Battery power supply with bidirectional battery charge controller
A bidirectional battery charge control system for a portable electronic device which uses a rechargeable main battery. The system enables the connection of an auxiliary battery to the device for inputting additional current to the device. Control of the current flow into and out of the auxiliary battery is performed by a bidirectional charger. The auxiliary battery can contain one or more readily available primary or secondary cells, and the bidirectional charger is such that an external charger connected to the device, generally used to charge the main rechargeable battery of the device, can also recharge a secondary cell or cells in the auxiliary battery, if such are installed. The use of such an auxiliary battery enables the main battery to be hard-wired into the device.
1. A battery power supply system for powering a portable electronic device, comprising:
a rechargeable battery;
a cavity for receiving an additional battery, said additional battery comprising of at least one primary cell and at least one rechargeable cell; and
a bidirectional charge controller operative to (a) control current flow between said additional battery and said rechargeable battery, (b) determine the battery chemistry of cells in said additional battery, and (c) prevent current flow into said additional battery if said additional battery comprises one or more primary cells,
wherein said bidirectional charge controller regulates current supplied from said additional battery to charge said rechargeable battery at a rate that (i) depends on the state of charge of said rechargeable battery, and (ii) is optimized for energy transfer from said additional battery.
2. A battery power supply system according to claim 1 and wherein said bidirectional charge controller controls current flow from said additional battery to said rechargeable battery, and from at least one of said rechargeable battery and an external current source to said additional battery.
3. A battery power supply system according to claim 1 and wherein said additional battery has a first nominal terminal voltage, said rechargeable battery has a second nominal terminal voltage, and said bidirectional charge controller converts current output from said additional battery at said first nominal terminal voltage to another voltage for at least one of powering said device and charging said rechargeable battery.
4. A battery power supply system according to claim 3 , and wherein said first nominal terminal voltage is lower than said second nominal terminal voltage.
5. A battery power supply system according to claim 3 , and wherein said first nominal terminal voltage is higher than said second nominal terminal voltage.
6. A battery power supply system according to claim 1 and wherein said additional battery comprises at least one primary cell, and wherein said power supply system initiates the drawing of current from said additional battery only when the rechargeable battery is depleted down to a preplanned criterion.
7. A battery power supply system according to claim 6 and wherein said preplanned criterion is that said rechargeable battery is at least 90% depleted.
8. A battery power supply system according to claim 1 and wherein said at least one rechargeable cell in said additional battery is either one of a NiMH and a NiCd cell.
9. A battery power supply system according to claim 1 and wherein said at least one primary cell in said additional battery is either one of an alkaline cell and a fuel cell.
10. A battery power supply system according to claim 1 and wherein said rechargeable battery is installed socketlessly into said device.
11. A battery power supply system according to claim 8 and wherein only said additional battery is readily accessible for replacement by a user.
12. A battery power supply system according to claim 1 and wherein said additional battery comprises at least one rechargeable cell, and said bidirectional charge controller preferentially draws current from said additional battery before drawing current from said rechargeable battery.
13. A battery power supply system according to claim 12 and wherein said preferential drawing of current from said additional battery before drawing of current from said rechargeable battery is operative to lengthen the lifetime of said rechargeable battery.
14. A battery power supply system according to claim 12 and wherein said rechargeable battery is used only after the additional battery is substantially depleted, such that the life of the rechargeable battery is lengthened.
15. A battery power supply system according to claim 1 and wherein said rechargeable battery is a Li-ion battery.
16. A battery power supply system according to claim 1 and wherein said portable electronic device is any one of a cellular telephone, a video camera and a laptop computer.
17. A battery power supply system according to claim 1 and wherein said additional battery is installed within said device.
18. A battery power supply system according to claim 1 and wherein said additional battery and said bidirectional charge controller are installed in a housing external to said device.
19. A battery power supply system according to claim 18 and wherein said housing comprises a single connector which both outputs current from said additional battery to said portable device, and which inputs charge current for said additional battery from an external charger.
20. A battery power supply system according to claim 3 and wherein said bidirectional charge controller converts current output from said additional battery at said first nominal terminal voltage to another voltage for powering said device, even if said rechargeable battery is depleted beyond a predetermined criterion.
21. A battery power supply system according to claim 1 wherein said bidirectional charge controller contains a microcontroller.
22. A battery power supply system according to claim 1 wherein said bidirectional charge controller is connected to said electronic device by at least one data communication line.
23. A battery power supply system according to claim 1 further comprising contact taps contacting the terminals of each cell of said additional battery, such that the battery chemistry of each cell in said additional battery can be determined.
24. A battery power supply system according to claim 1 wherein said additional battery comprises at least one primary cell.