A gel battery is a lead-acid battery with gelified electrolyte. It is one of the types of VRLA battery. Rechargeable gel batteries are primarily used in automobiles, boats, aircraft, and other motorized vehicles. Unlike a traditional wet-cell lead-acid battery, the cells of a gel battery are valve-regulated. Colloquially, these batteries are often called sealed batteries but this is not correct. This makes the battery independent of orientation, unlike normal lead-acid batteries, which must be kept upright. Another significant advantage of the gel battery over a traditional wet-cell is the virtual elimination of electrolyte evaporation, spillage (and subsequent corrosion issues), as well as resistance to extreme temperatures, shock, and vibration.

Special care has to be taken when charging maintenance-free batteries, so they do not gas. This means that instead of charging with a constant voltage (13.6 V for a 12 V battery) one would start with a constant current if the battery is low, and only for the last part of charging, when the inner resistance reaches a certain point, so that the charging voltage reaches the cell voltage, one switches to the constant voltage method and charges until the battery reaches its 13.6 V end voltage. Does this make any sense?

See also

• Rechargeable battery
• Absorbent glass mat

Rechargeable batteries