Custom voltage divider for Jumper T8SG running dTX

After inserting 4xAA Li-ion 3.7V cells i found out that voltage measurement caps at 9.09 volts. When investigating further i found that stock voltage divider (470k/750k) saturates the analog input of the controller at any voltage values above 9 volts. (divider makes it 3.5+ V) And 9 volts is basically deadly for 4S li-ion. So i had a way to monitor the voltage.

I managed to replace the 750K with a 2.2M resistor, putting the divided voltage well within the range of analog input.
I now can set up a minimum voltage and see the whole range of charge properly. Yet its wrong in the values.
Now i have an issue - i cant calibrate the battery sensor - 16.8V input is shown as ~8 and 12.8V is around 6V on the display. I tried addind tx-voltage-divider = 2.285 to hardware.ini yet it changes nothing. Any ideas how i can fix it and calibrate the displayed voltage?

running latest Deviation Nightly build from downloads page

As far as I know the only way to change the battery readout scaling is by changing the code. If you can build the code, the values to change are VOLTAGE_NUMERATOR and VOLTAGE_OFFSET in file target/tx/devo/devo7e/target_defs.h.

The value are used in the function PWR_ReadVoltage. Unfortunately I don't know how those constants are related to the voltage divider values. I'll check the history for any notes.

Running at 12-14 volts will put a lot of strain on the voltage regulator. Recommend using just 2 or 3 cells.

Where did you find "tx-voltage-divider"? Don't see anything to support that in the code.