At the moment I'm running an Arduino with an 1S LiPo (3.7V) with an
5v Step-Up regulator. Now I like to monitor also the lipo voltage with
an Analoge input. But when I do connected the battery to an Analog
Input it always reads ~5V.
How can I get the real value of around 4V?
I know this question has alredy been asked in the old forum but the solution didn't worked...
That doesn't sound right at all. Could you post a drawing showing how you have wired the batter/dc-dc convertor/arduino power and analog input pin/ and all the gound connections ?
I'm pretty sure you must have something wired incorrectly. What you wish to do should be straight forward.
It is possible that the step up regulator is generating noise that is giving you a false reading. Try and have a potential divider across the battery and measure across the bottom resistor. Also put some capacitance across the input, to try and reduce the noise.
Do you have a link to that DC/DC converter? I'm wondering if it could be an isolated converter (no ground continuity from input to outout) ? If not, can you use a ohm better and see if the negitive in and out pins show continuity?
The first way you showed it wired up should work if it's not a isolated converter. Not sure about it being a noise issue or not, only a scope would verify that or not.
retrolefty:
Do you have a link to that DC/DC converter? I'm wondering if it could be an isolated converter (no ground continuity from input to outout) ? If not, can you use a ohm better and see if the negitive in and out pins show continuity?
The first way you showed it wired up should work if it's not a isolated converter. Not sure about it being a noise issue or not, only a scope would verify that or not.