The invention relates to an electric circuit for an automobile, that comprises a ground line (M), an onboard network (R) with a battery (1) connected to the network (R) and to the ground (M) by a branch (b1) comprising a switch (K1) and by a second branch (b2) including a switch (K2), an alternator (3) connected to the battery, a starter and consumer members (4) connected to said onboard network and to the ground. The circuit further includes a voltage holding device that comprises a bridge (b3) connecting the branch (b1) to the branch (b2) and a capacitor (2) connected to the bridge (b3) at a location between the third switch (K2) and the second branch (b2), and an internal supply device (8) that allows the current flow in the second branch (b2) only when recharging the capacitor (2).