Maybe you mix something up here. The analog bestech BMS start to balance near HVC, the OZ890 stops to balance at HVC. That is the difference. You can set balance start voltage to any voltage for the OZ890, i use 3.8V for example. As said, HVC of the bestech is always very close to HVC, say you order 4.20V, you get a balance start voltage of 4.1V, that is how i ordered mine.
Anyway, I always set charge voltage above balance start voltage, but below HVC. This is how you did, too, if i get it right. Don't now if this is how "it should be done"... but at least this is the common sense here. And it works as intended that way.
You can find a complete list of features of the OZ890 in the datasheet. I have not found any hidden registers yet. All i can find in the cownboy tool can be found in the datasheet, too. If you have assignment problems here, you can compare register addresses from the Cowboy tool EEPROM file with the addresses given in the datasheet. That's how i did.
We finished to read and interpret the full list of registers by now...but do net yet have a GUI for that. As soon as we have, i can send you a µC you can use for debugging/monitoring with your PC. We proceed with writing all the settings now before we make the GUI so we finally have full access to the chip. Then we still want to add packet Error check, which does not work for the current version of the Cowboy tool as well.
I did not talk to O2 anymore, i'm a bit disappointed from their software development. Waiting years of it to come, but still no full access, no working Error check, still foulty readings when Error events occur (like current in HVC), still bugs in the connection...at least we got a Win7 x64 version now and can calibrate the Temp sensor and can check for PF error occurrence...what a break through
BTW, my external overtemp error seem to have it's reason in a faulty sensor. Tested a second board which works just fine with the Win7
