[buro9]

The patent mentions using multiple power acquisition methods to simply extend the life of the battery.

The patent also mentions many power savings features, basically putting the device into life-saving mode most of the time and only waking to perform a task or notify you of something.

If that's the case, then low power use when off is the priority for them, and if they are able to use drips of power from multiple sources to partially power that stand-by, then the battery only really gets used when you put the screen on... meaning that the device's standby time can be legitimately advertised as being some very long period of time.

And for an idea of standby power for a bluetooth device, let's go back to Casio ( http://world.g-shock.com/us/en/ble/function/ )...

> Since Bluetooth® v4.0 uses low-power near field communication technology, your function-packed G-SHOCK is able deliver to approximately two years of operation on a single coin type battery. This makes the watch's advanced functions practical for everyday use. Approximate battery life when communication function are used for 12 hours a day (tentative value).

2 years!

The iWatch (or whatever it's called) really is only going to drain the battery when that screen is on and in use.

[Samuel_Michon]

Interesting. Assuming the device has only Bluetooth 4.0 and not 2.1 or WiFi, then the only iDevices that would be compatible are the iPhone 4S and later, iPod touch 5th gen, iPad 4, and iPad mini.

Given the limited number of compatible iDevices, it might be prudent for Apple to hold out launching this snap bracelet device, at least until they launch the next generation of iPhones and iPod touches.

[allwein]

It might be a limited number of models, but there are more iPhone 5's and iPhone 4S's than all of the previous iPhone models combined.