Electricity: battery or capacitor charging or discharging – Battery or cell charging – With detection of current or voltage differential
Reexamination Certificate
2000-05-15
2001-04-17
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell charging
With detection of current or voltage differential
Reexamination Certificate
active
06218812
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to charging batteries, and more specifically to methods and systems for charging batteries and extending battery life.
Known methods of charging rechargeable batteries, such as lead-acid batteries found in automobiles and other electric vehicles, typically are constant voltage source chargers. Since the proper voltage for such a battery depends on a variety of factors including battery age, temperature, and the amount of charge in the battery, known constant voltage chargers tend to overcharge older or lower voltage or hotter batteries and tend to undercharge newer, cooler higher voltage batteries. In addition batteries tend to discharge over time due to an internal current draw or self discharge leakage between the cells of the battery. Depending on storage temperatures, known batteries discharge to a 50% charge anywhere from three to nine months.
It would be desirable to develop a battery charger and method of battery charging which can take into account the battery factors listed above and develop a more efficient charge for a battery to be charged. In addition it would be desirable to develop a method and system for retaining full charges on under utilized batteries, for example, batteries in an electric vehicle in storage for a winter.
BRIEF SUMMARY OF THE INVENTION
In an exemplary embodiment, a solid state battery charger algorithm implements an algorithm for charging batteries comprising the steps of supplying a constant current to the batteries being charged until the battery voltage reaches a first threshold voltage value, supplying a constant voltage to the batteries being charged until current being drawn by the batteries reaches a threshold current value, and supplying a constant current to the batteries being charged until a voltage rise per unit time threshold is met. The above described method overcomes overcharging and undercharging problems known to exist in known constant voltage supply battery chargers.
In addition the battery charging algorithm constantly monitors battery performance and can reinitiate a charging cycle when monitored battery parameters so dictate.
REFERENCES:
patent: 5670863 (1997-09-01), Broell et al.
patent: 5710506 (1998-01-01), Broell et al.
patent: 5744933 (1998-04-01), Inoue et al.
patent: 6008624 (1999-12-01), Bergstrom et al.
Armstrong Teasdale LLP
Horton Esq. Carl B.
Tso Edward H.
Wasserbauer Esq. Damian
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