Remote battery plant monitoring system

• US 6,532,425 B1
• Filed: 09/17/1999
• Issued: 03/11/2003
• Est. Priority Date: 09/18/1998
• Status: Expired due to Term

• Current Assignee: C&D Technologies Incorporated (Angel Holdings LLC)
• Original Assignee: C&D Technologies Incorporated (Angel Holdings LLC)
• Inventors: Bizouard, Jean, Boost, Mike
• Primary Examiner(s): Von Buhr, Maria N.
• Application Number:
  US09/398,587
• Time in Patent Office: 1,271 Days
• Field of Search: 320/116-126, 320/132-136, 320/148-154, 324/426-437, 702/60-65, 700/297, 700/298
• US Class Current: 702/63
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/371 with remote indication, e.g. on external chargers
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery

Abstract

A system for monitoring performance of one or more batteries in a battery plant facility. A set of sensors for each battery are used to measure a plurality of battery operation parameters comprising the battery current, battery voltage, and internal battery temperature of each said battery. A processor generates, for each battery, a plurality of battery status parameters comprising a true age parameter and a float capacity parameter. During a float period, the true age parameter is updated based on elapsed time corrected for battery temperature history and the float capacity is updated based on the most recent true age parameter. During a discharge period, the float capacity parameter is updated based on the evolution of plant voltage during the discharge. After the discharge period, at the beginning of a subsequent float period, the true age parameter is updated based on the float capacity parameter determined during the immediately previous discharge period.

Claims

1. A system for monitoring performance of one or more batteries in a battery plant facility, the system comprising:

(a) a set of sensors for each battery for measuring a plurality of battery operation parameters comprising the battery current, battery voltage, and internal battery temperature of each said battery; and

(b) a processor that generates, for each battery, a plurality of battery status parameters comprising a true age parameter and a float capacity parameter, wherein;

during a float period, the true age parameter is updated based on elapsed time corrected for battery temperature history and the float capacity is updated based on the most recent true age parameter;

during a discharge period, the float capacity parameter is updated based on the evolution of plant voltage during the discharge; and

after the discharge period and at the beginning of a subsequent float period, the true age parameter is updated based on the float capacity parameter determined during the discharge period.

2. The system of claim 1, wherein, after the discharge period and at the beginning of the subsequent float period, the float capacity parameter is updated based on the true age parameter after the true age parameter is updated.

3. The system of claim 1, wherein, during a float period, the true age parameter is periodically updated based on the elapsed time during a most recent elapsed time period, wherein the elapsed time is corrected for the average battery temperature history during the elapsed time period.

4. The system of claim 1, wherein, during a discharge period, the float capacity parameter is updated based on the evolution of plant voltage versus cumulated Ampere-hours, corrected for temperature and discharge rate.

5. The system of claim 4, wherein, during a discharge period, a plant float capacity parameter is calculated based on the previous battery float parameters and the evolution of plant voltage versus cumulated Ampere-hours, corrected for temperature and discharge rate, wherein each battery float capacity parameter is updated based on the plant float capacity parameter and the relative magnitude of the battery currents of each respective battery delivered during an initial portion of the discharge.

6. The system of claim 1, wherein the initial portion of the battery discharge is the first 5% of the battery discharge.

7. The system of claim 1, wherein the plurality of battery status parameters further comprise a remaining discharge time parameter which is repeatedly re-calculated, during a discharge period, based on the most recent battery float capacity parameter and cumulated Ampere-hours.

8. The system of claim 7, wherein the remaining discharge time parameter is corrected for temperature and rate of discharge.

9. The system of claim 1, wherein after the discharge period and at the beginning of the subsequent float period, the true age parameter is further updated to take into account the depth of the discharge during the discharge period and the total number of battery discharges.

10. The system of claim 1, wherein:

the battery current for a battery is a float current when the battery is in float mode; and

the plurality of battery status parameters further comprise a probability of failure parameter which is based on the evolution of the float current with time.

11. The system of claim 10, wherein the processor generates the probability of failure parameter based on the percentage change of the float current magnitude at the present time relative to the float current magnitude at a previous time period.

12. The system of claim 11, wherein the probability of failure parameter is corrected by taking into account the effect of true battery age and battery temperature on the float current.

13. The system of claim 1, wherein the plurality of battery status parameters further comprise a probability of failure parameter which is based on the true age parameter for the battery.

14. The system of claim 1, wherein the plurality of battery status parameters further comprise a probability of failure parameter which is based on the initial battery discharge current rate during a discharge.

15. The system of claim 1, wherein the plurality of battery status parameters further comprise an overall probability of failure parameter comprising the maximum of first, second, and third probability of failure parameters, wherein the first probability of failure parameter is based on the evolution of the float current with time, the second probability of failure parameter is based on the true age parameter for the battery, and the third probability of failure parameter is based on the initial battery discharge current rate during a discharge.

16. The system of claim 1, wherein each battery is a battery string comprising a plurality of series-connected battery cells.

17. The system of claim 16, wherein the one or more batteries comprise exactly four battery strings coupled in parallel in the battery plant.

18. The system of claim 16, wherein the battery operation parameters further comprise the midpoint string voltage for each battery string and the processor generates, for each battery, a midpoint to battery voltage ratio parameter, wherein the processor compares the midpoint to battery voltage ratio parameter to a threshold and generates an alarm signal in accordance with said comparisons.

19. The system of claim 18, wherein the processor is a microcontroller comprising a memory for storing battery discharge curves, battery temperature history, status thresholds, alarm events, and a history log, wherein the microcontroller runs a monitoring application program for generating the plurality of battery status parameters for each battery.

20. The system of claim 18, wherein the alarm signal is one of a signal used to trigger an alarm or a disconnect signal used to disconnect equipment powered by the batteries in the battery plant facility.

21. The system of claim 20, further comprising a user interface for allowing a user to set the status thresholds, means for transmitting the alarm signal to a remote location, and means for disconnecting the equipment in response to the disconnect signal.

22. The system of claim 18, wherein the processor compares each battery status parameter to both a respective minor and major threshold and generates, respectively, a minor and a major alarm signal in accordance with said comparisons, respectively, wherein the major thresholds are set so that a major alarm signal is generated when there is an actual or impending service-affecting failure in the batteries.

23. The system of claim 1, wherein the set of sensors comprise only passive sensors.