Like many others, my iPhone 5 battery is loosing its ability to hold a charge. I understand that a rechargable battery only had so-many charges in its life. To preserve the number of charges I have left in my battery, I've been turning my phone off when its not in use. I've been doing this between once and three times per day. I'm wondering how much power I'm using to power it back on. Am I better just putting it in airplane mode? I ended up buying a mophie battery case, but am still looking for an answer for my question. I can apply it to my iPad, before the battery on that runs out of charges as well.