How to Charge a Gel Battery With a Regular Chargerby Kelvin Hayes
Gel batteries, referred to as "gel cell," are sealed batteries filled with an electrolyte gel that reacts with lead plates. Generally, gel cell batteries last longer than sealed lead acid batteries, as they resist sulfation. Charging a gel battery with a lead acid charger is risky, since gel batteries require constant voltage charging, versus taper charging provided with lead acid chargers. It can be done if you monitor the charging process closely. When attempting to charge a gel battery with a lead acid charger, you must ensure the peak charging voltage does not exceed 14.7 volts, which would result in dried, non-conductive gel.
Attach the lead acid battery charger to your gel cell battery, connecting the red cable to the positive terminal and the black cable to the negative terminal.
Switch the charger settings to 2 amp /12 volt, also know as deep cycle. It's important to set it to deep cycle in order to mimic the charging characteristics of a CVC (constant voltage charger), the type of charger designed to charge deep cycle gel batteries.
Switch the charger to manual, not auto. Leaving it on auto will allow the charger to taper its voltage as it senses the gel battery reaching full charge. This does not mimic the CVC type of charge that gel batteries require.
Monitor the battery closely during the seven to 12 hours worth of charging, ensuring the voltage output reading on the charger never exceeds 14.7 volts. Also, monitor the charger's reading of the battery's charge. Once a 95 percent charge has been reached, remove the charger.