Methodology for charging batteries safely

1. A fault-detection apparatus for a charging system that charges a collection of interconnected battery cells, the apparatus comprising:

a) a data-acquisition system for receiving a set of data parameters from the collection while the charging system is actively charging the collection, the set of data parameters measured during a charge cycle that begins with V<V max and deltaT<(deltaT) max , wherein deltaT is a maximum difference in temperature between the cells throughout the collection and an ambient temperature, wherein (deltaT) max is a maximum acceptable difference in temperature that affects a change in voltage or current during charging;

b) a monitoring system evaluating said set of data parameters to identify a set of anomalous conditions; and

c) a controller comparing said set of anomalous conditions against a set of predetermined profiles indicative of an internal short in one or more cells of the collection, said controller establishing an internal-short state for the collection when said comparing has a predetermined relationship to said set of predetermined profiles.

2. The fault-detection apparatus of claim 1 , wherein the controller verifies that a charge current has not decreased or been interrupted, and that no additional load has been introduced, before establishing the internal-short state.

3. The fault-detection apparatus of claim 1 , wherein (deltaT) max is determined through testing and is contained in a look-up table.

4. The fault-detection apparatus of claim 1 , wherein the charging system includes a constant voltage charging phase applied to the collection and wherein said set of data parameters includes a battery current into the collection from the charger that increases during said charging phase and wherein said set of anomalous conditions includes said increasing battery current with respect to time.

5. The fault-detection apparatus of claim 1 , wherein the charging system includes a constant voltage charging phase applied to the collection and wherein said set of data parameters includes a battery current into the collection from the charger that increases during said charging phase and wherein said set of anomalous conditions includes said increasing battery current with respect to charge capacity.

6. The fault-detection apparatus of claim 1 , wherein the charging system includes a first charging phase including a constant current or constant power phase and a second charging phase including a constant voltage phase, applied to the collection and wherein said set of data parameters includes a first phase charging time and a second phase charging time and wherein said set of anomalous conditions includes a ratio of said first phase charging time to said second phase charging time that exceeds a predetermined value.

7. The fault-detection apparatus of claim 6 , wherein said predetermined value includes a maximum value predetermined for said specific combination of said ratio responsive to said first phase charging time and said second phase charging time.

8. The fault-detection apparatus of claim 1 , wherein the charging system includes a first charging phase including a constant voltage phase and a second charging phase including a constant power phase, applied to the collection and wherein said set of data parameters includes a first phase charging time and a second phase charging time and wherein said set of anomalous conditions includes a ratio of said first phase charging time to said second phase charging time that exceeds a predetermined value.

9. The fault-detection apparatus of claim 8 , wherein said predetermined value includes a maximum value predetermined for said specific combination of said ration responsive to said first phase charging time and said second phase charging time.

10. The fault-detection apparatus of claim 1 , wherein the charging system includes a charging phase, said charging phase including one of a constant current, a constant voltage, and a constant power, applied to the collection and wherein said set of data parameters includes a charge time associated with an associated charge rate and wherein said set of anomalous conditions includes said charge time at said associated charge rate exceeding a predetermined threshold maximum charge time specified for said associated charge rate.

11. The fault-detection apparatus of claim 1 , wherein said set of data parameters includes a rate of self-discharge for the collection after charging and wherein said set of anomalous conditions includes said rate of self-discharge exceeding a predetermined threshold rate of self-discharge for the collection.

12. The fault-detection apparatus of claim 11 , wherein said rate of self-discharge includes at least one selected from the group consisting of: (i) average watts responsive to a change in state of charge over time when not charging or driving exceeding said predetermined threshold, and (ii) a bleed Ah exceeding said predetermined threshold.

13. The fault-detection apparatus of claim 11 , wherein the collection includes a plurality of sub-collections of the lithium ion battery cells, wherein said set of data parameters includes a rate of self-discharge for each said subcollection and wherein said set of anomalous conditions includes a rate of self-discharge for a particular one of said subcollections having a statistically significant difference from an average rate of self-discharge of the collection excluding said particular one subcollection.

14. The fault-detection apparatus of claim 13 , wherein said rate of self-discharge of each said subcollection includes at least one selected from the group consisting of: (i) a bleed frequency, and (ii) a cumulative bleed Ah.

15. The fault-detection apparatus of claim 1 , wherein said set of data parameters includes a discharge capacity for the collection and a charge capacity for the collection and wherein said set of anomalous conditions includes a ratio of said discharge capacity to said charge capacity that exceeds a predetermined value.

16. The fault-detection apparatus of claim 15 , wherein said predetermined value includes a minimum value predetermined from a plurality of ratios determined from a plurality of ranges of non-anomalous discharge capacities for the collection to non-anomalous charge capacities for the collection.

17. The fault-detection apparatus of claim 1 , wherein said set of data parameters includes a charge Ah, a charge start SOC, a charge end SOC, and a stored Ah of the collection and wherein said set of anomalous conditions includes a ratio of said charge Ah to a product of a difference between said charge start SOC and said charge end SOC with said stored Ah that exceeds one.

18. The fault-detection apparatus of claim 1 , wherein said set of data parameters includes a periodic estimation of battery impedance during charging and an associated SOC for the collection wherein said set of anomalous conditions includes a difference between said estimation of battery impedance and a predetermined expected battery estimation at said associated SOC exceeding a predetermined threshold.

19. The fault-detection apparatus of claim 1 , wherein the set of data parameters includes a periodic temperature of one or more components of the collection during charging and wherein said set of anomalous conditions includes a difference between said temperature and a predetermined expected temperature exceeding a predetermined threshold.

20. A fault-detection method for a charging system that charges a collection of interconnected battery cells, the method comprising:

a) receiving a set of data parameters from the collection while the charging system is actively charging the collection, the set of data parameters measured during a charge cycle that begins with V<V max and deltaT<(deltaT) max , wherein deltaT is a maximum difference in temperature between the cells throughout the collection and an ambient temperature, wherein (deltaT) max is a maximum acceptable difference in temperature that affects a change in voltage or current during charging;

b) evaluating said set of data parameters to identify a set of anomalous conditions;

c) comparing said set of anomalous conditions against a set of predetermined profiles indicative of an internal short in one or more cells of the collection; and

d) establishing an internal-short state for the collection when said comparing has a predetermined relationship to said set of predetermined profiles.