Electricity: battery or capacitor charging or discharging – Battery or cell charging – Pulsed
Reexamination Certificate
2000-01-24
2001-05-08
Wong, Peter S. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell charging
Pulsed
C320S139000
Reexamination Certificate
active
06229287
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a battery charger of one or more chargeable batteries. More particularly, the present invention is directed to a system and device for charging a plurality of batteries in which both the input voltage from a power source and the level of charge provided to the charging batteries can be monitored and the system shut down when pre-set charge levels are reached. The present invention further includes a device that provides a charging current having a periodic pulsed variable frequency component that maintains the condition of the charged battery plates thereby extending the life of the battery.
Increasingly, batteries are being employed in a wide variety of applications as a source of electrical energy. Along with the increasing use of batteries, recharging of those batteries as they become depleted has become also increasingly prevalent. Frequently, the recharging of depleted batteries involves use of a current source such as an electric outlet. In some instances, however, it is more convenient, if not necessary, to recharge the batteries from another battery that provides the required energy source. Typical of these situations are boats and mobile homes which may have multiple batteries for various appliances and equipment in addition to the main battery that is used to start the vehicles engines. Clearly, in such instances, it is critically important that the charging of the secondary batteries from the main battery be in a controlled manner that both provides an adequate charge to the secondary batteries and does not deplete the primary battery so that it can no longer perform vital function of starting the vehicle's engine.
There is, therefore, the need for a battery charging system which monitors the level of charge applied to secondary batteries as well as the level of charge of remaining in the main battery from which the charging current is drawn and shuts down the system if either of these levels is passed. There is a further need for a battery charging system that is capable of charging multiple batteries either in series or in separate circuits without a drop in voltage. Still a further need is for a battery charging system having the aforementioned features which is capable of extending the life of the batteries being recharged especially wet cells such as lead acid batteries which have plates.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a device and system that achieves the aforementioned objectives and substantially obviates one or more of the problems that have arisen due to limitations and disadvantages of the related art.
Additional features and advantages of the invention will be set forth in the description which follows and in part will be apparent from the description or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the system of the invention as particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purposes of the invention as embodied and broadly described, the present invention is, in one embodiment, a battery charger for charging one or more chargeable batteries comprising a current controller connected between a DC power source and one or more chargeable batteries. The current controller comprises a current mode control for converting the DC current received from the DC power source to a higher voltage, a means for providing a variable voltage control signal to a pulse width modulator for producing a variable frequency range from the higher voltage DC current, and a timer for controlling a switch for producing periodic pulses of the DC current having the variable frequency range. An isolator is provided for receiving the DC current that includes the periodic pulses of variable frequency current from the current control and directing the received DC current into a plurality of outputs to the chargeable batteries. The current mode controller can include means for converting the DC charging current into AC charging current having higher AC voltage and means for rectifying the AC current back to DC current at the higher voltage. Monitors are also provided in accordance with the invention for monitoring the DC charging current from the DC power source and shutting down the system if the voltage of the DC power source falls below a pre-set level. Means are further provided in the system of the invention for shutting down the charger when the chargeable batteries are charged to a pre-set level.
In a preferred embodiment of the invention, the variable frequency range of the pulses of DC current is about 20 to about 100 KHz. In a further embodiment of the invention, the periodic pulses of DC current having the variable frequency range are of a duration of about 0.5 seconds of every 6 seconds.
It is to understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification and together with the description serve to explain the principals of the invention. Conventionally understood symbols have been used in the drawings to depict electronic components.
REFERENCES:
patent: 5264777 (1993-11-01), Smead
patent: 5617007 (1997-04-01), Keidl et al.
patent: 5905364 (1999-05-01), Ookita
Buchar Zdenek
Ferris Michael T.
Luk Lawrence
Wong Peter S.
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