Gel

How gel differs from AGM and flooded

Gel batteries use a silica-thickened electrolyte rather than free liquid acid or an absorbed glass mat, which makes them tolerant of being mounted at an angle and largely immune to spillage, but also more sensitive to overcharging than AGM. Charge voltages need to be set correctly for gel specifically; using an AGM or flooded charge profile on a gel bank tends to shorten its life through gradual overcharging, so checking your charger's gel setting, or setting a custom profile, matters more here than with some other battery types.

Gel batteries generally handle deep discharge cycling well and suit house banks that are cycled regularly, though they are less tolerant of high momentary current than a dedicated starting battery. As with any battery swap, check the charger, inverter/charger and any battery monitor in the system are all set for gel rather than left on a generic or flooded profile, since a mismatched profile is the most common cause of a gel bank underperforming its expected life.