manInTheMiddle

Good to hear that it worked okay for you.
 
Since Pylontech is not publishing release notes for the FW, it's hard to say what are the improvements and if they are significant or not.
Version 1.7 for US3000C is the first one that is able to report cells with the lowest/highest voltage/temperature in the stack, while not exhibiting "cell overvoltage" bug. Should work perfectly with the Victron Cerbo and CAN comm, if you have it.
Personally, I am running version 1.7 on 8 batteries in a stack for years, connected to non-Victron inverters. And I'm not planning to upgrade the FW, since the setup works fine for me.
Some of the newer FW versions are relevant for UP5000, since they allow higher discharging current that was not possible on UP5000 hardware in the past. (BIN file for US2000C, US3000C and UP5000 is unified.)
Also, beware that version 2.2 might introduce some unwanted features, like the mandatory heartbeat - see the discussion led by @Tinbum on the previous pages.
 
Anyway - if your battery has a fluctuating voltage issue, I would suggest you to contact Pylontech support via email first, since the solution might be a bit more complicated than just a FW upgrade.

God bless that one can un-brick the battery bricked by the wrong FW.
Also, it's good to know that Pylontech FW can be downgraded. Something, that's less and less possible in the enterprise IT world.

OK, I took the v1.7. Is there big enhancement for the v2.2?
It worked! Thank you!
It was the zip file not working, with the bin it was no problem. Now I have to observe if the battery voltage is still kind of 'jumping' ...
 

Seems like the old chip is now the new new chip.

They are shipping with FW 3.0 preloaded for the old chip? And even using the old chip for the new SerialNumbers, after C2? Hmm, what a mess 😮
 

The ZIP file method works great if the battery is not bricked. Once bricked, go with the BIN.
If you have US3000C battery with ...C3... in the serial number, then try to flash one of the attached BINs. Both are meant for the "New Chip":
Us_c_Nt_V1.7_Crc.bin US_E2_V2.2_Crc.bin

BTW,
A lot of GUI errors is caused by the locale of the computer not being set to EN-US. Since the first flash ended at 80%, it was clearly the wrong firmware. It's crucial to find a correct one first. When in boot-loader mode, flash the extracted BIN file directly, not ZIP.