Lora node - current drain in digital pin and accuracy

Hi,
Following your tutorials, I made a lora node with arduino pro mini 3.3v and a 16850 battery (3.7V). I also removed the voltage regulator to decrease power consumption. I am using soil moisture sensors that drain 24 mA each one and if I use the digital pins to power them, the voltage drops below its limit and gives random values.


Another question. If I don’t have a regulator, when the battery goes down I won’t have a stable power source on the sensor, can this affect accuracy?
Regards

Hi, 24mA for each pin should be ok, max is about 40mA so there is still some margin. However I don’t know why you observe the voltage drop? Do you mean the output from the sensor?

If you remove the voltage regulator then the board will be powered directly with what comes from the battery. It may affect reliability if the voltage decreases a lot. But this is quite normal and you won’t be able to avoid this even with the regulator because a regulator also need a significant difference in voltage to operate. So if the battery voltage drops, the regularor won’t work anymore. So in both cases, if the battery gets older then reliability issues occurs and it will be time to change the battery.

Hi Mr Pham, you are correct, the maximum is 40 mA but the drop voltaje at the pin output is huge, and the sensor is out of range…look at the figure.
So if I need accuracy I should work with a higher voltage that allows the regulator to continue working when it is unloaded. Maybe put a solar panel to increase autonomy …
And if the duration of the battery is more important, I remove the regulator, lowering the consumption and resign a bit of accuracy in the measurement.
What do you think?
Is it posible to have low power consumption and accuracy at the same time??
Regards!

I don’t really understand this figure. What pin is it? The output of the sensor? The digital pin that powers the sensors?