AUTOMOTIVE DUAL VOLTAGE BATTERY CHARGING SYSTEM

A dual voltage power supply, comprising at least one battery 20 with multiple battery modules Bi and a first set of switches S j for connecting the battery modules in series to thereby provide a first voltage to a first circuit in case the first switches S j are closed and to disconnect the series connection case the first switches S j are open, and at least one connection tap being connected to one of the battery modules B i to provide its voltage U 2 to a second circuit 2 operating at a lower voltage U2 than the first circuit 1 and being connected in parallel by a second set of switches P i+ , P i- to other battery modules B i , wherein the other battery modules B i are connected in parallel to each other and said one of the battery modules Bi in case the second set of switches Pi+, Pi- is closed and are not connected in parallel in case the second set of switches Pi+, Pi- is open, can be charged with off the shelf generators even if the combustion engines drives them with comparatively low rpm, if said one of the battery modules Bi supplies at least one DC/DC converter 30 for supplying the first circuit 2 during times of low power demand of the first circuit and if that at least one a capacitor C 1 is connected in parallel to the output of the DC/DC converter 30.