Disclosed is a voltage control device in a generator driven by an internal combustion engine. Said control device is fitted with a Load Response Function (LRF) which prevents a rapid increase in exciting current when a powerful electric consumer is turned on. Load Response function is inhibited during falling rotational speeds while the vehicle is running by an appropriate control circuit evaluating internal combustion engine speed and generator speed in order to avoid as much as possible voltage dips which occur when this function is activated.