Controlled fast charger

Claim 2

Apparatus for supplying a controlled charging current to a sealed rechargeable cell comprising: (a) means connectable to an external electrical source for providing charging current; (b) controllable switching means connected in series between said charging current means and said rechargeable cell and being operable between a conducting state, wherein said charging current is supplied to said cell, and a non-conducting state wherein said charging current is interrupted; (c) thermal sensing means including first means in thermal proximity to said rechargeable cell for sensing the temperature of said rechargeable cell, and second means for sensing the ambient temperature; and (d) switching control means responsive to said thermal sensing means for maintaining said switching means in the conducting state, and thereby providing a path for the delivery of said charging current to said rechargeable cell, until the cell temperature exceeds the ambient temperature by a predetermined amount and thereafter maintaining that temperature difference.

Claim 3

Apparatus for supplying a controlled fast-rate charging current to a sealed rechargeable cell comprising: (a) means connectable to an external electrical source for providing fast-rate charging current; (b) controllable electronic switching means having a conducting state and a non-conducting state and including an input terminal, an output terminal and a control terminal, wherein said input terminal is connected to said charging current means and said output terminal is connected to said rechargeable cell; (c) temperature sensing means including first means in thermal proximity to said rechargeable cell for sensing the temperature of said rechargeable cell, and second means for sensing the ambient temperature; and (d) electronic switching control means responsive to said temperature sensing means and operatively connected to said control terminal for generating a switching control signal for maintaining said controllable electronic switching means in the conducting state, and thereby providing a path for the delivery of said fast-rate charging current to said rechargeable cell, until the cell temperature exceeds the ambient temperature by a predetermined amount and thereafter maintaining that temperature difference.

Claim 4

Apparatus for supplying a controlled fast-rate charging current to a sealed rechargeable cell comprising: (a) means connectable to an external electrical source for providing fast-rate charging current; (b) controllable electronic switching means having a conducting state and a non-conducting state and including an input terminal, an output terminal and a control terminal, wherein said input terminal is connected to said charging current means and said output terminal is connected to said rechargeable cell; (c) temperature sensing means including first means in thermal proximity to said rechargeable cell for sensing the temperature of said rechargeable cell, and second means for sensing the ambient temperature; and (d) electronic switching control means responsive to said temperature sensing means and operatively connected to said control terminal for generating a switching control signal for maintaining said controllable electronic switching means in the conducting state, and thereby providing a path for the delivery of said fast-rate charging current to said rechargeable cell, until the cell temperature exceeds the ambient temperature by a predetermined amount and thereafter maintaining that temperature difference.

Claim 5

Apparatus for supplying a controlled fast-rate charging current to a sealed rechargeable cell comprising: (a) means connectable to an external electrical source for providing fast-rate charging current; (b) controllable electronic switching means having a conducting state and a non-conducting state and including an input terminal, an output terminal and a control terminal, wherein said input terminal is connected to said charging current means and said output terminal is connected to said rechargeable cell; (c) bridge network means connected in parallel across said rechargeable cell and including a first leg consisting of first temperature sensing means connected to first resistance means and a second leg consisting of second temperature sensing means connected to second resistance means, said bridge network means configured such that a voltage representative of the temperature of said rechargeable cell is developed across said first temperature sensing means and a voltage representative of the ambient temperature is developed across said second temperature sensing means; (d) operational amplifier means having an inverting input terminal, a noninverting input terminal and an output terminal, wherein said inverting input terminal is connected to said bridge network means to respond to he voltage developed across said first thermal sensing means and said noninverting input terminal is connected to said bridge network means to respond to the voltage developed across said second thermal sensing means; and (e) transistor switching means connected between the output terminal of said operational amplifier means and the control terminal of sid controllable electronic switching means for generating a control signal for maintaining said controllable electronic switching means in the conducting state, and thereby providing a fast-rate charging current path between said charging current means and said rechargeable cell, until the cell temperature exceeds the ambient temperature by a predetermined amount and thereafter maintaining that temperature difference.

Claim 6

Apparatus for supplying a controlled fast-rate charging current to a sealed rechargeable cell comprising: (a) means connectable to an external electrical source for providing fast-rate charging current; (b) controllable electronic switching means having a conducting state and a non-conducting state and including an input terminal, an output terminal and a control terminal, wherein said input terminal is connected to said charging current means and said output terminal is connected to said rechargeable cell; (c) bridge network means connected in parallel across said rechargeable cell and including a first leg consisting of first temperature sensing means connected to first resistance means and a second leg consisting of second temperature sensing means connected to second resistance means, said bridge network means configured such that a voltage representative of the temperature of said rechargeable cell is developed across said first temperature sensing means and a voltage representative of the ambient temperature is developed across said second temperature sensing means; (d) operational amplifier means having an inverting input terminal, a noninverting input terminal and an output terminal, wherein said inverting input terminal is connected to said bridge network means to respond to he voltage developed across said first thermal sensing means and said noninverting input terminal is connected to said bridge network means to respond to the voltage developed across said second thermal sensing means; and (e) transistor switching means connected between the output terminal of said operational amplifier means and the control terminal of sid controllable electronic switching means for generating a control signal for maintaining said controllable electronic switching means in the conducting state, and thereby providing a fast-rate charging current path between said charging current means and said rechargeable cell, until the cell temperature exceeds the ambient temperature by a predetermined amount and thereafter maintaining that temperature difference.

Claim 7

Apparatus as recited in claim 3 wherein said controllable electronic switching means includes silicon controlled rectifier means, said first temperature sensing means includes first thermistor means; and said second temperature sensing means includes second thermistor means.

Claim 8

Apparatus as recited in cliam 4 wherein the resistance versus temperature characteristics of said first thermistor means are approximately equal to the resistance versus temperature characteristics of said second thermistor means; and the value of said first resistance means is less than the value of said second resistance means.

Claim 9

Apparatus as recited in cliam 4 wherein the resistance versus temperature characteristics of said first thermistor means are approximately equal to the resistance versus temperature characteristics of said second thermistor means; and the value of said first resistance means is less than the value of said second resistance means.

Claim 10

Apparatus for supplying a controlled fast-rate charging current to a sealed rechargeable cell comprising: (a) means connectable to an external electrical source for providing fast-rate charging current; (b) controllable electronic switching means having a conducting state and a non-conducting state and including an input terminal, an output terminal and a control terminal, wherein said input terminal is connected to said charging current means and said output terminal is connected to said rechargeable cell; (c) bridge network means connected in parallel across said rechargeable cell and including a first leg consisting of first temperature sensing means connected to first resistance means and a second leg consisting of second temperature sensing means connected to second resistance means, said bridge network means configured such that a voltage representative of the temperature of said rechargeable cell is developed across said first temperature sensing means and a voltage representative of the ambient temperature is developed across said second temperature sensing means; (d) operational amplifier means having an inverting input terminal, a noninverting input terminal and an output terminal, wherein said inverting input terminal is connected to said bridge network means to respond to the voltage developed across said first thermal sensing means and said noninverting input terminal is connected to said bridge network means to respond to the voltage developed across said second thermal sensing means; (e) transistor switching means connected between the output terminal of said operational amplifier means and the control terminal of said controllable electronic switching means for generating a control signal for maintaining said controllable electronic switching means in the conducting state, and thereby providing a fast-rate charging current path between said charging current means and said rechargeable cell, until the cell temperature exceeds the ambient temperature by a predetermined amount and thereafter maintaining that temperature difference; and (f) third resistance means connected between the input and output terminals of said controllable electronic switching means for providing a slow rate charging current path between said charging current means and said rechargeable cell when said controllable electronic switching means is in the non-conducting state.

Claim 11

Apparatus for supplying a controlled fast-rate charging current to a sealed rechargeable cell comprising: (a) means connectable to an external electrical source for providing fast-rate charging current; (b) controllable electronic switching means having a conducting state and a non-conducting state and including an input terminal, an output terminal and a control terminal, wherein said input terminal is connected to said charging current means and said output terminal is connected to said rechargeable cell; (c) bridge network means connected in parallel across said rechargeable cell and including a first leg consisting of first temperature sensing means connected to first resistance means and a second leg consisting of second temperature sensing means connected to second resistance means, said bridge network means configured such that a voltage representative of the temperature of said rechargeable cell is developed across said first temperature sensing means and a voltage representative of the ambient temperature is developed across said second temperature sensing means; (d) operational amplifier means having an inverting input terminal, a noninverting input terminal and an output terminal, wherein said inverting input terminal is connected to said bridge network means to respond to the voltage developed across said first thermal sensing means and said noninverting input terminal is connected to said bridge network means to respond to the voltage developed across said second thermal sensing means; (e) transistor switching means connected between the output terminal of said operational amplifier means and the control terminal of said controllable electronic switching means for generating a control signal for maintaining said controllable electronic switching means in the conducting state, and thereby providing a fast-rate charging current path between said charging current means and said rechargeable cell, until the cell temperature exceeds the ambient temperature by a predetermined amount and thereafter maintaining that temperature difference; and (f) third resistance means connected between the input and output terminals of said controllable electronic switching means for providing a slow rate charging current path between said charging current means and said rechargeable cell when said controllable electronic switching means is in the non-conducting state.

Claim 12

Apparatus as recited in claim 6 wherein said controllable electronic switching means includes silicon controlled rectifier means; said first temperature sensing means includes first thermistor means; said second temperature sensing means includes second thermistor means, wherein the resistance versus temperature characteristics of said second thermistor means are approximately equal to the resistance versus temperature characteristics of said first thermistor means; and the value of said first resistance means is less than the value of said second resistance means.