough so that these values are accepted within the range of fluctuations that interfere with the in-vehicle electrical system. Thus, unwanted activation of the in-vehicle electrical system can be avoided. In this case, the in-vehicle electrical system would activate or wake up the control unit. Then, the control unit would be active for a certain duration and would consume current, which can be prevented according to the present invention. Enough time can be waited until the in-vehicle electrical system forgets the fault again before the next current pulse. Then, during the next current pulse, the charging current is perceived as a new, tolerable fault that remains below the upper limit of the fault, otherwise it would cause the in-vehicle electrical system to be woken up.

[0016] Current pulses can be applied to the battery in a periodic sequence at specific periodic time intervals. However, this is not absolutely necessary. Optionally, the current pulses can also be applied in an irregular sequence. The time intervals of the current pulses can correspond to the minimum time interval or be greater than the minimum time interval.

[0017] According to an advantageous design, the method can at least include the following steps: determining the voltages of the battery and the power supply by a control unit, where the control unit is electrically coupled to the power supply and the battery; checking whether there is a control pulse, especially a control pulse from a pulse generator, in the control unit when the voltage of the battery is less than the voltage of the power supply; switching a switching element by the control unit to supply a current pulse to the battery when there is a control pulse; checking whether the control pulse is turned off; blocking the switching element when the control pulse is turned off.

[0018] In this way, the battery can be charged with limited power without activating the in-vehicle electrical system. Provided that the power supply provides a voltage higher than the battery voltage. The sequence of current pulses can be advantageously controlled by a pulse generator that predetermines for the control unit the appropriate duration and time intervals for which the current pulses are supplied to the battery. Then, the control unit can supply the so-defined current pulses to the battery by manipulating a suitable switching element.

[0019] According to an advantageous embodiment of the method, the duration of the current pulse and the time interval between current pulses can be set manually according to predetermined parameters and / or determined according to the characteristic map of the vehicle and / or determined by measurements at the battery and / or the power supply. The predetermined parameters can in particular be determined by a specific on-vehicle electrical system. The trickle charging for the entire system can advantageously be adjusted to different vehicle systems. The necessary values can be set manually according to the parameters, read from the characteristic map of the corresponding vehicle, or determined by tests and measurements, so that the current pulse parameters of the charging electronics, in particular the length, level of the current pulse, and the time interval between current pulses, can be set appropriately.

[0020] According to an advantageous embodiment of the method, a solar module can be used as a power supply, wherein the electrical energy generated by the solar module is temporarily stored in an electrical buffer memory.

[0021] Using a solar module as an energy source offers the possibility of self-sufficient battery trickle charging based on relatively small solar panels. Even under adverse weather conditions in winter, such a solar module has proven to be sufficient. In addition, such a solar module can be implemented in a particularly simple and economical manner.

[0022] When there is solar radiation, the solar module generates electrical energy, which is directed to the buffer memory. The buffer memory can be in the form of, for example, a capacitor. Once the voltage of the buffer memory reaches a value significantly higher than the battery voltage, a current pulse can be supplied to the battery.

[0023] In this case, the buffer memory can advantageously be dimensioned such that the method according to the invention can thus be carried out with very low technical effort. In the case where the buffer memory is designed as a capacitor, in particular as a supercapacitor, i.e., a so-called ultracapacitor or several interconnected capacitors, which then has a capacitance, for example, higher than 1 farad, in particular higher than 10 farads, sufficient energy can thus be temporarily stored to provide an appropriate charging pulse for the trickle charging of the battery. Thus, for example, at least 1000 joules of electrical energy can be stored in such a buffer memory, so that a charging pulse with 100 joules of electrical energy can be output to the battery without immediately depleting the buffer memory.

[0024] In this embodiment of the buffer store, the control of the charging pulse can be particularly advantageously simplified, since the electrical energy stored in the capacitor changes its voltage, so that the charging pulse can start as soon as the voltage in the capacitor rises above a first value and then decreases substantially due to the discharge of the capacitor with the charging pulse of the battery, until the voltage of the capacitor substantially corresponds to the battery voltage, so that the voltage difference between the capacitor and the battery decreases and stops. The charging pulse can also be advantageously terminated when the voltage across the capacitor drops below the second value, since in this case, due to the smaller voltage difference between the capacitor and the battery, effective trickle charging of the battery hardly occurs. However, the charging pulse is terminated anyway at the latest after the maximum duration of the charging pulse, so that the requirement of keeping the on-board electrical system of the vehicle in passive mode can be met.

[0025] In order to implement the method according to the invention, the time sequence and duration of the charging pulses must also be controlled, switched and maintained, so that, for example, a simple clock generator or pulse generator can also be used for this purpose.

[0026] The method according to the invention can thus advantageously be implemented using capacitors of correspondingly large dimensions as buffer stores, since for this purpose the voltage at the capacitor is first determined and the charging pulse is determined by its duration and time sequence. Accordingly, a charging pulse from the buffer store to the battery begins when the voltage across the capacitor is above a first value and a minimum duration has elapsed since the end of the last charging pulse. Depending on the design of the components, in the case of such a large capacity of the buffer store, its discharge for trickle charging of the battery would be too long to enable the on-board electrical system of the vehicle to be in passive mode, so that the duration of the charging pulse itself can also be determined by the pulse generator in order to terminate charging pulses that are too long.

[0027] In this case, it is particularly advantageous if a first value of the voltage of the capacitor, above which a charging pulse can be initiated, is predetermined for the system and / or can be set in the system. The duration between charging pulses, in particular the duration between the end of a preceding charging pulse and the start of a current charging pulse, can also be predetermined and / or set by the system, in particular the pulse generator.

[0028] In the case of a system operating with a maximum duration of a charging pulse, which of course can also be predetermined and / or set, this duration can also be used directly between the start of consecutive charging pulses, since in this case the maximum duration of a charging pulse and the duration between the charging pulses can be added.

[0029] In order to meet the requirement of keeping the vehicle's on-board electrical system in the passive mode, and this condition is closely related to the parameters of the on-board electrical system and its activation, these parameters must also be considered in the voltage value and duration of the buffer memory, such that these parameters must always be adapted to the corresponding on-board electrical system and thus at least to the corresponding vehicle type. For this purpose, these values and parameters must be pre-determined and can be, for example, directly input, pre-set by the manufacturer and / or selected from the stored values. These values can also be determined at the beginning by testing the measurement system itself for trickle charging in the on-board electrical system and then the determined values are stored for conversion.

[0030] The setting of pre-defined and stored values can also be implemented, for example, based on vehicle data, can be determined from a characteristic diagram, or can also be achieved through communication between the system for trickle charging and the on-board electrical system itself.

[0031] Due to this advantageous design, a particularly simple system can be constructed and used to achieve trickle charging of the battery. In addition, such a system can always supply itself with energy for control through the buffer memory and thus does not require external energy for control. In the case where the buffer memory is completely emptied, no control charging pulses are required, and when the buffer memory is full again, the initial energy of the buffer memory can already be used for control, in particular to operate the pulse generator and determine the voltage at the buffer memory itself. In any case, the corresponding charging pulses are only emitted when the voltage is higher than the first value, so there is always sufficient energy in the buffer memory to operate the controller in advance.

[0032] Furthermore, this implementation allows for the complete autonomous control and arrangement of the system for trickle charging on or in the vehicle, thus also avoiding any impact on the on-board electrical system, because the basic requirement of keeping the vehicle's on-board electrical system in the passive mode and thus affecting it is always adhered to. In addition, apart from the charging pulses for trickle charging, the vehicle's battery remains technically completely unaffected and does not require any other adjustment.

[0033] According to an advantageous design, the method may further include:

[0034] Determining the voltage of the buffer memory by a control unit, wherein the control unit is electrically coupled to the buffer memory and the battery; checking whether it is possible or permitted to provide a current pulse in the case where the voltage of the buffer memory is greater than the voltage of the battery; switching a switching element by the control unit that provides a current pulse to the battery in the case where it is possible or permitted to provide a current pulse; checking whether the duration of the current pulse has ended; blocking the switching element in the case where the duration of the current pulse has ended.

[0035] In this way, the battery can be charged with limited power without activating the vehicle electrical system, provided that the voltage of the buffer memory significantly exceeds the voltage of the battery. Thereafter, it is checked in the control unit whether enough time has passed since the last current pulse so that a new current pulse can be emitted. Then, the control unit can supply the next current pulse to the battery by actuating the switching element. Then the end of the current pulse duration is checked. When the end is reached, the switching element is blocked, so that the current pulse is turned off. Thereafter, the control unit can switch again to determining the voltage of the buffer memory. Thus, by appropriately designing the solar module with respect to the size of the buffer memory, advantageous trickle charging can be achieved.

[0036] According to another aspect of the invention, there is provided an apparatus for trickle charging a battery of a vehicle using this method, which at least includes a power source that is electrically coupled to the battery via a control unit in an expected operation. In this case, the control unit is configured to supply a current pulse from the power source to the battery for a predetermined duration at a predetermined time interval.

[0037] Advantageously, there is provided an apparatus for an improved charging method for trickle charging a battery, which can charge the battery with low power, for example, via a solar module, without the active vehicle electrical system of the vehicle consuming more energy than the solar module can provide.

[0038] In order to be able to permanently charge the battery with low power to maintain the charge state, it is possible to avoid the unwanted activation of the vehicle electrical system that would occur in the case of a trickle charging current. Therefore, it is proposed to supply only a pulsed charging current to the battery. In this case, the current pulse is selected to be so short that the electronics of the vehicle electrical system are not activated and remain in a passive mode or a stationary mode, in which the next current pulse also occurs again only after a specific duration that allows the system to remain in the stationary mode. In this case, the current pulse is selected to be so short and to occur at such large time intervals that possible fault suppressions in the vehicle electrical system are suppressed as irrelevant, and the vehicle or its electrical consumers are not activated or "awakened".

[0039] The pulsation can advantageously be set according to the respective in-vehicle electronic devices used in the vehicle. The pulse length can be correspondingly selected to be short enough, and the charging current can be correspondingly selected to be small enough such that these values are accepted within the range of fluctuations that interfere with the in-vehicle electrical system. Thus, unwanted activation of the in-vehicle electrical system can be avoided, in which case the in-vehicle electrical system would activate or wake up the control unit. Then, the control unit would be active for a certain duration and would consume current, which can be prevented according to the present invention. Enough time can be waited until the in-vehicle electrical system forgets the fault again before the next current pulse, and then during the next current pulse, the charging current is perceived as a new, tolerable fault that remains below the upper limit of the fault, otherwise it would cause the in-vehicle electrical system to be woken up.

[0040] The device can be directly installed in the vehicle or added to the vehicle as a retrofit system. Due to the minimal intervention in the vehicle system, such a device as a retrofit system can also be installed and used permanently or only temporarily. Thus, for example, such a device can also be installed only for long-term shutdown, during parking, or during outdoor waiting times, and can also be removed again when the vehicle is running continuously and does not require trickle charging.

[0041] According to an advantageous design of the device, the control unit can include a pulse generator or be electrically coupled to a pulse generator. The pulse generator controls the sequence and duration of individual current pulses. The pulse generator can be connected to the control unit as a separate unit. Optionally, however, the pulse generator can also be integrated in the control unit.

[0042] According to an advantageous design of the device, the energy source can be configured as a solar module with an electrical buffer memory. In this case, the buffer memory can be configured to temporarily store the electrical energy of the solar module generated in the solar module.

[0043] Using a solar module as the energy source provides the possibility of self-sufficient battery trickle charging based on a relatively small solar panel. Such a solar module has proven to be sufficient even under adverse weather conditions in winter. In addition, such a solar module can be implemented particularly simply and economically and can be replaced in case of damage.

[0044] When there is solar radiation, the solar module generates electrical energy, which is directed to the buffer memory. The buffer memory can be in the form of, for example, a capacitor. Once the voltage of the buffer memory reaches a value significantly higher than the battery voltage, a current pulse can be provided to the battery.

[0045] Therefore, the proposed device advantageously has an energy self-supply. The control unit, which acts as a solar regulator, can be powered by the energy of the solar module. This means that at the moment the first sunlight beam arrives, a buffer memory, such as a capacitor, starts to be filled, and thus the capacitor is charged. Whether this is the first commissioning of the solar module or just driving out of an underground car park after a long parking period.

[0046] Once a voltage sufficient to operate the processor of the control unit is reached at the capacitor, the control unit can start the process. Since the capacitor only discharges to the maximum voltage of the battery during recharging, and this voltage is significantly higher than the operating voltage required by the processor, the solar module remains operational as long as the solar radiation is sufficient to compensate for the self-discharge due to the self-consumption of the control electronics by continuously providing solar energy.

[0047] According to an advantageous design of the device, the control unit can be configured to supply current pulses to the battery by manipulating a switching element. In particular, the switching element can be configured as a semiconductor switching element, especially a transistor. In particular, the switching element can be configured to switch a negative potential. The sequence of current pulses can be controlled by a pulse generator, which predetermines for the control unit the appropriate duration and time interval for which the current pulses are supplied to the battery. The control unit can then advantageously supply the so-defined current pulses to the battery by manipulating a suitable switching element.

[0048] The solar module can advantageously be electrically coupled to the buffer memory by a diode connected in the forward direction. In this case, the diode prevents the reverse discharge of the buffer memory when the solar radiation decreases. In addition, the buffer memory can be electrically coupled to the vehicle by a diode connected in the forward direction. This diode ensures that in case of a fault, the battery does not charge the buffer memory in reverse.

[0049] The power supply, especially the solar module, can advantageously be further electrically coupled to the battery via a resistor in order to limit the charging current based on the voltage difference between the buffer memory and the battery when the switching element is open.

[0050] According to an advantageous design of the device, the power supply can be electrically coupled to the vehicle via at least one electrical fuse. The fuse ensures that in case of a fault, the power supply is safely disconnected from the vehicle.

[0051] According to an advantageous design of the device, the power supply can be electrically coupled to the vehicle via an external starting support point. Thus, the device can be electrically connected to the vehicle in a particularly advantageous manner. Such external starting support points are generally common in vehicles. Thus, a permanent connection to the vehicle battery can be ensured. In this way, the charging current only flows in parallel with the other systems of the vehicle's on-board electrical system, rather than in series. In addition, no intervention in the battery interconnection is required, which is advantageous for safety reasons, especially for retrofit systems.

[0052] Further advantages can be seen from the following description of the drawings. The drawings show embodiments of the invention. The combination of the drawings, the description and the claims contains many features. A person skilled in the art will also conveniently consider these features individually and combine them into useful further combinations.

[0053] Wherein:

[0054] Figure 1 shows a system overview of a device for trickle charging a battery of a vehicle according to an embodiment of the invention;

[0055] Figure 2 shows the use of a device according to Figure 1 a flowchart of a method for trickle charging a battery of a vehicle;

[0056] Figure 3 shows a time series of current pulses for trickle charging a battery of a vehicle according to an embodiment of the invention;

[0057] Figure 4 shows a system overview of a device for trickle charging a battery of a vehicle according to another embodiment of the invention; and

[0058] Figure 5 shows the use of a device according to Figure 4 a flowchart of a method for trickle charging a battery of a vehicle.

[0059] In the drawings, the same or similar components are denoted by the same reference numerals. The drawings only show examples and should not be construed as restrictive.

[0060] Figure 1 shows a system overview of a device 100 for trickle charging a battery 40 of a vehicle 10 according to an embodiment of the invention.

[0061] The device 100 includes a power supply 12 which is electrically coupled to the battery 40 of the vehicle 10 via a control unit 20 in the intended operation. In this case, the device 100 is electrically coupled to the vehicle 10 via an external starting support point 70.

[0062] The control unit 20 is configured to supply a current pulse 50 of the power supply 12 having a predetermined duration 52 to the battery 40 at a predetermined time interval 54. To this end, as Figure 1 shown, the control unit 20 may be electrically coupled to a pulse generator 22, which provides a time basis for supplying the current pulse 50. Optionally, the pulse generator 22 may also be integrated into the control unit 20.

[0063] Figure 2 illustrates a method for trickle charging the battery 40 of a vehicle 10 using an apparatus 100 according to Figure 1 .

[0064] According to this method, the current pulse 50 of the power supply 12 is supplied to the battery 40 at a predetermined time interval 54 with a predetermined duration 52 until the voltage of the battery 40 is at least equal to the voltage of the power supply 12. In this case, the duration 52 of the current pulse 50 and the time interval 54 of the current pulse 50 are selected such that the on-board electrical system of the vehicle 10 remains in a passive mode.

[0065] Empirically, it has been determined that current pulses, for example, 4 seconds in length and with a pause of at least 15 seconds, are ignored by the on-board electrical system of the vehicle 10.

[0066] In Figure 3 , such a time sequence of the current pulse 50 is shown as an example. The current 61 varies between an off state 64 and an on state 62 according to time 60. The current pulse 50 has a duration 52 and is supplied at a minimum time interval 54. Optionally, a longer time interval 54 may be selected.

[0067] The method at least includes Figure 2 the steps shown. In step S100, the process is started. Then, in step S102, the voltages of the battery 40 and the power supply 12 are determined by the control unit 20.

[0068] In the next step S104, it is checked whether the voltage of the battery 40 is less than the voltage of the power supply 12. If this is not the case, the voltage determination is repeated in step S102.

[0069] This loop continues until the voltage of the battery 40 is lower than the voltage of the power supply 12.

[0070] Thereafter, in step S106, it is checked whether the control pulse of the pulse generator 22 generated in step S114 is present in the control unit 20. If this is not the case, the voltage determination is repeated in step S102.

[0071] In the presence of a control pulse, in step S108, the control unit 20 turns on a switching element 24, such as a switch or a transistor, that supplies a current pulse 50 to the battery 40.

[0072] Subsequently, in step S110, it is checked whether the control pulse is turned off again. If this is not the case, the process jumps back to step S108. This process is repeated until the control pulse is turned off.

[0073] In the case where the control pulse is turned off, in step S112, the switching element 24 is blocked, thereby terminating the current pulse 50. Thereafter, the cycle starts again from step S102.

[0074] The duration 52 of the current pulse 50 and the time interval 54 of the current pulse 50 can be manually set according to predetermined parameters. Alternatively or additionally, these values can be determined from a characteristic map of the vehicle 10. These values can also be determined by measurements at the battery 40 and / or the energy source 12.

[0075] In this way, the battery 40 can be charged with limited power without activating the on-vehicle electrical system. Provided that the voltage supplied by the power source 12 exceeds the voltage of the battery 40. The sequence of the current pulses 50 can be advantageously controlled by a pulse generator 22, which predetermines for the control unit 20 a suitable duration and time interval for which the current pulse 50 will be supplied to the battery 40. Then, the control unit 20 can supply the thus-defined current pulse 50 to the battery 40 by manipulating a suitable switching element 24.

[0076] Figure 4 A system overview of a device 100 for trickle-charging the battery 40 of a vehicle 10 according to another embodiment of the present invention is shown.

[0077] In this case, the energy source 12 is configured as a solar module 14 having an electrical buffer memory 16, where the buffer memory 16 is for temporarily storing the electrical energy of the solar module 14 generated in the solar module 14. The buffer memory 16 can be in the form of, for example, a capacitor.

[0078] The device 100 is electrically coupled to the battery 40 via a terminal 30 representing the positive potential of the battery 40 and a terminal 31 representing the negative potential of the battery 40 and / or the electric vehicle ground. The terminal 30 and the terminal 31 can be connected, for example, via an external starting support point 70 of the vehicle 10.

[0079] The control unit 20 can switch the current pulse 50 to the battery 40 by manipulating the switching element 24 via the negative potential, such as a transistor or another suitable semiconductor switching element. In this embodiment, the control unit 20 includes a pulse generator 22, which can simply be configured as a threshold generator.

[0080] The solar module 14 is electrically coupled to the buffer memory 16 via a diode 30 connected in the forward direction. In this case, the diode 30 prevents the reverse discharge of the buffer memory 16 when solar radiation decreases.

[0081] The power supply 12 is electrically coupled to the vehicle 10 via a diode 32 connected in the forward direction. This diode 32 ensures that in case of a fault, the battery 40 does not charge the buffer memory 16 in reverse.

[0082] The power supply 12 is electrically coupled to the battery 40 via a resistor 34 in order to limit the charging current based on the voltage difference between the buffer memory 16 and the battery 40 when the switching element 24 is open.

[0083] The power supply 12 is electrically coupled to the vehicle 10 via at least one electrical fuse 36. The fuse 36 ensures that in case of a fault, the power supply 12 is reliably disconnected from the vehicle 10.

[0084] The solar module 14 generates electrical energy under solar radiation, which is directed into the buffer memory 16. The buffer memory 16 can be in the form of, for example, a capacitor. Once the voltage of the buffer memory 16 reaches a value significantly higher than the battery voltage, a current pulse 50 can be supplied to the battery 40.

[0085] The proposed device 100 advantageously has energy self - supply. The control unit 20, acting as a solar regulator, is powered by the energy of the solar module 14. This means that at the moment when the second beam of sunlight arrives, the buffer memory 16, for example a capacitor, starts to be filled, and thus the capacitor is charged. Whether this is the first commissioning of the solar module 14 or just driving out of an underground parking lot after a long parking period.

[0086] Once a voltage sufficient to operate the processor of the control unit 20 is reached at the capacitor, the control unit 20 starts the process. Since the capacitor only discharges to the maximum voltage of the battery 40 during re - charging, and this voltage is significantly higher than the operating voltage required by the processor, the solar module 14 remains operational as long as solar radiation is sufficient to compensate for the self - discharge due to the self - consumption of the control unit 20 by continuously providing solar energy.

[0087] Figure 5 A flowchart of a method for trickle - charging the battery 40 of the vehicle 10 using the device 100 according to Figure 4 is shown.

[0088] After initialization, i.e., after reaching the processor operating voltage in step S200, in step S202, the control unit 20 starts measuring the voltage of the buffer memory 16, which is proportional to the charge state of the buffer memory 16 (e.g., a capacitor), and thus is a measurement of the stored content of the buffer memory 16.

[0089] If this charge state is high enough, i.e., the capacitor voltage is, for example, 2V higher than the battery nominal voltage, which is checked in step S204, then in step S206, the algorithm checks whether a current pulse 50 was emitted not long ago. Thus, the necessary charging pause, i.e., the minimum time interval 54 of the current pulse 50, is checked so that the vehicle electrical system of the vehicle 10 is not woken up.

[0090] When the charging pause has passed, for example, when the so-called charge enable flag is set, the switching element 24 is switched in step S208, and the buffer memory 16 discharges into the battery 40. A corresponding current pulse 50 is supplied to the battery 40.

[0091] During this process, in step S210, it is checked whether the end of the charging pulse duration, i.e., the end of the duration 52 of the current pulse 50, has been reached. If not, the switching element 24 remains open.

[0092] When the end of the charging pulse duration is reached, the switching element 24 is turned off in step S212, and the algorithm returns to the range of measuring the voltage of the buffer memory 16 in step S202.

[0093] In actual use, the duration of the charging pause may depend on solar radiation. On days without sunlight, the solar module 14 provides little energy, which causes the buffer memory 16 to charge very slowly, depending on the ratio of the size of the solar module 14 to the capacity of the buffer memory 16 (e.g., a capacitor). Thus, charging pauses of up to several minutes or all night are conceivable. On sunny days, the capacitor 16 can be charged in significantly less than 15 seconds. In this case, the control unit 20 must prevent the switching element 24 from switching too early.

[0094] List of reference numerals

[0095] 10 Vehicle

[0096] 12 Power supply

[0097] 14 Solar module

[0098] 16 Buffer memory

[0099] 20 Control unit

[0100] 22 Pulse generator

[0101] 24 Switching element

[0102] 30 Diode

[0103] 32 Diode

[0104] 34 Resistor

[0105] 36 Fuse

[0106] 40 Battery

[0107] 50 Current pulse

[0108] 52 Duration

[0109] 54 Time interval

[0110] 60 Time

[0111] 61 Current

[0112] 62 Conductive

[0113] 64 Cut-off

[0114] 70 External starting support point

[0115] 100 Device

Claims

1. A method for trickle charging a battery (40) of a vehicle (10), Among them, providing current pulses (50) from a power source (12) to the battery (40) for a predetermined duration (52) within a predetermined time interval (54) until the voltage of the battery (40) is at least equal to the voltage of the power source (12), wherein the duration (52) of the current pulses (50) and the time interval (54) of the current pulses (50) are selected such that the on - vehicle electrical system of the vehicle (10) remains in a passive mode, wherein the current pulses (50) are selected to be so short and occur at such large time intervals that fault suppression of the on - vehicle electrical system classifies the current pulses as irrelevant and the vehicle (10) and its power consumers in the on - vehicle electrical system are not activated.

2. The method according to claim 1, comprising at least the following steps - The voltages of the battery (40) and the power supply (12) are determined by the control unit (20), where, The control unit (20) is electrically coupled to the power source (12) and the battery (40); - in the case where the voltage of the battery (40) is less than the voltage of the power source (12), checking whether there is a control pulse in the control unit (20), in particular a control pulse from a pulse generator (22); - in the presence of the control pulse, switching a switching element (24) by the control unit (20), the control unit supplying the current pulse (50) to the battery (40); - checking whether the control pulse is turned off; - in the case where the control pulse is turned off, blocking the switching element (24).

3. The method according to claim 1 or 2, Among them, the duration (52) of the current pulses (50) and the time interval (54) of the current pulses (50) are manually set according to predetermined parameters and / or determined according to a characteristic map of the vehicle (10) and / or determined by measurements at the battery (40) and / or the power source (12).

4. The method according to any one of the preceding claims, Among them, a solar module (14) is used as the power source (12), wherein electrical energy generated by the solar module (14) is temporarily stored in an electrical buffer memory (16).

5. The method according to claim 4, further comprising - determining the voltage of the buffer memory (16) by means of the control unit (20), wherein, The control unit (20) is electrically coupled to the buffer memory (16) and the battery (40); - in the case where the voltage of the buffer memory (16) is greater than the voltage of the battery (40), checking whether it is possible or permitted to supply the current pulse (50); - in the case where it is possible or permitted to supply the current pulse (50), switching the switching element (24) by the control unit (20) that supplies the current pulse (50) to the battery (40); - checking whether the duration (52) of the current pulse (50) has ended; - in the case where the duration (52) of the current pulse (50) has ended, blocking the switching element (24).

6. An apparatus (100) for trickle charging a battery (40) of a vehicle (10) by the method according to any one of the preceding claims, the apparatus (100) comprising at least a power supply (12) electrically coupled to the battery (40) via a control unit (20) in an intended operation, Among them, the control unit (20) being configured to supply current pulses (50) from the power supply (12) to the battery (40) for a predetermined duration (52) in a predetermined time interval (54), and the control unit (20) including a pulse generator (22) or being electrically coupled to a pulse generator (22), characterized in that the pulse generator (22) is designed to be capable of generating current pulses (50) having a duration (52) and a time interval (54), the current pulses being selected such that the on-vehicle electrical system of the vehicle (10) remains in a passive mode, wherein the current pulses (50) are selected to be so short and occur at such large time intervals that fault suppression of the on-vehicle electrical system classifies the current pulses as irrelevant, and the vehicle (10) and its electrical power consumers in the on-vehicle electrical system are not activated.

7. The apparatus according to claim 6, Among them, the power supply (12) being configured as a solar module (14) having an electrical buffer memory (16), wherein the buffer memory (16) is configured to temporarily store electrical energy of the solar module (14) generated in the solar module (14).

8. The apparatus according to claim 7, characterized in that the electrical buffer memory (16) is designed as a capacitor having a capacitance of at least 1 farad, in particular a supercapacitor.

9. The apparatus according to any one of claims 6 to 8, Among them, the control unit (20) being configured to supply the current pulses (50) to the battery (40) by manipulating a switching element (24), in particular, wherein the switching element (24) is configured as a semiconductor switching element, in particular a transistor, in particular, wherein the switching element (24) is configured to switch a negative potential.

10. The apparatus according to any one of claims 6 to 9, Among them, the power supply (12) being electrically coupled to the vehicle (10) via at least one electrical fuse (36).

11. The apparatus according to any one of claims 6 to 10, Among them, the power supply (12) being electrically coupled to the vehicle (10) via an external starting support point (70).

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