[T-Mobile LG G2x] oOo B0XeR oOo:
If your phone is defective then you need to contact the manufacturer/provider and seek replacement. If unusual electricity or heat is observed then I would stop usage immediately. So there's my disclaimer :) but it seems like your comments are unique from what I've heard... if it doesnt charge above 45% and you've done several ROM flashes and tweaks then first assumptions would be you have a bad battery or a bad kernel that you flashed... (I'm just guessing without knowing any other details of your situation at all). The phone is going to get hot upon charge and heavy CPU usage. I dont know the stats but I think the batteries are rated around 130*F... the next time you notice it pull up any of those apps that have Battery Temp in it and see what it says. The issue is software related... firmware actually, its the drivers that control battery usage. Flashing a ROM may or may not affect that. There's so many variations and partials that you cant speculate. I'm sure that something will need to be done but what that is I dont know... it'll come though. Its just like anything, its a brand new device, heavily dependant upon many sensitive functions all working properly... dual core is a relatively new deal and its the 1st from both companies (TMob & LG)... thats why I never buy pilots of electronics, I wait till the bugs are resolved then buy. Until now :)

So I think all of us have the same frustrations with this paperweight, I know that I have seen differnet battery pulls just depending on the day (all other variables the same) and it's been +-2hrs which is a huge margin. I cant tell you how many times I need to send a basic email and after having to plug it in, then dealing with the GB 2.3 keyboard freeze up on me, I walk away as to not lose my cool and come back and the screen is just frozen black (aside from screenbleed:) So I had to pull the battery and wait for it to fire up etc all to send an email that shoud have taken 2minutes... that day was the time I thought I finally just couldn't do it anymore. So many issues all the same but different frequency. Anyway we have 2 options right... either we deal with it somehow to ride it out or we go return it and get an HD7 WinMo right :) dont forget to unroot... I truly things its just a terrible driver that is paired with a poorly matched battery and the slew of issues are just dependant upon services usages. I do know that these batteries have like a 'memory' almost meaning if the first few times you charge it to 50% then there's a good chance its not going to charge all the way to 100. I digress, here's the official release about the HTC battery trick... the first one was a reply from HTC the second one from SPRINT*.

==== TRY THIS, I HAVENT YET BUT MAKES SOME SENSE =====

1. Connect the phone to the charger and charge device until the LED turns green with the phone powered on. 2. Disconnect the phone, and power it off. 3. Reconnect the phone to the charger, and charge the device until the LED turns green again. 4. Disconnect the phone, power it on, and then power it off. 5. Reconnect the phone to the charger and charge until the LED turns green again. Power on and use.

====OR====

1) Turn your device ON and Charge the device for 8 hours or more 2) Unplug the device and Turn the phone OFF and charge for 1 hour 3) Unplug the device Turn ON wait 2 minutes and Turn OFF and charge for another hour Your battery life should almost double, we have tested this on our devices

*source:http://xdaforums.com/showthread.php?t=712990