JPH05333119A - Remaining battery level detector - Google Patents

Abstract

PURPOSE:To enable the residual capacity of a secondary battery to be accurately displayed by detecting the charging and discharging current of the secondary battery, and monitoring and saving the capacity thereof at all times. CONSTITUTION:The operation of a charging means 8 causes charging current i1 to flow to a secondary battery 1 via a diode 3 and a charging current detecting means 2, thereby charging the secondary battery 1. In this case, a microprocessor 9 calculates a charged amount as a product of a current value outputted from the means 2 and a charging time, and stores the calculated amount in a memory means 10. Then, the microprocessor 9 deducts a discharged amount from the charged amount, thereby calculating the residual capacity of the battery 1. Actually, however, a correction is made by multiplying the charged amount with a conversion efficiency factor K for charging, for the reason that the charged amount cannot be used as a 100% capacity amount, or the like. The microprocessor 9 is also connected to a display means 12 and a transistor 11 for periodically checking the residual capacity. In addition, the residual capacity of the battery 1 is detected, while a correction is being made therefor. Thus, accurate residual capacity display can be ensured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus using a secondary battery, and a secondary battery remaining amount detecting apparatus for displaying the remaining amount of the battery or the available time.

[0002]

2. Description of the Related Art In recent years, the use of secondary batteries has increased more and more with the spread of portable and mobile electronic devices.

Conventionally, as shown in FIG. 3, the method for detecting the remaining amount of the secondary battery has been performed by the voltage detecting means 22.
In FIG. 3, 21 is a secondary battery, 23 is its load, 24
Is a charging means, and 29 is a secondary battery remaining amount detecting device. The remaining amount detecting device 29 is composed of a voltage detecting means 22, a microprocessor 25 and a display means 26. When a current flows from the secondary battery 21 to the load 23, the voltage of the battery starts decreasing after a certain period of time as shown in FIG. At the time point t ₁ when the voltage drops to V ₁ , the microprocessor 25 notifies the display means 26 that the remaining amount of the secondary battery is low. After that, when the current continues to flow in the load 23, the voltage of the secondary battery 21 drops to V ₂ and the load 23 cannot maintain normal operation.

As described above, the conventional method for detecting the remaining amount of the secondary battery can also detect and notify that the remaining amount of the secondary battery has decreased before the operation of the load is stopped.

[0005]

However, in the above-mentioned conventional method for detecting the remaining amount of the secondary battery, since the remaining amount of the secondary battery is displayed only by monitoring the voltage, when the voltage of V ₁ in FIG. 4 is reached. For the first time, I found out that the battery was low
In addition, in a normal device, V ₁ and V ₂ are close to each other, so even if it is found that the remaining amount becomes small at t ₁ , it immediately becomes t ₂ , which is very inconvenient for practical use. It was

The present invention is intended to solve such a conventional problem, and an object thereof is to provide an excellent secondary battery remaining amount detecting device capable of accurately displaying the remaining amount of the secondary battery. is there.

A second object is to judge the life of the secondary battery and inform the user.

[0008]

In order to achieve the first object of the present invention, the charging unit and the discharging unit of the secondary battery are provided with respective detecting means to constantly monitor and store the capacity of the secondary battery. It was done like this.

In order to achieve the second object of the present invention, the conversion efficiency of the discharge amount with respect to the charge amount is obtained, and the life of the secondary battery is judged by the change of the conversion efficiency.

[0010]

With the above-described structure, the present invention can measure the charge amount and the discharge amount of the secondary battery, and thus can detect the remaining amount of the secondary battery.

Further, according to the present invention, since it is possible to know how much discharge amount can be taken out with respect to the charge amount, it is possible to grasp the deterioration of the capacity of the secondary battery, and it becomes necessary to replace the secondary battery. When you can display it.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, 1 is a secondary battery, 7 is its load, 8
Is a charging means and 19 is a secondary battery remaining amount detecting device. The secondary battery 1 is connected to the voltage detecting means 6, the charging current detecting means 2, and the discharging current detecting means 4. Charging current detection means 2
The discharge current detecting means 4 and the discharge current detecting means 4 are separated by diodes 3 and 5 depending on the direction of the current. The load 7 and the charging means 8 are connected to the diodes 3 and 5. A microprocessor 9 is connected to the charging current detecting means 2 and the discharging current detecting means 4 via the voltage detecting means 6. The microprocessor 9 is also connected to the storage means 10, the display means 12, and the regular remaining amount check transistor 11.

With respect to the secondary battery remaining amount detecting device having the above-described components, the relationship and operation of the components will be described below. In the above embodiment, in the section of FIG. 2, the charging current i ₁ from the charging means 8 flows through the diode 3 and the charging current detecting means 2 to the secondary battery 1, and the secondary battery 1 is charged. The charge amount is calculated by the microprocessor 9 as the product of the current value from the charge current detection means 2 and the charge time,
It is stored in the storage means 10. In the section of FIG. 2, the discharge current i ₂ flows from the secondary battery 1 through the discharge current detection means 4 and the diode 5. In the same manner as charging, the amount of discharge is calculated by the microprocessor 9 and stored in the storage means 10. If the efficiency of the secondary battery is 100%, (charge amount)-(discharge amount) = (remaining amount) ... (1), but in reality, the charge amount cannot be taken out as 100% capacity. Since the capacity of the battery is limited, the equation (1) is as follows.

A- (discharge amount) = (remaining amount) (2) where A is K · (charge amount) or the maximum capacity of the secondary battery, whichever is smaller K is the conversion efficiency of charge Both the conversion efficiency and the maximum capacity of the secondary battery are used as the average value of the type of battery used, and after that, the part where the difference occurs in actual use shall be corrected (charge to the maximum capacity or more. According to the prediction, the time required to reach V ₁ in FIG. 4 is 10 minutes, but if it is actually 9 minutes, the maximum capacity is multiplied by 0.9). By performing the correction in this way, in the case of the section of FIG. 2, the remaining amount up to t ₂ can be accurately known,
The remaining battery level of the secondary battery can be displayed accurately.

If the maximum capacity of the secondary battery is lower than a certain value or if the conversion efficiency K of the charge is less than a certain value, it is determined that the secondary battery has reached the end of its life, and the display means is automatically displayed. Can be notified that it is time to change.

The transistor 11 in FIG. 1 is a transistor that turns on when the maximum capacity of the secondary battery is confirmed.

The battery change timing can be displayed automatically at regular intervals or manually at a desired timing.

Further, in this embodiment, the current detecting means is provided separately for charging and discharging, but if the detecting means capable of detecting bidirectional current is used, the diodes 3 and 5 become unnecessary. Needless to say.

[0019]

As is apparent from the above description of the embodiments, the present invention has the following effects.

(1) Since the remaining amount of the secondary battery is detected while being corrected, it is possible to accurately display the remaining amount.

(2) Deterioration of the secondary battery can be grasped and can be displayed when the necessity of replacement arises.

[Brief description of drawings]

FIG. 1 is a block diagram of a secondary battery remaining amount detecting device according to an embodiment of the present invention.

FIG. 2 is a charge / discharge waveform diagram of the same remaining amount detection device.

FIG. 3 is a block diagram of a conventional secondary battery remaining amount detection device.

FIG. 4 is a voltage waveform diagram of a secondary battery

[Explanation of symbols]

1 Secondary Battery 2 Charging Current Detecting Means 4 Discharging Current Detecting Means 9 Microprocessor (Means for Calculating Remaining Battery Level) 10 Storage Means

Claims (2)

[Claims] 1. A charging current detecting means for measuring a charging current to a secondary battery, a discharging current detecting means for measuring a discharging current from the secondary battery, a means for storing a charging amount and a discharging amount, and a charging amount. 2. A secondary battery remaining amount detecting device comprising: a unit that calculates the remaining amount of the battery by subtracting the amount of discharge from the unit; and a storage unit that stores a coefficient that corrects the calculated remaining amount and the actual remaining amount. 2. A coefficient for correcting the calculated remaining amount and the actual remaining amount of the secondary battery is compared with a predetermined value for each, and the life of the secondary battery is detected when the coefficient is less than the predetermined value. The remaining amount detecting device for a secondary battery according to claim 1.