Two options for a browser that uses less battery than others. The first is Opera Mini. That was is very lightweight and barely uses any battery. The trade-off is that it feels like a mobile browser and doesn't offer much of the functionality of the modern mobile browsers that can also serve as true desktop browsers. The other is Atlas. I have just started using it. So far, it can do everything the other browsers do and is less battery intensive. The key is finding a browser that does not reload or work in the background when it's not the main app on screen.