question

Pylons have been around a long time.

There were some challenges in the early days especially with packs with varied levels of charge.

Nowadays, not so much of an issue. If you follow the docs and use the tools available they just work.

Had far more grief with other manufacturers.

I’d also question how well sized an environment is of someone who currently maintains they have issues.

There aren’t many (any?) who allow the mixing and matching they do, with the level of discharge and associated warranty.

That alone should speak volumes.

@sharpener

They do.

In each manual they describe that what is what their bms has. E.g. the us300C in section 2.1. Features (10) as one example.

Is it physically there (balance system), yes i have opened and repaired a few.

Problem with Pylontec is often not the battery or its design. But how they are used on systems, you know the systems where they 'dont need such a big bank because their loads are... Blah blah..." And the other issue can be caused by the 8 battery stack install, with take off on the ends only.... Working the end modules to death quite literally.

Thanks both, seems at most to be a bit of an urban myth.

I would add that my own limited experience has been adding a third Force L2 module after 6 months, I made a small effort to match the expected state of charge and it all settled down within 48 hours, though the differential did increase from 20mV to 30 and has remained thus ever since. However from the above link that is quite usual/acceptable and has certainly given me no trouble subsequently.

[For the original enquirer I should mention that both @Alexandra and @nickdb have a great deal of experience and are regular contributors to this forum on all manner of topics.]

@sharpener

I just put 4*US5000s all new, onto an MPPT. One was about 90% charged as I connected it the previous day, the others about 50% each. By the end of the day (about 3 hours) they were at an average of 65%. Next day all at 100%, internal cell balance difference less than 30mV. Remember this is across 4 banks of 15cells. 60cells in all. Guessing from the indicator lights flash patterns, the high charged battery was charging the lower charged batteries, but that's only a guess.

There's a lot of uninformed and misleading speculation on the web. But as @Matthias Lange - DE said in the other thread, 30mV is nothing. And it's dead on spec.

Active balancing might get to balanced quicker if things are a long way out. But gentle low current as used by Pylontech is very good.

@sharpener
You call also inform your friend that the Pylontech modules employ battery balance / protection chips from the Texas Instruments BQ778xx family.
For example:
https://www.ti.com/lit/ds/symlink/bq77915.pdf?ts=1689633051897&ref_url=https%253A%252F%252Fwww.ti.com%252Fsitesearch%252Fen-us%252Fdocs%252Funiversalsearch.tsp%253FlangPref%253Den-US%2526searchTerm%253DBQ77915%2526nr%253D484