An Apple patent (number 20110074360) for a power adapter with an internal battery has appeared at the US Patent & Trademark Office. It shows that Apple is working on a integrating rechargeable external battery pack -- with solar power features, no less -- into its standard charging cable for laptops and iOS devices.

Per the patent, the power adapter typically includes the battery as an integral component that is connected to a plug or other interface capable of mating with a power source, such as a wall socket. Thus, the adapter battery may provide power either to operate the device or charge a battery within (or otherwise associated with) the device even if the adapter is not connected to a power source. The inventors are Duncan Kerr, David Robbins Falkenburg and Michael Nugent.

Here's Apple's background and summary of the invention: "Rechargeable batteries may be found in a variety of portable electronic devices, including laptop computers, personal digital assistants (PDAs), cell phones, digital media players, cameras, etc. The rechargeable battery in such devices is typically charged using power supplied from a power adapter connected to an external power source. The power adapter may also be configured to provide power to run the device, in conjunction with charging the internal battery.

"Existing adapters do not include an battery source for powering electronic devices and/or powering an internal battery. As such, users desiring additional battery power will typically purchase an external battery that can be separately connected to the portable electronic device. However, such external batteries are generally cumbersome to use, at least because they must be unpacked for use and then repacked for storage. In addition, many users may forget to bring the external battery in addition to the adapter while in transit.

"What is needed is a way to combine a power adapter and a battery so that a user does not have to carry an additional external battery while traveling with a portable electronic device.

"Generally, embodiments discussed herein provide power to an electronic device from a battery external to the device but associated with a power adapter. The power adapter typically includes the battery as an integral component that is connected to a plug or other interface capable of mating with a power source, such as a wall socket. Thus, presuming the adapter is plugged into the electronic device, the adapter battery may provide power either to operate the device or charge a battery within (or otherwise associated with) the device even if the adapter is not connected to a power source.

"Further, the adapter may include a processor, such as a microcontroller, that may execute logical operations to intelligently determine how to distribute charge between the adapter battery and device battery, based at least in part on an operating state of the device. The adapter processor may communicate with a processor inside the device and, in some embodiments, the device processor may assist in such logical operations or may perform the operations and instruct the adapter processor accordingly. Thus, the adapter may vary its charging function depending on operating variables not only of the adapter itself, but also those of the device to which it is connected.

"One embodiment takes the form of an apparatus for providing power to an electronic device, including: a processor; a battery operatively connected to the processor; a power output operatively connected to the battery and configurable to be connected to the electronic device; a relay operatively connected to the battery and the processor; and a power input operatively connected to the battery and the relay.

"Another embodiment takes the form of a method for powering an electronic device from an adapter having an internal adapter battery The method may include the following operations: determining if the adapter is connected to a power source; in the event the adapter is connected to the power source, determine if the device is connected to the adapter; in the event the device is connected to the adapter, operating the device from the power source; and in the event the device is not connected to the adapter, charging the internal adapter battery."

In some embodiments, the power adapter may include an additional input configured to receive power from a trickle power source, such as a solar or photovoltaic cell, supplying a trickle voltage.

-- Dennis Sellers