Can I create my own good reading in µA?

Question

This multimeter is in between a Rpi0 3.3V pin and a BME280 sensor VCC. Most of the time the sensor is sleeping. You can see on the picture, the reading is 620µA, which seems high. Now if I use the range mA the reading is around 0.16mA. From this question (A really basic question about ammeters and their ranges) should I conclude to not use the µA range from this multimeter? Or is there a way to mitigate the shunt knowing both range reading?

Edit 2 sensor datasheet:

Edit 3 circuit: Black Crocodile to COM and red crocodile to INPUT of multimeter. The red wire doing an arc above the Raspberry pi 0 was not plugged to the 3.3V pin at the time of the picture.

Answer 1

The numbers you are seeing on the meter may be just the result of its inherent inaccuracy. The meter error is specified as \$\pm(1.0\% + 7)\$, where the "7" means a count of 7 in the least-significant digit.

If you are on the \$400\,\mu\text{A}\$ range the meter's accuracy is \$\pm 4.7\mu\text{A}\$. The error increases by a factor of ten as you increase the range by a factor of ten. On the \$40\,\text{mA}\$ range the error is \$\pm 0.47\,\text{mA}\$.

I think your measurements are just noise on the \$\text{mA}\$ range. If you are measuring \$620\mu\text{A}\$ then you must be on the \$4000\,\mu\text{A}\$ range, and the inaccuracy of that value is \$\pm 47\mu\text{A}\$.

Answer 2

Check out the resistance that the meter has when used as an ammeter for very low currents. Most multimeters don’t behave like an ideal ammeter ( a short circuit), and so you can get quite a bit of voltage drop across the meter when measuring micro amps. This leads to big errors in low voltage circuits.