Hello,
I have searched the documents and spreadsheets to try and find a MQTT topic to enable and disable the charger in the Multiplus2.
I have mapped the power assist, Mode and AC input limit, the last one I am missing is the Charger ON/OFF.
Does anyone have this topic?
Kind regards
Andy
There is only the soft switch for on, off, charger only, inverter only. The latter disables all charging but drops grid.
The system is a converter, it switches between invert and charge as needed, but cannot do both. You can’t explicitly disable charging and remain grid attached.
Should we understand that when you uncheck the “Enable charger” below, it will also disconnect from grid?
You can set the charge current to 0A as an alternative.
I suppose that it will work as the VEConfigure allows it to be set to 0A.
Or maybe the float and absorption voltages to a lower value in order for the battery to not charge?
Like modifying the CVL by the BMS to a much lower value to forbid the charging…
But I don’t know if the above suggested options are available through MQTT and I may be talking nonsense.
or set desired SOC to actual SOC
Inverter only doesn’t work in this situation, It then starts to use the battery and ignores AC In.
It is the enable charger tick box I want to find the MQTT topic for. I have managed to do this with the tick box for power assist so I can change that on the fly so to speak to enable a lower power generator on the system.
I have also found the documentation that lists the values for the MODE topic and you have ON OFF Charger Only and Inverter Only……. and also 251 - which is passthrough. If I write 251 to the topic it doesnt work and reverts to last known good configuration.
My charge current is controlled by the BMS so I dont want to start changing that, but I may have to set it to 0 as suggested.
In summary the client wants an ESS type sheduled charge overnight based on predicted solar the next day. The client is off grid and uses a generator.
Many thanks for your suggestions.
Am i understanding correctly?
The system is offgrid.
it will only ac charge if the generator is providing power? And sometimes they just want the generator to run and pass through to loads only at night if the solar the following day predicted is enough?
Yes that is the simplified version.
The system is managed by Home assistant through MQTT.
I know I could probably use the relay in the Cerbo to stop the charge using the temp input of the Multiplus, but the client wants a software solution.
Driving the relay on the cerbo would still require a software solution and is probably the easiest with the ability to program an override as well.
The only other way is to ride the input current limit to limit it to the ac load value.
Although as a side note generators are often killed by low load long runtimes; it is usually best to run them a short time and at the best efficiency range. And is usually more fuel efficient as well.
So let them charge up to the soc that you know will carry them through.
If the solar does not pick up today the generator may run for 50kw tonight. (As the generator plus solar is still lower than consumption and that looks to be the shortfall)
I understand the thought of charge up to a SOC you know but that’s not possible in this case due to big variations on load with no way of knowing day to day.
I will use a relay on the cerbo, or another external relay for now while I try and find another way.
If i find another solution elsewhere I will post it to help anyone in the future.
Thanks for your suggestions.
Yeah. Same with the site above. It was bumped up based on the forecast Vs expected/forecast load.
Will be keen to hear how you tackled it.
if you have a SOC of lets say 65% and set desired SOC to 65% there will be no charging
I do the same with discharging as i don´t want the MP2 to discharge when my wallbox is using cheap energy
But you have to store the old desired SOC in a helper variable, send the old value when you want to charge again
Thanks, it’s a way round it.
We just want to arrive at a SOC and then disable the charger.
Thanks for your input.
