Hello everyone!
We use a Victron System aboard a sailboat, consisting of a Cerbo, various Charge Controllers (MPPT for the solar panels) and a Multiplus II (24V 3kV)
This winter we added a waterboiler as a dump load and followed the instructions to activate AC2 out with the programmable relay in the Assistants to turn on when batteries reach 95 and turn off when they are at 93%. So far all works well, but I now realized that the priority of AC1 is no longer given. So basically I would like to keep the inverter working at 2kW or less.
- The Boiler on AC2 out uses about 1.2kW
- so during the day usually no problem UNLESS the kettle or induction stove is started, in which case I would like the Multiplus to turn off the AC2 Out right away and restart ones the loads on AC1 are low enough to restart the boiler.
I would be super grateful if someone could point me in the right direction on how to get this done… Thank you already!
One option is to use the generator assistant, but reverse logic is used as both SOC and power can be used in this. See the links to the archive community. You could also use multiple relay assistants, some on power, some on SOC but you need to make sure of the logic in the order of them. You can also use Node Red.
You can also search on here for dump load, many posts are available.
Dump load link 1
Dump load link 2
Thank you for the feedback and the links.
The dump load is working just fine on our end, what I could nnot work out yet though is how to make sure that the AC Out 1 is always Prioritized over AC Out 2 or in order words how do I get the system to shut off AC Out 2 ones AC Out 1 is consuming more than say 500W? The answer to that I could not yet find in your links…
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
Thank you for spelling it out for me, this really does help! I just made the changes and will test while the battery is still almost full to see how it goes!
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Just did the test run, and the dump load works (not sure if it will turn off when battery is low) however it does not switch off when I turn on f.ex. the stove that consumer 100W so it is trying to run both which is very much on the limit of the inverter…
My next try now is to set it up with 3 assistants for “programmable relay”
Assistant 1: Turn AC2Out on when charge is higher than 96% and load less than 400W for 300sec
Assistant 2: Turn AC2Out off if loads higher than 1800W for 5 seconds
Assistant 3: Turn AC2Out off if SOC is lower than 90%
Problem here is: It does turn Off the AC2 out but then switches On and off until I manually turn off one of the loads. It seems like it just ignores to check for load again before turning back on? Not ure if my description makes any sense 
I have not used the relay assistants but from other posts you need to get the order of them correct and also they act like OR rather than AND.
From https://www.victronenergy.com/live/assistants:start
Combining multiple Assistants
Multiple Assistants can be used in one unit. For example the Programmable Relay is often used multiple times. When doing so; this is how they are evaluated:
- an ON condition always has priority over an OFF condition - multi criteria in the ON ( or OFF ) list go by the OR principle
Therefore, your dump load will turn on If the SOC is above 96% OR the load is below 400W. The assistants are constantly run through in a cycle and checked against the conditions. So the logic goes
SOC > 96% turn on dump load
Power < 1800W so dump load stays on
Extra load is turned on so power > 1800W
Power > 1800W so dump load is turned off
SOC > 96% so the dump load is turned back on
Power > 1800W so dump load is turned off
…
…
…
I am not sure how to get around this with the relay assistant. I always thought the generator assistant got around this but it was tricky to set up because of the reverse logic.
Node Red would do this much easier.
That explanation makes sense, thank you for this!
I would be happy to use the generator option (ties a knot in my mind trying to reverse everything) but in general the dump load part seems to work, only it does not turn off when too much load…
I looked into Node Red as well but honestly… not sure how to make that happen One person’t easy is an other persons headache…
The other option wouldd be to simply wire a actual switch on the water heater and turn it off while cooking (which is the main big power sucker) Or maybe there is a way to use the Cerbo as a switch?!
Really sorry about all the questions, but my mind is not great for this kind of stuff…
The Cerbo relay could be used but based on its own it is not very clever. The Cerbo also has a generator start/stop function that uses multiple triggers which controls one of the Cerbo relays that could then be connected to the Multiplus Aux input as a signal or drive its own 230V contactor.
At this point I am open for any option, as long as it works… happy to try different things, as long as it doesn’t involve complex coding…
