OK, after ultra-hyper-mega-slow shipping from digikey, parts finally arrived to my house.
Re-soldered resistor and recoms, re-flashed FW to rev.1, powered up with low cell battery, checked with 25V...
Then checked logs and found this:
- great_vdiv.png (33.41 KiB) Viewed 12894 times
Real voltage - 21.6-24V (current-limited PSU, was a bit floating on such low current).
After some measuring i discovered that in fact they sent me 80K resistors, not 8.45K...
I won't wait another month for some small resistors to arrive, will try to make something from existing parts around....
At least, powering from 6S works fine now.