Batteries will freeze if they aren't charged. Adding acid won't keep them from freezing if they're dead. If you tried charging them individually and the charger was turning on and off you may have a shorted battery. Have you checked them with a digital volt meter? The first thing you need to do is determine if your batteries are bad and you'll need a digital volt meter. Without knowing the condiition of your batteries it's going to be hard to help you.