I'm using an ESP32 with a 12V battery and solar panel. I've created a voltage divider for 0-15v (3.3v input to MCU at 15v at battery side). For that I used a 100kOhm , and 300kOhm to get a 0.3 ratio.
For measuring purposes, result measured is close enough (0.1v error), but Battery-wise, selecting those resistors were a good choice ?
MCU is powered using that 12v battery, using a buck converter.
12v battery is used, since it has a much bigger capacity (7Ah).
Charge voltages can get up to 13.5-14.0v, I took 15v as a upper limit.
4. The reason for asking was NOT about what ratio is better (0.3 or 0.25) in voltage divider, but what is right for consuming less power due to that R selection, since it seems battery drainage is faster than I expected.