How low should I let the battery get % wise before charging back up to calibrate???

For calibration, it's all the way to 0% and back to 100%. Apple says you only need to do this once per month, not everyday.

The rest of the time, it doesn't matter what % the battery is at when you start charging.

There is more info on this topic on the apple website

For general information on care of Apple batteries check out:

http://www.apple.com/batteries

There's a bit more info on iPhone batteries here:

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

If you're having battery life issues, you're much better off playing with your settings and doing things like turning off blue tooth if you're not using it, turning off notifications for apps you don't use often (or don't need notified about), checking how often you have e-mail and calendar accounts set to "fetch" updates.

If all else fails, you can try the "backup" / "restore" trick.

The recalibrating just makes the "% battery indicator" more accurate, it doesn't change how long the battery lasts or "condition" the battery or anything like that.

Lithium-ion is a very clean system and does not need formatting when new, nor does it require the level of maintenance that nickel-based batteries do. The first charge is no different than the fifth or the 50th. Formatting makes little difference because the maximum capacity is available right from the beginning. Nor does a full discharge improve the capacity once faded. In most cases, a low capacity signals the end of life. A discharge/charge may be beneficial for calibrating a “smart” battery, but this service only addresses the digital part of the pack and does nothing to improve the electrochemical battery. Instructions to charge a new battery for eight hours are seen as “old school” from the nickel battery days.

Let it go completely down to 0, then charge it back up to 100%. The problem is with how much charge it "thinks" it has. On Monday night I watched the entire first quarter of the dolphins - jets game on the Justintv app using AirPlay mirroring, all while it showing 1%! Since then I've had battery life that is very consistent with what my old iPhone 4 had. For instance, I unplugged at 4:30 this morning and with moderate use and not playing with any settings I'm at 52% right now at 6:42 pm. Just my experience.