I was able to tweak FF18 to get decent battery life. FH13 made it worse. Wifi now won't shut off when phone goes in to sleep mode. Even with it set to "never on in sleep mode" in the settings.
Interesting! I can no longer go to Menu > Settings > About phone > System updates >Update Android??? "Update Android" is no longer an option. In fact, can't find it ANYWHERE.
I have installed FH13 I can verify it solves absolutely nothing! All outstanding issues that exist in FF18 are still present including horrible battery life.