This is a few things we know about batteries and using them to supply DC energy. First of all normal car batteries (and large industrial CAT Batteries) were never meant to be storage facilities. They are to be used to start a vehicle. When they refer to Cold Cranking Amps", that is just what they are good for. If a car battery is let to discharge, they never take a full charge again. With the eventually of being rendered useless (unless someone devises a way to recycle the fluids/plates, etc.). I would never rely on a car battery for constant DC power usage. The best batteries (recommended by a friend who is a Solar Energy Expert) are the batteries designed to be used for Golf Carts. They can be drained right down to zero and take a full recharge successfully. These can be connected in series and form a large storage unit for electrical power.
Offered by Cat.