I hope this is not considered as advertising. First I searched Amazon and Ebay for new battery, but reading comments, every item on sale, had at least one comment that it's a fake. Local LG service didn't want to hear anything about selling me only the battery (which is understandable). I purchased mine from spareslg.com.
When removing back cover, don't use opening tool near the SIM card tray. Side frame is very thin between SIM card tray and back cover and may break. This happened to me. Small side frame piece broke loose from there, where it has different structure. If that happens to you, use tweezers to put that small piece back in place and toothpick to apply very small droplet of super glue to into the cracks. Don't apply glue straight from nozzle or you overflow you phone with glue! Then push out SIM card tray to be sure that you didn't glue it together with that small plastic frame piece (or remove it before gluing) .
