Schumacher Electric Corporation

Thomas Finis Johnson

John S Whiting

John F Waldron

David R Pacholok

Xiao Ping Chen

A battery charger is disclosed for use with various batteries, such as automotive- and marine-type batteries. In accordance with an aspect of the invention, the charging current is alternated between non-zero DC charging current levels. By alternating the charging current between non-zero DC charging levels, the battery can be charged to a higher capacity (i.e., ampere hours) faster, thus reducing the charging time and at the same time allow the rating of the battery charger to be increased. In accordance with another important aspect of the invention, the technique for alternating the charging current can be implemented in both linear- and switched-mode battery chargers.

Battery charger and method utilizing alternating DC charging current

A battery charger is disclosed for use with various batteries, such as automotive and marine-type batteries. In accordance with an aspect of the invention, the charging current is alternated between non-zero DC charging current levels. By alternating the charging current between non-zero DC charging levels, the battery can be charged to a higher capacity (i.e., ampere hours) faster, thus reducing the charging time and at the same time allow the rating of the battery charger to be increased. In accordance with another important aspect of the invention, the technique for alternating the charging current can be implemented in both linear and switched-mode battery chargers.

A protection system and method for a battery charger is disclosed for detecting a thermal runaway condition in a battery during charging in order to protect the battery when such a thermal runaway condition has been detected. The protection system in accordance with the present invention does not require external temperature sensors nor does it rely on actions by the technician or user. Briefly, the protection system includes one or more electrical sensors normally provided with conventional battery chargers for sensing one or more electrical parameters during charging and providing an indication of a possible thermal runaway condition based upon the trend of the electrical charging parameters. In general, the protection system monitors the charging characteristics of a battery for a complete or partial charging cycle. If the charging characteristics deviate from a normal or otherwise indicate an anomaly, as determined by software, the system assumes there may be a thermal runaway condition and executes a protection measure, such as terminating charging of the battery. Even though the anomaly may not be the result of a thermal runaway condition, the protection system in accordance with the present invention treats the anomaly as an indication of a thermal runaway condition even though some other problem is the reason for the anomaly. For example, when the anomaly is the result of a bad cell, battery charging is terminated to prevent a thermal runaway condition and not because a thermal runaway condition is detected.

Thermal runaway protection system for a battery charger

A high frequency battery charger includes a converter, drive logic, and control logic. The converter transforms a DC voltage into a high frequency AC voltage. The drive logic controls a conversion of the high frequency AC voltage through a train of pulses. The control logic adjusts the output of the converter to maximize a charging cycle of a battery. The method of transforming an AC input into a direct current output used to charge a rechargeable battery includes transforming an AC input into a first DC output; transforming the first DC output into a high frequency AC output; transforming the high frequency AC output into a second DC output; and passing a charging current to an external load when the load is correctly connected to an output.

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Schaumburg, IL, United States of America

Thomas Finis Johnson