Hi everyone,

When using a V1.1 Grove Voltage Divider to check a stable 12V (provided by a 2A wall adapter) the readings are off by about 0.6V. (12.7 vs actual 12.08-12.11). I’m running this from an Arduino Nano with the groove board, powered by my PC’s USB port.

- I checked with a second identical V1.1 Divider (on a different Pin) and got the same measurements.
- I measured the 12V using 2 voltmeters (12.08-12.11)
- I tried both the 3 and 10 setting.
- I used the provided x * sensorValue * 4980 / 1023.00 with 1000-10000 samples with a 2 ms delay.
- I’m seeing the same voltage differences when also reading other voltages from other sources.

I’ve collected the 12V results into an array and did some math on them and the sensed voltage looks stable but not accurate:

10 setting:

Array Min : 12656.00

Array Max : 12705.00

Array Square Sum : ovf

Array Arithmetic Average : 12697.16

Array Geometric Average : 12697.18

Array RMS Average : 12697.18

Array Extended RMS Average : 12697.52

Array Q1 : 12705.00

Array Q2 (Median) : 12705.00

Array Q3 : 12705.00

Array IQR : 0.00

Array Standard Deviation : 18.05

3 setting:

Array Min : 12778.00

Array Max : 12822.00

Array Square Sum : ovf

Array Arithmetic Average : 12796.12

Array Geometric Average : 12796.06

Array RMS Average : 12796.12

Array Extended RMS Average : 12796.04

Array Q1 : 12793.00

Array Q2 (Median) : 12793.00

Array Q3 : 12807.00

Array IQR : 14.00

Array Standard Deviation : 10.23

How can I fix this? Thank you for your time.