The new sine wave inverter-charger combination of the series Xtender is a result of development for many years. The new smart boost function permits the support of external selectable sources, i.e. the inverter can switch an existing electric net or a generator, in order to make possible e.g. the start of air conditioning systems with weak land connection or generators. The Xtender series can also be combined with already existing inverters, in order to increase the available power delivering. A pure sine wave voltage, an extraordinary overload and a very high efficiency enable the safe start up of motor consumers with a high inrush current. Connected to shore power it will automatically charge batteries with a PFC regulated stage and in addition deliver 230 V for AC supplied devices. The power-sharing function allows an automatic reduction of the charging current to the load limit of the AC source.