Anti-swell protection circuit for battery cells
View Patent ↗The present invention provides a protection circuit and method for preventing a battery from swelling in one embodiment. The protection circuit includes: a voltage monitoring circuit that monitors a voltage across the battery; a control circuit that receives voltage information from the voltage monitoring circuit; and a discharge circuit that turns on to discharge the battery upon receiving a signal from the control circuit. The control circuit includes: a timer that sets predetermined time periods; a signaling section that outputs the signal to the discharge circuit after a first predetermined time period if the voltage stays above a first predetermined voltage threshold without charging or discharging to a load for the first predetermined time period; a sleep mode applying section that applies a sleep mode when the voltage falls below a second predetermined voltage threshold; and a load disconnecting section that disconnects the load if a wake-up command is not issued during the sleep mode for a third predetermined time period. Alternatively, the protection circuit may include a swell monitoring device that monitors a swell associated with the battery; a control circuit that receives swell information from the swell monitoring device; and a discharge circuit that turns on to discharge the battery upon receiving a signal from the control circuit.
1. A protection circuit configured to be coupled to a battery and a load for preventing the battery from swelling, the protection circuit comprising:
a voltage monitoring circuit that monitors a voltage across the battery;
a control circuit that receives voltage information from the voltage monitoring circuit; and
a discharge circuit that turns on to discharge the battery upon receiving a first signal from the control circuit,
wherein the control circuit comprises:
a timer that sets predetermined time periods;
a signaling section that outputs the first signal to the discharge circuit after a first predetermined time period if the voltage stays above a first predetermined voltage threshold without charging or discharging to the load for the first predetermined time period;
a sleep mode applying section that applies a sleep mode when the voltage falls below a second predetermined voltage threshold; and
a load disconnecting section that disconnects the load if a wake-up command is not issued during the sleep mode for a third predetermined time period.
2. The protection circuit according to claim 1 , wherein:
the discharge circuit turns off to stop the discharging of the battery upon receiving a second signal from the control circuit, wherein the signaling section outputs the second signal to the discharge circuit when the voltage falls below the second predetermined voltage threshold; and
the sleep mode applying section applies the sleep mode after a second predetermined time period if the voltage stays below the second predetermined voltage threshold without charging or discharging to the load for the second predetermined time period.
3. The protection circuit according to claim 1 , further comprising:
a temperature measuring device,
wherein the control circuit receives temperature information from the temperature measuring device and determines the predetermined time periods based on the temperature information for the timer.
4. The protection circuit according to claim 1 , wherein the control circuit further comprises:
a third signaling section that emits a third signal after the discharge circuit turns on to discharge the battery, whereby a user is warned of a status of the battery.
5. The protection circuit according to claim 1 , wherein the battery is a Lithium Sulfur battery.
6. The protection circuit according to claim 1 , wherein the discharge circuit discharge the battery with a discharge current value in a range between 10 mA and 1000 mA.
7. The protection circuit according to claim 1 , wherein:
the battery is a plurality of batteries;
the voltage monitoring circuit is a plurality of voltage monitoring circuits respectively coupled to the plurality of batteries; and
the discharge circuit is a plurality of discharge circuits respectively coupled to the plurality of batteries and respectively coupled to the plurality of voltage monitoring circuits through the control circuit, wherein:
a first voltage monitoring circuit monitors a first voltage across a first battery;
a second voltage monitoring circuit monitors a second voltage across a second battery;
the control circuit receives the voltage information from the first and second voltage monitoring circuits, respectively;
a first discharge circuit turns on to discharge the first battery upon receiving a fourth signal from the control circuit; and
a second discharge circuit turns on to discharge the second battery upon receiving a fifth signal from the control circuit, wherein the control circuit comprises:
the signaling section that outputs the fourth signal to the first discharge circuit after the first predetermined time period if the first voltage stays above the first predetermined voltage threshold without charging or discharging to the load for the first predetermined time period, and the fifth signal to the second discharge circuit after the first predetermined time period if the second voltage stays above the first predetermined voltage threshold without charging or discharging to the load for the first predetermined time period; and
the sleep mode applying section that applies the sleep mode when at least one voltage falls below the second predetermined voltage threshold.
8. The protection circuit according to claim 7 , wherein:
the first discharge circuit turns off to stop the discharging of the first battery upon receiving a sixth signal from the control circuit, wherein the signaling section outputs the sixth signal to the first discharge circuit when the first voltage falls below the second predetermined voltage threshold;
the second discharge circuit turns off to stop the discharging of the second battery upon receiving a seventh signal from the control circuit, wherein the signaling section outputs the seventh signal to the second discharge circuit when the second voltage falls below the second predetermined voltage threshold; and
the sleep mode applying section applies the sleep mode after the second predetermined time period if at least one voltage stays below the second predetermined voltage threshold without charging or discharging to the load for the second predetermined time period.
9. A protection circuit configured to be coupled to a battery and a load for preventing the battery from swelling, the protection circuit comprising:
a swell monitoring device that monitors a swell associated with the battery;
a control circuit that receives swell information from the swell monitoring device; and
a discharge circuit that turns on to discharge the battery upon receiving a signal from the control circuit,
wherein the control circuit comprises:
a timer that sets predetermined time periods;
a signaling section that outputs the signal to the discharge circuit when the swell associated with the battery reaches a predetermined swell value;
a sleep mode applying section that applies a sleep mode after a predetermined discharging time period if the discharge circuit is on for the predetermined discharging time period; and
a load disconnecting section that disconnects the load if a wake-up command is not issued during the sleep mode for a predetermined sleep time period.
10. The protection circuit according to claim 9 , wherein the battery is a Lithium Sulfur battery.
11. The protection circuit according to claim 9 , wherein:
the battery is a plurality of batteries;
the swell monitoring device is a plurality of swell monitoring devices respectively coupled to the plurality of batteries; and
the discharge circuit is a plurality of discharge circuits respectively coupled to the plurality of batteries and respectively coupled to the plurality of swell monitoring devices through the control circuit, wherein:
a first swell monitoring device monitors a first swell associated with a first battery;
a second swell monitoring device monitors a second swell associated with a second battery;
a control circuit receives the swell information from the first and second swell monitoring devices, respectively;
a first discharge circuit turns on to discharge the first battery upon receiving a first signal from the control circuit; and
a second discharge circuit turns on to discharge the second battery upon receiving a second signal from the control circuit, wherein the control circuit comprises:
the signaling section that outputs the first signal to the first discharge circuit when the first swell associated with the first battery reaches the predetermined swell value, and the second signal to the second discharge circuit when the second swell associated with the second battery reaches the predetermined swell value; and
the sleep mode applying section that applies the sleep mode if the discharging of at least one battery continues for the predetermined discharging time period.
12. The protection circuit according to claim 11 , wherein the control circuit further comprises:
a third signaling section that emits a third signal after at least one discharge circuit turns on for discharging, the third signal having an identification of at least one battery with the swell that has reached the predetermined swell value, whereby a user is warned of a status of the at least one battery with the identification.
13. A method for preventing a battery from swelling, the method comprising steps of:
monitoring a voltage across the battery;
setting predetermined time periods;
discharging the battery through a discharge circuit after a first predetermined time period if the voltage stays above a first predetermined voltage threshold without charging or discharging to a load for the first predetermined time period;
applying a sleep mode when the voltage falls below a second predetermined voltage threshold; and
disconnecting the load if a wake-up command is not issued during the sleep mode for a third predetermined time period.
14. The method according to claim 13 , further comprising a step of:
stopping the discharging of the battery when the voltage falls below the second predetermined voltage threshold,
wherein the step of applying the sleep mode is performed after a second predetermined time period if the voltage stays below the second predetermined voltage threshold without charging or discharging to the load for the second predetermined time period.
15. The method according to claim 13 , further comprising steps of:
measuring ambient temperature; and
determining the predetermined time periods based on results obtained in the measuring step.
16. The method according to claim 13 , further comprising a step of:
emitting a signal after the discharging starts, whereby a user is warned of a status of the battery.
17. The method according to claim 13 , wherein the discharging is performed with a discharge current value in a range between 10 mA and 1000 mA.
18. The method according to claim 13 , wherein:
the battery is a plurality of batteries;
in the monitoring step, a first voltage across a first battery is monitored, and a second voltage across a second battery is monitored;
in the discharging step, the first battery is discharged through a first discharge circuit coupled to the first battery after the first predetermined time period if the first voltage stays above the first predetermined voltage threshold without charging or discharging to the load for the first predetermined time period, and the second battery is discharged through a second discharge circuit coupled to the second battery after the first predetermined time period if the second voltage stays above the first predetermined voltage threshold without charging or discharging to the load for the first predetermined time period; and
in the applying step, the sleep mode is applied when at least one voltage falls below the second predetermined voltage threshold.
19. The method according to claim 18 , further comprising a step of
stopping the discharging of the first battery when the first voltage falls below the second predetermined voltage threshold, and the discharging of the second battery when the second voltage falls below the second predetermined voltage threshold, wherein
the step of applying the sleep mode is performed after the second predetermined time period if the voltage across at least one battery stays below the second predetermined voltage threshold without charging or discharging to the load for the second predetermined time period.
20. A method for preventing a battery from swelling, the method comprising steps of:
monitoring battery strain by strain gauge;
a control circuit receives battery strain information from strain gauge; and
wherein the control circuit determines battery swell based on received battery strain information;
discharging the battery through a discharge circuit when the swell associated with the battery reaches a predetermined swell value;
applying a sleep mode after a predetermined discharging time period; and
disconnecting the load if a wake-up command is not issued during the sleep mode for a predetermined sleep time period.
21. The method according to claim 20 , wherein the discharging is performed with a discharge current value in a range between 10 mA and 1000 mA.
22. The method according to claim 20 , wherein:
the battery is a plurality of batteries;
in the monitoring step, a first swell across a first battery is monitored, and a second swell across a second battery is monitored; and
in the discharging step, the first battery is discharged through a first discharge circuit coupled to the first battery when the first swell associated with the first battery reaches the predetermined swell value, and the second battery is discharged through a second discharge circuit coupled to the second battery when the second swell associated with the second battery reaches the predetermined swell value.
23. The method according to claim 22 , further comprising a step of:
emitting a signal after the discharging of at least one battery starts, wherein the signal includes an identification of at least one battery having the swell that has reached the predetermined swell value, whereby a user is warned of a status of the at least one battery with the identification.