Glad to hear that you got it working, about the voltage I’m not sure. I looked into the ArduPilot code and the call of the register 0x09 requires PEC support, which requires a version greater than 0011b. Maybe this was added after I programmed this.
uint8_t version = (data & 0xF0) >> 4;
// version less than 0011b (i.e. 3) do not support PEC
if (version < 3) {
_pec_supported = false;
_pec_confirmed = true;
return true;
}
Maybe try a large specification info…
The responsible ArduPilot code can be found here: https://github.com/Vabe7/ardupilot/blob/master/libraries/AP_BattMonitor/AP_BattMonitor_SMBus_Generic.cpp