Multiple Battery Sensing - Change in Readings after battery disconnects


I am using an Arduino Uno to simultaneously read the voltages of 4 batteries and display them every certain time interval. Each battery is under 5 volts (so no divider needed), they are all on their own separate circuit with a resistor. Each circuit is then plugged into an analog pin to read the voltage.

It mostly works fine, but when I see when one battery hits its cut off, the voltage readings of the other 3 batteries abruptly changes by like ~.3 to .5 Volts. Then the same thing happens again when another battery hits its cut off. I am hoping the batteries can hit their cut off at different times and not effect their neighbors' voltage readings.

My question is, is this supposed to happen with the arduino uno? Is there a way around it? I am trying to figure out if there is something wrong with my circuit, like if I am not properly commonly grounding everything, or if this is just something that is going to happen no matter what. If I know its not normal, then I can start trouble shooting the circuit, but I don't want to burn hours of time if this is a known issue and I can't get around it.

Thank you for your time!

We can't see your code, we can't see your schematic.

This is more meant to be a high level general question; I am not technically sure if I am allowed to post the code/schematic in an open public forum despite myself being the author of both.

More just seeing if anyone has read in multiple battery voltages before with an arduino and if they have experienced something similar and can point my troubleshooting efforts in the right direction.

If there's bad impedance matching, you can sometimes do the trick of reading each input twice, but ignoring the first reading.

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@MechanicalFox, your topic was moved to a more suitable location on the forum.

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