Judging by a patent application, Apple's got some interesting ideas about dealing with batteries for a variety of devices.

Some may find this ironic, given Apple's current propensity for devices with fixed batteries (iPod, iPhone, MacBook Pro).

Still, the idea is to have smart batteries that can be used in many different types of device, ranging from headsets through wireless mice to phones and even notebooks.

Charging slots would be built into computers, and when a battery starts to run low, the system would tell the user which slot contains a compatible battery that's ready to go. When the computer is part of a network, it might recommend the use of a battery that's been fully charged by another system.

The batteries would contain enough smarts to negotiate the most appropriate power drain or charging profile. So if a device needed a higher current than the battery could safely provide, nothing would happen.

And when the battery needs charging, the charger would deliver power at the rate would optimise the charge time and overall battery life. For example, a reconditioning charge might be applied after a certain number of normal charge cycles.

One suggested scheme involves four classes of batteries, each intended for use in a devices such as notebooks, handheld devices such as phones, wireless mice, and Bluetooth headsets.

The description even includes the idea of a replaceable (and recyclable) battery core that can be removed from the shell and battery electronics when it reaches the end of its useful life. One proposal is that this process could be carried out by an automated kiosk.

If you want to read the details of the proposal, search for document number 20090035609 at the US Patent and Trademark Office.