I am wondering what is the best usage for the battery. Should I use it from full charge all the way to empty or should i charge every night just in case i need it? Does it matter , as far as battery longevity?
I dont think it matters if you do a full cicle every time you charge (from 0% to 100%). I would do that, but then I have to charge the phone during the day and it sucks.
You should top off the charge as often as possible. Lithium batteries do better if they don't get discharged to their lower levels. Granted your battery won't go bad in a month if you drain it over and over but it could be the difference in it lasting 3 years vs 4 or 5.
It is best to charge the phone whenever it suits you. Fully charging and draining the battery cycle after cycle is not recommended. Fully draining the battery is only necessary once a month.
I've always charged every night since Li-ion batteries became the norm. Never experienced any battery issues ever. Why would I not want to start my day with a full tank each morning. The flip side of that would be worrying about charging sometime during the day. Charging nightly is stress free usage all the next day
I usually charge at the first warning if 20%. Then let it charge to around 90%. Maybe twice a month I let it run down to zip, then charge it up to 100+% without using the phone while charging.
Charge it whenever you are around an outlet. Won't hurt the battery. Do some Reserch on lithium batteries thought because a lot of people run them down to nothing which is said to be be very bad for lithium batteries. I never run mine down and still have a few iPhone 4's that last almost a full day.