Add Support for Hoymiles MS-A2 Battery via MQTT

[nacho26]

I can already get the SOC and Power via MQTT from Devices with this configuration:

• name: msa2
  type: custom
  power:
  source: mqtt
  topic: homeassistant/sensor/MSA-280024341346/quick/state
  jq: .bat_p
  soc:
  source: mqtt
  topic: homeassistant/sensor/MSA-280024341346/quick/state
  jq: .soc
  capacity: 2.24

However, the MS-A2 can also be controlled via MQTT in terms of power output. I would like the MS-A2 not to charge the car battery when I am fast charging it, etc. In this case, it would be good if EVCC took control and switched off the storage device and then switched back to standard mode so that the connection from the MS-A2 to the Shelly Pro 3EM could take over control again. Some people may also find it interesting that EVCC takes over control.

I found a tip here on how this can be achieved:

https://community.home-assistant.io/t/hoymiles-ms-a2-battery-and-mqtt/901059

"If you want to use MQTT to control the battery, change
homeassistant/select/MSA-XXXXXXXXXX/ems_mode/command from general to mqtt_ctrl and update homeassistant/number/MSA-XXXXXXXXXX/power_ctrl/set values every 59 seconds.

Update interval: minimum 0.2 seconds, no longer than 1 minute. It will automatically switch back to “inherent logic” after 1 minute. And within the minute, the value must be changed. It is sufficient to change the decimal place, e.g., 100 —> 100.1.

E.g. to prevent the Battery from discharging at night change the value from 0.0 to 0.1 every 55 seconds.

If you want to use the inherent logic change homeassistant/select/MSA-XXXXXXXXXX/ems_mode/command from mqtt_ctrl to general."

[andig]

Using custom devices as you do is exactly the way to go. You'll need to implement the battery mode setting.

[nacho26]

I don't think it will work. All you can do today is set the system so that it transfers control to MQTT via “homeassistant/select/<dev_id>/ems_mode/command” value mqtt_crtl, or reset it to “normal” mode via the general value.
Then, in MQTT mode, you can use “homeassistant/number/<dev_id>/power_ctrl/set” to set a watt value that determines whether charging or discharging takes place.

I'm not sure how this can be mapped via the battery mode (1: normal, 2: hold, 3: charge).

If I'm lucky, control via MQTT could result in the power value initially being set to 0 watts input or output. This would then correspond to the battery mode hold, and if you then reset it to normal, you would set it to general again. However, I'm also not sure how I can map the battery mode from EVCC to mqtt_ctrl or general?