[pio_masaki]

It varies widely depending on usage, radio usage, signal strength, hacks/tweaks etc.

In a call with a supposedly full battery, I get an hour or so. With nothing but texting it'll last a couple days easy. Without using much of the radio (no calls or texts) and some software usage it lasts around 5 days. I have my backlight on 100% and beam receiving off, 30 second power down if idle, no BT or wifi. I carry a spare with me and tend to swap around 30-50% in case I get a call, normal stock batteries. On my extended the thing just lasted until the end of days no matter what i did. Ok, not really, but it was easily twice the normal battery.