Temperature compensation in recharging of batteries

• US 20070210742A1
• Filed: 03/10/2006
• Published: 09/13/2007
• Est. Priority Date: 03/10/2006
• Status: Active Grant

• Current Assignee: Trojan Battery Company
• Original Assignee: Trojan Battery Company
• Inventors: Brecht, William
• Granted Patent: US 7,589,491 B2
• Time in Patent Office: Days
• US Class Current: 320/104
• CPC Class Codes: H02J 7/007194 of the battery

Abstract

Temperature compensation methods and equipment for charging electric storage batteries are described. Control over battery charging includes measurement of battery temperature at the commencement of a charging event, and use of inflection analysis of a charger voltage-time curve to detect the attainment of a distinctive signal point in the event. To compensate for the variations with initial battery temperature on the relation of the signal point to a different battery condition of interest, control of a charging event includes use of the measured battery temperature to obtain from a controller memory information about the applicable values of process parameters pertinent to those temperature-variable process factors. The temperature of a battery charger which includes such controls preferably is used as a workable approximation to battery temperature, so that batteries of conventional construction can benefit from use of the disclosed methods and equipment.

Claims

1. A method for charging flooded deep cycle lead acid batteries comprising the steps of:

effectively measuring the temperature of such a battery having an initial charge deficiency,

applying to the battery a first amount of charging energy adequate, in combination with the initial charge condition of the battery, to cause the battery to attain a detectable charge state which is less than a full charge condition and which has a temperature-variable determinable relation to a full charge condition, and

applying to the battery a further second increment of charging energy which is adequate, in combination with the initial charge condition and the first amount of charging energy, to overcharge the battery to a particular extent which can vary with battery temperature and the quantity of which is determined as a selected percentage of the first amount of charging energy when the detectable state is attained and with respect to a battery having the measured temperature.

2. The method according to claim 1 in which determining the quantity of the second increment of charging energy includes evaluating the relation Q_D=Q_S(1+x)/p in which Q_D is the total charging energy to be delivered to the battery in the period from the commencement of a battery charge event of interest to the end of that event, Q_S is the first amount of charging energy, and, for a battery having the measured temperature, x is the decimal equivalent of the particular percentage and p is the decimal value of the ratio of the first amount of charging energy to the initial charge deficiency of the battery.

3. The method according to claim 2 including the further steps of providing information describing the variations in the values of p and of x with battery temperature, and obtaining from that information the values of p and of x for the measured temperature.

4. The method according to claim 3 in which said information is provided substantially in tabular form.

5. The method according to claim 3 in which said information is provided substantially in algorithmic form.

6. A method according to claim 1 further comprising the step of providing information describing the variation with temperature of a) the relation of the first amount of charging energy to the initial charge deficiency of the battery, and b) the relation of total charging energy deliverable to the battery to attain full charge and effective conditioning of the battery to the initial charge deficiency of the battery.

7. The method according to claim 6 in which determination of the quantity of the second amount of charging energy includes obtaining from said information the value of said relations for the measured temperature.

8. The method according to claim 7 in which said information is provided substantially in tabular form.

9. The method according to claim 7 in which said information is provided substantially in algorithmic form.

10. The method according to claim 1 in which the step of effectively measuring the temperature of such a battery comprises measuring the temperature of a battery charger with which the battery is associated.

11. The method according to claim 10 in which the operation of measuring the temperature of a battery charger is conducted in associated with the commencement of application of the first amount of charging energy to the battery.

12. A method for controlling charging of an electric storage battery in which a relation between a particular charge state of the battery and a detectable condition in a battery charging event is a relation which varies with temperature, and which the method includes the steps of:

effectively measuring the temperature of such a battery,

applying to the battery an amount of charging energy adequate, in combination with an initial charge condition of the battery, to cause the battery to attain the detectable charge state,

detecting the detectable charge state, and

by reference to the measured temperature and to information about the effect of temperature on that relation, determining the quantity of further charging energy applicable to the battery to cause the battery to attain a desired condition.

13. The method according to claim 12 in which the desired condition is a condition of overcharge.

14. The method according to claim 12 in which the desired condition is a condition of full charge.

15. The method according to claim 12 in which detection of the detectable charge state includes inflection analysis.

16. A battery charger which includes a temperature sensor by which a measurement of charger temperature can be made, and a memory in which a measurement of charger temperature can be stored.

17. A battery charger according to claim 16 in which the memory includes information describing the variation with temperature of values of variables pertinent to effective charging and controlled overcharging of a flooded deep-cycle lead acid battery.

18. A battery charger according to claim 17 which includes circuitry and related devices arranged to accumulate charging energy delivered to a battery in a period commencing with the supply of charging energy to a battery connected to the charger, and circuitry operable to detect a zero value of the second derivative with respect to time of the voltage aspect of charging energy delivered to a battery connected to the charger.

19. A battery charger according to claim 18 in which said information includes information describing the variation with temperature of the relation of the amount of charging energy delivered in the period from commencement of a battery charging event to detection during that event of a zero value of said second derivative to the amount of the initial charge deficiency of a battery connected to the charger during that event.

20. A battery charger according to claim 18 in which said information includes information describing the variation with temperature of the relation of total charging energy deliverable to a battery to attain full charge and effective conditioning of the battery to the initial charge deficiency of the battery.

21. A battery charger according to claim 17 in which said information is in substantially tabular form.

22. A battery charger according to claim 17 in which said information is in substantially algorithmic form.

23. A battery charger according to claim 16 including circuitry for detecting a detectable condition of the battery in the course of a battery charging event, and in which the memory includes information describing the effect of temperature on the relation between the detectable condition and a particular different battery condition.

24. A battery charger according to claim 23 in which the different battery condition is full charge of the battery.