System and Method for Charging of a Rechargeable Battery

• US 20140132225A1
• Filed: 06/21/2011
• Published: 05/15/2014
• Est. Priority Date: 06/21/2011
• Status: Active Grant

• Current Assignee: Husqvarna AB (HUSQVARNA)
• Original Assignee: Husqvarna AB (HUSQVARNA)
• Inventors: Jgenstedt, Patrik
• Granted Patent: US 9,728,991 B2
• Time in Patent Office: Days
• US Class Current: 320/160
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage

Abstract

A method of charging a battery (50). The method comprises the step of supplying (101) an essentially constant charging current (C) of a predetermined first magnitude (C1) from a power source (10) to the battery (50), during a first constant current mode (CC1) of charging. Furthermore the method comprises the step of switching (102) to a second constant current mode (CC2) of charging when a battery voltage (Vb) reaches a predetermined threshold value (Vt1); and the step of supplying (103) an essentially constant charging current (C) of a predetermined second magnitude (C2) to the battery (B), during the second constant current mode (CC2) of charging. The second magnitude (C2) is lower than the first magnitude (C1).

Claims

1. A method of charging a battery, which method comprises:

supplying an essentially constant charging current of a predetermined first magnitude from a power source to the battery, during a first constant current mode of charging;

switching to a second constant current mode of charging when a battery voltage reaches a predetermined threshold value; and

supplying an essentially constant charging current of a predetermined second magnitude to the battery, during the second constant current mode of charging, wherein the second magnitude is lower than the first magnitude.

2. The method according to claim 1, which method furthermore comprises:

switching from the second constant current mode of charging to a constant voltage mode of charging, when the battery voltage reaches a second predetermined threshold value and

limiting the current sourced into the battery such that an essentially constant battery voltage is maintained during the constant voltage mode of charging.

3. The method according to claim 2, wherein the method furthermore comprises ending the constant voltage mode of charging and terminating charging when the charging current sourced to the battery drops below a predetermined magnitude threshold value or a time period elapsed since the start of the constant current mode of charging exceeds a predetermined threshold value.

4. The method according to claim 1, wherein the step of switching to a second constant current mode of charging comprises opening a switch which is arranged to open when the battery voltage reaches a predetermined threshold value, wherein the switch is arranged in parallel with a current limiting device, sourcing current into the battery when the switch is open.

5. The method according to claim 4, wherein the current limiting device comprises a component from the group comprising:

a low power switch regulator, a resistor, a linear regulator.

6. The method according to claim 1, wherein the battery is arranged in a robotic garden tool.

7. A system for charging a battery, which system comprises a first charge controlling unit arranged to supply an essentially constant charging current of a predetermined first magnitude from a power source to the battery, during a first constant current mode of charging;

a second charge controlling unit arranged to switch to a second constant current mode of charging when a battery voltage reaches a predetermined threshold value and to supply an essentially constant charging current of a predetermined second magnitude to the battery, during the second constant current mode of charging, wherein the second magnitude is lower than the first magnitude.

8. The system according to claim 7, wherein the second charge controlling unit furthermore is arranged to switch from the second constant current mode of charging to a constant voltage mode of charging, when the battery voltage reaches a second predetermined threshold value;

and to limit the current sourced into the battery such that an essentially constant battery voltage is maintained during the constant voltage mode of charging.

9. The system according to claim 8, wherein the system furthermore comprises control means arranged to end the constant voltage mode of charging and terminating charging when the charging current sourced to the battery drops below a predetermined magnitude threshold value or a time period elapsed since the start of the constant current mode of charging exceeds a predetermined threshold value.

10. The system according to claim 7, wherein the second charge controlling unit comprises a switch which is arranged to open when the battery voltage reaches a predetermined threshold value, and a current limiting device arranged in parallel with the switch, wherein the current limiting device is arranged to source current into the battery when the switch is open.

11. The system according to claim 10, wherein the current limiting device comprises a component chosen from the group comprising:

a low power switch regulator, a resistor, a linear regulator.

12. The system according to claim 7, wherein the battery is arranged in a robotic garden tool.