Multiple function current-sharing charging system and method

1. A method of charging two rechargeable power supplies comprising:

providing a charging system;

providing a universal serial bus (USB) connection;

sending an identification signal via the USB connection, using the USB's data lines;

providing a first charging current to a first rechargeable power supply via the USB connection using the V-bus power line, the first charging current enabled to exceed USB current draw limitations;

recognizing the identification signal to draw the first charging current at a level that exceeds USB current draw limitations;

drawing the first charging current that exceeds USB current draw limitations;

determining an available second charging current based on a difference between the first charging current and a maximum output of the charging system; and

while continuing to provide the first charging current using the USB's V-bus power line, charging a second rechargeable power supply by providing the second charging current based on the available second charging current.

2. The method of claim 1 where the second charging current comprises the majority of the available second charging current.

3. The method of claim 1 further comprising:

determining that the first rechargeable power supply is substantially charged; and

applying to the second charging current a full charging current of the second rechargeable power supply.

4. The method of claim 1 where the second rechargeable power supply comprises a rechargeable battery configured to be substitutable for a battery in the first rechargeable power supply.

5. The method of claim 1 where as the first rechargeable power supply charges, gradually reducing power of the first charging current applied to the first rechargeable power supply.

6. A method of charging two rechargeable power supplies, the power supplies in devices, comprising:

providing a charging system;

providing universal serial bus (USB) connections at the charging system and the devices;

sending an identification signal via a first USB connection, using the first USB's data lines, to a first device with a first rechargeable power supply;

sending an identification signal via a second USB connection, using the second USB's data lines, to a second device with a second rechargeable power supply;

providing a first charging current to the first rechargeable power supply via the first USB connection using a first V-bus power line, the first charging current enabled to exceed USB current draw limitations;

recognizing the identification signal to draw the first charging current at a level that exceeds USB current draw limitations;

drawing the first charging current such that USB current draw limitations are exceeded;

determining an available second charging current based on a difference between the first charging current and a maximum output of the charging system; and

while continuing to provide the first charging current using the USB's V-bus power line, charging a second rechargeable power supply by providing a second charging current based on the available second charging current.

7. The method of claim 6 further comprising:

recognizing the identification signal to draw the second charging current at a level that exceeds USB current draw limitations; and

drawing the second charging current such that USB current draw limitations are exceeded.

8. The method of claim 7 where the second charging current comprises the majority of the available second charging current.

9. The method of claim 6 further comprising:

determining that the first rechargeable power supply is substantially charged; and

applying to the second charging current a full charging current of the second rechargeable power supply.