JP2001095171A - Charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charger which enables the power supply to load by heating a secondary battery to such a level that the battery can exhibit performance without incurring the deterioration of the life at low temperature on a level such that the battery can not exhibit performance. SOLUTION: A charge control circuit 3 controls a charge current supply circuit 2 so that it may judge the capacity from the detected battery voltage when a heating switch 6 is turned on and that it may supply a charge current being a low current for heating a secondary battery 20 when the full charge condition is judged. Under this charge, the charge control circuit 3 monitors the temperature of the battery pack 2 including the secondary battery 20 by the detection output of the temperature sensor 21, and when the detected temperature goes up to a specified temperature, it stops the output of the charge current by controlling the charge current supply circuit 1. If it is judged to be not in full charge condition, the charge control circuit 3 charges the secondary battery 20 quickly by controlling the charge current supply circuit 1 so that it may supply a large charge current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery pack comprising a charger and a nickel metal hydride battery.

[0002]

2. Description of the Related Art Conventionally, among charging devices for supplying current to a battery, there has been no heating device in which a user consciously warms a low-temperature battery and considers the life.

[0003]

Due to the characteristics of the battery itself, a secondary battery, especially a nickel-metal hydride battery, cannot exhibit its battery performance at low temperatures despite its full charge (full charge) state. However, there is a problem that necessary power cannot be supplied to a load such as the above.

[0004] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a battery capable of exhibiting battery performance at a low temperature at which battery performance cannot be exhibited without causing deterioration in life. It is an object of the present invention to provide a charging device capable of heating a secondary battery and supplying power to a load.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a secondary battery, a charging current supply circuit for supplying a charging current to the secondary battery, and a charging current supply circuit. A charging device comprising a charger comprising a charge control circuit for controlling a charging current supplied to the secondary battery, comprising a heating switch for giving an instruction for heating the secondary battery to the charge control circuit. When the heating switch is turned on, the charge control circuit determines the remaining capacity of the secondary battery, and supplies a charging current of a low current enough to warm the secondary battery when the secondary battery is fully charged. The charging current supply circuit is controlled as described above, and when the battery is not fully charged, the charging current supply circuit is controlled so as to supply a normal charging current to the secondary battery to increase the charging capacity. I do.

According to a second aspect of the present invention, in the first aspect of the present invention, a temperature detecting means for detecting a temperature of the secondary battery is provided,
When the heating switch is turned on and the charging current supply circuit supplies a low-current charging current to the fully charged secondary battery, the temperature of the secondary battery reaches a predetermined temperature. Is detected by the temperature detecting means, the charging current supply circuit is controlled so as to stop supplying the charging current to the secondary battery.

According to a third aspect of the present invention, in the second aspect of the present invention, the charging control circuit stops the supply of the charging current to the secondary battery and then reduces the temperature of the secondary battery to a predetermined temperature. When the temperature is detected by the temperature detecting means, the charging current supply circuit is controlled so as to restart the supply of the charging current.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the charging control circuit charges the secondary battery when the secondary battery is not fully charged, so that the secondary battery is fully charged. The charging current supply circuit is controlled so as to stop supplying the charging current when it is detected that the power supply has been stopped.

According to a fifth aspect of the present invention, in the first aspect of the present invention, a discharge circuit for the secondary battery is provided, and the charge control circuit is configured such that when the heating switch is turned on, the charge capacity of the secondary battery is in a fully charged state. In this case, the charging current supply circuit is controlled to supply a charging current to the secondary battery until the secondary battery is fully charged after discharging a predetermined amount of electricity by the discharging circuit. And

According to a sixth aspect of the present invention, there is provided a secondary battery, a charging current supply circuit for supplying a charging current to the secondary battery, and a charging device for controlling a charging current supplied from the charging current supply circuit to the secondary battery. In a charging device including a charger including a control circuit, a temperature detecting unit for detecting a temperature of the secondary battery is provided, and the charging control circuit monitors a temperature of the secondary battery detected by the temperature detecting unit after the charging is completed. A charging current supply circuit is controlled so that a low-current charging current is turned on / off and supplied to a secondary battery so that the detected temperature falls within a predetermined temperature range.

According to a seventh aspect of the present invention, a secondary battery, a charging current supply circuit for supplying a charging current to the secondary battery, and charging for controlling a charging current supplied from the charging current supply circuit to the secondary battery. In a charging apparatus including a charger including a control circuit, a heating unit that heats the secondary battery is provided, and a heating switch is provided. When the heating switch is turned on, the heating unit heats the secondary battery. Characterize.

According to an eighth aspect of the present invention, in the sixth aspect of the invention, there is provided a blower fan for blowing air heated by the heating means to the secondary battery.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

(Embodiment 1) The charging device of this embodiment is
As shown in FIG. 1, the battery pack 2 includes a battery pack 2 and a charger including a charging current supply circuit 1 and a charging control circuit 3 for controlling an output of the charging current supply circuit 1.

The charging current supply circuit 1 includes an AC cord 10 connected to an outlet of a commercial power supply, an input circuit 11 including a transformer connected to the AC cord 10 and configured to reduce the voltage of the commercial power supply, and an output from the input circuit 11. A rectifying / smoothing circuit 12 for rectifying and smoothing an alternating current, an inverter power supply circuit 13 for converting a dc obtained by rectifying and smoothing into an alternating current of a predetermined voltage, a means for rectifying and converting an output of the inverter power supply circuit 13 to a direct current, and Current output circuit 14 including means for detecting current supplied to secondary battery 20 of battery pack 2
And a switching control circuit 15 for controlling the switching of the inverter power supply circuit 13.

The battery pack 2 includes a secondary battery 20 such as a nickel-metal hydride battery and a temperature sensor 21 for detecting the temperature of the battery pack 2. The secondary battery 20 is connected to the current output circuit 14 of the charging current supply circuit 1. Connected to the current output circuit 14
The battery is charged by the output current from the battery. The voltage between both ends of the secondary battery 20 is input to an external voltage detection circuit 4 to detect the voltage between both ends, and the detection output of the temperature sensor 21 is input to the temperature detection circuit 5, and the battery pack including the secondary battery 20 2 is detected.

The charge control circuit 3 is operated by a power source obtained from the output of the rectifying / smoothing circuit 12 of the charging current supply circuit 1 (FIG. 1).
0), charging from the detection output of the voltage detection circuit 4 (battery)
The capacity is determined, and the temperature of the battery pack 2 is determined from the detection output of the temperature detection circuit 5, and the output from the current output circuit 14 of the charging current supply circuit 1 is determined based on these determinations and the operation of the heating switch 6. A current switching function for switching the magnitude of the current, and a function for controlling the inverter power supply circuit 13 through the switching control circuit 15 based on the output current value detected by the current output circuit 14 so as to obtain the switched charging current. , And the inverter power supply circuit 13 and the switching control circuit 15 constitute a constant current control circuit. The current output circuit 14 includes an output rectifier for rectifying the output of the inverter power supply circuit 13 and a current detection resistor for detecting a charging current (see FIG. 10).

Next, the operation of this embodiment will be described with reference to the flowchart of FIG.

First, when charging is performed, when it is determined that the battery performance is sufficient because the ambient temperature is high or the battery temperature is high, the user performs charging without turning on the heating switch 6.

In this case, the charge control circuit 3 determines the capacity based on the battery voltage detected by the voltage detection circuit 4, and determines a period during which the capacity is low and the battery is not in a fully charged (full) state (for example, as shown in FIG. Battery voltage V corresponding to 95% capacity
The inverter power supply circuit 13 of the charging current supply circuit 1 is controlled through the inverter control circuit 15 so that a large charging current for rapid charging can be obtained during (until a is detected). This control is feedback control based on the output current value detected by the current output circuit 14,
Is maintained at a constant current value.

As the charging proceeds, the battery temperature rises. When the temperature rise rate ΔT / Δt exceeds a certain value, the charge control circuit 3 determines that the battery is fully charged, and the charge control circuit 3 Stop supply.

On the other hand, when it is determined that the battery temperature is low, or when the battery pack is mounted on a load and the ambient temperature is low and the battery performance is not sufficient, the battery pack 2 is inserted into the charger. The user turns on the heating switch 6 in the mounted state.

When the heating switch 6 is turned on, the charging control circuit 3 first determines the capacity of the secondary battery 20 from the detected battery voltage as shown in FIG. Is determined, the charging current supply circuit 1 is controlled so as to supply a charging current for heating the secondary battery 20. In this case, without overcharging the secondary battery 20,
In order to heat, control is performed so that the charging current becomes low as shown in FIG.

Under this charge, the charge control circuit 3 monitors the temperature of the secondary battery 20 based on the detection output of the temperature sensor 21, and when the detected temperature rises to a predetermined temperature T, controls the charge current supply circuit 1 to charge the battery. Stop the current output to prevent overcharging more than necessary.

On the other hand, if it is determined that the battery is not fully charged in the above determination, the charging control circuit 3 supplies a large charging current to the battery pack 2 as shown in FIG. The charging current supply circuit 1 is controlled to rapidly charge the secondary battery 20. As the charging proceeds, the temperature of the secondary battery 20 rises as shown in the figure and reaches the predetermined temperature T. However, the supply of the charging current is continued in consideration of usability, and the full charge determination is made based on the above-mentioned ΔT / Δt. Heat until done. And when it is determined that the battery is fully charged,
The supply of the charging current is stopped (II in FIG. 2). Of course, if the temperature of the battery pack 2 has not reached the predetermined temperature T at the time of the full charge determination, the battery pack 2 is charged with a low current and heated until the temperature of the battery pack 2 reaches the predetermined temperature T. (I of FIG. 2) <For example, when a battery having a battery capacity of 80% is charged>.

As described above, in the present embodiment, when the user determines that the battery performance cannot be exhibited from the battery temperature or the ambient temperature, the battery pack 2 is mounted on the charger and the heating switch 6 is turned on. Thus, the heating can be performed without overcharging with the charging current according to the remaining capacity of the secondary battery 20.

After the supply of the charging current to the secondary battery 20 is stopped, when it is detected that the temperature of the secondary battery 20 has dropped to a predetermined temperature, the charging is performed so as to restart the supply of the charging current. The charge control circuit 3 may be operated so as to control the current supply circuit 1. (Embodiment 2) In Embodiment 1, the heating switch 6 is provided, and when heating is required by the user, the heating switch 6 is turned on to heat the secondary battery 20 of the battery pack 2. In this embodiment, the heating switch 6 is omitted as shown in FIG.
The automatic heating based on the detected temperature is performed.

In this embodiment, the secondary battery 2 of the battery pack 2 is
0 is detected by the temperature sensor 21, but the battery voltage is not detected, and when the battery pack 2 is mounted on the charger, the charge control circuit 3 sends the battery pack 2 from the inverter power supply circuit 13 through the current output circuit 14. The switching control circuit 15 is controlled so that the charging current supplied to the secondary battery 20 becomes a current corresponding to the rapid charging, and the full charge determination based on ΔT / Δt is performed based on the temperature detected by the temperature sensor 21. Then, control is performed to stop charging when the battery is fully charged.

After determining that the battery pack 2 is fully charged, the charging control circuit 3 performs the automatic heating control shown in the flowchart of FIG.

That is, after the charging is completed, the low current described above is supplied to the secondary battery 20 to heat the secondary battery 20, and the temperature of the battery pack 2 is monitored by the temperature sensor 21. As shown, when the temperature of the battery pack 2 reaches the first predetermined temperature T1, the charging with the low current is stopped as shown in FIG. Even after the stop, the temperature of the battery pack 2 is monitored by the temperature sensor 21 and the detected temperature becomes the second temperature.
When the temperature drops to the predetermined temperature T2, the charging with the low current is restarted. Thereafter, the above control operation is repeated to maintain the temperature of the battery pack 2 between T1 and T2.

As described above, in this embodiment, the temperature of the battery pack 2 can be automatically maintained at a temperature at which battery performance can be exhibited without providing a heating switch.

(Embodiment 3) In this embodiment, as shown in FIG. 9, when the heating switch 6 is turned on, the secondary battery 20 of the battery pack 2 is controlled under the control of the charging control circuit 3. A switch SW such as a relay for connecting the discharge circuit 7 to the secondary battery 20 is provided while disconnecting the discharge circuit 7 from the output of the charging current supply circuit 1.
To discharge a predetermined amount of electricity, and then switch the switching means SW to perform a switching operation.
0 is connected to the output of the charging current supply circuit 1 to perform charging.

That is, in this embodiment, when the heating switch 6 is turned on by the user, the secondary battery 20 in a fully charged (full) state is discharged by the discharging circuit 7, and the battery pack 2 is discharged by the discharging. , And then charge the secondary battery 20 until it is fully charged. This charge control is performed by the above-described ΔT / Δt control. Heating switch 6
Is also performed by the above-described ΔT / Δt control.

(Embodiment 4) In the above embodiments, the battery pack 2 is heated by charging or discharging. However, in this embodiment, as shown in FIG. And a blower fan 9 for applying the heated heat to the battery pack 2. The power sources of the heating means 8 and the blower fan 9 are obtained from a power supply circuit 30 of the charge control circuit 3. The power supply circuit 30 receives an output of the rectifying / smoothing circuit 12 in the charging current supply circuit 1 as an input.

The current output circuit 14 includes an output rectifier circuit 14a and a current detection resistor 14b, and the charge control circuit 3 detects the magnitude of the charging current based on the voltage across the current detection resistor 14b.

FIGS. 11 (a) and 11 (b) show a side view and a top view of the charger main body 40 of the present embodiment, and a mounting portion 4 for mounting the battery pack 2 is provided on one side of the upper surface of the charger main body 40.
1 and a light-emitting diode LED for display at a substantially central portion.
And an operation part of the heating switch 6 is exposed, and an AC cord 1 for connecting to a power outlet is provided on a side surface.
0 is derived.

FIG. 12 shows a cross-sectional structure of the mounting portion 41. The heating means 8 is mounted on a circuit board 42 on which the circuit components of the charger provided on the bottom of the charger main body 40 are mounted. A blower fan 9 is provided in the information of the heating means 8, an intake hole 43 is provided in the charger main body 40 near the position where the heating means 8 is provided, and the battery pack 2 is mounted on the mounting portion 41 when the battery pack 2 is mounted. A grid-like hot air outlet 45 is opened on the upper surface of the charger main body 40 so as to face the grid-like hole 44 provided in the lower part of the battery pack, and the air heated by the heating means 8 is supplied to the battery pack by the blower fan 9. 2 can be fed as shown by an arrow.

The operation of this embodiment will be described with reference to the flowchart shown in FIG.

First, when the battery pack 2 is mounted on the mounting portion 41 of the charger main body 40, the battery pack 2 is detected by mounting detection means (not shown) in the charger main body 40. When the switch 6 is not turned on, the charging control circuit 3 controls the inverter power supply circuit 13 through the switching control circuit 15 so as to supply the normal rapid charging current from the charging current supply circuit 1, and eventually the temperature sensor 2
When the full charge is determined by the ΔT / Δt control based on the detected temperature of No. 1, the normal charging in which the supply of the charging current is stopped is performed.

On the other hand, when the heating switch 6 is turned on by the user, the charging control circuit 3 stops the supply of the charging current from the charging current supply circuit 1 to start the energization of the heating means 8 and the blower fan. 9, the hot air is blown into the battery pack 2 through the hot air outlet 45 and the grid holes 44 by the blower fan 9. As a result, the temperature of the battery pack 2 increases. On the other hand, the charge control circuit 3 monitors the temperature detected by the temperature sensor 21 via the temperature detection circuit 5, and when the detected temperature reaches a predetermined value T,
The heating unit 8 and the blower fan 9 are turned off to stop heating and stop the fan. At the same time, the light emitting diode LED blinks to indicate that the secondary battery 20 in the battery pack 2 has reached the predetermined temperature T. In addition, you may make it notify by a buzzer instead of the light emitting diode LED.

As described above, in this embodiment, since the heating is not performed by the charging current, the battery is not overcharged and the secondary battery is not deteriorated. The fact that the predetermined temperature T has been reached is indicated by the light emitting diode L
Since it is displayed by ED, it is easy for the user to understand.

[0042]

According to the first aspect of the present invention, the secondary battery and the secondary battery
A charging current supply circuit for supplying a charging current to the secondary battery, and a charger comprising a charging control circuit for controlling a charging current supplied from the charging current supply circuit to the secondary battery. The charge control circuit includes a heating switch for giving an instruction for heating to the charge control circuit. When the heating switch is turned on, the charge control circuit determines the remaining capacity of the secondary battery and is in a fully charged state. In such a case, the charging current supply circuit is controlled so as to supply a charging current of a low current enough to warm the secondary battery, and when the battery is not fully charged, the normal charging current is supplied to the secondary battery. Since the charging current supply circuit is controlled to increase the charging capacity, the secondary battery can be heated so that the battery performance can be obtained when the temperature of the battery itself or the ambient temperature is low enough that the battery performance cannot be obtained. Yes, and full For the secondary battery state can warm without degrading the life, also for the secondary battery is not fully charged there is an effect that it is possible to eliminate insufficient charging simultaneously.

According to a second aspect of the present invention, in the first aspect of the present invention, a temperature detecting means for detecting a temperature of the secondary battery is provided.
When the heating switch is turned on and the charging current supply circuit supplies a low-current charging current to the fully charged secondary battery, the temperature of the secondary battery reaches a predetermined temperature. Is detected by the temperature detecting means, the charging current supply circuit is controlled so as to stop supplying the charging current to the secondary battery, so that the fully charged secondary battery can be heated to an appropriate temperature.

According to a third aspect of the present invention, in the second aspect of the present invention, the charging control circuit stops the supply of the charging current to the secondary battery and then reduces the temperature of the secondary battery to a predetermined temperature. Since the charging current supply circuit is controlled so as to restart the supply of the charging current when the temperature is detected by the temperature detecting means, the temperature of the secondary battery can be maintained at a predetermined temperature in addition to the above-described effects.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the charging control circuit causes the secondary battery to be charged when the secondary battery is not in a fully charged state and the secondary battery is in a fully charged state. Since the charging current supply circuit is controlled so that the charging current supply is stopped when it is detected that the battery has become depleted, it is possible to charge an undercharged secondary battery without overcharging, and to heat the battery so that the battery performance can be improved. Can also.

According to a fifth aspect of the present invention, in the first aspect of the present invention, a discharging circuit for the secondary battery is provided, and the charging control circuit is configured to set the charging capacity of the secondary battery to a fully charged state when the heating switch is turned on. In such a case, the charging current supply circuit is controlled to supply a charging current to the secondary battery until the secondary battery is fully charged after discharging a predetermined amount of electricity by the discharging circuit. In addition to the heating of the secondary battery, the secondary battery can be heated by the heat generated by the discharge.

According to a sixth aspect of the present invention, there is provided a secondary battery, a charging current supply circuit for supplying a charging current to the secondary battery, and a charge for controlling a charging current supplied from the charging current supply circuit to the secondary battery. In a charging device including a charger including a control circuit, a temperature detecting unit for detecting a temperature of the secondary battery is provided, and the charging control circuit monitors a temperature of the secondary battery detected by the temperature detecting unit after the charging is completed. Since the charging current supply circuit is controlled so that the low-current charging current is turned on and off and supplied to the secondary battery so that the detected temperature falls within the predetermined temperature range,
The temperature of the secondary battery can be automatically maintained within a certain range so that the battery performance of the secondary battery can be exhibited without deteriorating the life of the secondary battery.

According to a seventh aspect of the present invention, there is provided a secondary battery, a charging current supply circuit for supplying a charging current to the secondary battery, and a charging device for controlling a charging current supplied from the charging current supply circuit to the secondary battery. In a charging apparatus including a charger including a control circuit, a heating unit for heating the secondary battery is provided, and a heating switch is provided. When the heating switch is turned on, the secondary battery is heated by the heating unit. The temperature of the rechargeable battery can be set to a temperature at which battery performance can be exhibited, and the rechargeable battery is not heated using the charging current. Has no effect.

According to an eighth aspect of the present invention, in addition to the sixth aspect of the present invention, a blower fan for blowing the air heated by the heating means to the secondary battery is provided. The secondary battery can be efficiently heated.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram according to a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the above.

FIG. 3 is an explanatory diagram showing a relationship between a battery temperature and a charging capacity according to the first embodiment.

FIG. 4 is an explanatory diagram of a heating operation for the fully charged secondary battery according to the first embodiment;

FIG. 5 is an explanatory diagram of a heating operation for the same uncharged secondary battery.

FIG. 6 is a circuit configuration diagram according to a second embodiment of the present invention.

FIG. 7 is a flowchart for explaining the operation of the above.

FIG. 8 is a timing chart showing a heating operation of the above.

FIG. 9 is a circuit configuration diagram according to a third embodiment of the present invention.

FIG. 10 is a circuit configuration diagram according to a fourth embodiment of the present invention.

FIG. 11A is a side view of the charger main body of the above battery charger.
(B) is a top view of a charger main body same as the above.

FIG. 12 is an enlarged sectional view of a main part of the charger main body according to the third embodiment.

FIG. 13 is a flowchart for explaining the operation of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Charge current supply circuit 2 Battery pack 3 Charge control circuit 4 Voltage detection circuit 5 Temperature detection circuit 6 Heating switch 10 AC code 11 Input circuit 12 Rectification smoothing circuit 13 Inverter power supply circuit 14 Current output circuit 15 Switching control circuit 20 Secondary battery 21 Temperature sensor

Continued on the front page F term (reference) 5G003 AA01 BA01 CA02 CB01 CC02 DA04 EA05 FA08 GB03 GC05 5H030 AA03 AA04 AS06 BB01 BB21 FF22 FF41 5H031 AA02 KK03

Claims (8)

[Claims] 1. A charging system comprising: a secondary battery; a charging current supply circuit for supplying a charging current to the secondary battery; and a charging control circuit for controlling a charging current supplied from the charging current supply circuit to the secondary battery. A charging device comprising a heating switch for giving an instruction for heating the secondary battery to the charging control circuit, wherein the charging control circuit turns on the heating switch when the heating switch is turned on. Judging the remaining capacity, if the battery is fully charged, the charging current supply circuit is controlled to supply a charging current of a low current enough to warm the secondary battery, and if the battery is not fully charged, A charging device, wherein a charging current supply circuit is controlled so as to increase a charging capacity by supplying a charging current in a normal state to a secondary battery. And a charging control circuit for supplying a low charging current to the fully charged secondary battery from the charging current supply circuit when a heating switch is turned on. When the temperature detecting means detects that the temperature of the secondary battery has reached a predetermined temperature during the operation, the charging current supply circuit is controlled so as to stop supplying the charging current to the secondary battery. The charging device according to claim 1, wherein And a charging control circuit for controlling the charging current when the temperature detecting means detects that the temperature of the secondary battery has dropped to a predetermined temperature after stopping supplying the charging current to the secondary battery. The charging device according to claim 2, wherein the charging current supply circuit is controlled so as to restart the supply of the charging current. And a charging control circuit for charging the secondary battery when the secondary battery is not fully charged, and supplying a charging current when detecting that the secondary battery is fully charged. The charging device according to claim 1, wherein the charging current supply circuit is controlled so as to stop. 5. A discharging circuit for a secondary battery, wherein a charging control circuit is configured to discharge the secondary battery by a discharging circuit when the charge capacity of the secondary battery is fully charged when the heating switch is turned on. 2. The charging device according to claim 1, wherein after discharging the amount of electricity, the charging current supply circuit is controlled to supply a charging current to the secondary battery until the secondary battery is fully charged. 6. A charge comprising a secondary battery, a charge current supply circuit for supplying a charge current to the secondary battery, and a charge control circuit for controlling a charge current supplied from the charge current supply circuit to the secondary battery. A charging device comprising a temperature detector for detecting the temperature of the secondary battery; a charging control circuit for monitoring the temperature of the secondary battery detected by the temperature detecting device after charging is completed, and detecting the detected temperature at a predetermined temperature. A charging device, characterized in that a charging current supply circuit is controlled so as to turn on and off a low current charging current and supply the charging current to a secondary battery so that the charging current falls within the range. 7. A charging system comprising a secondary battery, a charging current supply circuit for supplying a charging current to the secondary battery, and a charging control circuit for controlling a charging current supplied from the charging current supply circuit to the secondary battery. A heating device for heating a secondary battery, and a heating switch, wherein when the heating switch is turned on, the heating device heats the secondary battery. . 8. The charging device according to claim 6, further comprising a blowing fan for blowing air heated by the heating means to the secondary battery.