Pack battery charging method, pack battery, and power source device
A pack battery charging method is a charging method for connecting pack battery to charger and charging pack battery at a constant voltage and a constant current. Pack battery detects a degree of deterioration of battery and a supply voltage at which charger charges pack battery, and specifies a charging termination current from both the supply voltage of charger and the degree of deterioration of battery to perform charging.
1. A pack battery charging method for connecting a pack battery to a charger and charging the pack battery by switching from constant-current charging to constant-voltage charging, the method comprising:
detecting, by the pack battery, a degree of deterioration of a battery and a charging voltage at which the charger charges the pack battery;
determining a charging termination current based on both a supply voltage of the charger and the degree of deterioration of the battery for terminating charging of the pack battery during the constant-voltage charging; and
terminating charging of the pack battery when a charging current for charging the pack battery decreases to the charging termination current during the constant-voltage charging as the charging voltage reaches the supply voltage of the charger.
2. The pack battery charging method according to claim 1 , further comprising:
increasing the charging termination current as the degree of deterioration of the battery increases; and
increasing the charging termination current as the supply voltage of the charger increases.
3. The pack battery charging method according to claim 1 , further comprising:
storing, by the pack battery, the charging termination current with respect to the degree of deterioration of the battery and the supply voltage of the charger in a look-up table; and
determining the charging termination current based on the degree of deterioration of the battery and the supply voltage of the charger in accordance with storage of the look-up table.
4. The pack battery charging method according to claim 1 , further comprising:
storing, by the pack battery, a function for determining the charging termination current based on the degree of deterioration of the battery and the supply voltage of the charger; and
determining the charging termination current based on the degree of deterioration of the battery and the supply voltage of the charger based on the function.
5. The pack battery charging method according to claim 1 , wherein the pack battery incorporates a lithium ion secondary battery.
6. A pack battery connected to a charger and charged by switching from constant-current charging to constant-voltage charging, the pack battery comprising:
a detection circuit that detects a charging voltage from the charger and a degree of deterioration of a battery;
an arithmetic circuit that calculates a charging termination current for terminating charging of the pack battery during the constant-voltage charging based on a supply voltage of the charger and the degree of deterioration detected by the detection circuit; and
a signal terminal that detects the charging termination current calculated by the arithmetic circuit and outputs a charging stop signal to the charger when a charging current for charging the pack battery decreases to the charging termination current during the constant-voltage charging as the charging voltage reaches the supply voltage of the charger.
7. The pack battery according to claim 6 , wherein the arithmetic circuit includes a memory that stores a look-up table that determines the charging termination current based on the degree of deterioration of the battery and the supply voltage of the charger, and determines the charging termination current based on the degree of deterioration of the battery and the supply voltage of the charger based on the look-up table stored in the memory.
8. The pack battery according to claim 6 , wherein the arithmetic circuit includes a memory that stores a function for determining the charging termination current based on the degree of deterioration of the battery and the supply voltage of the charger, and determines the charging termination current based on the degree of deterioration of the battery and the supply voltage of the charger based on the function stored in the memory.
9. The pack battery according to claim 6 , wherein the pack battery incorporates a lithium ion secondary battery.
10. A power source device comprising:
a charger; and
a pack battery connected to the charger and charged by switching from constant-current charging to constant-voltage charging, wherein
the pack battery includes:
a detection circuit that detects a charging voltage from the charger and a degree of deterioration of a battery;
an arithmetic circuit that calculates a charging termination current for terminating charging of the pack battery during the constant-voltage charging based on a supply voltage of the charger and the degree of deterioration detected by the detection circuit; and
a signal terminal that detects the charging termination current calculated by the arithmetic circuit and outputs a charging stop signal to the charger when a charging current for charging the pack battery decreases to the charging termination current during the constant-voltage charging as the charging voltage reaches the supply voltage of the charger, and
the charger includes a charging stop circuit that is connected to the signal terminal and stops charging of the pack battery with the charging stop signal input from the signal terminal.
11. The power source device according to claim 10 , wherein the arithmetic circuit includes: a memory that stores a look-up table for determining the charging termination current based on the degree of deterioration of the battery and the supply voltage of the charger; and determines the charging termination current based on the degree of deterioration of the battery and the supply voltage of the charger based on the look-up table stored in the memory.
12. The power source device according to claim 10 , wherein the arithmetic circuit includes a memory that stores a function for determining the charging termination current based on the degree of deterioration of the battery and the supply voltage of the charger, and determines the charging termination current based on the degree of deterioration of the battery and the supply voltage of the charger based on the function stored in the memory.
13. The power source device according to claim 10 , wherein the pack battery incorporates a lithium ion secondary battery.