How to use the MCP3008-I/P chip to help your Raspberry Pi read digital data from analog sensors
How to read data from analog sensors using an MCP3008 with Raspberry Pi
GitHub - Maker-Melissa/Hackulator-Battery-Monitor: This is a Simple Battery Monitor that sits in the System Tray on a Raspberry Pi system that interfaces with a MCP3002/MCP3008 ADC.
9 Raspberry Pi Analog to Digital Conversion using MCP3008 ADC – 36 Projects
PiCheckVoltage : monitor battery voltage - Raspberry Pi Forums
DSAIL power management board: Powering the Raspberry Pi autonomously off the grid - ScienceDirect