Happens sometimes: seems like battery is asleep (Seplos + Deye) but keeps supplying inverter

Hi all,

Having learned a lot from the forum I finally put together my own installation. I have a Deye 8K inverter, 10kw solar farm and a DYI 16S energy storage using Eve 280ah cells and Seplos 2.0 BMS. Everything works as expected, I can store energy and release to the grid or to my local consumption.

In some rare cases (approximately 1 out of 100 commands sent to the inverter), I have observed issues between the Seplos BMS and the Deye inverter. This results in the system not charging or discharging as expected. Instead, the battery appears to supply low stable power (around 1.4-1.8 amps) to the inverter. Please refer to the example chart below, illustrating how the battery-supplied power defaults to around 1.7 amp (the blue line) and remains at that level until the system is restarted, all while the battery SOC continues to decline.



The problem can be resolved by restarting the inverter, after which the system resumes charging or discharging as expected. The commands for charging or discharging are sent directly from the inverter (I used scheduled time slots). I am using a communication cable linking the battery and the inverter through the CAN port.

I suspect that the issue may be attributed to either (a) fluctuations in the overall grid or (b) a combination of power consumption variations from local devices causing sudden changes in the home network or (c) high frequency fluctuations in DC cables between the inverter and BMS.

Anyone has experienced anything similar or has any thoughts to share? Much appreciated. Thank you!

Forgot to add that Deye keeps blaming Seplos BMS and Seplos BMS keeps blaming Deye. None of the logs show a specific event but the Deye runtime log does show some unbalanced pull from the grid. Maybe someone smarter than I can speculate what is going on here. See how imbalanced the CT1 is relative to CT2 and CT3 (highlighted in red). In normal conditions these are rather balanced.

skylimit22 said:

Forgot to add that Deye keeps blaming Seplos BMS and Seplos BMS keeps blaming Deye. None of the logs show a specific event but the Deye runtime log does show some unbalanced pull from the grid. Maybe someone smarter than I can speculate what is going on here. See how imbalanced the CT1 is relative to CT2 and CT3 (highlighted in red). In normal conditions these are rather balanced.

View attachment 201428

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Where did you get this list? I don't see it in my web interface.

I have SUN-8K-SG04LP3, it has zero problems when L2 is 4kW and L1, L3 are 50W both on input (CT side) and output (LOAD).
Your unbalance is perfectly normal. I have set 50W minimum load from the grid, and at the moment CT1= +31W, CT2= +40W, CT3= -28W (added +/- signs for clarity). When I got it in 2022 I was worried about it, but its fine, 50W is very low for minimum, if I set it to 100-200 it's much better looking on the CT's. My configuration is "Export to CT"