JPH03180781A - Charging device - Google Patents

Abstract

PURPOSE:To accurately decide the charging/discharging degree of battery to be charged and to enable the corresponding quantitative display by comparing a voltage between terminals of the battery with characteristic data of the battery in the case of connecting a specified load different from a charging circuit. CONSTITUTION:The charging circuit 14 is made working state by a process control circuit 22 then a switch 20 is connected to the contact point (a) to charge the battery 10. During the charging, the switch 20 is connected to the contact point (b) in a very short time for the battery 10 for every specified time interval or in accordance with the operation of a switch 26. With this procedure, the battery 10 is discharged by a resistor 16, and the voltage V0 between the terminals of battery 10 is measured 12 at the time point when a transient phenomenon of the discharge start time is over and the voltage value V0 is sent to the circuit 22. Since data of the discharge characteristic at the time when a specified load is connected to the battery and of the charge characteristic at the time when the battery is charged with a specified current are stored in a memory 28, the voltage value V0 is adapted to these data by the circuit 22, and an applicable charging degree, time required for charging and remaining time for use are read out then displayed 24.

Description

[Detailed description of the invention] [Industrial application field] The present invention is a secondary type ltI! The present invention relates to a charging device for charging a battery.

[Prior Art] Conventional chargers are equipped with a means for notifying the user when charging is complete, but this generally monitors the terminal voltage of the rechargeable battery being charged and waits until the terminal voltage reaches a predetermined level. When this value is reached, it is assumed that charging is complete and a predetermined display is displayed.

[Problem to be solved by the invention] However, in the conventional example, it is not possible to quantitatively know the time until charging is completed during charging, and it is not possible to quantitatively know how long it will take to charge the battery while it is being charged. It was not possible to obtain specific information such as whether the battery was fully charged or not.

An object of the present invention is to provide a charging device that can obtain such information.

[Means for Solving the Problems] The charging device according to the present invention measures the voltage across the terminals of the battery when a predetermined load different from the charging circuit is connected, and connects this inter-terminal voltage with the predetermined load. The present invention is characterized in that the charging/discharging state of the battery is determined by comparing the characteristic data of the battery in the above case.

[Function] By the means described above, it is possible to accurately determine the degree of charging and discharging of the battery to be charged, and to obtain a corresponding quantitative display.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a block diagram of an embodiment of the present invention. 1
0 is the battery to be charged; 12 is the voltage measurement circuit 14 that measures the voltage between the terminals of the battery 10;
16 is a resistor for measuring the degree of charge of the battery 10, that is, the degree of charge; 20 is a charging circuit 1;
4 output, resistor 16 or 18 can be selectively connected to battery 10
A switch 22 connected to the voltage measuring circuit 1 controls the operation of the charging circuit 14 and switching of the switch 20.
24 is a display device that displays the calculation results and control status of the calculation control circuit 22. Further, 26 is an instruction switch that instructs the arithmetic and control circuit 22 to measure the degree of charge of the battery 10, and 28 is a memory that stores data on the charging and discharging characteristics of the battery 10 to be charged.

When the arithmetic control circuit 22 charges the battery 10,
The charging circuit 14 is activated and the switch 20 is connected to the a contact point. Then, during charging, the switch 20 is connected to the b contact for a very short time at predetermined time intervals for the battery 10, or in response to the operation of the switch 26. This results in
The battery 10 is discharged by the resistor 16, and when the transient phenomenon at the start of discharge ends, the voltage across the terminals of the battery 10 is measured by the voltage measuring circuit 12, and the measured voltage value is sent to the arithmetic control circuit 22.

Figure 2 shows a Ni-Cd secondary battery with a predetermined load (resistance 16
) are connected. The vertical axis represents the voltage between the terminals, and the horizontal axis represents the elapsed time, and it can be seen that the voltage between the terminals monotonically decreases as time passes.

Assuming that the lowest voltage between the terminals at which the device to be used can operate is 8, the usable time is T2. FIG. 3 shows charging characteristics when a Ni--Cd secondary battery is charged with a predetermined current.

The vertical axis is the voltage between the terminals, and the horizontal axis is the time. When the battery is fully charged, the voltage between the terminals decreases a little, so it can be determined whether the battery is fully charged or not. Note that T is the time required to fully charge a battery that has been discharged to below (2).

Memo 1J28 by converting the discharge characteristics shown in Figure 2 into data.
If the voltage between the terminals is measured when the predetermined load 16 is connected, the degree of charge of the target battery can be quantitatively determined. That is, the arithmetic control circuit 22
The initial inter-terminal voltage V when the resistor 16 is connected to
is applied to determine the degree of charge.

Table 1 is a table obtained by converting the discharge characteristics shown in FIG. 2 and the charging characteristics shown in FIG. 3 into data, and is stored in the memory 28. A in Table 1 is numerical data from 100 to 0 indicating the degree of charge,
B is data indicating the time from 0 to T until full charge,
C is data indicating the time T2 to 0 until the lowest working voltage vt is reached. For example, when the voltage across the terminals of the half-α battery is vo, the usable time C0 from FIG. 2 is TI! To
(minutes). This state is To/r, x 100(
%) can be considered to be used, and this is stored in variable A of memory 28 as 80. From now on, it is predicted that the battery will be fully charged in TF X TO/Ti (minutes).

FIG. 4 shows an operation flowchart of the arithmetic control circuit 22. First, the arithmetic control circuit 22 puts the charging circuit 14 into an operating state (Sl). After that, the switch 20 is connected to the b contact (Sl), and the voltage between the terminals of the battery 10 due to the resistor 16 is
0 is measured by the voltage measuring circuit 12 (S3). Voltage between terminals measured with S3 ■. is applied to the table in the memory 28 (Table 1), and the respective data of the charging degree A1, the time required for charging B1, and the remaining usable time C are read out (S4), and transferred to the display device 24 for display (S4). S5).

If the value of A is less than 100, it is not in a fully charged state, so connect the switch 20 to the a contact and charge it for a predetermined period of time (S7, 8.9), or according to the operation of the switch 26. (SIO), return to S2 and perform measurement.

Also, even during charging, the voltage measurement circuit 12
Measure the voltage between the terminals of S8 (5ll), and if it does not decrease,
Return to , continue charging, and if it decreases (Sl 1),
Substitute the voltage value between the terminals at full charge ■ into the variable ■, and proceed to S4.
Returning to step S12, A equal to 100 is read out from the memory 28.

If A is equal to 100 in S6, the charging circuit 14 is stopped (S12) because it is fully charged, and the process ends.

In the above embodiment, the degree of charge was determined quantitatively by applying the voltage between the terminals of the battery when a predetermined load was connected to the discharge characteristics, but of course, when the load was connected to the battery for a predetermined time, By applying the change in the discharge characteristics to the discharge characteristics, the degree of charge can be determined with even higher accuracy. Furthermore, after charging is temporarily stopped, the voltage between the terminals in a substantially no-load state and the voltage between the terminals in a state where a predetermined load resistance is connected are measured, and the degree of charging is determined from the difference voltage. You can also do it.

[Effects of the Invention] As can be easily understood from the above explanation, according to the present invention, it becomes possible to quantitatively know the degree of charge of the battery, the time required for full charging, the usable time, etc.

[Brief explanation of drawings]

FIG. 1 is a configuration block diagram of an embodiment of the present invention, FIG. 2 is a discharge characteristic diagram, FIG. 3 is a charging characteristic diagram, and FIG. 4 is an operation flowchart of the arithmetic control circuit 22. 10: Battery -2: Voltage measurement circuit 14: Charging circuit 16; Resistor 20: Switch 22: Arithmetic control circuit
24: Display device 26: Switch 28: Memory

Claims (1)

[Claims] The battery can be charged by measuring the voltage across the terminals of the battery when a predetermined load different from the charging circuit is connected, and by comparing this voltage between the terminals and the characteristic data of the battery when the predetermined load is connected. A charging device characterized by determining a discharge state.