This relates to an electric system for a motor vehicle, the vehicle including at least one power supply battery, the electric system including an electric charger intended to be connected, on the one hand, to the battery and, on the other hand, to an electric network outside the vehicle supplying an AC voltage or to electric equipment, and a microcontroller, the charger being able to charge the battery from an external electric network or to allow the battery to power the equipment, the microcontroller being configured to: a) command the opening and closing of each switch of the first bridge and of the second bridge of the converter; b) activate the second operating mode of the first bridge or of the second bridge; and c) activate the second operating mode of the first bridge or of the second bridge.

A method (400) for operating an electrically driven vehicle (300), comprising the following steps: emitting a signal for controlling (420) a connectable charging means (160) for charging an intermediate circuit capacitor (140); determining (440) a voltage at an intermediate circuit capacitor (140) or of the charge thereof; emitting a signal for closing (460) the switches (130) for connecting the traction battery (150) to the high-voltage grid (110) as a function of the determined voltage or charge.

The maximum time that external components of a switch mode power supply over-conduct is determined by an actual ambient temperature at which the devices are operating before they are turned on. Their operation time is thus extended when temperatures are low and decreased when temperatures are high.

The invention relates to a method for monitoring the operation of a vehicle electrical system (50), in which the component temperature (62) of a component (56) in the vehicle electrical system channel (52, 54), the ambient temperature (66) of the component (56) and the current (70) flowing through the component (56) are ascertained in a vehicle electrical system channel (52, 54) of the vehicle electrical system (50), and then, if overloading of the component (56) is detected, a period of time (72) to overloading of the component (56) is calculated,
wherein a heat input (P.sub.in) into the component (56) and a heat loss (P.sub.out) of the component (56) are used to ascertain the period of time (72) to overloading of the component (56).