Battery runs low too fast

It could be a couple of things, but mostly its either the 3g connection being used 100% or the gps. If you have a "push" email account set up, and use it all day, or Ive had bad luck with certain im clients, some have a "battery save" option in the settings. Using wifi when avalible saves on the 3g load. Are you running the standard rom, and do you have any shells over it?

Also if you are on the border of coverage from 3G to EDGE, or equally spaced between local towers, this will cause your battery to get eaten alive, as the phone powers the radio up to a high level to acquire the best signal for you constantly.

As an example: I recently spent the day a at an outdoor event that was in a much more rural area than where I work & live. The whole time, I noticed that my signal kept switching from 1 bar of 3G > No Signal > 3 bars of EDGE, and then back again - over and over again as I moved around. 

Now, normally my battery will start the day at 100% and be down to 70-65% by the end of my 8+ hour work day, but after 6 hours of the constant signal searching (and taking about a half-dozen photos) I had gone from 95% battery when I arrived to an alarming 19% when I left!

So check your reception around where you live, work, or spend a lot of time - that could be part of the problem. The same effect can happen if you put your eXpo in a drawer or bag throughout the day - it has to work harder to maintain a signal, and thus more battery.

RC

I have my own method and have read that it right and have read that it's wrong. I am no engineer or chemistry professor. I have not seen any empirical data to support any method of "conditioning" for a lithium ion or lithium polymer battery. I have had good results with my method and that's why I have stuck with it. Whenever I get electronics with a new Lithium battery, I will completely charge it before the first use, making sure not to let it overcharge too much. I then run the device until the battery is completely dead and I cannot turn on the device anymore. I will repeat that process two more times before putting the device, or at least it's battery, into regular use. I do not hold to a specific amount of charge before charging under normal use. If the battery is less than 50% when I'm done using it, I charge it. I leave the device on the charger and don't worry about over-charging the battery anymore at that point.

I work a 10 hour day. Yesterday I got home with 78% battery. No voice calls or texting but I do stream audio over bluetooth whenever I'm in the car, yesterday that was probably an hour total. I did also do a little surfing on the internetz. Some days, with heavier usage, I get home just in time to plug it into the wall before shutting itself down. Monday as I pulled into the driveway, I got "the battery is critically low" streamed through my car stereo, (10%) but I had tunes all the way home.

I turn that off cause it slows down my texting anyways hahahahaaa

I had the same problems as all the posters but then I realize it may be a simple matter of turning your phone off in the settings when not it use.  My phone turns off in a minute when I'm not using it and now it can go 2 days without a charge.

It doesn't turning it totally OFF, when you get a call or a text it'll pop back to life, otherwise, I either let it turn off on its own or push the lock button to get the black screen to turn it off.