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Battery Charging Circuit

IP.com Disclosure Number: IPCOM000084703D
Original Publication Date: 1975-Dec-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Harr, JD: AUTHOR

Abstract

This circuit affords a smaller and less expensive electromagnetic transformer than is used with the conventional circuitry.

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Battery Charging Circuit

This circuit affords a smaller and less expensive electromagnetic transformer than is used with the conventional circuitry.

Nickel-cadmium cells 11,12,13 and 21,22 and 23 used in portable equipment are plugged into the respective terminals for charging. Alternating-current supply voltage is applied at terminals 31 and 32 of the primary winding of a transformer
34. The terminals 35 and 36 of the secondary winding are connected between a common wire grounded to the charging unit chassis and diodes 41,42,43 and 51,52,53. The diodes serve both to rectify the secondary voltage and to prevent cells that are nearly charged from discharging into the cells yet to be charged. Resistors 61, 62,63 and 71,72,73 are connected in series to the diodes in the cells individually and serve to limit the charging current. The two groups of diodes are connected for operating on the two halves of the alternating-supply voltage, whereby one group of cells is charged on one half of the cycle and the other group of cells is charged on the remaining half-cycle.

This connection reduces the maximum current in the secondary winding to one half that for the normal half-wave battery charging circuit. The unidirectional current of the conventional half-wave charging circuit tends to cause saturation of the transformer core. With the bidirectional characteristic of this circuitry, it lowers the tendency towards saturation and affords a further reduction in size of the tra...