There are two divisions and three main types of batteries used in renewable energy systems. The divisions are flooded and sealed batteries. Flooded batteries (lead acid batteries) use a fluid electrolyte such as lead acid, have ports to access their cells’ fluid reservoirs, and require maintenance (adding fluid). Sealed batteries (sealed AGM and sealed gel batteries) use non-fluid electrolytes contained in inaccessible cells. There is only one flooded type: flooded lead-acid batteries. Sealed batteries include AGM batteries and gel cell batteries. Call a solar expert today with questions or for assistance at 866-274-0642 .