Sorry yet another post on the issue since I do not find the solution.
I have a Multiplus II with a Pylontech US3000C that has been working OK for 3 months, the battery was charging to 100%
After 2 cloudy weeks the batteries could not be charged to 100%, they stayed with SoC between 50 and 80% with the battery life option enabled.
Last Sunday it was sunny but the the system behaves weird:
-SoC increased from ãround 60% to 89% in a normal way, but afterwards it is blocked. A couple of hours with the MMPTs inyecting around 1000watt did not increase the SoC over 89%. The voltage was slightly increasing to 50,5 and temperature from 21 to 23 deg. Min cell 3.330 and max 3.332, it seems to be balanced.
Still cloudy and I tried yesterday to charge the battery with the grid but it has the same effect, I inyected 1000watt during 1 hour but the 1 kwh only increased the Voltage till 50,8 (and back to 50.5V when the charging stops). Cells continue having a good balancing around 3,386 to 3.388V. Temperature increased from 21 to 26deg but not the voltage nor the SoC.
I read in another post that at 89% the balancing starts, but my cells seem to be balanced. Another suggestion is firmware ulgrade to v2.8, I will try to make the cable and load it.
I am quite puzzled. I was expecting that at least the voltage would raise to 51-52V, even if the SoC is not increased by the internal logic of the BMS. How can the battery absorve so much power apparently for nothing? The battery capacity is 3,5 Kwh, can it waste so much power for balancing or other BMS stuff without increasing at least the voltage? Or may be I have to try longer (4-8hr) with a lower current. What is the recommended current and time to cross the 89% barrier?
There are SoC-Voltage curves from other LIFEPO manufacturers.
https://www.jackery.com/blogs/knowledge/ultimate-guide-to-lifepo4-voltage-chart
They could explain that the voltage does not increase with the SoC during most of the charging, but if I am close to 89% I would expect more voltage variations. I can try to inyect more than 1 kwh to see if I cross the magic 89% barrier... but instead of saving energy with the battery I am wasting a lot
Thanks
Carlos
