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Topic starter
January 4, 2025 9:06 pm
I was trying to top charge( 58.3V ) my 3 battery packs and switched the 18KPV to stop charging at 58.3V instead of 101% SoC and it was putting in 4kW of power until I changed a BMS setting I thought needed changing and now it's only charging at 600W. I can't get it back to using all the PV and it's back to selling excess back to the grid even though the batteries are at 98% or better yet, 52.6V.
Is there something I can switch or do I have to wait until a nights discharge and a charge cycle restarts?
Topic starter
January 5, 2025 6:02 pm
It's now exporting 2kw to the grid even though the batteries are at 77%/52.5V. Anyone know which setting will stop it from feeding the grid with battery charge needed?
January 5, 2025 6:14 pm
Which BMS setting did you change? And what is the "BMS Limit Charge" value reported by the 18K?
Topic starter
January 5, 2025 7:02 pm
Which BMS setting did you change? And what is the "BMS Limit Charge" value reported by the 18K?
I had changed the setting on the BMS Config page which said 15S for the battery configuration to 16S and that bounced the battery(rebooted) but also showed grossly incorrect battery cell voltages. I quickly changed that setting back to 15S and saw the battery cells and information go back to reasonable numbers.
The BMS Limit Charge is/was either 553A or 150A depending on if it is reporting 1 or 3 battery packs.
So I think the BMS communications with the inverter has degraded. I switched my battery IDs around and made my #2 battery the #0 battery and now the Inverter is pushing most all of the PV to the batteries and is not back-feeding the grid.
FYI, the Tian Power/Basengreen BMS settings software really sucks.
January 5, 2025 7:30 pm
The BMS Limit Charge value changes dynamically (at least it does with the EG4 BMS). You could look at the data history and see what the value was when the 18K was only charging with 600w, just to see if there's any correlation. I have found that regardless of the charging settings on the inverter, the 18K will only supply as much charging current as that BMS limit allows.
To compare the BMS limit with the charging current, the values in the data history log are named "MaxChgCurr" and "BatCurrent".
DougL reacted
Topic starter
January 5, 2025 8:26 pm
@jlankford great idea looking at the inverter data details.
I can see when it happened, at 11:35a and that's what I see when I look at historic graphs. but the correct battery BMS Limit Charge value has been back to 553A well after that and as of this morning but it wasn't until I changed the primary battery that it started working as before. Going to dig more into these data elements to see if I can pinpoint what changed.
BTW, the Tian/Basengreen software Config element I changed was cell count and I think I found the problem.
for one thing, I should have isolated the battery communications I was changing the cell count on. i believe the software got a bad read or I misread 16S for 15S. Either way, the previous primary battery, the one which was communicating with the inverter, was only showing 15 cells and it's summed voltage was only for 15 cells AND the cell count setting was showing 15S. I changed the cell count to 16S and as expected the 16 cells showed and the summed voltage was correct. I also looked at my 2 other batteries and battery #1 also had 15S so I changed that to 16S and I didn't have to change the new/current primary which was #2 previously as it was showing 16S and all 16 cells.
I knew something was up with battery #1 because the bluetooth app was showing an error for cell 16, 0 voltage. After setting the BMS to 16S now the bluetooth app shows correct data. Cockpit error possibly due to a bad communications reading since I see lots of comm read fails when I'm reading from the BMS. ugh. And it's only talking at 9600 baud!
January 5, 2025 8:49 pm
FWIW, when looking at the BMS data or changing settings on an EG4 battery, you have to take the battery offline communications-wise. The battery can't communicate with both a laptop and the inverter at the same time. It's possible that there's a software corner-case in the inverter where they didn't take into account the BMS parameters might be changing, etc. while the BMS is still communicating. With an EG4 batt the communications is basically re-initialized with the inverter, so I can imagine the inverter software expecting to get all new readings for all the BMS parameters whenever a BMS setting is changed, and might get very confused if anything in the battery was changed on the fly.
You might need to get in the habit of rebooting everything whenever you're messing with your batteries' BMS.
This post was modified 2 days ago by JLankford
DougL reacted
Topic starter
January 5, 2025 9:48 pm
I agree that is a good idea. Thanks for the feedback!
