...in area and volume to the power and screen size of the device its fitted to. With functions and usage equal, the battery life is, or has bern broadly similar, when comparing roughly the same era of manufacture.
Until...
Ios6.1 arrived(or whatever one it was). Where by new functions and notifications where added. Non of these apply to ipad 1, as it is running at full capacity already. Some of these apply to ipad mini. All of them apply to iPhone 5.
As you can probably guess, the battery life is directly proportionate for each device, in that the functions drain the battery more and more until the latest version of the software is used.
UNTIL...
The extra functions of the 6.1 are turned off. Notifications being a main one, where it is constantly scanning numerous apps for updates. Most of these appa are rarely used. Email, push notifications can be minimised, data retrieval minimised etc. the list goes on.
Standby time drastically improves. That's fine. Except browsing is still killing the battery. Why is that?