Low battery indicator

Projects General Guidance
1

Hello,
I have an arduino nano 33 BLE and i read accelerometer and gyroscope data from it and i classify them with machine learning to different activities.
I have an rgb led that is turned on every time i do a specific activity.
I would like to ask if it is possible to make another led turned on every time the battery is getting lower, with a 9v battery, connected to the vin pin.
I know this battery is not the best option but i use it because its easier.
I have found this circuit for arduino uno:

Can i use the same to my arduino nano 33 BLE or is there any case that i will burn it? Is it safe enough?

2

Most people would use a simple resistive voltage divider to reduce the battery voltage to be within the range of the Nano 33 ADC. 22K + 10K for a reduction ratio of 10/32 would be fine for a 9V battery, but you might want to calibrate it if you use standard tolerance resistors.

For lower power drain use 220K + 100K, but add a 10 nF capacitor from ADC input to GND.

3

Hi, @spiros99
Welcome to the forum.

Can you please tell us your electronics, programming, arduino, hardware experience?

You need to Google;

potential dividers arduino

Thanks.. Tom.. :smiley: :+1: :coffee: :australia:

4

Thank you very much! It really helped me :smile:

5

When it is time to put the LED on, make it blink with a low duty cycle.
That way you don't fully deplete your ailing battery so quickly.

6

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