Just replaced my starting battery with a new, wet cell unit and decided to install a 4w Coleman solar trickle charger to keep the battery charged up. After 5 days on the solar charger at the mooring my battery was weak and had to jump it with an external charger to get the engine to start. Is it possible that the solar array is discharging my battery at night? Coleman says this particular unit doesn’t require a regulator. Do I need a better/larger solar panel to keep the battery charged up?