I am monitoring the voltage of a 4 cell LiPo battery (max voltage 16.8V, maximum advertised current output = 60A) using a sensor with a maximum input of 3.2V.
I am using a 2-resistor voltage divider with R1 = 22KΩ and R2 = 4.7KΩ. This maps the maximum battery voltage to approximately 2.95V.
Vout = (R2 / (R1 + R2)) * Vin = (4.7KΩ / 26.7KΩ) * 16.8V = 2.95V
Once I have these values, how do I calculate the required wattage of the resistors R1 and R2?
As a practical matter I see many people using 1/4 watt resistors, but I'm interested in understanding the calculation myself.