Measuring the battery level powering the arduino

Question

I would like to power my arduino nano with a 9V battery, but I would also like to measure the voltage of the battery to know its charge level.
Can I use the MAX471 Voltage Current Sensor module by connecting the VIN pin to my battery and VOUT to my arduino ?

• Dave Newton: hackaday.io/project/25461-reading-the-max471-sensor-module, also github.com/wisewolf/Arduino-Power-Meter.
• jsotola: what kind of a 9 V battery?
• Boggyman: If you only need to measure voltage, why not use an Arduino A/D input? All you need to do is connect a voltage divide across the 9V terminals to divide down to the A/D range. Use big resistors in the 100K to 1Meg range for low drain.
• DataFiddler: @Boggyman: If there are other analogRead channels active, 100k to 1M might be a bit high to load the ADC in time. An additional capacitor in parallel to the voltage divider low side might help...
• NOMAD: @jsotola This is a 9V GF22

Answer 1

If you want measuring a "battery level" in mAh for example, you must measure Voltage AND Current, so INA219 is a better deal (it is a I2C control).

• NOMAD: Are you sure that this would allow me to power my Arduino, if so is there a difference in autonomy with this module rather than the assembly of @Boggyman (less wasting) ?