Self-diagnosis system for an energy storage device

1. A self-diagnosis system for an energy storage device, the energy storage device comprising a plurality of electrochemical cells, said self-diagnosis system comprising:

a cell selector for selecting individual ones of the electrochemical cells; and

a processing unit coupled to said cell selector, said processing unit being operative for:

deriving information regarding a respective internal resistance of each one of the electrochemical cells selected by said cell selector; and

deriving an indication of a state of health of the energy storage device based at least in part on the information regarding the respective internal resistance of each one of the electrochemical cells selected by said cell selector.

2. A self-diagnosis system as claimed in claim 1 , wherein said processing unit is operative for:

for each particular one of the electrochemical cells selected by said cell selector:

receiving information regarding at least one voltage of that particular one of the electrochemical cells;

obtaining information regarding a current flowing in that particular one of the electrochemical cells; and

deriving the information regarding the respective internal resistance of that particular one of the electrochemical cells based at least in part on

(i) the information regarding the at least one voltage of that particular one of the electrochemical cells and (ii) the information regarding the current flowing in that particular one of the electrochemical cells.

3. A self-diagnosis system as claimed in claim 2 , further comprising:

voltage measurement means coupled to said processing unit, said voltage measurement means being operative for providing to said processing unit the information regarding the at least one voltage of each particular one of the electrochemical cells selected by said cell selector.

4. A self-diagnosis system as claimed in claim 3 , wherein the information regarding the at least one voltage of each particular one of the electrochemical cells selected by said cell selector includes information regarding an initial voltage of that particular one of the electrochemical cells and information regarding a subsequent voltage of that particular one of the electrochemical cells.

5. A self-diagnosis system as claimed in claim 4 , further comprising:

a current source coupled to said processing unit, said current source being operative for causing a current having a specific value to flow in each particular one of the electrochemical cells selected by said cell selector;

wherein the information regarding the current flowing in each particular one of the electrochemical cells selected by said cell selector is indicative of the specific value of the current flowing in that particular one of the electrochemical cells.

6. A self-diagnosis system as claimed in claim 5 , wherein the specific value of the current flowing in each particular one of the electrochemical cells selected by said cell selector is substantially constant.

7. A self-diagnosis system as claimed in claim 1 , wherein said processing unit is operative for:

determining a highest internal resistance value based at least in part on the information regarding the respective internal resistance of each one of the electrochemical cells selected by said cell selector; and

deriving the indication of the state of health of the energy storage device based at least in part on the highest internal resistance value.

8. A self-diagnosis system as claimed in claim 7 , wherein said processing unit comprises a memory for storing data representative of state of health as a function of internal resistance, and wherein said processing unit is operative for:

correlating the highest internal resistance value to the data representative of state of health as a function of internal resistance so as to derive the indication of the state of health of the energy storage device.

9. A self-diagnosis system as claimed in claim 5 , wherein the current caused by said current source to flow in each particular one of the electrochemical cells selected by said cell selector causes a charge of that particular one of the electrochemical cells.

10. A self-diagnosis system as claimed in claim 5 , wherein the current caused by said current source to flow in each particular one of the electrochemical cells selected by said cell selector causes a discharge of that particular one of the electrochemical cells.

11. A self-diagnosis system as claimed in claim 1 , wherein said processing unit is further operative for:

deriving information regarding a state of charge of the energy storage device based at least in part on the indication of the state of health of the energy storage device.

12. A self-diagnosis system as claimed in claim 11 , wherein said processing unit is further operative for:

deriving information regarding energy flowing in or out of the energy storage device by monitoring current flow in the energy storage device over time; and

updating the information regarding the state of charge of the energy storage device based at least in part on the information regarding energy flowing in or out of the energy storage device.

13. A self-diagnosis system as claimed in claim 12 , wherein said processing unit is further operative for:

deriving information indicative of a period of time for which the energy storage device is capable of providing a given current, based at least in part on the updated information regarding the state of charge of the energy storage device.

14. A self-diagnosis system as claimed in claim 1 , further comprising a communication port communicatively coupled to said processing unit, said processing unit being operative for:

releasing the indication of the state of health of the energy storage device to an entity external to the energy storage device via said communication port.

15. A self-diagnosis system as claimed in claim 11 , further comprising a communication port communicatively coupled to said processing unit, said processing unit being operative for:

releasing the information regarding the state of charge of the energy storage device to an entity external to the energy storage device via said communication port.

16. A self-diagnosis system as claimed in claim 13 , further comprising a communication port communicatively coupled to said processing unit, said processing unit being operative for:

releasing the information indicative of a period of time for which the energy storage device is capable of providing a given current to an entity external to the energy storage device via said communication port.

17. A self-diagnosis system as claimed in claim 1 , wherein said processing unit is further operative for:

deriving information indicative of a period of time for which the energy storage device is capable of providing a given current, based at least in part on the indication of the state of health of the energy storage device.

18. A self-diagnosis system as claimed in claim 10 , wherein the energy storage device is adapted to be connected to a load, and wherein the respective discharge of each particular one of the electrochemical cells selected by said cell selector is applied to the load.

19. An energy storage device comprising:

a plurality of electrochemical cells; and

a self-diagnosis system comprising:

a cell selector for selecting individual ones of said electrochemical cells; and

a processing unit coupled to said cell selector, said processing unit being operative for:

deriving information regarding a respective internal resistance of each one of said electrochemical cells selected by said cell selector; and

deriving an indication of a state of health of said energy storage device based at least in part on the information regarding the respective internal resistance of each one of said electrochemical cells selected by said cell selector.

20. A method for self-diagnosis of an energy storage device, the energy storage device comprising a plurality of electrochemical cells, said method comprising:

selecting individual ones of the electrochemical cells;

deriving information regarding a respective internal resistance of each selected one of the electrochemical cells; and

deriving an indication of a state of health of the energy storage device based at least in part on the information regarding the respective internal resistance of each selected one of the electrochemical cells.