If you use the generator assistant then you can tell that to shut off ac2 out if the inverter load to above or below a certain power in Watts, this is covered in the links. You should be able to do the same with the relay assistant if you get the logic of the order of the assistants correct.
Here is an example I had running for a while using the generator assistant.
As the reverse logic is used for starting and stopping the dump load (immersion heater) the 6 steps in the assistant translate to
- Use ACOut2 relay to start immersion
- Open relay to stop immersion
- Stop immersion when load higher than 1500W for 10 seconds
and start immersion when load lower than 250W for 120 seconds. - Stop immersion when SOC is less than 60%
- Start immersion when state of charge is higher than 70%
- The immersion is started when AC1 is available
All of the above means that
When on shorepower
The immersion heater is enabled
When on battery power
If the SOC is above 70% AND the power is below 250W then the immersion is enabled
until either the SOC falls below 60% or the power rises above 1500W when it will be disabled