Automatic Generator Chnge-over switch

[Chris Rodgers]

Hi
We are working on a project using 3 X KH10.5's in parallel - on single phase - and there is an existing generator with and automatic changeover switch. We require the functionality to read the battery SoC or Voltage to initiate the start on the generator when there is no grid present. Our thinking is when grid is absent to start the gennie at 20% SoC and when the batteries get to 95% OR if the grid returns before charge reaches 95% to switch back to batteries or grid via the changeover switch.

Anyone done something like this before?

[Dave Foster]

I’ve not heard of that being done, but nice idea.

To get the battery SoC you would need some kind of local computer processing that would need to access either the foxesscloud or if you want ultimate reliability via modbus direct to the inverter.

You could use a raspberry pi running home assistant, running an automation to signal the changeover switch - bit of a learning curve to get that running, and there is help on here to do that - but once you have it you can pretty much automate whatever you want.

If you don’t want to get into local processing and keep it very simple, directly monitoring the battery voltage would be a good way to do it - LifePO4 batteries have a very flat power curve so it would be relatively accurate to measure falling battery voltage and trip the generator.

[Chris Rodgers]

Thanks Dave, I think we will go down the modbus road. Just need to learn from the gennie supplier what the Raspberry Pi needs to send them to initiate the dry-contact start sequence.

[Dave Foster]

Thanks Dave, I think we will go down the modbus road. Just need to learn from the gennie supplier what the Raspberry Pi needs to send them to initiate the dry-contact start sequence.

No problem, - just to mention you can add an I/O board to the PI and the home assistant OS can close a dry-contact if that makes it easier.