Thought my stock battery loosing power day by day and getting a new battery is the only way to solve my problem. Hearing some good thing from my friend about his S4 mpj extended battery and glad they also provide battery(5000mah) for LG Optimus L7. Since I was fed up with the stock battery, I ordered one online immediately and received it few days ago. The battery was 30 bucks with free shipping. I put it in, not too much extra bulk, and noticed it had 10% battery left.
I then began watching a movie(around 1½ hrs) on to let the battery run dry but it got through the whole movie! My old stock battery would probably have died in the first 10minutes..lol..