battery voltage measurement
gillesBaubrand 2026-06-12 20:27:20 281 Views1 Replies I bought a FireBeetle 2 ESP32-C6; the battery voltage measurement system is a bit off. The two 1-MΩ resistors in the voltage divider circuit are too high. You need to reduce the value to 150 kΩ; that way, the input current on the GPIO0 pin won’t interfere with the current in the voltage divider circuit.
Thanks for the feedback. Yes, a 1MΩ + 1MΩ divider has relatively high impedance, so the ADC reading may be affected by GPIO/ADC input leakage and sampling behavior.
Using lower values such as 150kΩ + 150kΩ can improve measurement stability, but it will also increase standby current. So this is a trade-off between battery voltage accuracy and low-power consumption.
For low-power applications, it is usually better to keep the original design and improve the result by software calibration, multiple sampling, and averaging. If higher voltage accuracy is required, reducing the divider resistance is a reasonable modification.
Yx 
