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Comment on How to improve my battery measurement circuit?

Could you do similar to diagram 2, but instead of an N-FET use a P-FET between the battery and first resistor in the potential divider? Add a gate pull up to source, have the micro pull the gate down to take a measurement. The micro will see 0V or divided battery voltage.

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nilclass@discuss.tchncs.de ⁨1⁩ ⁨year⁩ ago

Could you do similar to diagram 2, but instead of an N-FET use a P-FET between the battery and first resistor in the potential divider?

That’s a great idea! Unfortunately I don’t have a P-FET lying around, so cannot try it right now.

Or use a zener/TVS diode instead of second resistor to clamp the voltage instead of dividing (more robust).

Not sure I understand this point. Which resistor would you replace with a diode?

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- Yonrak@feddit.uk ⁨1⁩ ⁨year⁩ ago
  
  Not sure I understand this point. Which resistor would you replace with a diode?
  
  Sorry, I think I was talking nonesense (doing this in my head and just woke up 😅).
  
  Not sure it’ll work with just a P-FET actually. You’ll likely need to control the PFET with a NFET, otherwise you still end up with too high a voltage on your control pin when the FET is off due to the gate pullup (unless you can use a fet with a very high Vgs Threshold).
  
  The above comment about diodes was to protect the microcontroller pin, but you end up not being able to control the FET doing it that way.
  
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