I've got an offgrid cabin with:
- 4x 200AH 12V semi traction batteries (classis lead acid)
- 150/45 BlueSolar charger
- MultiPlus 24/1600/40
- raspberry Pi running Venus OS and 2 usb dongles for Multi / BlueSolar MPPT
Now I have a big relay in the battery positive terminal.
This big relay gets steered by a SSR relay on port 26 of the RPi in the ground of it's steering wire.
This SSR also cut's the ground of the PSU of the RPi effectively stopping the Pi and disconnecting the battery from the system.
Now if sufficient power is present from solar the Multi would run on that power and give 'low battery' warnings. When the sun sets the Multi would 'starve' of power and the other way around in the morning, it would start it's internals at the first light (maybe multiple times as clouds hinder the solar).
Will that harm the Multi?
background: reason for building this, I'd like to use my system until I leave, then have a system that loads the battery to 95% SoC and thereafter disconnects the battery.
I do need the Multi top be on to help with SoC calculation, alternatively I could rely on the 'storage' mode of the MPPT and turn off the Multi with the switch on the housing before I leave (I don't need 220v during that time.)
