I am looking for 12 volt deep cycle battery on sale for solar power. I am trying to go green at my home in Alabama. I know that I am going to get good discount on used batteries for sale which I really want because I canât afford new and expensive batteries. But I am skeptical about these batteries. How can I check whether used batteries for sale are better and safe? What are thing that I should look out for when buying these batteries. I would really appreciate your useful information regarding this. Thanks.