I have the HTC Incredible (probably going to exchange for the X) and when new, the OEM battery life was frightening. From my experience it did take several charge cycles for the battery to reach peak performance. In the beginning I let the battery go completely dead (let the phone shut-off) and I re-charged it with the phone turned off. I understand there are debates about proper charging and I don't want to stir that up. I'm simply sharing my (arguably successful) experience - good, bad or indifferent. In any case, I did this about 4 times. And now when I charge it, I (try to whenever possible) leave it plugged-in for at least three additional hours. The phone is left on. Now I have no trouble getting a good 24-30 hours of moderate-to-heavy use before the charge dips below 10%. Also, I purchased the Seidio 1750 mAh extended battery and went through the same process. The 1750 provides 30-40 hours of moderate-to-heavy use. I'm sure everyone's mileage will vary. There's a nice free app in the Android Market called Battery Indicator that resides in the notification bar. It provides temperature information and informs you how long the battery has been in service since the last charge or unplug. I've found it to be very handy and useful. I believe an extended battery for the X is available soon which will be a nice boost. Hope this helps.