When should I charge my iphone 5

http://www.apple.com/batteries/iphone.html

you can charge it whenever you feel like it. But at least once a month let the battery die out and do a full recharge.

i think it's really a matter of preference. but, i am pretty anal about charge cycles, so like you, i typically wait between 10 to 20%. thing being, i always have a charger or some means of charging nearby.

if i know i will be away from a charger all day, and i have a long day ahead of me, i top it off. it's rare though.

remember every time you plug in your phone, you use a charge cycle.

this was required with older ni-cad or ni-mh batteries (like 10 years ago) to recalibrate. not required (and not recommended) with li-ion.

Thanks for the heads up.

what if my phone completely dies and i fully charge it. while anything happen to the battery.

Had this same question, and found some good suggestions on the Lifehacker site:

http://lifehacker.com/5875162/how-often-should-i-charge-my-gadgets-battery-to-pr olong-its-lifespan

Basically, small charges to keep it between the 40%-80% range is best, with a full discharge to 0% 1x a month and keeping it cool recommended. Don't let it stay on a charger when fully charged as well. Here's to our batteries' long lives- Cheers!