Battery bank unit, remaining charge time calculation method, and remaining charge time calculation program

Abstract

To provide a battery bank unit that can accurately calculate time required for finishing charging.SOLUTION: A battery bank unit comprises: a first battery bank and a second battery bank that are connected in parallel; and a control device that performs first bank charging to charge only the first battery bank after collective charging in which the first battery bank and the second battery bank are collectively charged, and performs second bank charging to charge only the second battery bank after the first bank charging. The control device calculates residual time for finishing charging of the battery bank unit on the basis of the temperature of the battery bank unit at time of starting the collective charging.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a battery bank unit, a method for calculating remaining charge time, and a program for calculating remaining charge time. [Background technology]

[0002] Patent Document 1 discloses a battery bank unit that discharges power to a load device connected to an external power source when the external power source is unable to supply power due to a power outage. The battery bank unit includes multiple battery banks. Each of the multiple battery banks is composed of multiple secondary batteries and connected in parallel. The multiple battery banks are charged with power from the external power source during normal operation.

[0003] The battery bank unit is configured so that the multiple battery banks are charged in sequence, and the battery bank that is not being charged can discharge to the load device, so that the battery bank unit can discharge to the load device even while it is being charged. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-10250 A Summary of the Invention [Problem to be solved by the invention]

[0005] For example, in managing a load device, there is a demand for knowing the time required for charging of a battery bank unit to be completed while the battery bank unit is being charged.

[0006] An object of the present disclosure is to provide a battery bank unit that can accurately calculate the time required to complete charging. [Means for solving the problem]

[0007] The battery bank unit according to the present disclosure includes a first battery bank and a second battery bank connected in parallel, and a control device that performs lump-sum charging, in which the first battery bank and the second battery bank are charged together, followed by first bank charging, in which only the first battery bank is charged, and that performs first bank charging, in which only the second battery bank is charged, after the first bank charging, in which the control device calculates the remaining time until charging of the battery bank unit is complete based on the temperature of the battery bank unit when lump-sum charging begins.

[0008] The remaining charge time calculation method of the present disclosure is a method in which a computer calculates the remaining time until charging of a battery bank unit is completed, in which a first battery bank and a second battery bank connected in parallel to the first battery bank are charged together, followed by first bank charging, in which only the first battery bank is charged, and then first bank charging, in which only the second battery bank is charged, and includes obtaining the temperature of the battery bank unit at the start of the lump-sum charging and calculating the remaining time based on the temperature of the battery bank unit.

[0009] The remaining charge time calculation program of the present disclosure causes a computer that controls a battery bank unit in which a first battery bank and a second battery bank connected in parallel to the first battery bank are charged together, followed by first bank charging in which only the first battery bank is charged, and then first bank charging in which only the second battery bank is charged, to execute the following steps: acquiring the temperature of the battery bank unit at the start of the lump-sum charging; and calculating the remaining time until charging of the battery bank unit is completed based on the temperature of the battery bank unit. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a battery bank unit that can accurately calculate the time required to complete charging. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating a battery bank unit according to a first embodiment of the present disclosure. [Figure 2] Battery bank unit block diagram [Figure 3] Diagram showing a table [Figure 4] 1 is a flowchart illustrating steps executed by the control device when charging the battery bank unit. [Figure 5] Time chart when the flowchart in Figure 4 is executed [Figure 6A] Flowchart executed by the control device when calculating the remaining time [Figure 6B] Continuation of the flowchart in Figure 6A [Figure 7A] A flowchart executed when a control device according to a second embodiment of the present disclosure calculates a remaining time. [Figure 7B] Continuation of the flowchart in Figure 7A DETAILED DESCRIPTION OF THE INVENTION

[0012] First Embodiment A battery bank unit according to a first embodiment of the present disclosure will be described below with reference to the drawings. Fig. 1 is a schematic diagram of a battery bank unit 1 according to the first embodiment of the present disclosure. The battery bank unit 1 supplies power to a load device 3 connected to an external power source 2 when the external power source 2 experiences a power outage. The battery bank unit 1 is also charged by power from the external power source 2.

[0013] The external power supply 2 is, for example, a device that converts commercial AC power into DC power and outputs the DC power. The load device 3 is a device (for example, a server device) that operates on DC power.

[0014] As shown in FIG. 1, the battery bank unit 1 includes an input / output terminal 10, first and second battery banks 20, 30, a charge / discharge circuit 40, and a control device 50.

[0015] The input / output terminal 10 is connected to a power supply line 4 that supplies power from an external power supply 2 to a load device 3 .

[0016] The first and second battery banks 20, 30 are configured by connecting a plurality of secondary batteries (e.g., nickel-metal hydride secondary batteries) in series. The secondary batteries may be lithium-ion secondary batteries or other secondary batteries other than nickel-metal hydride secondary batteries. The first and second battery banks 20, 30 are configured similarly to each other. The first and second battery banks 20, 30 are connected in parallel to each other.

[0017] The charge / discharge circuit 40 functions as a circuit for charging and discharging the first and second battery banks 20, 30 via the input / output terminals 10. The charge / discharge circuit 40 includes a step-up DC / DC converter 41, a selector switch 42, a first charge switch 43, a first discharge switch 44, a second charge switch 45, and a second discharge switch 46.

[0018] The step-up DC / DC converter 41 is a power conversion device that steps up the power supplied from the external power supply 2 and outputs the power.

[0019] The changeover switch 42 switches the voltage value applied to the first and second battery banks 20, 30. In the changeover switch 42, a first terminal 42a is connected to the output terminal of the step-up DC / DC converter 41, and a second terminal 42b is connected to the input / output terminal 10. In addition, a third terminal 42c is connected to the first and second battery banks 20, 30 via the first and second charging switches 43, 45.

[0020] When the selector switch 42 is in the on state, the first terminal 42a and the third terminal 42c are connected, and the power output from the step-up DC / DC converter 41 is supplied to the first and second battery banks 20, 30 via the first and second charging switches 43, 45. On the other hand, when the selector switch 42 is in the off state, the second terminal 42b and the third terminal 42c are connected, and the power output from the external power supply 2 is supplied to the first and second battery banks 20, 30 via the first and second charging switches 43, 45.

[0021] When the first charging switch 43 is in an on state, it allows charging of the first battery bank 20, and when it is in an off state, it does not allow charging of the first battery bank 20. In the first charging switch 43, a first terminal 43a is connected to the third terminal 42c of the selector switch 42, and a second terminal 43b is connected to the positive electrode of the first battery bank 20. The negative electrode of the first battery bank 20 is connected to ground.

[0022] When the first discharge switch 44 is in an ON state, it allows the first battery bank 20 to discharge, and when it is in an OFF state, it does not allow the first battery bank 20 to discharge. In the first discharge switch 44, a first terminal 44a is connected to the positive electrode of the first battery bank 20, and a second terminal 44b is connected to the input / output terminal 10.

[0023] When the second charging switch 45 is in an ON state, it allows charging of the second battery bank 30, and when it is in an OFF state, it does not allow charging of the second battery bank 30. In the second charging switch 45, a first terminal 45a is connected to the third terminal 42c of the selector switch 42, and a second terminal 45b is connected to the positive electrode of the second battery bank 30. The negative electrode of the second battery bank 30 is connected to ground.

[0024] When the second discharge switch 46 is in an on state, it allows the second battery bank 30 to discharge, and when it is in an off state, it does not allow the second battery bank 30 to discharge. In the second discharge switch 46, a first terminal 46a is connected to the positive electrode of the second battery bank 30, and a second terminal 46b is connected to the input / output terminal 10.

[0025] Fig. 2 is a block diagram of the battery bank unit 1. As shown in Fig. 2, the battery bank unit 1 further includes a current sensor 60, a first voltage sensor 61, a first temperature sensor 62, a second voltage sensor 63, and a second temperature sensor 64.

[0026] The current sensor 60 detects the value of a current flowing in from or out of the power supply line 4 via the input / output terminal 10. Specifically, the current sensor 60 detects the value of a current between the input / output terminal 10 and the connection point 40a of the charge / discharge circuit 40. The first voltage sensor 61 detects the voltage value of the first battery bank 20. The first temperature sensor 62 detects the temperature of the first battery bank 20.

[0027] The second voltage sensor 63 detects the voltage value of the second battery bank 30. The second temperature sensor 64 detects the temperature of the second battery bank 30. The current sensor 60, the first voltage sensor 61, the first temperature sensor 62, the second voltage sensor 63, and the second temperature sensor 64 each transmit their detection values ​​to the control device 50.

[0028] The battery bank unit 1 further includes a third voltage sensor (not shown) that detects a power supply voltage value, which is the voltage value of the external power supply 2. The control device 50 detects a power outage of the external power supply 2 based on the power supply voltage value detected by the third voltage sensor.

[0029] The control device 50 controls the states of the switches 42 to 46 to control charging and discharging of the battery bank unit 1. The control device 50 has a storage unit 51. The storage unit 51 stores a table T shown in FIG.

[0030] Table T is a table that is referenced when the control device 50 calculates the remaining time, which is the time required for charging of the battery bank unit 1 (described later), to be completed. Table T associates the temperature with the lump-sum charging time, the first bank charging time, the second bank charging time, and the amount of voltage drop. In Table T, the temperature is divided into a total of eight temperature zones, with the range from 0°C to 60°C being divided into six zones of 10°C each. It goes without saying that the temperature range of each temperature zone and the number of temperature zones are not limited to those shown in FIG. 3. The lump-sum charging time, the first bank charging time, the second bank charging time, and the amount of voltage drop will be described in detail below.

[0031] The control device 50 also calculates the SOC (State of Charge) of the battery bank unit 1 by a known method based on the current value detected by the current sensor 60. The SOC of the battery bank unit 1 is a charging rate (%) corresponding to the total charge amount of the first and second battery banks 20 and 30.

[0032] Next, the charging control of the battery bank unit 1 executed by the control device 50 will be described with reference to the flowchart of FIG. 4 and the time chart of FIG.

[0033] When charging control has not started, the selector switch 42 and the first and second charging switches 43 and 45 are in the OFF state, and the first and second discharging switches 44 and 46 are in the ON state, allowing the first and second battery banks 20 and 30 to discharge. As described above, the first and second battery banks 20 and 30 are configured identically and connected in parallel. Therefore, the voltages and charge amounts of the first and second battery banks 20 and 30 are approximately equal. Therefore, the SOC of the battery bank unit 1 and the SOC of the first and second battery banks 20 and 30 are approximately equal.

[0034] The control device 50 starts charge control when it detects connection to the external power source 2 based on the detection value of the third voltage sensor, or when it detects that the power outage of the external power source 2 has ended.

[0035] The control device 50 starts the batch charging process in S1. The batch charging process is a process for charging the first and second battery banks 20, 30 at the same time. Specifically, as shown in Fig. 5, the control device 50 switches the selector switch 42 and the first and second charging switches 43, 45 from an OFF state and an ON state to an ON state (time t0).

[0036] The first and second discharge switches 44, 46 remain in the on state, so that the battery bank unit 1 can discharge to the load device 3 even if the external power supply 2 experiences a power outage during the batch charging process.

[0037] When the simultaneous charging process starts (time t0), power is supplied from the step-up DC / DC converter 41 to the first and second battery banks 20, 30, and the voltage values ​​of the first and second battery banks 20, 30 increase.

[0038] 5, the voltage value indicated by the solid line represents the voltage value of the first battery bank 20, and the voltage value indicated by the dashed-dotted line represents the voltage value of the second battery bank 30. Before the start of the simultaneous charging process and during the simultaneous charging process, the voltage values ​​of the first and second battery banks 20, 30 are approximately equal. In other words, the lines indicating the voltage values ​​of the first and second battery banks 20, 30 overlap and are shown by the solid line.

[0039] Next, in S2, the control device 50 determines whether the bank voltage value, which is the voltage value of the battery bank unit 1, is equal to or greater than the power supply voltage value. Specifically, the bank voltage value is the average value of the voltage value of the first battery bank 20 and the voltage value of the second battery bank 30. Note that the bank voltage value may be the voltage value of one of the first and second battery banks 20, 30. If the bank voltage value is lower than the power supply voltage value (NO in S2), the batch charging process continues.

[0040] On the other hand, if the voltage values ​​of the first and second battery banks 20, 30 increase and the bank voltage values ​​become equal to or greater than the power supply voltage value (YES at time t1; S2), the control device 50 ends the batch charging process at S3 and starts the first bank charging process.

[0041] The first bank charging process is a process for charging only the first battery bank 20. In the first bank charging process, the first battery bank 20 is fully charged to a voltage value higher than the power supply voltage value. In the first bank charging process, the second battery bank 30 is not charged.

[0042] Specifically, the control device 50 switches the second charging switch 45 to the OFF state and switches the first discharging switch 44 to the OFF state (time t1). As a result, power from the step-up DC / DC converter 41 is supplied only to the first battery bank 20, and the voltage value of the first battery bank 20 further increases from the power supply voltage value. In the first bank charging process, the first discharging switch 44 is in the OFF state, and the first battery bank 20 is not discharged. This makes it possible to prevent a voltage value higher than the power supply voltage value from being applied to the load device 3, and ultimately to prevent a malfunction of the load device 3.

[0043] Meanwhile, charging of the second battery bank 30 is stopped, and the voltage value of the second battery bank 30 gradually decreases due to self-discharge. During the first bank charging process, the second discharge switch 46 is in the ON state. Therefore, even if the external power supply 2 experiences a power outage during the first bank charging process, the second battery bank 30 can discharge to the load device 3.

[0044] Next, in S4, the control device 50 determines whether the first battery bank 20 is fully charged. Specifically, the control device 50 determines whether the value detected by the first temperature sensor 62 is a predetermined first temperature. The first temperature is the temperature at which the first battery bank 20 is fully charged. If the value detected by the first temperature sensor 62 is lower than the first temperature (NO in S4), the control device 50 continues charging only the first battery bank 20.

[0045] On the other hand, when the first battery bank 20 is fully charged and the detection value of the first temperature sensor 62 reaches the first temperature (time t2; YES in S4), the control device 50 stops charging the first battery bank 20 in S5.

[0046] Specifically, the control device 50 switches the first charging switch 43 to the OFF state (time t2). This stops charging the first battery bank 20, and the voltage value of the first battery bank 20 gradually decreases due to self-discharge. At this time, the temperature of the first battery bank 20 is higher than the temperature of the second battery bank 30. Therefore, the amount of drop in the voltage value of the first battery bank 20 per unit time is greater than the amount of drop in the voltage value of the second battery bank 30 per unit time.

[0047] Next, in S6, the control device 50 determines whether the voltage value of the first battery bank 20 is equal to or lower than the power supply voltage value. If the voltage value of the first battery bank 20 is higher than the power supply voltage value (NO in S6), the control device 50 maintains the state in which charging of the first and second battery banks 20, 30 is stopped.

[0048] On the other hand, when the voltage value of the first battery bank 20 becomes equal to or lower than the power supply voltage value (time t3; YES in S6), the control device 50 ends the first bank charging process and starts the second bank charging process in S7.

[0049] The second bank charging process is a process for charging only the second battery bank 30. In the second bank charging process, the second battery bank 30 is fully charged to a voltage value higher than the power supply voltage value. In the second bank charging process, the first battery bank 20 is not charged.

[0050] Specifically, the control device 50 switches the second charging switch 45 to the ON state, switches the first discharging switch 44 to the ON state, and switches the second discharging switch 46 to the OFF state (time t3). As a result, power is supplied from the step-up DC / DC converter 41 only to the second battery bank 30, and the voltage value of the second battery bank 30 rises and exceeds the power supply voltage value. In the second bank charging process, the second discharging switch 46 is in the OFF state, and the second battery bank 30 is not discharged. This makes it possible to prevent a voltage value higher than the power supply voltage value from being applied to the load device 3, and ultimately to prevent a malfunction of the load device 3.

[0051] Meanwhile, charging of the first battery bank 20 remains stopped, and the voltage value of the first battery bank 20 gradually decreases due to self-discharge. During the second bank charging process, the first discharge switch 44 is in the ON state. Therefore, even if the external power supply 2 experiences a power outage during the second bank charging process, the first battery bank 20 can discharge to the load device 3.

[0052] Next, in S8, the control device 50 determines whether the second battery bank 30 is fully charged. Specifically, the control device 50 determines whether the detection value of the second temperature sensor 64 has reached a predetermined second temperature. The second temperature is the temperature at which the second battery bank 30 is fully charged. If the detection value of the second temperature sensor 64 is lower than the second temperature (NO in S8), the control device 50 continues charging only the second battery bank 30. Note that the second temperature may be the same as the first temperature, which is the temperature at which the first battery bank 20 is fully charged.

[0053] On the other hand, when the second battery bank 30 is fully charged and the detection value of the second temperature sensor 64 reaches the second temperature (time t4; YES in S8), the control device 50 stops charging the second battery bank 30 in S9.

[0054] Specifically, the control device 50 switches the second charging switch 45 to the OFF state (time t4). This stops charging the second battery bank 30, and the voltage value of the second battery bank 30 gradually decreases due to self-discharge. At this time, the temperature of the second battery bank 30 is higher than the temperature of the first battery bank 20. Therefore, the amount of drop in the voltage value of the second battery bank 30 per unit time is greater than the amount of drop in the voltage value of the first battery bank 20 per unit time.

[0055] Next, in S10, the control device 50 determines whether the voltage value of the second battery bank 30 is equal to or lower than the power supply voltage value. If the voltage value of the second battery bank 30 is higher than the power supply voltage value (NO in S10), the control device 50 maintains the state in which charging of the first and second battery banks 20, 30 is stopped.

[0056] On the other hand, when the voltage value of the second battery bank 30 becomes equal to or lower than the power supply voltage value (time t5; YES in S10), the control device 50 ends the second bank charging process in S11. Specifically, the control device 50 switches the selector switch 42 to the OFF state and the second discharge switch 46 to the ON state (time t5). This ends the charging of the battery bank unit 1. The control device 50 determines the SOC of the battery bank unit 1 at the time when charging of the battery bank unit 1 is completed to be 100%.

[0057] The battery bank unit 1 may have three or more battery banks. When the number of battery banks is m, the m battery banks are charged at once in the batch charging process. After the batch charging process is completed, each of the m battery banks is charged one by one in turn, similar to the first and second bank charging processes described above.

[0058] Next, the control executed by the control device 50 to calculate the remaining time will be described with reference to the flowcharts in Figures 6A and 6B. The remaining time is the time required to complete charging of the battery bank unit 1. The control device 50 calculates the remaining time while executing the above-mentioned charging control.

[0059] In S20, the control device 50 obtains from table T the lump-charge time, the first bank charge time, and the second bank charge time associated with the temperature at the start of the lump-charge process of the battery bank unit 1. The temperature of the battery bank unit 1 is, for example, the average temperature of the first and second battery banks 20, 30. Note that the temperature of the battery bank unit 1 may be the temperature of one of the first and second battery banks 20, 30.

[0060] The lump-sum charging time corresponds to the time required from the start (time t0 in FIG. 5) to the end (time t1 in FIG. 5) of the lump-sum charging process when the SOC of the battery bank unit 1 at the start of the lump-sum charging process is a predetermined first predetermined charging rate (e.g., 0%). The first predetermined charging rate is an arbitrary value determined through an experiment or the like to determine the lump-sum charging time to be stored in advance in table T.

[0061] The first bank charging time corresponds to the time required from the start (time t1) to the end (time t3) of the first bank charging process. The second bank charging time corresponds to the time required from the start (time t3) to the end (time t5) of the second bank charging process. The bulk charging time, first bank charging time, and second bank charging time are determined for each temperature range by actual measurement in advance, such as through experiments, and are stored in Table T.

[0062] When charging of the battery bank unit 1 begins, for example, if the temperature of the battery bank unit 1 is 25°C, the control device 50 obtains from table T in Figure 3 the lump-sum charging time "A3", the first bank charging time "B3", and the second bank charging time "C3" corresponding to the temperature "20°C or higher and lower than 30°C".

[0063] Subsequently, the control device 50 calculates the remaining time in S21. Specifically, the control device 50 calculates the remaining time at the start of charging, which is the remaining time at the start of charging, using equation (1).

[0064] (Number 1) Remaining time at start of charging = Tm0+Tm1+Tm2 …(1)

[0065] In equation (1), Tm0, Tm1, and Tm2 are the lump charge time, the first bank charge time, and the second bank charge time obtained from table T.

[0066] The control device 50 also notifies the load device 3 of the calculated remaining time at the start of charging. The load device 3 displays the remaining time at the start of charging on a display or other display unit. This allows the manager of the load device 3 to know the time from the start of charging of the battery bank unit 1 to the completion of charging.

[0067] Furthermore, the control device 50 measures the time elapsed since the start of charging of the battery bank unit 1. Then, at every predetermined time interval, the control device 50 subtracts the elapsed time from the remaining time at the start of charging calculated in S21 to calculate the remaining time at that time and update the remaining time to the latest version, and notifies the load device 3 of the updated remaining time. The load device 3 displays the updated remaining time on the display unit.

[0068] Next, the control device 50 determines whether or not the lump-sum charging process has ended in S22. If the lump-sum charging process is being executed (NO in S22), the control device 50 continues updating and notifying the remaining time.

[0069] When the lump-sum charging process has ended (YES in S22), the control device 50 corrects the remaining time in S23. Specifically, the control device 50 corrects the remaining time based on the actual lump-sum charging time, which is the time actually required for the lump-sum charging process. The control device 50 subtracts the actual lump-sum charging time from the lump-sum charging time obtained from table T, and adds the calculated value to the remaining time at the time when the lump-sum charging process ended.

[0070] That is, the control device 50 corrects the remaining time using the difference between the experimental value (lump charge time) of the time required for the lump charge process and the actual measurement value (actual lump charge time). This allows the control device 50 to accurately correct the remaining time when the lump charge is completed. Note that the control device 50 does not have to correct the remaining time in S23.

[0071] Next, in S24, the control device 50 updates the lump-sum charge time. Specifically, the control device 50 updates the lump-sum charge time in table T that corresponds to the temperature at the start of charging of the battery bank unit 1 with the actual lump-sum charge time. For example, if the temperature of the battery bank unit 1 is 25°C at the start of charging of the battery bank unit 1, the control device 50 updates the lump-sum charge time "A3" in table T that corresponds to a temperature of "20°C or higher and lower than 30°C" with the actual lump-sum charge time.

[0072] Next, in S25, the control device 50 determines whether charging of the first battery bank 20 has stopped during the first bank charging process. If the first battery bank 20 is not fully charged and charging of the first battery bank 20 has not stopped (NO in S25), the control device 50 continues updating and notifying the remaining time.

[0073] On the other hand, when the first battery bank 20 reaches a fully charged state and charging of the first battery bank 20 stops (YES in S25), the control device 50 determines in S26 whether the temperature of the first battery bank 20 is equal to or lower than a first threshold temperature. The first threshold temperature is the temperature of the first battery bank 20 when the rate of drop per unit time of the voltage value of the first battery bank 20 is approximately constant. At the time when charging of the first battery bank 20 stops (time t2), the temperature of the first battery bank 20 is relatively high and the rate of drop per unit time of the voltage value of the first battery bank 20 is relatively large. Thereafter, as the voltage value of the first battery bank 20 decreases due to self-discharge, the rate of drop per unit time of the voltage value of the first battery bank 20 decreases and becomes approximately constant after point P (time t10) in FIG. 5 . In other words, the first threshold temperature is determined to be the temperature of the first battery bank 20 at point P. The first judgment temperature is determined in advance by actual measurement through an experiment or the like.

[0074] The control device 50 may calculate the first judgment temperature. Specifically, the control device 50 calculates the first judgment temperature by adding a predetermined first predetermined temperature to the temperature of the first battery bank 20 at the start of the batch charging process. The first predetermined temperature is determined in advance by actually measuring, through an experiment or the like, the relationship between the temperature of the first battery bank 20 at the start of the batch charging process and the temperature of the first battery bank 20 at which the amount of drop in the voltage value of the first battery bank 20 per unit time becomes approximately constant. The first judgment temperature may be the temperature obtained by adding the first predetermined temperature to the temperature of the first battery bank 20 at the start of the first bank charging process.

[0075] If the temperature of the first battery bank 20 is higher than the first determination temperature (NO in S26), the control device 50 continues updating and notifying the remaining time. If the temperature of the first battery bank 20 drops to or below the first determination temperature (YES in S26), the control device 50 obtains the voltage drop amount from table T in S27. Specifically, the control device 50 obtains the voltage drop amount corresponding to the temperature of the first battery bank 20 at that time from table T.

[0076] For example, if the temperature of the first battery bank 20 at that time is 45°C, the control device 50 obtains the voltage drop amount "V5" corresponding to the temperature "40°C or higher but lower than 50°C" from Table T in FIG. 3. The voltage drop amount is the amount of drop per unit time in the voltage value of the first battery bank 20 after the first battery bank 20 is fully charged and charging is stopped. The voltage drop amount is determined for each temperature range by actual measurement in advance, such as through experiments, and is stored in Table T.

[0077] Next, in S28, the control device 50 corrects the remaining time. First, based on the voltage drop amount obtained from table T, the control device 50 calculates a first charging stop time, which is the time required from when the temperature of the first battery bank 20 becomes equal to or lower than the first judgment temperature until the second bank charging process starts (time t3). Specifically, the control device 50 calculates the first charging stop time by subtracting the power supply voltage value from the voltage value of the first battery bank 20 when the temperature of the first battery bank 20 becomes equal to or lower than the first judgment temperature, and dividing the subtracted value by the voltage drop amount obtained from table T.

[0078] The control device 50 corrects the remaining time based on the calculated first charging stop time. Specifically, the control device 50 corrects the remaining time by replacing the remaining time at the time when the temperature of the first battery bank 20 becomes equal to or lower than the first threshold temperature with the sum of the calculated first charging stop time and the second bank charging time acquired in S20. After the temperature of the first battery bank 20 becomes equal to or lower than the first threshold temperature, the control device 50 subtracts the elapsed time since the temperature of the first battery bank 20 became equal to or lower than the first threshold temperature from the corrected remaining time at predetermined intervals to calculate the remaining time at that time and update the remaining time to the latest value. The control device 50 then notifies the load device 3 of the updated remaining time. This allows the control device 50 to accurately correct the remaining time while charging of the first battery bank 20 is stopped during the first bank charging process.

[0079] Next, in S29, the control device 50 determines whether or not the second bank charging process has started. If the second bank charging process has not started (NO in S29), the control device 50 continues updating and notifying the remaining time.

[0080] On the other hand, if the second bank charging process has started (YES in S29), the control device 50 corrects the remaining time in S30. Specifically, the control device 50 replaces the remaining time at time t3 (when the second bank charging process starts) with the actual first bank charging time, which is the time actually required for the first bank charging process. Furthermore, if the control device 50 corrects the remaining time at time t3, it updates the latest remaining time as follows. That is, after time t3, the control device 50 subtracts the elapsed time from time t3 from the actual first bank charging time at predetermined intervals to calculate the remaining time at that time and update the latest remaining time. Then, the control device 50 notifies the load device 3 of the updated remaining time.

[0081] As described above, the first and second battery banks 20, 30 are configured similarly to each other, and the ambient environments (temperature, humidity, etc.) of the first and second battery banks 20, 30 are substantially the same. Therefore, the time actually required for the second bank charging process is substantially equal to the actual first bank charging time. In other words, when the first bank charging process is completed, the control device 50 can accurately correct the remaining time by replacing the remaining time with the actual first bank charging time, and notify the user of the corrected remaining time. Note that the control device 50 does not have to correct the remaining time at S30.

[0082] Next, in S31, the control device 50 determines whether charging of the second battery bank 30 has stopped during the second bank charging process. If the second battery bank 30 is not fully charged and charging of the second battery bank 30 has not stopped (NO in S31), the control device 50 continues updating and notifying the remaining time.

[0083] On the other hand, when the second battery bank 30 reaches a full charge state and charging of the second battery bank 30 stops (YES in S31), the control device 50 determines in S32 whether the temperature of the second battery bank 30 is equal to or lower than a second threshold temperature. The second threshold temperature is the temperature of the second battery bank 30 when the rate of drop per unit time of the voltage value of the second battery bank 30 is approximately constant. At the time when charging of the second battery bank 30 stops (time t4), the temperature of the second battery bank 30 is relatively high and the rate of drop per unit time of the voltage value of the second battery bank 30 is relatively large. Thereafter, as the voltage value of the second battery bank 30 decreases due to self-discharge, the rate of drop per unit time of the voltage value of the second battery bank 30 decreases and becomes approximately constant after point Q (time t11) in FIG. 5 . In other words, the second threshold temperature is determined to be the temperature of the second battery bank 30 at point Q. The second judgment temperature is determined in advance by actual measurement through an experiment, etc. If the first and second battery banks 20, 30 have the same configuration, the second judgment temperature may be the same as the first judgment temperature.

[0084] The control device 50 may calculate the second judgment temperature. Specifically, the control device 50 calculates the second judgment temperature by adding a predetermined second predetermined temperature to the temperature of the second battery bank 30 at the start of the simultaneous charging process. The second predetermined temperature is determined in advance by experimentally measuring the relationship between the temperature of the second battery bank 30 at the start of the simultaneous charging process and the temperature of the second battery bank 30 at which the amount of drop in the voltage value of the second battery bank 30 per unit time becomes approximately constant. The second judgment temperature may be a temperature obtained by adding the second predetermined temperature to the temperature of the second battery bank 30 at the start of the second bank charging process. Furthermore, if the first and second battery banks 20, 30 have the same configuration, the second predetermined temperature may be the same as the first predetermined temperature.

[0085] If the temperature of the second battery bank 30 is higher than the second determination temperature (NO in S32), the control device 50 continues updating and notifying the remaining time. If the temperature of the second battery bank 30 drops to or below the second determination temperature (YES in S32), the control device 50 obtains the voltage drop amount from table T in S33. Specifically, the control device 50 obtains the voltage drop amount corresponding to the temperature of the second battery bank 30 at that time from table T.

[0086] For example, if the temperature of the second battery bank 30 at that time is 45° C., the control device 50 obtains from table T the voltage drop amount "V5" corresponding to the temperature "40° C. or higher and lower than 50° C.."

[0087] Next, in S34, the control device 50 corrects the remaining time. First, based on the voltage drop amount obtained from table T, the control device 50 calculates a second charging stop time, which is the time required from when the temperature of the second battery bank 30 becomes equal to or lower than the second judgment temperature until the second bank charging process ends (time t5). Specifically, the control device 50 calculates the second charging stop time by subtracting the power supply voltage value from the voltage value of the second battery bank 30 when the temperature of the second battery bank 30 becomes equal to or lower than the second judgment temperature, and dividing the subtracted value by the voltage drop amount obtained from table T.

[0088] The control device 50 corrects the remaining time based on the calculated second charging stop time. Specifically, the control device 50 corrects the remaining time by replacing the remaining time at the time when the temperature of the second battery bank 30 became equal to or lower than the second threshold temperature with the calculated second charging stop time. After the temperature of the second battery bank 30 becomes equal to or lower than the second threshold temperature, the control device 50 subtracts the elapsed time since the temperature of the second battery bank 30 became equal to or lower than the second threshold temperature from the corrected remaining time at predetermined intervals to calculate the remaining time at that time and update the remaining time to the latest value. The control device 50 then notifies the load device 3 of the updated remaining time. This allows the control device 50 to accurately correct the remaining time while charging of the second battery bank 30 is stopped during the second bank charging process.

[0089] Next, the control device 50 determines whether the second bank charging process has ended in S35. If the second bank charging process has not ended (NO in S35), the control device 50 continues updating and notifying the remaining time.

[0090] On the other hand, if the second bank charging process has ended (YES in S35), the control device 50 updates the first and second bank charging times in S36. Specifically, the control device 50 updates the first bank charging time in table T that corresponds to the temperature at the start of charging of the battery bank unit 1 with the actual first bank charging time. For example, if the temperature of the battery bank unit 1 is 25°C at the start of charging of the battery bank unit 1, the control device 50 updates the first bank charging time "B3" in table T that corresponds to a temperature of "20°C or higher and lower than 30°C" with the actual first bank charging time.

[0091] Furthermore, the control device 50 updates the second bank charging time in table T, which corresponds to the temperature at the start of charging the battery bank unit 1, with the actual second bank charging time, which is the time actually required for the second bank charging process. For example, if the temperature of the battery bank unit 1 is 25°C at the start of charging the battery bank unit 1, the control device 50 updates the second bank charging time "C3" in table T, which corresponds to a temperature of "20°C or higher and lower than 30°C," with the actual second bank charging time. After updating the second bank charging time, the control device 50 ends control for calculating the remaining time.

[0092] The actual lump-charge time, the actual first bank charge time, and the actual second bank charge time vary depending on the ambient environment of the battery bank unit 1, the power supply voltage value, the temperatures of the first and second battery banks 20, 30, aging of the battery bank unit 1, and the degree of deterioration of the first and second battery banks 20, 30 (hereinafter referred to as the ambient environment of the battery bank unit 1). Therefore, by updating Table T with the actual lump-charge time, the actual first bank charge time, and the actual second bank charge time, the values ​​stored in Table T can be adapted to the ambient environment of the battery bank unit 1. Therefore, by updating Table T to adapt to changes in the ambient environment of the battery bank unit 1 every time the first and second battery banks 20, 30 are charged, the control device 50 can accurately calculate the remaining time when charging control is performed.

[0093] Second Embodiment Next, a second embodiment of the present disclosure will be described, focusing mainly on differences from the first embodiment. The table T of the second embodiment does not have a voltage drop amount. Furthermore, the control performed by the control device 50 of the second embodiment to calculate the remaining time differs from that of the first embodiment. The control to calculate the remaining time in the second embodiment will be described below with reference to FIGS. 6A, 7A, and 7B.

[0094] When the control device 50 starts the control for calculating the remaining time, it executes S20 to S25 of Fig. 6A in the same manner as in the first embodiment. When charging of the first battery bank 20 is stopped (YES in S25), the control device 50 calculates a first actual drop amount, which is the actual drop amount per unit time of the voltage value of the first battery bank 20 at that time, in S126 of Fig. 7A.

[0095] Next, in S127, the control device 50 determines whether the first actual drop amount is equal to or less than a predetermined amount. The predetermined amount is a value determined in advance by actual measurement, such as through experiments, and is set to the value of the first actual drop amount at point P in Figure 5. In other words, the predetermined amount is the value of the first actual drop amount when, after charging of the first battery bank 20 has stopped, the first actual drop amount has decreased and become substantially constant.

[0096] If the first actual drop amount is greater than the predetermined amount due to a relatively high temperature of the first battery bank 20 (NO in S127), the control device 50 continues calculating the first actual drop amount (S126) and updating and notifying the remaining time. On the other hand, if the voltage value and temperature of the first battery bank 20 decrease and the first actual drop amount becomes equal to or less than the predetermined amount (YES in S127), the control device 50 corrects the remaining time in S128.

[0097] Specifically, the control device 50 calculates a second first charging stop time, which is the time required from the point at which the first actual drop amount becomes equal to or less than a predetermined amount until the second bank charging process begins, and corrects the remaining time based on the calculated second first charging stop time.

[0098] The control device 50 calculates the second first charging stop time by subtracting the power supply voltage value from the voltage value of the first battery bank 20 at the time when the first actual drop amount becomes equal to or less than the predetermined amount, and dividing the subtracted value by the first actual drop amount at the time when the first actual drop amount becomes equal to or less than the predetermined amount.

[0099] Furthermore, the control device 50 corrects the remaining time by replacing the remaining time at the time when the first actual drop amount becomes equal to or less than the predetermined amount with the sum of the calculated second first charging stop time and the second bank charging time acquired in S20. After the first actual drop amount becomes equal to or less than the predetermined amount, the control device 50 subtracts the elapsed time from the time when the first actual drop amount became equal to or less than the predetermined amount from the corrected remaining time at predetermined time intervals to calculate the remaining time at that time and update the remaining time to the latest. The control device 50 then notifies the load device 3 of the updated remaining time.

[0100] Subsequently, the control device 50 executes S129 to S131 in the same manner as S29 to S31 in the first embodiment.

[0101] Then, when charging of the second battery bank 30 is stopped (YES in S131), the control device 50 calculates in S132 a second actual drop amount, which is the actual drop amount per unit time of the voltage value of the second battery bank 30 at that time.

[0102] Next, in S133, the control device 50 determines whether the second actual drop amount is equal to or less than a second predetermined amount. The second predetermined amount is a value determined in advance by actual measurement, such as through experiments, and is set to the value of the second actual drop amount at point Q in FIG. 5. In other words, the second predetermined amount is the value of the second actual drop amount when the second actual drop amount decreases and becomes substantially constant after charging of the second battery bank 30 stops. Note that if the first and second battery banks 20, 30 have the same configuration, the second predetermined amount may be the same value as the predetermined amount.

[0103] If the second actual drop amount is greater than the second predetermined amount due to a relatively high temperature of the second battery bank 30 (NO in S133), the control device 50 continues calculating the second actual drop amount (S132) and updating and notifying the remaining time. On the other hand, if the voltage value and temperature of the second battery bank 30 decrease and the second actual drop amount becomes equal to or less than the second predetermined amount (YES in S133), the control device 50 corrects the remaining time in S134.

[0104] Specifically, the control device 50 calculates a second second charging stop time, which is the time required from the time when the second actual drop amount becomes a second predetermined amount to the end of the second bank charging process, and corrects the remaining time based on the calculated second second charging stop time.

[0105] The control device 50 calculates the second second charging stop time by subtracting the power supply voltage value from the voltage value of the second battery bank 30 at the time when the second actual drop amount becomes equal to or less than the second predetermined amount, and dividing the subtracted value by the second actual drop amount at the time when the second actual drop amount becomes equal to or less than the second predetermined amount.

[0106] Furthermore, the control device 50 corrects the remaining time by replacing the remaining time at the time when the second actual drop amount becomes equal to or less than the second predetermined amount with the calculated second second charging stop time. After the second actual drop amount becomes equal to or less than the second predetermined amount, the control device 50 subtracts the elapsed time from the time when the second actual drop amount becomes equal to or less than the second predetermined amount from the corrected remaining time at predetermined time intervals to calculate the remaining time at that time and update the remaining time to the latest. The control device 50 then notifies the load device 3 of the updated remaining time.

[0107] Subsequently, the control device 50 executes S135 and S136 in the same manner as S35 and S36 in the first embodiment, and ends the control for calculating the remaining time.

[0108] The present disclosure is not limited to the embodiments described above, and various modifications to the present embodiments and combinations of components from different embodiments are also included within the scope of the present disclosure, as long as they do not deviate from the gist of the present disclosure.

[0109] For example, equation (1) may be changed to the following equation (2). (Number 2) Remaining time when charging starts =Tm0×(100-So) / (100-α)+Tm1+Tm2 …(2)

[0110] In equation (2), So (%) is the SOC of the battery bank unit 1 at the start of charging control (time t0), and α (%) is the first predetermined charging rate, which is the SOC of the battery bank unit at the start of the experiment that determines the total charging time to be stored in table T.

[0111] Equation (2) differs from equation (1) in that "Tm0" is multiplied by "(100-So) / (100-α)." As described above, Tm0 is the lump-sum charging time, and corresponds to the time required from the start (time t0) to the end (time t1) of the lump-sum charging process when the SOC of the battery bank unit 1 at the start of charging is the first predetermined charging rate (α).

[0112] Also, "(100-So) / (100-α)" is the ratio of the amount of charge required for the SOC of battery bank unit 1 to increase from So to 100% to the amount of charge required for the SOC of battery bank unit 1 to increase from α to 100%.

[0113] Therefore, "Tm0×(100-So) / (100-α)" in equation (2) corresponds to the time required from the start (time t0) to the end (time t1) of the lump-sum charging process when the SOC at the start of lump-sum charging of the battery bank unit 1 is So.

[0114] That is, using equation (2), it is possible to calculate the remaining time at the start of charging, excluding the time required to charge the battery bank unit 1 to the charge amount corresponding to the SOC at the start of the batch charging. That is, the control device 50 calculates the remaining time until charging of the battery bank unit 1 is completed based on the temperature of the battery bank unit 1 and the SOC of the battery bank unit at the start of the batch charging process. Therefore, the control device 50 can accurately calculate the remaining time at the start of charging.

[0115] The control device 50 may also start charging control when the SOC of the battery bank unit 1 drops below a predetermined second predetermined charging rate (e.g., 90%) due to natural discharge of the first and second battery banks 20 and 30. The second predetermined charging rate is determined so that the SOC of the battery bank unit 1 does not become relatively low due to natural discharge. The second predetermined charging rate and the first predetermined charging rate may be set equal. In this case, Tm0 (lump charge time) in equations (1) and (2) is determined based on the second predetermined charging rate, and becomes a relatively accurate time when the SOC of the battery bank unit 1 at the time when charging control starts is equal to the second predetermined charging rate. Therefore, when the SOC of the battery bank unit 1 at the time when charging control starts is equal to the second predetermined charging rate, the control device 50 can more accurately calculate the remaining time.

[0116] Furthermore, in S30, the control device 50 may correct the remaining time based on a corrected charging time obtained by adding a charging time corresponding to the amount of voltage drop caused by self-discharge of the second battery bank 30 during the first bank charging process to the actual first bank charging time. Specifically, the control device 50 calculates the corrected charging time by multiplying the actual first bank charging time by a predetermined coefficient (e.g., 1.05). The predetermined coefficient is determined in advance by experimentally measuring the amount of voltage drop caused by self-discharge of the second battery bank 30 during the first bank charging process. The control device 50 corrects the remaining time at time t3 (the start of the second bank charging process) by replacing it with the corrected charging time.

[0117] The first and second battery banks 20, 30 may be configured differently. In this case, the temperature, the batch charging time, the first bank charging time, the second bank charging time, the voltage drop amount, and the second voltage drop amount, which is the amount of drop per unit time in the voltage value of the second battery bank 30 after the second battery bank 30 is fully charged, may be associated with each other in table T. In this case, the control device 50 acquires the second voltage drop amount in S33.

[0118] In addition, if the first and second battery banks 20, 30 are configured differently from each other, the remaining time may not be corrected at the start of the second bank charging process, i.e., S30 in FIG. 6B and 130 in FIG. 7A may not be executed.

[0119] The battery bank unit 1 may be configured so that the first and second battery banks 20, 30 are detachable. The battery bank unit 1 does not have to include the first and second battery banks 20, 30 as its own components. In other words, the battery bank unit 1 may be configured to include the input / output terminal 10, the charge / discharge circuit 40, the control device 50, and the sensors 60 to 64. In this case, by retrofitting the first and second battery banks 20, 30 separately, the battery bank unit 1 can function as a backup device for the external power source 2.

[0120] The storage unit 51 may be configured separately from the control device 50 and capable of communicating with the control device 50. In this case, the storage unit 51 may be connected to the control device 50 via a network such as the Internet so that the information in the table can be shared among multiple battery bank units 1, and the multiple battery bank units 1 can update the table to store more accurate information. The control device 50 may be configured separately from the battery bank unit 1. In this case, the control device 50 can remotely control the battery bank unit 1 and calculate the remaining time via a network such as the Internet. The storage unit 51 may store a remaining charge time calculation program that calculates the remaining time, and the control device 50 may calculate the remaining time as described above by reading and executing the remaining charge time calculation program. [Industrial Applicability]

[0121] The present disclosure is suitably used as a battery bank unit. [Explanation of symbols]

[0122] 1 Battery bank unit 20 First Battery Bank 30 Second Battery Bank 50 Control device T-table

Claims

1. a first battery bank and a second battery bank connected in parallel; a control device that performs first bank charging to charge only the first battery bank after batch charging to charge the first battery bank and the second battery bank at the same time, and that performs second bank charging to charge only the second battery bank after the first bank charging; A battery bank unit comprising: the control device calculates a remaining time until charging of the battery bank unit is completed based on a temperature of the battery bank unit at the time the batch charging is started; The control device The information can be acquired from a table in which the temperature, a lump-sum charging time that is the time required for the lump-sum charging, a first bank charging time that is the time required from the start of the first bank charging to the start of the second bank charging, and a second bank charging time that is the time required from the start of the second bank charging to the completion of charging of the battery bank unit are associated with each other, calculating the remaining time based on the lump-sum charge time, the first bank charge time, and the second bank charge time, which are associated with the temperature of the battery bank unit at the start of the lump-sum charge, and the temperature of the battery bank unit at the start of the lump-sum charge; The control device updating the table based on an actual lump-sum charging time, which is the time actually required from the start of the lump-sum charging to the start of the first bank charging, an actual first bank charging time, which is the time actually required from the start of the first bank charging to the start of the second bank charging, and an actual second bank charging time, which is the time actually required from the start of the second bank charging to the completion of charging of the battery bank unit; Battery bank unit.

2. the control device corrects the remaining time based on at least one of the actual batch charging time and the actual first bank charging time while the battery bank unit is being charged. The battery bank unit according to claim 1 .

3. a first battery bank and a second battery bank connected in parallel; a control device that performs first bank charging to charge only the first battery bank after batch charging to charge the first battery bank and the second battery bank at the same time, and that performs second bank charging to charge only the second battery bank after the first bank charging; A battery bank unit comprising: the control device calculates a remaining time until charging of the battery bank unit is completed based on a temperature of the battery bank unit at the time the batch charging is started; The control device The information can be acquired from a table in which the temperature, a lump-sum charging time that is the time required for the lump-sum charging, a first bank charging time that is the time required from the start of the first bank charging to the start of the second bank charging, and a second bank charging time that is the time required from the start of the second bank charging to the completion of charging of the battery bank unit are associated with each other, calculating the remaining time based on the lump-sum charge time, the first bank charge time, and the second bank charge time, which are associated with the temperature of the battery bank unit at the start of the lump-sum charge, and the temperature of the battery bank unit at the start of the lump-sum charge; The table stores a voltage drop amount during a period when charging of the first battery bank is stopped, in association with the temperature; The control device in the first bank charging, after the first battery bank reaches a fully charged state, charging of the first battery bank is stopped until a voltage value of the first battery bank drops to a power supply voltage value before starting the second bank charging; When the temperature of the first battery bank becomes equal to or lower than a predetermined threshold temperature, a first charging suspension time is calculated based on the voltage drop amount associated with the predetermined temperature, the first charging suspension time being the time required from when the temperature of the first battery bank becomes equal to or lower than the threshold temperature until charging of the second battery bank is started; correcting the remaining time based on the first charging stop time; Battery bank unit.

4. a first battery bank and a second battery bank connected in parallel; a control device that performs first bank charging to charge only the first battery bank after batch charging to charge the first battery bank and the second battery bank at the same time, and that performs second bank charging to charge only the second battery bank after the first bank charging; A battery bank unit comprising: the control device calculates a remaining time until charging of the battery bank unit is completed based on a temperature of the battery bank unit at the time the batch charging is started; The control device The information can be acquired from a table in which the temperature, a lump-sum charging time that is the time required for the lump-sum charging, a first bank charging time that is the time required from the start of the first bank charging to the start of the second bank charging, and a second bank charging time that is the time required from the start of the second bank charging to the completion of charging of the battery bank unit are associated with each other, calculating the remaining time based on the lump-sum charge time, the first bank charge time, and the second bank charge time, which are associated with the temperature of the battery bank unit at the start of the lump-sum charge, and the temperature of the battery bank unit at the start of the lump-sum charge; The control device in the first bank charging, after the first battery bank reaches a fully charged state, charging of the first battery bank is stopped until a voltage value of the first battery bank drops to a power supply voltage value before starting the second bank charging; calculating an actual drop amount, which is an actual drop amount of a voltage value of the first battery bank per unit time, while charging of the first battery bank is stopped during the first bank charging; calculating a second charging suspension time, which is a time required from when the actual drop amount becomes equal to or less than a predetermined amount to when the second bank charging starts, based on the actual drop amount when the actual drop amount becomes equal to or less than a predetermined amount; correcting the remaining time based on the second charging stop time; Battery bank unit.

5. 1. A remaining charge time calculation method in which a computer calculates a remaining time until charging of a battery bank unit is completed, the remaining time being calculated by a computer, the remaining time being calculated being a battery bank unit in which a first battery bank and a second battery bank connected in parallel to the first battery bank are charged together, followed by first bank charging, in which only the first battery bank is charged, and then second bank charging, in which only the second battery bank is charged, acquiring a temperature of the battery bank unit at the start of the simultaneous charging; obtaining the lump-sum charging time, the first bank charging time, and the second bank charging time associated with the temperature of the battery bank unit at the start of the lump-sum charging from a table in which a temperature, a lump-sum charging time that is the time required for the lump-sum charging, a first bank charging time that is the time required from the start of the first bank charging to the start of the second bank charging, and a second bank charging time that is the time required from the start of the second bank charging to the completion of charging of the battery bank unit are associated with each other, and calculating the remaining time; updating the table based on an actual lump-sum charging time, which is the time actually required from the start of the lump-sum charging to the start of the first bank charging, an actual first bank charging time, which is the time actually required from the start of the first bank charging to the start of the second bank charging, and an actual second bank charging time, which is the time actually required from the start of the second bank charging to the completion of charging of the battery bank unit; A method for calculating remaining charge time, including:

6. a computer that controls a battery bank unit in which a first battery bank and a second battery bank connected in parallel to the first battery bank are charged together, followed by first bank charging in which only the first battery bank is charged, and in which second bank charging in which only the second battery bank is charged after the first bank charging, acquiring temperatures of the battery bank units at the start of the simultaneous charging; a step of obtaining the lump-sum charging time, the first bank charging time, and the second bank charging time associated with the temperature of the battery bank unit at the start of the lump-sum charging from a table in which the temperature, the lump-sum charging time being the time required for the lump-sum charging, the first bank charging time being the time required from the start of the first bank charging to the start of the second bank charging, and the second bank charging time being the time required from the start of the second bank charging to the completion of charging of the battery bank unit are associated with each other, and calculating the remaining time until charging of the battery bank unit is completed; updating the table based on an actual lump-sum charging time, which is the time actually required from the start of the lump-sum charging to the start of the first bank charging, an actual first bank charging time, which is the time actually required from the start of the first bank charging to the start of the second bank charging, and an actual second bank charging time, which is the time actually required from the start of the second bank charging to the completion of charging of the battery bank unit; A remaining charge time calculation program that executes the above.

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