It bothers me to see how often technology is used to counter a poor system design. It just doesn't make any sense. And often times, the technology isn't being used for its actual purpose.
A prime example of this is charge controllers. A charge controller is a device that takes the input power from the solar module and regulates the output. By doing this, a charge controller can provide the right type of energy required by your battery. More advanced charge controllers can actually assist in the maintenance of the battery itself.
So far so good! However, the charge controller's efforts are really only as good as the overall system design. The available energy of a system is not based on the battery capacity. The true limiting factor in available energy is the solar module production. The solar module is the fuel for the battery. A charge controller cannot compensate for a lack of energy production. You must properly pair your solar module production with your battery. Otherwise, your result will be deficit cycling. Or in simple terms, you have a battery that just won’t last.