Review on High-Efficiency 12V Monocrystalline Solar Panel by Newpowa - 5W PV Module for Battery Maintenance and Trickle Charging in RVs, Marine Boats, and Off-Grid Systems by Joey Quade

Using this panel to service the Power-Sonic PS-1250 F2 12V 5Ah SLA battery for small trolling motors/short range installations. Everything worked fine after the initial install, 2 trips there and back to the dock and back. Since then, the battery has not fully charged even after a few days in the blazing sun and is empty after a few hundred meters. I don't have a diode in my circuit. Can the panel drain the battery? I'm not sure if the charger is the weak link in the setup, but the battery isn't charging, so I think that's the problem.