Battery, Usage under General Settings

I have an iPhone on Verizon, not sure if that should matter or not but I've noticed sometimes the usage shows up on my iPhone display and other times it appears blank. Is there something that controls whether or not it appears? I know it says it shows the usage after the iPhone has been fully charged, but sometimes it seems like it's there initially after I charge it and then later on it disappears.

This is from the iPhone user manual. Maybe it will help.

"Usage—Amount of time iPhone has been awake and in use since the last full charge. iPhone is awake whenever you’re using it—including making or receiving phone calls, using email, sending or receiving text messages, listening to music, browsing the web, or using any other iPhone features.iPhone is also awake while performing background tasks, such as fetching email messages."

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So does this mean after you turn the phone off, even if there's 90% battery life left, when you turn it back on the usage figures will not show?

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I just tuned my iPhone off, which I never do, and back on with battery of 78%. The usage data stayed. My iPhone is AT&T so it my not be the same results since the iOS is not totally the same.

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If the iPhone is genuinely powered off, then there will be almost no power drain except to keep the clock running. You could leave it that way for weeks and then boot it back up ready to use.

However, when the iPhone is just sleeping (aka, on stand-by), even if you've placed the phone in airplane mode and turned off all tasks running in the background, there is some power drain devoted to maintaining the phone's ability to immediately respond when you press one of the buttons. The screen may be blank, but clock and calendar continue to function, the memory is active, the accelerometer is still working, and the computer is awaiting input from the de-powered sensors when they turn back on.

All these things require some electricity, and although the iPhone is extremely efficient, it probably can sit sleeping no longer than 2-3 weeks without draining the battery. If you've turned OFF airplane mode, then it lasts even less time. And battery drain then depends on how strong the cell signals are and whether you have bluetooth, wi-fi, cellular data, and 3G enabled.

I have an AT&T iPhone, but perhaps the following is true for the Verizon variety, too: In the Settings app, under "General" there is a switch to turn on Battery percentage. With that switch activated, your battery icon will always indicate the percentage of power remaining in the battery.