JPH0831459A - Charging method for secondary battery - Google Patents

Abstract

PURPOSE:To secure proper charging easily without causing overcharge in a secondary battery used with repetition of charge and discharge. CONSTITUTION:A secondary battery provided with a memory element in which charging date/time data, charging voltage data, and charging quantity data are inputted at the time of resetting from a charger 2 in previous charging is set on the charger 2 under control of a microcomputer storing reference data of charge/discharge characteristics. The inputted data at the time of previous charge is then compared with the reference data, used discharge quantity including self-discharge quantity is calculated, so charging is performed within the used discharge quantity, and at the time of resetting from the charger 2, new charging date/time data, charging voltage data, and uncharged quantity are inputted into the memory element of the secondary battery 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging method for a secondary battery, and more particularly to a charging method for preventing overcharge of the secondary battery.

[0002]

2. Description of the Related Art Secondary batteries represented by nickel-hydrogen secondary batteries or nickel-cadmium secondary batteries are widely used as operating power sources for various equipment systems such as mobile phones and portable image pickup devices. Has been converted.
In other words, this type of secondary battery can be used as a semi-permanent power source because it can repeatedly perform securing and storing of electric power by charging operation and driving (discharging) of the load using the secured or stored power as a power source. It has been put into practical use by being incorporated into various equipment systems.

By the way, in any case of the secondary battery, charging and discharging are the main functions as described above, and from the viewpoint of safety, the end voltage of charge and the end voltage of discharge are set as the respective limits. Charging and discharging are performed with a voltage within the limit range. Then, in a device system that uses a secondary battery built in as a drive source such as a mobile phone by repeatedly charging and discharging, it is charged every time it is set in the charger,
Rate of increase or decrease of battery voltage per unit time (dV / dt
Or- △ V) ... Voltage differential control ... or battery temperature rise rate (dT / dt) ... Temperature differential control ... etc. Is used as a measure of termination or termination of charging. Commonly used. In addition, at times, while the battery is set in the charger and charging is started, the charger is often reset on the way (before full charge) to function as a driving power supply.

[0004]

However, each time the battery is charged in the charger, the battery is charged in a condition that the discharge amount is relatively small or the battery voltage is still close to the full charge. It may be done. In other words, in general, a secondary battery has a usage pattern in which a fully charged state is charged and a discharged state is repeatedly used.However, for example, in the case of a mobile phone, the function as a driving source is always ensured. However, even if a sufficient amount of charge is still retained (held), it is often set in a charger and charged. The charge stop at this time is also performed by the voltage differential control or the temperature differential control, as in the case of the full charge-discharge termination cycle, which is a general usage pattern, as described above.

However, as is well known, there is a so-called time delay in the rise of the battery voltage (a steep rise of the voltage) or the rise of the temperature (a steep rise of the temperature) per unit time immediately before full charge in the secondary battery. Therefore, there is a possibility that overcharging may occur in the charge stop method in which the steep rise in voltage or the steep rise in temperature is used as a guide. That is, in the charging of the secondary battery, the battery voltage gradually rises as the charging progresses (elapses), and the battery voltage rises sharply immediately before full charge. However, if recharging (halfway charging before the discharge end time) is started at the time when the battery voltage rises immediately before the full charge, the battery voltage rises abruptly in a time-delayed state, resulting in so-called overcharge. After
Charging will be stopped. Such a phenomenon occurs not only in the case of the voltage differential control method but also in the case of the temperature differential control method. And the occurrence of such overcharge,
This will lead to damage and damage to the secondary battery, raising the problem of loss of function of the secondary battery.

The present invention has been made in consideration of the above circumstances, and provides a charging method which can easily ensure proper charging of a secondary battery used by repeated charging and discharging without causing overcharging. For the purpose of provision.

[0007]

A method of charging a secondary battery according to the present invention is a method of charging a secondary battery, wherein when the battery is reset from a charger in the previous charging, the charging date and time data, Set the secondary battery with a memory device that inputs charging voltage data and charge amount data into a microcomputer-controlled charger that stores reference data of charge / discharge characteristics, and compare the input data and the reference data from the previous charge , Calculates the used discharge amount including self-discharge amount, charges within this used discharge amount, and when resetting from the charger, new charging date, hour data, charging voltage data and uncharged amount are secondary It is characterized in that it is input to a memory element of a battery. That is, the present invention is a required recharge, at the time of the previous charge,
The charging date data, charging voltage data, etc. input to the memory element of each secondary battery are related to the relationship between the discharge amount and the usage (discharge) time in the normal continuous use (continuous discharge) provided on the charger side. In comparison with the reference (standard) value, the current charging amount is set, and in preparation for the next charging, current charging date data, charging voltage data, etc. are input to the memory element and overcharged. It is the essence to surely prevent.

FIG. 1 schematically shows the above-described embodiment. When the secondary battery 1 to be charged is set in the charger 2, the charging data at the previous charging is attached to the charger 2. Input to the microcomputer. That is, at the time of resetting from the charger 2 at the time of the previous charge, the date, time data, charge voltage data, and the previous charge amount of the previous charge input to the memory element attached to each secondary battery are charged. When the rechargeable secondary battery 1 is set in the charger 2, the data is input to the microcomputer attached to the charger 2. Here, the microcomputer has a built-in reference (standard) value in normal continuous use (continuous discharge), and compares it with charging data at the time of previous charging input from the secondary battery 1 side to be charged, The required charge amount (replenishment amount) is calculated, and when the required charge amount is reached, charging is stopped. Further, after the charging is stopped (finished), when the secondary battery 1 to be charged is reset from the charger 2, the charging data at the moment of the reset (day, time data, charging voltage data, current charging amount, etc.) Are input to the memory element attached to the secondary battery 1 to be charged.

Then, the charger 2 for the secondary battery 1 to be charged.
It is desirable to use the battery removal detection lever 3 as shown in the schematic plan view of FIG. 2 for setting and resetting. In the battery removal detection lever 3, when the charged secondary battery 1 is set, the lever 3a is pushed, the built-in micro switch is turned on, and when the charged secondary battery 1 is reset, the micro switch is turned off. Here, the battery removal detecting lever 3 is an electrode terminal (+ terminal, − terminal, thermistor terminal, data terminal) of the secondary battery 1 to be charged.
It operates immediately before the battery comes off, detects battery removal, and
Data communication between the charger 2 and the secondary battery 1 to be charged, that is, the date, time data, charging voltage data, next time of the current charging data in the memory element attached to the secondary battery 1 to be charged The required amount of charge is input when the battery is charged.

In the present invention, as a power source for charging, a commercial AC power source converted into a direct current having an appropriate voltage is used. In addition, a power source composed of, for example, a fuel cell is used. Alternatively, electric power generated from a gasoline engine or a diesel engine may be used.

[0011]

According to the secondary battery charging method of the present invention, when recharging, the charging data from the previous charging is used as a reference (standard).
By comparing with the discharge characteristic data, the used discharge amount including self-discharge is calculated, and the charging within the used discharge amount is surely performed. In other words, by combining the charge data for each secondary battery and the normal continuous discharge characteristic data, charging is always performed within the proper range. However, it is easily prevented or avoided, and the function as a driving power supply is maintained.

[0012]

Embodiments of the present invention will be described below with reference to FIGS. 1 and 3.

As shown schematically in the embodiment of FIG. 1, the rechargeable secondary battery 1 is set in the charger 2 also in the present invention. At this time, in the case of the present invention, the memory element provided for each secondary battery 1 to be charged is
The charging data at the time of the previous charging such as the date, the time data, the charging voltage data, and the charging amount at the time of the reset from the charger 2 are input. Then, the charging data for each secondary battery 1 to be charged is input to the microcomputer attached to the charger 2.

Here, the microcomputer has a built-in reference (standard) characteristic value in a normal continuous use (continuous discharge) as shown by a curve A in FIG. 3, for example. That is, the rated load of each secondary battery for each product type and standard (for example, 140mA)
Of the discharge characteristic when the battery is discharged at, that is, the decrease (change) curve data of the battery voltage with the discharge time,
It is input to the microcomputer attached to the. In FIG. 3, the point (t ₁ , V ₁ ) is the battery voltage value at the rated discharge time t ₁ , and the point (t ₃ , V ₃ ) is the battery voltage value at the rated discharge time t ₃ .

On the other hand, since the secondary battery 1 to be charged is charged, the battery voltage value from the time of the previous charging (t ₁ ) to the time of setting this time in the charger 2 (t ₃ ) is the point (t ₃ , V ₂ ), the amount of discharge used during this period is as shown by the curve B. The battery voltage value V _{2 at} this time corresponds to the point (t ₂ , V ₂ ) on the reference discharge characteristic curve A. Here, if a so-called rated discharge between t ₁ ~t ₃ were to continue, the battery voltage value when you set the current of the charger 2 (t ₃₎ indicates the point (t _3, V ₃₎ Although it should be, the fact that the discharge voltage value at the point (t ₃ , V ₂ ) is shown indicates that the so-called rated discharge is intermittently performed. That is, when the secondary battery 1 to be charged is reset from the charger 2 (t ₁ ), when it is set this time (t ₁ ).
_3), it is divided into time (t ₂₎ from the reset corresponding to the rated discharge voltage (V _2). Specifically, | t
₁ -t ₂ | × 140 mA ... rated discharge _{...... (1) | t 2 -t} 3 | × 8 mA ... is organized as a discharge ... (2) in the self-discharge + standby mode, the battery charger of the previous charge After resetting from 2, the discharge usage amount during the current charging is set in the charger 2 is the above equation (1) + (2). Therefore, it is sufficient to charge this discharge usage amount.

Next, a description will be given of charging when the amount of discharge used was not charged at the previous charging (charging was stopped halfway). The secondary battery is fully charged at the time of shipment, and the charge data at that time, that is, the date, time, and voltage value (for example, 10) at the time of shipment are input to a memory element. After that, when the secondary battery was set in a charger with a microcomputer with built-in data and it was attempted to charge for the first time, and the voltage value of the battery to be charged was 4, for example, the usage amount including self-discharge was 10−4. = 6. Therefore, the rechargeable amount at this time is 6, but it becomes necessary to reset and use it from the charger during charging. Assume that it has been reset. In other words, the discharge is started at the state of charge 6, and the uncharged (insufficient) charge amount 4 remains as the charge amount for the next time. All of these data are input when the battery to be charged is reset from the charger, and the self-discharge amount and the rated discharge amount are determined by the standard of each secondary battery.

This relationship is generally expressed in the form of equations as follows.

B _{n + 1} = B _n + (amount used at the n-th time)-
(The actual charge amount at the nth time) Here, B _{n + 1} is the charge amount that can be charged in the next charge, and B _{n + 1.
n} is the amount of charge that should be charged this time (the value stored in the secondary battery), and at the time of B _{n + 1} = 0, the charging is completed when the battery is fully charged.

[0019]

As can be seen from the above description of the embodiments, in the charging method of the present invention, the charging data is input to the memory element attached to each secondary battery at the end of the previous charging, and the charging data at the time of the previous charging is stored. Since the charging data is compared with the standard data of the corresponding secondary battery and the rechargeable amount is calculated to control the required charging, overcharging can be reliably avoided. Further, even in recharging before full charge, or recharging before full charge and after charging is completed, the rechargeable amount is accurately calculated and controlled, so that required charging can be performed easily. In other words, the rechargeable battery that is repeatedly recharged and functions as a semi-permanent drive source can be used as a semi-permanent drive source for the rechargeable battery by avoiding functional reduction due to overcharging and even damage or damage. The function can be secured.

[Brief description of drawings]

FIG. 1 is a block diagram schematically showing an embodiment example of a constant current charging method for a secondary battery according to the present invention.

FIG. 2 is a plan view showing a schematic configuration example of a battery removal detection lever used in an embodiment example of a constant current charging method for a secondary battery according to the present invention.

FIG. 3 is a discharge voltage characteristic diagram for explaining the basic concept of the constant current charging method for a secondary battery according to the present invention.

[Explanation of symbols]

1 ... Rechargeable secondary battery with memory element 2 ... Charger with microcomputer 3 ... Battery removal detection lever 3a ... Detection lever

Claims (1)

[Claims] 1. A secondary battery with a memory element, which is a method of charging a secondary battery, in which data of a charging date, time data, charging voltage data, and charging amount data are input when resetting from a charger at a previous charging. Is set to the microcomputer-controlled charger that stores the reference data of the charge / discharge characteristics, the input data at the time of the previous charge and the reference data are compared, and the used discharge amount including the self-discharge amount is calculated. Charging within the amount and at the time of resetting from the charger, new charging date, time data, charging voltage data and uncharged amount are input to the memory element of the secondary battery. How to charge.