Maintenance-free energy storage power supply with automatically chargeable lithium battery pack and control method thereof

Abstract

This invention discloses a maintenance-free energy storage power supply capable of automatically charging and activating a lithium battery pack. It mainly includes a lithium battery pack, a battery soft-start board, a bidirectional AC / DC converter and AC output switching unit, an activation condition judgment circuit, an AC / DC charging board, and a lithium battery pack activation port. The invention also discloses a control method for the aforementioned energy storage power supply. When the mains power is normally input, AC power is output through a bypass to charge the lithium battery pack. When the mains power is not effectively input, the lithium battery pack outputs AC power through a reverse inverter. After the lithium battery pack is severely depleted and stops working, once the mains power is restored, the activation condition judgment circuit will detect and determine whether to charge and activate the lithium battery pack. This invention can automatically charge and activate the severely depleted and unusable lithium battery pack built into the energy storage power supply when the mains power is restored. The method is simple and reliable, solving problems such as inconvenient battery pack maintenance, and enabling unattended and maintenance-free operation of the energy storage power supply.

Description

Technical Field

[0001] This invention relates to an energy storage power supply with a built-in lithium battery pack, and more particularly to a maintenance-free energy storage power supply and its control method that enables the battery management unit of the built-in lithium battery pack to stop working due to reasons such as prolonged power outages, and to automatically activate and resume working when the mains power is restored. Background Technology

[0002] The rapid development of power electronics technology and energy storage materials has led to the widespread adoption and application of energy storage power supplies. These power supplies come in a variety of types, with common examples including uninterruptible power supplies (UPS), emergency power supplies (EPS), and various off-grid or grid-connected photovoltaic energy storage systems. They are widely used in data processing centers, signal rooms, security alarm systems, homes, and outdoor camping, ensuring users can still use AC power during power outages. The main components of an energy storage power supply include battery packs, battery management units, inverters, and AC chargers. Bidirectional conversion technology allows the inverter and charging hardware power modules to be integrated into one, significantly reducing material costs and resulting in higher integration, smaller size, and lighter weight for energy storage power systems.

[0003] During the widespread adoption of energy storage power supplies, deep discharge of batteries often occurs due to various circumstances. This results in the batteries failing to provide emergency power during mains power outages or malfunctions due to undervoltage, preventing them from inverting. Therefore, as a crucial component of energy storage power supplies, the proper use and maintenance of batteries has become a significant issue in their development. Lithium-ion batteries are widely used in energy storage power supplies due to their light weight, small size, and high power density. However, lithium-ion battery packs require safe management, such as ensuring consistent capacity or voltage across individual cells and implementing overcurrent, over / undervoltage, short-circuit, and overtemperature protection. When a lithium-ion battery pack is severely depleted, the voltage may drop, causing the battery management unit (BMU) to stop working. In such cases, an external charger is usually needed to directly recharge the positive and negative terminals of the battery pack to reactivate the BMU and allow the battery pack to output power normally. This maintenance process is cumbersome and makes it difficult to achieve self-checking and self-recovery after the device is powered on.

[0004] Therefore, it is necessary to study and implement a simple and reliable method to automatically charge and activate the fed lithium battery pack. This method fully considers the self-testing and self-recovery problems of unattended equipment and has high application value. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a maintenance-free energy storage power supply and its control method that can automatically activate and restore the lithium battery pack to normal operation when the mains power is restored after the lithium battery pack stops working due to mains power failure or other reasons.

[0006] Technical Solution: The maintenance-free energy storage power supply with automatic charging and activation of lithium battery packs according to the present invention includes an energy storage power supply body and an energy storage power supply activation control module; wherein, the energy storage power supply body includes a lithium battery pack, a battery soft starter board, and a bidirectional AC / DC converter and AC output switching unit. The lithium battery pack is connected to the bidirectional AC / DC converter and AC output switching unit through the battery soft starter board for forward charging and reverse inversion operation modes; the energy storage power supply activation control module is used to activate the lithium battery pack after the mains power is connected when the lithium battery pack fails to receive power. It includes an activation condition judgment circuit, an AC / DC charging board, and a lithium battery pack activation port. The activation condition judgment circuit includes a pair of detection terminals and an output terminal. The detection terminals are respectively connected to the positive DC side terminal of the bidirectional AC / DC converter and AC output switching unit and the negative terminal of the lithium battery pack activation port. The output terminal is connected to a controlled switch controlling the input terminal of the AC / DC charging board. The controlled switch is connected in series between the AC / DC charging board and the live wire of the mains power input.

[0007] The activation condition judgment circuit includes a normally closed optocoupler relay and a comparator for determining whether the lithium battery pack has met the activation conditions. The normally closed optocoupler relay compares the sampled output voltage of the lithium battery pack with a preset threshold value. When the sampled voltage does not exceed the threshold value, its primary side is not conducting and its secondary side is directly connected; when the sampled voltage exceeds the threshold value, its primary side is conducting and its secondary side is turned off.

[0008] The lithium battery pack includes a lithium battery module and a battery management unit, which is connected to the battery soft starter board via a circuit breaker.

[0009] The battery management unit is equipped with a negative terminal controlled switch, which is a pair of N-channel MOSFETs connected in series back-to-back between the negative terminal of the bidirectional AC / DC converter and AC output switching unit and the negative terminal of the lithium battery pack.

[0010] The battery soft start board has a built-in pre-charge circuit and a positive terminal controlled switch; the positive terminal controlled switch is connected in series between the DC side positive terminal of the bidirectional AC / DC converter and AC output switching unit and the positive terminal of the lithium battery pack.

[0011] The bidirectional AC / DC converter and AC output switching unit is equipped with an AC output controlled switch and a mains input controlled switch. When there is mains input, both the AC output controlled switch and the mains input controlled switch are turned on. When there is no mains input, the AC output controlled switch is turned on and the mains input controlled switch is turned off.

[0012] The lithium battery pack activation port has a built-in reverse connection protection diode and fuse.

[0013] This invention also discloses a control method for the above-mentioned maintenance-free energy storage power supply that can automatically charge and activate lithium battery packs. The control method includes the following steps depending on the mains power connection status of the energy storage power supply and whether the lithium battery pack is working properly:

[0014] (1) When the energy storage power supply has mains power input, the mains power input bypasses the AC output controlled switch and the mains power input controlled switch inside the bidirectional AC / DC conversion and AC output switching unit (500) to output AC power. At the same time, the mains power is positively power factor corrected and isolated DC conversion through the bidirectional AC / DC conversion and AC output switching unit, and the lithium battery pack is charged first with constant current and then with constant voltage through the battery soft start board.

[0015] (2) When there is no mains power input, the DC output of the lithium battery pack is generated by the bidirectional AC / DC converter and AC output switching unit through reverse inverter mode and output through AC output controlled switch (K4) after passing through the battery soft start board. After long-term operation, the DC side of the bidirectional AC / DC converter and AC output switching unit is undervoltage protected. At this time, the battery management unit and the battery soft start board are still working normally. If the mains power input is restored in time, the mains power is still output through the bidirectional AC / DC converter and AC output switching unit, and the lithium battery pack is charged by forward conversion.

[0016] (3) If the mains power input is not restored for a long time in step (2), the lithium battery pack will continue to be discharged by the inverter until it is undervoltage and there is no output, and the energy storage power supply will no longer work; the static loss of the battery management unit causes the lithium battery pack to develop into a deep discharge state, i.e., a power-out state, at which time the battery management unit fails and does not work.

[0017] (4) When the mains power input is restored in step (3), the negative terminal controlled switch built into the battery management unit is invalid, so the lithium battery pack cannot be charged in the positive charging mode through the bidirectional AC / DC converter and AC output switching unit; the activation condition judgment circuit detects the real-time voltage of the lithium battery pack and compares it with the reference voltage. If the current real-time voltage of the lithium battery pack is less than the preset threshold value, the controlled switch is enabled, the AC / DC charging board receives AC input, and then the lithium battery pack is activated and charged with a small current through the lithium battery pack activation port.

[0018] (5) After the lithium battery pack is activated in step (4), the battery management unit resumes effective operation, and its built-in controlled switch is enabled. The mains power input charges the lithium battery pack through the battery soft start board in the forward charging mode via the bidirectional AC / DC converter and AC output switching unit. Furthermore, once the activation condition judgment circuit detects that the real-time voltage of the lithium battery pack exceeds the threshold value, the controlled switch is disabled, the AC / DC charging board stops working, and the lithium battery pack will only store electricity through the power conversion of the bidirectional AC / DC converter and AC output switching unit in the energy storage power supply body until it is fully charged.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: even if the built-in lithium battery pack of the energy storage power supply is severely depleted and cannot be charged and stored normally, it can still achieve self-charging and activation of the lithium battery pack when the mains power is detected to be restored. The method is simple and reliable, and the response speed is fast. It avoids the problems of untimely and inconvenient manual maintenance, and can realize unattended and maintenance-free operation of the energy storage power supply. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the maintenance-free energy storage power supply structure of the present invention;

[0021] Figure 2(a) is a schematic diagram of the main structure of the energy storage power supply of the present invention;

[0022] Figure 2(b) is a schematic diagram of the main body of the energy storage power supply of the present invention operating in AC bypass output mode;

[0023] Figure 2(c) is a schematic diagram of the main body of the energy storage power supply of the present invention operating in inverter output mode;

[0024] Figure 3(a) is a schematic diagram of the activation condition judgment circuit in one embodiment of the present invention;

[0025] Figure 3(b) is a schematic diagram of the technical solution of the AC / DC charging board AC input controlled mode in one embodiment of the present invention;

[0026] Figure 4(a) is a schematic diagram of the technical solution of the AC / DC charging board in one embodiment of the present invention;

[0027] Figure 4(b) is a simplified block diagram of the control section of the AC / DC charging board in one embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the technical solution for the activation port of the lithium battery pack of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0030] Figure 1This is a schematic diagram of the structure of a maintenance-free energy storage power supply that can automatically charge and activate a lithium battery pack according to the present invention. It includes a lithium battery pack 100, a battery soft start board 400, a bidirectional AC / DC converter and AC output switching unit 500, an activation condition judgment circuit 600, an AC / DC charging board 700, and a lithium battery pack activation port 800. It also includes a lithium battery pack circuit breaker S1 and an input terminal controlled switch K3.

[0031] The lithium battery pack 100 includes a lithium battery group 200 and a battery management unit 300. The battery management unit 300 has a common interface to the outside. The negative terminal controlled switch K1 is integrated in the battery management unit 300. In this embodiment, K1 is a pair of back-to-back N-channel MOSFETs (metal-oxide-semiconductor field-effect transistors) connected in series. The lithium battery pack 100 is connected to a battery soft starter board 400 via a circuit breaker S1. The battery soft starter board 400 has a built-in pre-charge circuit and a positive terminal controlled switch K2. The battery soft starter board 400 is connected to the DC side of a bidirectional AC / DC converter and AC output switching unit 500. The bidirectional AC / DC converter and AC output switching unit 500 can realize forward charging and reverse inverter operation modes respectively, and has a built-in bypass and inverter output switching circuit.

[0032] Figure 2(a) is a schematic diagram of the main structure of the energy storage power supply. The lithium battery pack 100, the battery soft start board 400, and the bidirectional AC / DC converter and AC output switching unit 500 are the main body of the energy storage power supply. The working mode is determined according to the operating conditions, load size, availability of mains power, battery capacity, etc.

[0033] Figure 2(b) is a schematic diagram of the main body of the energy storage power supply working in AC bypass output mode. When the energy storage power supply has mains power input, the mains power input bypasses AC power output through the AC output controlled switch K4 and the mains power input controlled switch K5 set inside the bidirectional AC / DC conversion and AC output switching unit 500. At the same time, the mains power is charged by constant current and then constant voltage through the positive power factor correction (PFC) and isolation DC conversion of the bidirectional AC / DC conversion and AC output switching unit 500, and then through the battery soft start board 400.

[0034] Figure 2(c) is a schematic diagram of the main body of the energy storage power supply working in the inverter output mode. When there is no mains power input, the system's external AC output is completely connected from the lithium battery pack 100 to the DC side of the bidirectional AC / DC converter and AC output switching unit 500 through the soft starter board 400. The AC output is obtained through reverse inverter conversion and then through the AC output controlled switch K4.

[0035] Based on the aforementioned main body of the energy storage power supply, the activation condition judgment circuit 600, AC / DC charging board 700, and lithium battery pack activation port 800 are components of the present invention to ensure that even in the case of severe power depletion, the lithium battery pack can automatically activate to normal use state once it detects the mains power input.

[0036] Figure 3(a) is a schematic diagram of the activation condition judgment circuit in a specific embodiment of the present invention. The detection terminal of the activation condition judgment circuit 600 is connected to the positive terminal of the DC side of the bidirectional AC / DC converter and AC output switching unit 500 and the negative terminal of the lithium battery pack activation port 800, respectively, which are the corresponding 48Vout and OUT- electrical nodes. The voltage of the lithium battery pack 200 is judged by real-time grounding to determine whether it needs to be activated automatically. In this embodiment, integrated circuits such as TL431, optocoupler relay, and transistor are used. Among them, U300 is a 1b normally closed optocoupler relay. The scheme samples the output voltage of the lithium battery pack 200 and compares it with the +2.5V reference of TL431. When the sampled voltage does not exceed the threshold value, the primary side of U300 is not conducting, its secondary side is directly conducting, the transistor Q300 is conducting, and the IPRLY1 node outputs a valid signal. If the sampled voltage exceeds the threshold value, the primary side of the U300 optocoupler relay is conducting, which enables and turns off its secondary side, and the output terminal of the IPRLY1 node is no longer a valid signal.

[0037] Figure 3(b) is a schematic diagram of the technical solution for the AC / DC charging board's AC input controlled mode. The electrical node IPRLY1 is provided by the activation condition judgment circuit 600. The input terminal of the AC / DC charging board 700 is connected to the mains power by the controlled switch K3. In this embodiment, the controlled switch K3 specifically adopts the RY300 relay. Only when the activation condition judgment circuit 600 outputs a valid signal will the signal switch Q302 be turned on, pulling the OP-Chrg.Relay-L node signal low, causing the coil of the relay RY300 to be powered by +12V, and then normally turn on to start activating and charging the lithium battery pack 200.

[0038] Figure 4(a) is a schematic diagram of the technical solution of the AC / DC charging board. The AC input first passes through a fuse and then EMI treatment, and then is rectified. The uncontrolled rectification or power factor correction (PFC) circuit can be reasonably selected according to the charging power. After rectification, DC / DC isolation conversion begins (flyback, forward, half-bridge, full-bridge and other conversion forms can be selected in sequence according to the power). The secondary side is rectified again to obtain a stable DC output.

[0039] Figure 4(b) is a simplified block diagram of the loop control section of the AC / DC charging board. It adopts a dual-loop control structure with an outer voltage loop and an inner current loop. The inner current loop controls the output current, keeping it constant within a certain voltage range. The outer voltage loop maintains the highest output voltage at the specified voltage. The self-activation process of the lithium battery pack 200 mainly occurs in the current loop, and it only enters the voltage loop after reaching the specified voltage, i.e., the threshold value. This scheme uses devices such as the AP4310 integrated chip with U401 dual operational amplifier and built-in reference, and the PC817B optocoupler with U400. Both the voltage loop and the current loop adopt a PI regulator structure. VOUT+ and IS are the collected voltage and current signals, respectively. The voltage loop and the current loop are switched by diodes. When the output voltage or current meets the corresponding conditions, the corresponding loop is activated, and its internal operational amplifier branch becomes effective and enters actual control. During the entire activation charging process, the AC / DC charging board 700 can perform constant current and then constant voltage charging on the lithium battery pack 100 through the lithium battery pack activation port 800.

[0040] Figure 5 The schematic diagram shows the technical solution for the activation port of the lithium battery pack. The activation port 800 of the lithium battery pack has a built-in reverse connection protection Schottky diode D500 and a fuse F500. The reverse connection protection diode D500 prevents damage to components caused by the positive and negative terminals of the output side of the AC / DC charging board 700 being directly connected to the lithium battery pack 100 in the wrong direction, and also prevents accidental short circuits between the positive and negative terminals of the lithium battery pack 200. When an unmatched charger is manually connected to the activation port 800 of the lithium battery pack, causing excessive charging current, the built-in fuse F500 will blow, thus preventing damage to the lithium battery pack 200.

[0041] When the energy storage power supply has mains power input, the mains power input is bypassed by the AC output controlled switch and the mains power input controlled switch inside the bidirectional AC / DC conversion and AC output switching unit to output AC power. At the same time, the mains power is positively power factor corrected and isolated DC-DC converted through the bidirectional AC / DC conversion and AC output switching unit, and the lithium battery pack is charged first with constant current and then with constant voltage through the battery soft start board.

[0042] During the disconnection and reconnection of the mains power to the energy storage power source, the lithium battery pack 100 is automatically activated by the activation condition judgment circuit 600, the AC / DC charging board 700, and the lithium battery pack activation port 800. The specific steps are as follows:

[0043] A: When there is no mains power supply, the DC output of the lithium battery pack 100 is converted into AC output by the bidirectional AC / DC converter and AC output switching unit 500 through reverse inverter after passing through the battery soft start board 400. After running for a long time, the DC side of the bidirectional AC / DC converter and AC output switching unit 500 will be undervoltage protected. At this time, the battery management unit 300 and the battery soft start board 400 are still working normally. If the mains power input is restored in time, the mains power will still be output through the bidirectional AC / DC converter and AC output switching unit 500, while the forward converter charges and stores energy for the lithium battery pack 100.

[0044] B: If the mains power is not effectively connected for a long time, the lithium battery pack 100 will be undervoltage and have no output due to inverter discharge, and the entire energy storage power supply will lose power and stop working. Since the battery management unit 300 also has static losses, over time, the lithium battery pack 200 will develop into a deep discharge state, i.e., a power-out state. At this time, the battery management unit 300 will fail and stop working.

[0045] C: When the mains power input is restored, the lithium battery pack 100 cannot be charged through the forward charging mode of the bidirectional AC / DC converter and AC output switching unit 500 because the built-in controlled switch K1 of the battery management unit 300 is invalid. After the activation condition judgment circuit 600 detects the real-time voltage of the lithium battery pack 200, it compares it with the reference voltage. If the current voltage of the lithium battery pack 200 is less than the threshold value, the controlled switch K3 is enabled, the AC / DC charging board 700 receives AC input, and then the lithium battery pack 800 is activated and charged with a small current through the lithium battery pack activation port 800.

[0046] D: After the lithium battery pack 100 is activated, the mains power input charges the lithium battery pack 100 through the battery soft start board 400 in the forward charging mode via the bidirectional AC / DC converter and AC output switching unit 500. Furthermore, once the activation condition judgment circuit 600 detects that the real-time voltage of the lithium battery pack 200 exceeds the threshold value, the controlled switch K3 is disabled, the AC / DC charging board 700 stops working, and the lithium battery pack 200 will only store electricity through the power conversion of the mains power via the bidirectional AC / DC converter and AC output switching unit 500 in the energy storage power supply body until it is fully charged.

Claims

1. A maintenance-free energy storage power supply capable of automatically charging and activating a lithium battery pack, characterized in that, The system includes an energy storage power supply unit and an energy storage power supply activation control module. The energy storage power supply unit includes a lithium battery pack (100), a battery soft starter board (400), and a bidirectional AC / DC converter and AC output switching unit (500). The lithium battery pack (100) is connected to the bidirectional AC / DC converter and AC output switching unit (500) via the battery soft starter board (400) for forward charging and reverse inverter operation. The energy storage power supply activation control module is used to activate the lithium battery pack (100) after mains power is connected in the case of a power failure. It includes an activation condition judgment circuit (600), an AC / DC charging board (700), and a lithium battery pack activation port (800). The circuit (600) includes a pair of detection terminals and an output terminal. The detection terminals are respectively connected to the positive DC side of the bidirectional AC / DC converter and AC output switching unit (500) and the negative terminal of the lithium battery pack activation port (800). The output terminal is connected to the input terminal controlled switch (K3) of the AC / DC charging board (700), and the input terminal controlled switch (K3) is connected in series between the AC / DC charging board (700) and the live wire of the mains input. The activation condition judgment circuit (600) includes a normally closed optocoupler relay and a comparator for judging whether the lithium battery pack (100) has reached the activation condition. The normally closed optocoupler relay compares the sampled output voltage of the lithium battery pack (100) with a preset threshold value. When the sampled voltage reaches the threshold value, the relay detects the voltage at the specified threshold. When the voltage does not exceed the threshold value, its primary side is not conducting and the secondary side is directly connected; when the sampled voltage exceeds the threshold value, its primary side is conducting and the secondary side is turned off; the lithium battery pack (100) includes a lithium battery group (200) and a battery management unit (300), the battery management unit (300) is connected to the battery soft start board (400) via a circuit breaker (S1); the battery management unit (300) is provided with a negative terminal controlled switch (K1), the negative terminal controlled switch (K1) is a pair of N-channel MOSFETs connected in series back-to-back between the negative terminal of the bidirectional AC / DC converter and AC output switching unit (500) and the negative terminal of the lithium battery group (200); the battery soft start board (400) has a built-in pre-charge circuit and a positive terminal controlled switch (K2); the positive A terminal controlled switch (K2) is connected in series between the positive terminal of the DC side of the bidirectional AC / DC converter and AC output switching unit (500) and the positive terminal of the lithium battery pack (100); the bidirectional AC / DC converter and AC output switching unit (500) is equipped with an AC output controlled switch (K4) and a mains input controlled switch (K5). When there is mains input, both the AC output controlled switch (K4) and the mains input controlled switch (K5) are turned on. When there is no mains input, the AC output controlled switch (K4) is turned on and the mains input controlled switch (K5) is turned off; the lithium battery pack activation port (800) has a built-in reverse connection protection diode and fuse; the steps are as follows, depending on the mains connection status of the energy storage power supply and whether the lithium battery pack (100) is working properly: (1) When the energy storage power supply has mains power input, the mains power input bypasses the AC output controlled switch (K4) and mains power input controlled switch (K5) inside the bidirectional AC / DC conversion and AC output switching unit (500) to output AC power. At the same time, the mains power is positively power factor corrected and isolated DC conversion through the bidirectional AC / DC conversion and AC output switching unit (500), and the lithium battery pack (100) is charged first with constant current and then with constant voltage through the battery soft start board (400). (2) When there is no mains power input, the DC output of the lithium battery pack (100) is generated by the bidirectional AC / DC converter and AC output switching unit (500) through the battery soft start board (400) and then output through the AC output controlled switch (K4) via the reverse inverter. After long-term operation, the DC side of the bidirectional AC / DC converter and AC output switching unit (500) is undervoltage protected. At this time, the battery management unit (300) and the battery soft start board (400) are still working normally. If the mains power input is restored in time, the mains power is still output through the bidirectional AC / DC converter and AC output switching unit (500) and the lithium battery pack (100) is charged in the forward conversion. (3) If the mains power input is not restored for a long time in step (2), the lithium battery pack (100) continues to discharge through the inverter until it is undervoltage and there is no output, and the energy storage power supply will no longer work; the static loss of the battery management unit (300) causes the lithium battery pack (200) to develop into a deep discharge state, i.e., a power-out state, at which time the battery management unit (300) fails and does not work. (4) When the mains power input is restored in step (3), the negative terminal controlled switch (K1) built into the battery management unit (300) is invalid, so the lithium battery pack (100) cannot be charged in the positive charging mode through the bidirectional AC / DC conversion and AC output switching unit (500); the activation condition judgment circuit (600) detects the real-time voltage of the lithium battery pack (200) and compares it with the reference voltage. If the current real-time voltage of the lithium battery pack (200) is less than the preset threshold value, the controlled switch (K3) is enabled, the AC / DC charging board (700) receives AC input, and then the lithium battery pack (200) is activated and charged with a small current through the lithium battery pack activation port (800); (5) After the lithium battery pack (100) is activated in step (4), the battery management unit (300) resumes effective operation. Its built-in controlled switch (K1) is enabled. The mains power input charges the lithium battery pack (100) through the battery soft start board (400) in the forward charging mode via the bidirectional AC / DC converter and AC output switching unit (500). Furthermore, once the activation condition judgment circuit (600) detects that the real-time voltage of the lithium battery pack (200) exceeds the threshold value, the controlled switch (K3) is disabled, the AC / DC charging board (700) stops working, and the lithium battery pack (200) will only store electricity through the power conversion of the bidirectional AC / DC converter and AC output switching unit (500) in the energy storage power body until it is fully charged.

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