Low cost universal battery charger for small type nickel-cadmium or alkaline batteries

Abstract

Abstract A low cost universal battery charger for recharging different size rechargable small batteries of the ''''A-A'''', ''''C'''', and ''''D'''' nickel-cadmium, alkaline or ''''dry cell'''' type directly from an automobile or other 6-12 volt battery source of direct current using only passive components. The battery charger comprises a molded insulating housing a plurality of separate different size compartments each dimensioned to receive respective different ones of the small batteries to be recharged. Internal contacts are secured within each of the compartments for physically engaging the terminals of the respective size batteries to be recharged in that compartment and to establish a closed electrical circuit through the battery. External contacts are mounted on the exterior of the insulating housing and are electrically connected to respective ones of the internal contacts for connecting the different size batteries disposed in the compartments in circuit relationship with a recharging direct current voltage source that preferably comprises an automobile battery of 6-12 volt rating. Conductors having readily detachable terminal connectors serve to connect the external contacts to the automobile battery serving as a recharging direct current voltage source to thereby energize the different size battery receiving compartments within the housing. A plurality of different value current adjusting (voltage dropping) resistors preferably are molded within the battery housing and means are provided for selectively connecting a desired value current adjusting resistor in circuit relationship with the automobile battery recharging direct current voltage source and the internal contact means of the different size battery receiving compartments for adjusting the value of the charging current supplied to each of the compartments to a preselected desired value in accordance with the rating of the small battery to be recharged in that compartment. Additionally, plug-in resistors and suitable receptacles are provided in certain forms of the invention for connecting additional resistors in parallel circuit relationship with the molded-in current adjusting resistors for appropriately adjusting the current value supplied to a given battery receiving compartment to a different current value whereby the battery receiving compartment can accommodate batteries of the same physical size but requiring different value recharging currents. Also, a second receptacle can be formed in the insulating housing for receiving detachable thermally sensitive switches which are connected in series circuit relationship with the internal contacts of at least one of the battery receiving compartments whereby the thermally sensitive switch physically senses the temperature of the battery being recharged and interrupts the recharging current upon an over-temperature condition being sensed. If desired the thermally sensitive switch can be permanently built into the battery recharger rather than making it in the form of a detachable attachment and preferably comprises a bimetal switch. In still a different form of the invention the plurality of different value current adjusting resistors are comprised by resistive cables which have different values of resistance and also serve as the conductor for Selectively connecting the external contacts to the automobile battery serving as a recharging direct current voltage source. In still another form of the invention, the plurality of different value current adjusting resistors is comprised by a single multitap resistor and a selector switch is provided for connecting a desired value of current adjusting resistance in circuit relationship with the automobile battery serving as the recharging direct current voltage source and the internal contacts of a selected one of the different size battery receiving compartments.

Inventors

• 👤 K Fister

Bibliographic Details