Hi all.

I am trying to help my neighbour with his system. I have helped with settings before as his installer did a runner, but his current situation has me stumped. I need to maximise his battery usage to improve efficiency, but the SOC does not seem to be accurate.

The battery is charged and discharged daily. However, the SOC never seems to change (fixed at 72%). This has been the case for the last couple of months. I will post screenshots from the Sunsynk web portal.

I still need to check the inverter settings, but wanted to see if I could figure out the problem before going over there. I have access to his Sunsynk plant - If there are settings that might be helpful with diagnostics, please let me know and I will post the relevant screenshots.

Any suggestions welcome. Thanks.

System: Sunsynk 8kw, 2x 7.1kw batteries (cannot recall the brand).

c

Shut down the complete system.

1. Isolate the pv.

2. Shut inverter down.

3. Shut both batteries down: Then check:

4. Comms cable between batteries are properly connected.

5.Comms cable ( Can or RS485) is properly plugged in on battery side and inverter side. If Can is used to correct ports if RS485 is used to correct both on battery side and on inverter.

Restart system Battery Inverter Pv.

Go the the Li-bms page on the inverter and ensure the inverter is receiving data from the master battery bms. See screenshot 1.

Then check if inverter battery setup page is configured correctly. Screenshot 2. My screenshots is based on Lfp 5kwh Sunsynk battery.

Edited January 28Jan 28 by TaliaB
Added context

17 minutes ago, TaliaB said:

Shut down the complete system.

1. Isolate the pv.

2. Shut inverter down.

3. Shut both batteries down: Then check:

4. Comms cable between batteries are properly connected.

5.Comms cable ( Can or RS485) is properly plugged in on battery side and inverter side. If Can is used to correct ports if RS485 is used to correct both on battery side and on inverter.

Restart system Battery Inverter Pv.

Go the the Li-bms page on the inverter and ensure the inverter is receiving data from the master battery bms. See screenshot 1.

Then check if inverter battery setup page is configured correctly. Screenshot 2. My screenshots is based on Lfp 5kwh Sunsynk battery.

Thank you, that is great feedback, very detailed and easy to follow. I will try this and report back - thank you!!

On 2026/01/28 at 8:10 AM, TaliaB said:

Shut down the complete system.

1. Isolate the pv.

2. Shut inverter down.

3. Shut both batteries down: Then check:

4. Comms cable between batteries are properly connected.

5.Comms cable ( Can or RS485) is properly plugged in on battery side and inverter side. If Can is used to correct ports if RS485 is used to correct both on battery side and on inverter.

Restart system Battery Inverter Pv.

Go the the Li-bms page on the inverter and ensure the inverter is receiving data from the master battery bms. See screenshot 1.

Then check if inverter battery setup page is configured correctly. Screenshot 2. My screenshots is based on Lfp 5kwh Sunsynk battery.

@TaliaB thank you again for your advice. I was eventually able to go around and restarted the system. We got it back up and running again and the SOC is accurate again.

Really appreciate your advice