Hi I am trying to find out if the fan on the MultiPlus will start if I am using 4-500w for an hour.
I am interested in this model MultiPlus 24/1200/25-16
but I think all MultiPlus are using the same fan for all the models.
So if you use a hairdryer or similar do the fan start?
Most likely yes - certainly not at the lower values, but up higher yes - the Multplus units use FETs for switching the voltage, they have heatsinks on them, but invariably they will get hot, even with minimal loads - it is all very dependant on the environment. Some people may have installations where it is 30DegC in the shade (here in Australia for instance.) so the expectation is they would likely be on even with your lowest load.
In the smaller units however the fan noise is not that much, they are basically a 110mm PC type fan.
Hairdryer - would definitely cause the fan to come on. Minimum power for a lot of Hairdryers will be around 1200watts - keep in mind the 1200VA has a Peak Continuous Power value of 1000W - so using the table below you could calculate that you might only get 20 minutes out of the hairdryer, and this also means the FETs will be running at Full capacity, and the internal Fan will absolutely be running.
You could always use the 'Silence fan' assistant, but it will cause the Multi to shut down sooner from over temperature, it depends on your priority?
https://www.victronenergy.com/live/assistants:overview_of_available_assistants#silence_fan
