Accumulators especially studied for the security, the radio commands and the significant currents (alarms, etc). These accumulators have the advantage of being tight and without maintenance (gelled electrolyte). The nominal voltage of a lead accumulator is 2 volts per element. The refill of a lead accumulator is carried out with a current whose tension must be constant and who should not exceed 2,3V by element, at a temperature of 20