Abstract: A monitoring system for a battery system of a transportation vehicle having a primary monitoring device for providing control functions and/or supervisory functions for the battery system and a connecting arrangement for the exchange of control signals and/or supervisory signals with the primary monitoring device, wherein the connecting arrangement is electrically connected to the primary monitoring device and wherein a secondary monitoring device for providing a reduced range of the control functions and/or supervisory functions is electrically connected to the connecting arrangement.

Abstract: A monitoring system for a battery system of a transportation vehicle having a primary monitoring device for providing control functions and/or supervisory functions for the battery system and a connecting arrangement for the exchange of control signals and/or supervisory signals with the primary monitoring device, wherein the connecting arrangement is electrically connected to the primary monitoring device and wherein a secondary monitoring device for providing a reduced range of the control functions and/or supervisory functions is electrically connected to the connecting arrangement.

Abstract: The present invention relates to a method and a suitable apparatus for determining the state of a rechargeable battery and for checking contact resistances in a battery system. According to the invention, an impedance curve is determined using signals at different frequencies and a value for an area, which results from the impedance curve, is then calculated from a predetermined threshold value and an x axis. The value for the area is a measure of the ageing of the battery. A control signal is generated on the basis thereof. In one preferred embodiment, said control signal is used to drive a signaling apparatus and thus to present the state of the battery to a user. The present invention can be used, for example, in motor vehicles that are electrically driven.