This is what I have for my 14 ft Jon and I have had no battery trouble since Bass Pro Shops® XPS® Intelligent Technology Series On-Board Marine Battery Charger - XPS iT 5/5 https://www.basspro.com/Bass-Pro-Shops-XPS-Intelligent-Technology-Series-OnBoard-Marine-Battery-Charger-XPS-iT-5/5/product/10224684/
Nothing like wonting to go fishing and having discharged batters.