Sorry, looks like no one knows. I've not seen this sort of thing published. Might be worth asking your dealer. But I guess you have a better chance with a 500.
I've asked local dealer who doesn't know and have emailed sales@victronenergy.com but no reply. Tempted to buy another brand now. My current inverter is fine, it's just the fan noise (and ultimately fan bearing longevity) that's making me think about changing it
I expected there to be a manufacturer chart showing still air temperature and constant load when it operates with and without fan.
I can't answer your question directly, but I have a Phoenix Inverter 12/375 with a constant load of about 150W in my boat. Temperatures are always around 25°C or slightly above. I've never noticed the fan running. It is either particularly quiet or switched off.
I have a little 12/250 Phoenix. A 100W continuous load causes the fan to switch on after about 30 minutes. It does go off again after a minute or two and then off again for about 10 minutes.
This is at a more comfortable room temperature of 18°C though.
Thanks all. Seems like 1/3 load is about where the fan might occasionally turn on so with fridge only the 375W would probably be fan off. However I think I'll get the 500W as it's standby load is virtually the same as the 375W and even though the fan might be very quiet fans do wear out
