Battery systems provide a green power supply. A battery pack is always delivered fully charged, just as we deliver our generators with a full fuel tank. A battery pack can operate completely autonomously or in combination with an external electrical supply such as a generator or the grid. Typical applications are construction sites or festivals where the average energy consumption (kWh) is rather low but there are short periods where higher power (kW) is needed. As the average energy draw is rather low, it can be fed via a low-power connection from the grid or from a small generator. The battery supplies the peaks via a 2-way inverter converter (AC > DC > AC). Here, the battery box acts as a buffer. The battery systems are equipped with an intelligent control system that, among other things, can automatically start a generator when the battery falls below a certain level or when the power consumption becomes too high for the batteries. In the latter case, the power of the external supply, mains or generator, is added to that of the battery system. Advantages of battery systems: no emission of harmful gases, virtually noiseless, so ideal for circumstances where a traditional generator is too noisy and also, e.g., for power supply during the night, maintenance-free, etc. Battery packs are available in various capacities (kW) and with various storage capacities (kWh). The number of batteries determines the storage capacity.