Doesn't make a difference
The recommendation is that you try to avoid letting it drop below 30%. Full discharge of lithium ion puts the battery under unnecessary stress. Quick charge which is is not an issue for the iPhone also tends to strain the battery.
Best way is to keep the battery between 30 and 80%. Which is quite difficult. I would use it normally, not allowing it to fully discharge, except a full discharge so that it turns off once or twice a month.
http://www.apple.com/batteries/maximizing-performance/ mentions nothing about 30%??
That article appears to make no mention of battery maintenance.http://www.apple.com/batteries/maximizing-performance/ mentions nothing about 30%??
It is not 1998 any more so don't stress.... IMHO
The recommendation is that you try to avoid letting it drop below 30%. Full discharge of lithium ion puts the battery under unnecessary stress. Quick charge which is is not an issue for the iPhone also tends to strain the battery.
My housemate has a 5 year old iPhone 4 and its battery is still fine. She doesn't follow any 30%-80% rules.
If she did it'd be more healthy.
She gets a day or more out of it. Like it did when it was new.
So I don't agree.