Redundant battery protection system and method
View Patent ↗An enhanced battery pack having an enhanced protection system addresses a potential weakness of the conventional protection system of a conventional battery pack. The enhanced protection system includes both the convention protection circuit and a redundant protection circuit. The redundant protection circuit is either a duplicate copy of the conventional protection circuit or is at least a functional equivalent of the conventional protection circuit. The components of the redundant protection circuit are electrically coupled into the enhanced battery pack in a parallel fashion with the corresponding components of the conventional protection circuit. Consequently, if one or more components of the conventional protection circuit fail due to defective conditions of the one or more components of the conventional protection circuit, the redundant protection circuit will still be operable to allow the enhanced battery pack to function while the enhanced protection system continues to protect the enhanced battery pack.
1. A battery pack comprising:
a first external terminal;
a second external terminal;
a first battery cell electrically coupled with the first external terminal and the second external terminal;
a first electrical switch electrically coupled in series with the first battery cell and the first external terminal;
a first protection circuit electrically coupled to the first battery cell and electrically coupled to the first electrical switch, the first protection circuit having a first state when a first electrical condition of the first battery cell exists and having an absence of the first state when the first condition does not exist, the first electrical switch configured to be in an electrically open circuit state to prevent electrical current from flowing through the first electrical switch when the first state of the first protection circuit exists and to be in an electrically closed circuit state to allow electrical current to flow through the first electrical switch when the first state of the first protection circuit is absent;
a second electrical switch electrically coupled in series with the first battery cell and the first external terminal, the second electrical switch electrically coupled in parallel with the first electrical switch; and
a second protection circuit electrically coupled to the first battery cell and electrically coupled to the second electrical switch, the second protection circuit having a first state when the first electrical condition of the first battery cell exists and having an absence of the first state when the first condition does not exist, the second electrical switch configured to be in an electrically open circuit state to prevent electrical current from flowing through the second electrical switch when the first state of the second protection circuit exists and to be in an electrically closed circuit state to allow electrical current to flow through the second electrical switch when the first state of the second protection circuit is absent.
2. The battery pack of claim 1 wherein the first electrical switch is a first pair of transistors.
3. The battery pack of claim 2 wherein the first pair of transistors are MOSFET transistors.
4. The battery pack of claim 1 wherein the first protection circuit has the first state when an overvoltage condition exists with the battery cell.
5. The battery pack of claim 1 further including a plurality of battery cells and wherein the first protection circuit is electrically coupled to the plurality of battery cells, the first protection circuit configured to be in the first state if at least one of the plurality of battery cells is in the first condition.
6. The battery pack of claim 1 wherein the battery cell is a Li ion battery cell.
7. The battery pack of claim 1 further comprising a discrete device electrically coupled between the first protection circuit and the battery cell.
8. The battery pack of claim 1 wherein the discrete device is an electrical resistor.
9. The battery pack of claim 1 wherein the battery cell includes a first terminal and a second terminal and the first protection circuit is coupled to the first terminal and the second terminal of the battery cell.
10. A battery pack comprising:
a first external terminal;
a second external terminal;
a plurality of battery cells electrically coupled to one another and the first external terminal and the second external terminal in series;
a first transistor pair of a charge transistor and a discharge transistor electrically coupled in series with the plurality of battery cells and the first external terminal;
a first integrated circuit electrically coupled to each of the plurality of battery cells, and electrically coupled to the first transistor pair, the first integrated circuit having a first state when a first electrical condition of at least one of the plurality of battery cells exists and having an absence of the first state when the first condition does not exist, the first transistor pair configured to be in an electrically open circuit state to have an absence of electrical continuity between the first external terminal and the plurality of battery cells when the first state of the first integrated circuit exists and to be in an electrically closed circuit state to have electrical continuity between the first external terminal and the plurality of battery cells when the first state of the first integrated circuit is absent;
a second transistor pair of a charge transistor and a discharge transistor electrically coupled in series with the plurality of battery cells and the first external terminal, the second transistor pair electrically coupled in parallel with the first transistor pair;
a second integrated circuit electrically coupled to each of the plurality of battery cells, and electrically coupled to the second transistor pair, the second integrated circuit having a first state when the first electrical condition of at least one of the plurality of battery cells exists and having an absence of the first state when the first condition does not exist, the second transistor pair configured to be in an electrically open circuit state to have an absence of electrical continuity between the first external terminal and the plurality of battery cells when the first state of the second integrated circuit exists and to be in an electrically closed circuit state to have electrical continuity between the first external terminal and the plurality of battery cells when the first state of the second integrated circuit is absent.
11. The battery pack of claim 10 wherein the first transistor pair are MOSFET transistors.
12. The battery pack of claim 10 wherein the first integrated circuit has the first state when an overvoltage condition exists with at least one of the plurality of the battery cells.
13. The battery pack of claim 10 wherein the plurality of the battery cells are Li ion battery cells.
14. The battery pack of claim 10 further comprising a discrete device electrically coupled between the first integrated circuit and one of the plurality of the battery cells.
15. The battery pack of claim 14 wherein the discrete device is an electrical resistor.
16. The battery pack of claim 10 wherein each of the plurality of the battery cells includes a first terminal and a second terminal and the first integrated circuit is coupled to the first terminal and the second terminal of each of the plurality of the battery cells.
17. An apparatus comprising:
a first terminal;
a second terminal;
a battery cell electrically coupled to the first and second terminals;
a first electrical switch electrically coupled in series with the battery cell and the first terminal;
a first protection circuit electrically coupled to the battery cell and the first electrical switch, the first protection circuit having a state, the first electrical switch configured to be in an electrically open circuit state to prevent electrical current from flowing through the first electrical switch when the state of the first protection circuit exists and to be in an electrically closed circuit state to allow electrical current to flow through the first electrical switch when the state of the first protection circuit is absent;
a second electrical switch electrically coupled in series with the battery cell and the first terminal, the second electrical switch electrically coupled in parallel with the first electrical switch; and
a second protection circuit electrically coupled to the battery cell and the second electrical switch, the second protection circuit having a state, the second electrical switch configured to be in an electrically open circuit state to prevent electrical current from flowing through the second electrical switch when the state of the second protection circuit exists and to be in an electrically closed circuit state to allow electrical current to flow through the second electrical switch when the state of the second protection circuit is absent.
18. The apparatus of claim 17 wherein the battery cell is a first battery cell, and wherein the apparatus further comprises a second battery cell electrically coupled to the first and second terminals.
19. The apparatus of claim 17 wherein the first protection circuit has the state when an electrical condition of the battery cell exists and wherein the state of the first protection circuit is absent when the electrical condition of the battery cell does not exist.
20. The apparatus of claim 17 wherein the first protection circuit has the state when a device to which the apparatus is electrically coupled has an undesirable condition.