Hello everybody,
after adding a third Pylontech US2000, I'm experiencing the Pylontech battery alarm Internal Failure.
First of all, my previous setup:
Multiplus-II GX (Venus OS 2.82), combined with 2 Pylontech US2000B-Plus (according the the part number) and an EM24, configured as a grid tied ESS system (AC IN connected only); grid tied PV micro inverter (Hoymiles)
The setup ran just fine, no problems at all. Even high load (2000W, deliberately limited in the settings) never threw any alarm.
Then I decided to add another US2000, this time it's a US2000C.
The SOC indicator of all modules showed the same number of leds lighting.
I connected the cables as mentioned in the manual and the Multiplus-II GX detected them correctly, the US2000C being the master.
I started to use a fan heater (1400W) the same evening, eventually the new module threw an Internal Failure alarm. Strangely, just 2-3 minutes earlier, the Maximum Cell Voltage shot from 3.29 V to 4.10 V. Just before that event, the Minimum Cell Voltage and Maximum Cell Voltage were just 0.02-0.03 V apart. Switching it off and on got it back working again.
The next days, the error came back again, even at night where there was almost no load (100-150W) at an SOC of 49%.
I kept the modules in Keep batteries charged mode over night. The next morning the Multiplus-II GX still reported being in Absorption mode.
Unfortunately, the error occurred again. So yesterday evening, I started to charge module per module separately (Keep batteries charged mode, all wires to the other modules disconnected). The SOC of all modules was off, especially from the new one. Every module was in Absorption mode when I ended the charge, the difference between the Minimum Cell Voltage and Maximum Cell Voltage was just 0.02 V. Every module didn't light up the SOC leds, so according to the manual, the module was in idle.
So I tried it another time. This time, I had some load (800-900 W, 25 minutes), the error didn't occur. Some time later (1 hour) I had some more load on it again (2100W, 42.6A, 49.56V, Minimum Cell Voltage 3.28V, 4.10V) and the error came back.
Was I not patient enough and should've kept it in Keep batteries charged mode until Absorption ended? Can Absorption end at all?
Does anybody have a clue the problem is and how it could be solved?
Thanks in advance.