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I use a power bank to power my Raspberry Pi, and I want to create script to turn off the Raspberry Pi when the battery level is low, but I cannot find any command to visualize the battery level.

I don't know if is possible. Does such a command exist?

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No Raspberry Pi can correctly measure its input voltage without at least one additional component.

https://github.com/aboudou/picheckvoltage

Some Raspberries can detect whether the input voltage is below 4.65 V or not - and provide a simple answer of yes/no , true/false. They use this binary distinction to display the undervoltage symbol.

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  • This is using a sledge hammer to crack a nut! An ADC to convert voltage then a program to monitor voltage is overkill. If you wanted to do this all you need is a comparitor and 2 resistors. Using a linear regulator is inefficient, and 1A inadequate for the Pi.
    – Milliways
    Jul 27, 2016 at 7:09
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    That gives only a yes/no answer to "Is the voltage too low ?'" , doesn't it ? I think the Pi can already "measure" that : raspberrypi.org/forums/viewtopic.php?t=82373
    – flakeshake
    Jul 27, 2016 at 7:16
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    As @MohammadAli said in the comments, monitoring the output voltage of a power bank is meaningless: the output will stay close to 5V until the cell is empty and you have to shut down. Feb 7, 2017 at 8:48
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Ideally you would need access to the battery terminals (not the 5V) to be able to measure it and feed into the software. For that I have been using the analog-to-digital converter ADS1115 and this tutorial from Adafruit https://learn.adafruit.com/adafruit-4-channel-adc-breakouts/python-circuitpython .

You would the need to know which voltage is "low enough" and then issue a shutdown command to the Pi. I've seen some solutions posted here, like this one: How to check how much battery is left on my Raspberry Pi in the terminal?

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