Hi,
should you charge & uncharge an iPad (4) completely?

Greetings,
Pete

[P]

No. This is advice for an older generation of batteries and does not apply anymore.

[subego]

Doesn't it sorta apply?

With the current generation, the battery itself doesn't need to be drained. In fact, a full drain is bad for it. Ideally, it shouldn't get below 30%.

That said, devices using current generation batteries need to pull off a little trick. There's no way to directly measure how much charge is left except when it's fully charged, or almost dead. If it's in between, all the device can do is guess how much battery is left.

The most useful piece of information it can have to make the guess is how much time it takes to get from a full charge to dead. If this doesn't happen every now and again, the guess will start to drift away from reality.

The fix is easy. Let it drain to a few percent from a full charge without plugging it in. This will let your device recalibrate its guess, and you're good to go!

This doesn't need to happen often. Once every six months is plenty. As I said above, a full drain isn't good for the battery, so it's not something you want to do constantly. It will probably happen naturally anyways.

[P]

Apple's devices (and I think any high quality mobile device these days) do this already. They drain one battery cell at a time every now and then to recalibrate.

[subego]

Interesting!

I'm thinking in terms of a single cell, but it makes sense there are multiple cells involved.