The battery computer MT 40000 is a compact indicating instrument. It also displays the charge status of the on-board battery via a bar display on the side, and the remaining charge display shows at a glance how long the consumers can still be operated at the current power consumption. All data is easy to retrieve and the functions are clearly and logically structured. The voltage (V) of the on-board battery and starter battery as well as the currently flowing charge/discharge current can also be read. Time and date can also be displayed. The display is equipped with a backlight and a switching threshold is freely programmable. Thus it is possible to automatically switch on a consumer when a certain capacity is exceeded, which then switches off again when a certain value is fallen below again.