First, my phone is rooted using Gingerbreak. Then i used Titanium Backup to uninstall all kinds of LG apps i don't use, like Weather, Finance, Carhome etc. I did this days after i got the phone so it's a while since then. So over time i did these things....
I installed all sorts of task killers and free system monitor apps to see what was causing bad battery. I had also installed juice defender and a program called CPU Tuner that adjusts CPU after battery life, so it uses less CPU as the battery get's lower. None of this was working and i was getting worse battery if anything. 10 hours of idle and the battery was down to 75%
So what i did 2 days ago, was buy an app called System Panel by NextApp which is a resource monitor tool that can record what is going on in the background without using much battery. Next i started uninstalling apps like CPU tuner, Juice defender and even Titanium Backup. Then i kept moitoring use and noticed that the Battery widget was always using the CPU a little bit and also Email, so i removed the Battery widget and closed the Email task. I then charged the phone fully and went out to do some business. When i got home like 5 hours later, to my surprise, the phone was at 96% battery. It has used almost no battery even though i had used the camera and taken 3 pictures, made a couple of phone calls and had 3G enable (data was disable though). So i looked at the records of the monitoring from SystemPanel and after i uninstalled TitanumBackup, removed Battery widget and killed Email, the CPU activity was much lower, and only thing using CPU was background system files.
So now, after 21 hours, my phone is at 80% battery after light use and it's only draining very slowly. I've made phone calls, used camera, used Wifi, used Market to update apps and download and install apps.
I highly recommend you remove battery widget and any other LG widgets or apps that you really don't need. It seems there is nothing wrong with the phone itself, it's a matter of not using bad apps or widgets that is draining the battery. I am very happy now with my battery use. And if you have 3$ to spare, i can highly recommend System Panel.
If you want to know anything, just ask.