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I have a 5V arduino pro micro. I want to power it with a 3.7V lipo.

  • Should I use a step up module to convert it to 5V?

I also want to measure the voltage of the battery.

  • How can I do this?

Because I read that the power source also the reference voltage is so I cant measure it with an analog pin right?

I also use a lipo charging module to charge the battery.

Thanks for helping!

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2 Answers 2

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You can read the Arduino's supply voltage see here How to measure the supply voltage of Arduino without using an analog pin Alternatively use the internal 1.1V reference and a suitable voltage divider to read the lipo's voltage

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    I was just thinking if I use a step up module wouldn't the supply voltage be alwast 5V so I could use a analog pin without problems?
    – Robbe
    Dec 31, 2019 at 16:18
  • Yes, if the output of said module is always 5V, best would be to use one of those charger boards with over-current and over-discharge protection. Or use a reference design.
    – aaa
    Dec 31, 2019 at 17:42
  • Do you recommand a specific charger?
    – Robbe
    Jan 1, 2020 at 15:07
  • Because I don't know any, I've never seen or used them.
    – Robbe
    Jan 1, 2020 at 17:38
  • You could use arduino.stackexchange.com/a/50771/521 trick to calibrate the supply voltage, then measure the LIPO voltage on an analog pin and scale it appropriately.
    – Dave X
    Jan 23, 2022 at 22:10
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Yes, you should use a boost converter to convert the 3.7V from your battery to the 5V that the Arduino requires.

As I understand it, measuring voltage to determine charge level does not work well with lithium chemistry batteries since they hold a nearly constant voltage until they are almost completely depleted. Generally lithium batteries include a chip that measures current in and out and lets you query their charge level.

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    I don't think my battery has it. I bought this battery banggood.com/nl/… and this charging module banggood.com/nl/…. I was thinking to buy this converter banggood.com/…
    – Robbe
    Dec 31, 2019 at 20:07
  • Yeah, you need a smart charging module then, as Paul says in a comment on the other answer.
    – Duncan C
    Dec 31, 2019 at 20:32
  • What do you mean?
    – Robbe
    Dec 31, 2019 at 20:47
  • I mean that you should not use a dumb charger to charge a lipo battery. You need an intelligent charge controller.
    – Duncan C
    Jan 1, 2020 at 0:06
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    On this website the show the percentage of capacity in function of the voltage read from the lipo so it should be possible? google.com/amp/s/blog.ampow.com/lipo-voltage-chart
    – Robbe
    Jan 1, 2020 at 12:19

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