Overkill BMS communication to inverter

[Alan J]

I recently installed an EG4 18k PV inverter. So far I like it a lot. But I have no way to connect comms from my existing 16s3p battery pack using 230AH cells and three Overkill BMSs to the inverter. Since Overkill BMSs are very popular among the forum members I am surprised that I can't find any discussion of this issue when I search the threads. Is there an easy fix?
If not, are there any setting parameters that I can enter to keep the inverter from draining my batteries below 90% SOC when on grid? Without comms the EG4 requires "lead acid" as the selected battery type. Although I have entered 690Ah as the capacity, designated "Charge first" (battery first, then load, then grid) and entered 90% SOC as the discharge cutoff for on grid, the inverter still periodically drains my batteries to 50-70% SOC while displaying greater than 90% SOC in the inverter display. I don't see how the inverter could possibly know the state of charge of the batteries without comms input from the BMSs. The primary purpose of my system is to provide backup power during our frequent grid outages. Grid support is a secondary priority.

Appreciate any insight or help.
Alan

 

[meetyg]

Look at this:
Thread 'CAN and RS485 BMS Interface with multiple emulated Inverter protocols for JkBms Jbd BMS Daly 123Smart' https://diysolarforum.com/threads/c...tocols-for-jkbms-jbd-bms-daly-123smart.65443/

 

[Quattrohead]

SOC is currently wildly optimistic and fairly useless on these inverters, use voltage setting instead. It is on their list of improvements to be made in the firmware.

 

[Alan J]

Thank you, meetyg. I have a lot to learn before I can even begin to understand that project, but it is encouraging that someone is working on it. Hopefully, this or another solution will include Overkill BMS.

Thank you, Quattrohead. Your comment on SOC fits with my observations. From other sources I have 53.2V as the setting for 90% depth of discharge. So, I've changed the battery discharge control setting from SOC to voltage and set 53.2V as the on grid discharge cutoff, and 48V as the off grid discharge cutoff. My understanding is that this should result in the batteries maintaining 90% SOC while on grid, and not discharging below ~10% SOC during grid outages. Is that right?

 

[Quattrohead]

Yeah that seems around about right but obviously monitor it for a few cycles and see whether it works out for you.