Dear Arduino Community,
Recently I have been working on a project to detect pollutant concentrations in the air and report them live. I am using an Arduino Nano to process data from the DHT11, MQ-135, Figaro 2600, and Figaro 2602 sensors which I have integrated onto a PCB. The processed data is sent to a NodeMCU module which uses its WIFI capabilities to send the values in PPM to a ThingSpeak channel. Attached below is an image of the current circuit I am working with. I need help powering the circuit. I prototyped the project using 6V AA battery packs which only lasted for about 8 hours in earnest. Now, I need a method to provide a stable output of 5V to each sensor and meeting the minimum requirements of the Nano and NodeMCU. I cannot really consider intermittent data collection since the whole idea is to record data continuously. I need a relatively inexpensive and small method of powering the circuit since I building 20 of these units and placing them outside near highway tunnels, chemical waste dumps, and factory units. I was considering solar power, but I am inexperienced with how to implement a reliable system. If you could please provide some guidance I would greatly appreciate it!
Thank you in advance.
**P.S. I understand the way I made the circuit is not the best. I could have just use 5V and GND markers instead of drawing the wire.