# Battery Monitor

Day 77 of the 100 Days 100 IoT Projects collection. Board: ESP8266.

Watch a 18650 cell's voltage through a divider on the ESP8266, reported to Blynk. Never guess battery level again.

## How it works

A resistor divider scales the 18650 cell's voltage down into the ESP8266's ADC range, and periodic readings go up to Blynk as a battery gauge. Voltage maps to charge level through the cell's discharge curve, so the dashboard shows a meaningful percentage instead of raw volts.

## What you'll learn

- Voltage divider design
- Battery discharge curves
- Remote battery telemetry
- ADC range scaling

Full project (code, wiring diagram, Wokwi simulation): https://github.com/kritishmohapatra/100_Days_100_IoT_Projects/tree/main/Battery_Monitor_with_Blynk_IoT

Summary by SkillShop. Code and diagrams belong to the original repo.