I have been integrating a Multiplus Compact 24/1600 (Multiplus) into the electrical system on board my sail cutter for about 5 years. It is connected to 2 x 24V 220Ah AGM batteries from 2017 and to an Isolation Transformer 3600. Since last year in autumn I have had problems with the inverter function of the Multiplus. The Multiplus works normally if it is connected to the 230V grid. The batteries are charged and the 230V system on board is also supplied with power from the grid via the Multiplus. The moment I disconnect the Multiplus from the grid, the Multiplus goes into alarm mode. The red LED lights up permanently. If I then connect the Multiplus to the grid, the Multiplus functions normally. Before the start of the new season this year I wanted to dismantle the Multiplus to send it in for repair, but before the start I checked the function and the inverter worked even with a large load of approx. 1000W. A week later the inverter did not work again. Does anyone have any idea what is going on? I had also checked the connection between battery and Multiplus.
Many thanks in advance