Question about Maxxtro Mobile Power KV-300 Power Inverter 300W

My Mobile Power KV-300 is already a few years old and works quite well so far. Initially, the fan was annoying. But for some time now, the (whistling) warning tone, which should actually switch on at 11.2 volts, has been annoying. In my case, it starts at 12.2 (still charged). It's almost unbearable in the caravan.
If someone can tell me the manufacturer, I could ask them...

Yes, this inverter has a fan. I've also had one without, but it always shut down because the temperature was too high. For stationary projects I would tend towards a solar inverter, my Morningstar SureSine-300 is fanless and stays cool, but would be too heavy for mobile use.