Gel

Charge profiles for gel batteries

Gel batteries have a narrower charging voltage window than flooded lead-acid or AGM types, and overcharging even slightly shortens their life significantly, so the charger or alternator regulator needs a gel-specific charge profile rather than a generic setting. Check that any existing charger, solar controller or alternator regulator on board has a gel option before connecting new gel batteries, since running the wrong profile is one of the most common reasons gel batteries underperform.

Gel cells tolerate deep cycling well and are sealed against spillage, which suits enclosed battery compartments, but they are also more sensitive to high charge currents than AGM, so multi-stage chargers need their absorption and float voltages set correctly for gel rather than left on a default lead-acid curve.