I have an issue with reading battery voltages of three 12 volt batteries using an ESP-01 and an ADS1115. I have been graphing the measurements and the all of the graphs have a temperature component to the readings. As the outside temperature increases, so does the reading from the ADS1115. I have verified that battery voltages do not change with the temperature. I have also recreated the problem by heating up my project case and seeing a great increase in the readings. Both of my voltage divider resistors are made of the same material, so I would have thought that the changes in resistance would affect both components and not change the reading much. I have replaced the LD1117 with a 3.3v buck converter and the problem still exists.
Details of my project are located here: https://hackaday.io/project/167291-rv-battery-monitor
ThingSpeak data graphs: https://thingspeak.com/channels/870224
Any ideas where the temperature component error is originating?