well there still is something spookie in this formula.The real thing is that in testing it works.I have a 5V power supply connected to A0 pin.I defined the VBATSCALE 50 (as it say in 0.1V steps). i can see the analogRead function reading correctly the pin.I have initialized the led on pin 13 and VBATLEVEL1_3S to 45.
With the potmeter if i turn down the supply to less than 4.5Volts on the analog pin the led start blinking.i tryed different voltage levels and it works perfectly.I just dont understand the math under that formula.Still must be something with that shift.