Hello all, this is my first post but I am trying to learn as much as possible for a project that I just got some parts in for.
I am working on a datalogging device that will read the value from a load cell and record it to an SD card to be read later and inputted into excel. I am pretty sure that I have all of the physical aspect down, and I recognize that there will be some pretty fair inaccuracies because I am only using one load cell and I am limited to the 10 bit resolution of the Arduino Uno's ADC.
What I am working on now is making sure that the battery backup system is working properly, and I believe that everything on the battery's side is working quite well, it is charging, and it is capable of outputting a well regulated 5V (I measured it to be 5.08V). I am running into a problem with the delivery of that voltage to the Arduino. I have been using the Vin and Gnd pins, but the 5v pin only outputs 4.18v by my measurements, which I think could really skew the values that are read from the load cell, since it is expecting 5v.
I think that my options at this point, if I want to compensate for this difference, are to either supply the power from the battery directly to the 5v pin, or I could pull the Vin pin to the ARef and compensate for that in the coding.
I am not familiar with either of these options, so any and all input would be greatly appreciated. If any more information would help you guys out, I would be happy to provide it, feel free to ask. Thanks in advance for your help.