Regulator for charging a rechargeable storage device from a photovoltaic cell

A charging system comprising, in combination:

• a photovoltaic cell having a pair of cell terminals;
• a rechargeable storage device having a pair of device terminals;
• and
• a circuit for regulating charging of the rechargeable storage device by means of the photovoltaic cell, the circuit including:
• a pair of input terminals for coupling to the cell terminals;
• a pair of output terminals for coupling to the device terminals;
• switching means for selectively establishing and breaking an electrical connection between said input terminals and said output terminals;
• means coupled to the device terminals for providing a signal proportional to a terminal voltage across the output terminals;
• first causing means responsive to the signal and a first voltage limit for causing the switching means to establish an electrical connection thereby permitting a current of a predetermined magnitude to flow between the input terminals and the output terminals when the signal is equal to a first predetermined proportion of the first voltage limit;
• and
• second causing means responsive to the signal and a second voltage limit for causing the switching means to establish an electrical connection between the input terminals and the output terminals when the signal is equal to a second predetermined proportion of the second voltage limit, thereby permitting the current of a predetermined magnitude to flow between the input terminals and the output terminals.

A circuit for regulating charging of a rechargeable storage device having a pair of device terminals by a photovoltaic cell having a pair of cell terminals, the circuit comprising:

• a pair of input terminals for coupling to the cell terminals;
• a pair of output terminals for coupling to the device terminals;
• a transistor for selectively establishing and breaking an electrical connection between the input terminals and the output terminals;
• means coupled to the device terminals for providing a signal proportional to a terminal voltage across the output terminals;
• a first operational amplifier responsive to the signal and to first and second voltage limits for causing the transistor to establish an electrical connection between the input terminals and the output terminals when the signal is equal to a predetermined proportion of the first voltage limit and for causing the transistor to break the electrical connection between the input terminals and the output terminals when the signal is equal to a predetermined proportion of the second voltage limit;
• and
• a second operational amplifier responsive to the signal and to third and fourth voltage limits for causing the transistor to establish an electrical connection between the input terminals and the output terminals when the signal is equal to a predetermined proportion of the third voltage limit and for causing the transistor to break the electrical connection between the input terminals and the output terminals when the signal is equal a predetermined proportion of the fourth voltage limit;
• wherein a current of a predetermined magnitude is permitted to flow between the input terminals and the output terminals when the transistor is caused to establish an electrical connection by either of the first and second operational amplifiers;
• and
• wherein the current is not permitted to flow between the input terminals and the output terminals when the transistor breaks the electrical connection.

A charging system comprising, in combination:

• a photovoltaic cell having a pair of cell terminals;
• a rechargeable storage device having a pair of device terminals;
• and
• a circuit for regulating charging of the rechargeable storage device by a photovoltaic cell, the circuit comprising:
• a pair of input terminals for coupling to the cell terminals;
• a pair of output terminals for coupling to the device terminals;
• a transistor for selectively establishing and breaking an electrical connection between the input terminals and the output terminals;
• means coupled to the device terminals for providing a signal proportional to a terminal voltage across the output terminals;
• a first operational amplifier responsive to the signal and to first and second voltage limits for causing the transistor to establish an electrical connection between the input terminals and the output terminals when the signal is equal to a predetermined proportion of the first voltage limit and for causing the transistor to break the electrical connection between the input terminals and the output terminals when the signal is equal to a predetermined proportion of the second voltage limit;
• and
• a second operational amplifier responsive to the signal and to third and fourth voltage limits between the first and second voltage limits for causing the transistor to establish an electrical connection between the input terminals and the output terminals when the signal is equal to a predetermined proportion of the third voltage limit and for causing the transistor to break the electrical connection between the input terminals and the output terminals when the signal is equal a predetermined proportion of the fourth voltage limit;
• wherein a current of a predetermined magnitude is permitted to flow between the input terminals and the output terminals when the transistor is caused to establish an electrical connection by either of the first and second operational amplifiers;
• and
• wherein the current is not permitted to flow between the input terminals and the output terminals when the transistor breaks the electrical connection.

A regulator circuit for connection between solar cell terminals and rechargeable battery terminals, said regulator circuit comprising:

• first reference means for providing a first reference voltage;
• second reference means for connection to the battery terminals and for providing a second reference voltage;
• a single controllable switch means having open and closed conditions for connecting the solar cell terminals to the battery terminals in response to a control signal;
• first control means responsive to said first and said second reference voltages for providing said control signal to close the single controllable switch from when said second reference voltage is at a first low level until said second reference voltage is at a first high level;
• and
• second control means responsive to said first and second reference voltages for providing said control signal to close the single controllable switch from when said second reference voltage is at a second low level until said second reference voltage is at a second high level;
• wherein said second low level and said second high level are between said first low level and said first high level.