USCG Office of Boating Safety Boating Safety Circular #78 ---------------------------------------------- Consumer Advisory - Danger of Explosion If Sealed Valve Regulated(SVR) Gel Cell Batteries Improperly Recharged -------- The American Boat and Yacht Council (ABYC) Project Technical Committee for DC Electrical Systems recently informed the Coast Guard that an explosion can occur when gel cell batteries are recharged with battery chargers which are not automatic temperature-sensing voltage-regulated chargers. According to East Penn, a manufacturer of gel cell batteries, SVR (Sealed Valve Regulated) batteries work on the "recombination principle." This means that the hydrogen that is normally produced on the negative plate in all lead-acid batteries, recombines with the oxygen produced on the positive plate to form H20 or water. This water replaces the moisture in the gel. The oxygen is trapped in the cell by special pressurized sealing vents. If an SVR gel cell battery is overcharged, the hydrogen and oxygen will be produced faster than they can recombine, and will be driven out of the sealing vents and lost to the atmosphere. Hydrogen gas released by a battery is extremely flammable and requires only a source of igniton to set it off. Some explosions have occurred. SVR gel cell batteries are advertised as "maintenance free" and as "sealed," which may lead boat owners to believe that gel cell batteries do not emit hydrogen gas during charging and are completely safe to put anywhere on a boat. These claims are true as long as the manufacturer's instructions for charging are carefully followed. Automatic, temperature-sensing, voltage- regulating battery chargers must be used. Charge voltage must be limited to 13.8 to 14.1 volts maximum. Constant voltage chargers must never be used. In addition to the explosion dangers associated with recharging with the wrong equipment, overcharging or undercharging an SVR gel cell battery also reduces performance and battery life. Before using and recharging gel cell batteries boat owners should read the instructions, or contact the manufacturer, to be sure they have the correct type of battery charger, and are recharging it in accordance with the manufacturer's specifications. Last Modified On: Monday, March 20, 2000