Battery chargers

• US 20040135553A1
• Filed: 12/23/2003
• Published: 07/15/2004
• Est. Priority Date: 12/24/2002
• Status: Active Grant

• Current Assignee: Makita Corporation
• Original Assignee: Makita Corporation
• Inventors: Sakakibara, Kazuyuki
• Granted Patent: US 7,106,027 B2
• Time in Patent Office: Days
• US Class Current: 320/150
• CPC Class Codes: H01M 10/46 Accumulators structurally combined with charging apparatus circuits for charging H02J7/00
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Battery pack (50) may include rechargeable batteries (55) and first temperature sensor TM1 for detecting the temperature of batteries (55). Battery charger (10) may include power source circuit (32) for supplying charging current to batteries (55) of battery pack (50). Battery charger (10) may also include second temperature sensor TM2 located in the vicinity of power source circuit (32). Battery charger (10) may further include a processor for controlling power source circuit (32). The processor may select charging current that will be supplied by power source circuit (32) to batteries (55) based at least upon battery temperature from first temperature sensor TM1 and power source circuit temperature from second temperature sensor TM2, and supply the selected charging current to batteries (55).

Claims

1. An apparatus comprising:

a battery pack comprising battery cells and a first temperature sensor coupled to the battery cells, and

a battery charger comprising a power source circuit arranged and constructed to supply charging current to the battery cells, a second temperature sensor coupled to the power source circuit and a processor arranged and constructed to (i) select charging current that will be supplied by the power source circuit to the battery cells based at least upon battery temperature from the first temperature sensor and power source circuit temperature from the second temperature sensor, and (ii) supply the selected charging current to the battery cells.

2. An apparatus as in claim 1, wherein the processor is further arranged and constructed to calculate battery temperature increase rate based upon signals from the first temperature sensor and power source temperature increase rate based upon signals from the second temperature sensor, and select charging current that will be supplied by the power source circuit to the battery cells based further upon the calculated temperature increase rates.

3. An apparatus as in claim 2, wherein the processor is further arranged and constructed to (1) select a first allowable charging current value based upon the battery temperature and the calculated battery temperature increase rate, (2) select a second allowable charging current value based upon the power source circuit temperature and the calculated power source circuit temperature increase rate, and (3) select the smaller of the first and second allowable charging current values as the charging current that will be supplied by the power source circuit to the battery cells.

4. An apparatus as in claim 3, wherein the processor is further arranged and constructed to terminate the supply of charging current to the battery cells based upon a determination that relatively low first allowable charging currents have been repeatedly selected over series of intervals.

5. A battery charger adapted to supply current to a removable battery pack comprising battery cells, a first temperature sensor coupled to the battery cells and a charging terminal, comprising:

a power source circuit,

a second temperature sensor coupled to the power source circuit,

a first terminal arranged and constructed to couple to the first temperature sensor,

a second terminal coupled to the power source circuit and arranged and constructed to conduct charging current via the charging terminal to the battery cells, and

a controller coupled to the first terminal, the second temperature sensor and the power source circuit, the controller being arranged and constructed to select the amount of charging current supplied to the second terminal based at least upon battery temperature signal received from the first terminal and power source circuit temperature signal received from the second temperature sensor.

6. A battery charger as in claim 5, the controller is further arranged and constructed to calculate battery temperature increase rate based upon signals received from the first terminal and power source temperature increase rate based upon signals from the second temperature sensor, and select charging current that will be supplied by the power source circuit to the second terminal based further upon the calculated temperature increase rates.

7. A battery charger as in claim 6, wherein the controller is further arranged and constructed to (1) select a first allowable charging current value based upon the battery temperature and the calculated battery temperature increase rate, (2) select a second allowable charging current value based upon the power source circuit temperature and the calculated power source circuit temperature increase rate, and (3) select the smaller of the first and second allowable charging current as the charging current that will be supplied by the power source circuit to the second terminal.

8. A battery charger as in claim 7, wherein the controller is further arranged and constructed to terminate the supply of charging current to the second terminal based upon a determination that relatively low first allowable charging currents have been repeatedly selected over series of intervals.