JPH11150882A - Method for charging battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve usefulness of portable equipment by widening the limit of battery characteristics, by setting charging commenceable temperature and charging stopping temperature of a battery to be charged at every kind of battery based on the output of a kind-of- battery discriminating means which discriminates the kind of the battery to be charged. SOLUTION: When a nickel-hydrogen battery pack 2 or a nickel-cadmium battery pack is connected to a battery charger 1 while the charger 1 is in a battery-connection waiting state, a kind-of-battery discriminating circuit 18 discriminates the kind of the battery from Vcc voltage dividing value of resistors 17 and 6. Since the nickelcadmium battery pack has not T-terminal, the Vcc voltage dividing value become the Vcc voltage dividing value itself and it can be discriminated easily that the battery connected to the charger 1 is the pack 2. When the nickel-hydrogen battery pack 2 is connected, therefore, a battery temperature detecting circuit 16 detects the temperature of the battery from the Vcc voltage dividing value of a resistor 15 and a thermistor 5 and, when the temperature is <=40 deg.C, the charger 1 is kept in the waiting state until the temperature of the battery is warmed. When the temperature of the battery is >=40 deg.C, the charger 1 is kept in a waiting sate until the battery is cooled. When the temperature of the battery is between 0 deg.C and 40 deg.C, a charging control circuit 19 is turned on and starts the constant-current charging of the battery by using the electric current from a DC power source 9 through (+) and (-) terminals and a resistor 11 for detecting current.

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 charging a secondary battery such as a nickel cadmium battery (hereinafter referred to as a nickel cadmium battery) and a nickel hydride battery.

[0002]

2. Description of the Related Art Nickel-cadmium batteries have been used as power supplies for portable devices such as video cameras, personal computers, and power tools, but recently nickel-metal hydride batteries have been used due to environmental issues and demands for higher capacity. It has become.

[0003] Compared to nickel-cadmium batteries, nickel-metal hydride batteries are characterized by a small change in battery voltage during charging, a large temperature rise, and a narrow chargeable battery temperature range.
For this reason, some measures must be taken to enable the charger to charge both the nickel-cadmium battery and the nickel-metal hydride battery. In particular, in applications such as rechargeable batteries used for professional power tools, where rapid charging and large-current discharging are repeated frequently in both winter and summer, a wide rechargeable battery temperature range is important. For example, in a cold region, it is desirable that the battery can be charged up to −10 ° C., and it is desirable that a warmed battery immediately after a large current discharge can be charged when the temperature drops to 60 ° C. The battery temperature range at which charging can be started at the present time is as follows.
It is requested that charging be stopped at 65 ° C, but in the case of nickel-metal hydride batteries, charging is started at 0 ° C to 40 ° C and charging stopped at 60 ° C to prevent performance deterioration. is necessary. Several methods have been proposed for charging various batteries having different characteristics with a single charger in a short time, safely and without excess or deficiency. This method will be described as a conventional example.

(1) Japanese Patent Application Laid-Open No. 7-123604 discloses that a battery voltage during a pulse current charge, a battery voltage during a pause in charging, and a battery temperature during charging are read. Stop charging when dropped -Δ
In the V method, a battery having a large temperature rise has a rise in battery temperature per unit time, that is, the ΔT / Δt method, and a battery that is charged at a constant voltage at the end of charging stops charging for a constant voltage duration. Also disclosed is a method in which the chargeable battery temperature range is limited, and when the battery temperature at the start of charging is high, the charging current is reduced and the charging stop temperature is raised.

(2) Japanese Patent No. 2645913 discloses a method of discriminating a nickel-cadmium battery and a nickel-metal hydride battery, and reducing the -ΔV of a nickel-metal hydride battery having a small change in battery voltage. (3) JP-A-1-190226 discloses that the type of a battery is determined, and the type of battery having a large change in battery voltage is determined by the -ΔV method.
A method of stopping charging of a battery of a type having a large temperature rise by the ΔT / Δt method is disclosed.

[0006]

However, in the above prior art, the temperature of the rechargeable battery differs depending on the type of the battery, and the temperature range of the rechargeable battery is wide from low to high as long as safety and performance degradation limit permit. No consideration is given to the fact that it is more convenient to use. In the above prior art (1), a battery type discriminating function is not added, and a rechargeable battery temperature range is constant irrespective of the type of battery, so that performance degradation and usability are not compatible. In the above prior arts (2) and (3), there is no limitation on the temperature range of the rechargeable battery, so that the usability immediately after the purchase of the battery is good, but the performance immediately deteriorates. That is, at the time of low-temperature charging, the internal gas pressure rises, the safety valve operates, and the capacity decreases due to electrolyte leakage. At the time of high-temperature charging, the organic material constituting the battery is thermally degraded, causing a short-circuit failure and a reduction in capacity. SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned disadvantages of the prior art, to widen the rechargeable battery temperature range as long as battery performance permits, and to improve the usability of portable equipment using batteries.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a battery type determining means for determining the type of a battery to be charged, and to determine a battery temperature at which charging can be started or a battery temperature at which charging is stopped based on an output of the battery type determining means. This is achieved by setting for each type.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a charging apparatus to which the present invention is applied will be described with reference to FIGS. The charging device 1 includes a nickel-metal hydride battery pack 2 or a nickel-cadmium battery pack 3
Are connected via corresponding terminals. The nickel-metal hydride battery pack 2 includes a plurality of unit cells 4 connected in series, a positive terminal 2 a, a negative terminal 2 d, a battery temperature detecting thermistor 5 connected to the negative electrode of the unit cell 4, and a thermistor 5 connected to the charging device 1. A battery type determining resistor 6 connected to the negative pole of the unit cell 4, and a T terminal 2c connecting the resistor 6 to the charging device 1. NiCad Battery Pack 3
Indicates a plurality of cells 7 connected in series, a positive terminal 3a, a negative terminal 3d, and a negative
It comprises a battery temperature detecting thermistor 8 connected to the pole, and an S terminal 3b for connecting the thermistor 8 to the charging device 1.

The charging apparatus 1 includes a DC power source 9 serving as an energy source, a nickel-metal hydride battery pack 2 and a nickel-cadmium battery pack 3.
A constant current circuit 10 for charging the battery pack with a constant current, a positive terminal 1a, a negative terminal 1d for connecting the battery pack and the charging device,
S terminal 1b, T terminal 1c, current detection resistor 11 connected in series with the charging loop, current detection circuit 12 for detecting charging current from voltage across resistor 11, peak voltage detection for detecting peak value of battery voltage Circuit 13, stabilized voltage Vcc
14. A resistor 1 connected to the stabilized voltage Vcc14 and the S terminal 1b and connected to the thermistors 5, 8 of the battery packs 2, 3.
5, a resistor 6 connected between the stabilized voltage Vcc14 and the T terminal 1c through the T terminal 2c of the nickel-metal hydride battery pack 2.
, A battery type discriminating circuit 18 for discriminating the type of battery from the Vcc divided values of the resistors 17 and 6, a current detecting circuit 12, a peak voltage detecting circuit 13, a battery temperature detecting circuit 16, a battery type discriminating. It comprises a charge control circuit 19 for turning on and off the constant current circuit 10 by the output of the circuit 18.

Next, the charging flowchart of FIG. 3 and FIGS.
This will be described with reference to the charging characteristic graph of FIG. Charging device 1
When the nickel-metal hydride battery pack 2 or the nickel-cadmium battery pack 3 is connected in the battery connection standby state (step 101), the battery type determining circuit 18 determines the type of the battery from the Vcc partial pressure values of the resistors 17 and 6 ( Step 10
2). Since the NiCd battery pack 3 has no T terminal, Vc
The c partial pressure value becomes Vcc itself, and the nickel-metal hydride battery pack 2 and the nickel-cadmium battery pack 3 can be easily distinguished.

If the connected battery pack is a nickel-metal hydride battery, the battery temperature Tb is detected by the battery temperature detection circuit 16 from the resistor 15 and the Vcc partial pressure value of the thermistor 5 (step 103). Until the battery warms up, the battery at 40 ° C. or higher enters a standby state (step 103) until it cools down. If the battery temperature Tb is 0 ° C. ≦ Tb ≦ 40 ° C., the charging control circuit 19 turns on the constant current circuit 10, and the DC power supply 9 to the constant current circuit 10 to the + terminal 1a to the + terminal 2a to the plurality of cells 4 --- terminal 2d--terminal 1d--current detection resistor 1
The constant current charging is started along the route from 1 to DC power supply 9 (step 104). 4 and 5 show the progress of charging of the nickel-metal hydride battery pack 2. When the battery temperature at the start of charging is low (FIG. 4), the peak of the battery voltage appears remarkably at the end of charging, and charging is stopped at the peak of the battery voltage by the operation of the peak voltage detecting circuit 13 (step 10).
5, 111). When the battery temperature at the start of charging is high (FIG. 5), since the peak of the battery voltage does not appear remarkably at the end of charging, the peak voltage detection circuit 13 does not work, and the battery temperature is 60 ° C.
The charging is stopped at the time point when the charging time is reached (steps 106 and 11).
1).

If the connected battery pack is a NiCd battery, the battery temperature Tb is detected by the battery temperature detecting circuit 16 from the resistor 15 and the Vcc partial pressure value of the thermistor 8 (step 1).
07), the battery at −10 ° C. or lower is in a standby state until the battery is warmed, and the battery at 60 ° C. or more is cooled (step 107). If the battery temperature Tb is −10 ° C. ≦ Tb ≦ 60 ° C., the charge control circuit 19 turns on the constant current circuit 10, and the DC power supply 9 to the constant current circuit 10 to the + terminal 1a to the + terminal 2a to the plurality of cells. The constant current charging is started along the route from 7 to -terminal 2d to -terminal 1d to current detection resistor 11 to DC power supply 9 (step 108). 6 and 7 show the progress of charging of the NiCd battery pack 3. When the battery temperature at the start of charging is low (FIG. 6), the peak of the battery voltage appears remarkably at the end of charging, and charging is stopped at the peak of the battery voltage by the operation of the peak voltage detecting circuit 13 (step 10).
9, 111). When the battery temperature at the start of charging is high (FIG. 7), since the peak of the battery voltage does not appear remarkably at the end of charging, the peak voltage detecting circuit 13 does not operate, and the battery temperature is 65 ° C.
The charging is stopped at the time point when the charging time is reached (steps 110 and 11).
1).

[0013]

According to the present invention, the chargeable battery temperature range can be widened to the characteristic limit of each battery by setting the charge start battery temperature and the charge stop battery temperature for each type of battery. The usability of the portable device can be improved without deteriorating the performance of the battery.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a charging device employing a charging method of the present invention.

FIG. 2 is a block diagram showing an embodiment of a charging apparatus to which the charging method of the present invention is applied.

FIG. 3 is a flowchart showing processing steps of the charging method of the present invention.

FIG. 4 is a graph showing charging characteristics of a nickel-metal hydride battery.

FIG. 5 is a graph showing charging characteristics of a nickel-metal hydride battery.

FIG. 6 is a graph showing charging characteristics of a nickel-cadmium battery.

FIG. 7 is a graph showing charging characteristics of a nickel-cadmium battery.

[Explanation of symbols]

2 is a nickel hydride battery pack, 3 is a NiCd battery pack, 6, 15, 17 are resistors, 5 is a thermistor, 14
Is a stabilized voltage, 16 is a temperature detection circuit, and 18 is a battery type determination circuit.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuhiro Takano 1060 Takeda Hitachinaka City, Ibaraki Prefecture Inside Hitachi Koki Co., Ltd.

Claims (1)

[Claims] 1. A method for charging a battery, comprising: battery type determination means, wherein the output of the battery type determination means appropriately changes a charging control method according to the type of battery. A method for charging a battery, wherein a lower limit of a startable battery temperature, an upper limit of a charge startable battery temperature, or a charging stop temperature is individually set for each type of battery.