with reference to fig4 the present improvements provide a rapid charger for sealed storage cells of reduced bulk and weight by way of example for a 7 ampere hour battery the weight of the needed transformer 92 is reduced from approximately 14 kg to 4 kg the value of the power consumed in the a c mains by the said charger and also the value of the effective current flowing through the circuit do not exceed the corresponding values for a transformer type charger regulation of the charging current is u00b1 2 at the high rate and u00b1 15 at the low rate in order to prevent accidental shock by contact between the operator and an element under voltage the device or system of fig5 a and 5b is completed by two safety relays the control windings of which are designated 111 and 112 respectively for as long as the battery tap 15 39 a is not connected to the circuit the charging circuit is isolated from the mains by the gaps at two contacts 113 and 114 of the relay 112 when the battery tap is in position the contacts are inaccessible the coil or relay 111 is then fed with continuous voltage off at the terminals of zener diodes 84 and 85 through intermediary of studs 15 and 15a of the tap which are then interconnected.