Have you ever got the 20% battery remaining or even the 10% battery remaining message and thought to yourself, man that went quick! I have an iPhone 4, Verizon, and the battery lasted about a day. I thought this was great, as I use my phone a lot and receive a lot of texts, emails, push notifications, ECT. Last night I got home late and usually just make it to bed in time to charge my phone. But this time it shut down and went to the low battery screen were you must plug it in before it boots back up. Today before bed I am sitting about 40% and had to take a double look on that as I used a lot more today than before. This got me thinking about how often you should drain the battery to that level and if it really does help. I would say do this whenever you notice substantial battery loss in a day’s time. For me it seems to work. While this worked for an iPhone 4, I would think it would work on older models as well. So before you go calling apple try using the battery to the farthest it will god and charge it to the max and try it out the next day.