After placing a cage around the ends of the high power resistor loads, a test was ran with the new amp meter to verify the robot shop amp meter was being properly read by the UNO. Here is the excerpt of that first test:

Keep in mind that the layout of the comma separated values are:

Program State, Time, Voltage, Current, Resistor loads active, UNO USB voltage

Looking at time stamps 65 and 70 shows the USB voltage changed values along with the current and voltage readings. The external ammeter and voltmeter were not fluctuating this drastically. This appeared that the USB voltage that was seen by the UNO was affecting the reading of the current and voltage.

A discrepancy was also seen in the overall reading that was adjusted out with the newly added offset feature. But the adjustment was not able to correct the change in readings as the USB voltage fluctuated. This can be seen by the next test:

Wanting to get rid of the fluctuation, I chose to use an external 9V supply to feed the UNO. This still did not fix the problem as seen by the next test:

At this point, I started to wonder if it was the external supply or the 5V regulator built into the UNO board. I knew the Relay board could pull a load, but this load may be more than the UNO could supply. To bypass this, I placed an external supply feeding directly into the relay board and USB voltage only to feed the UNO. This did work as seen by the test results:

The voltage reported by the UNO locked into 5.051V and only once deviated to 5.073V. Along with this, by using the correct offsets for voltage and amperage, the UNO reported values consistent with the external ammeter and volt meter.

The next step is to install a dedicated 5V regulator that will only feed the relay board and be fed by the 12V battery. This will cause a small deviation in the current readings if wired before the ammeters. This will have to be installed after the ammeters so that they will see the current flow.

The problem that I do have with this discovery is that the calculations to correct for this discrepancy were not working. This will also be looked into further.