UG56 Smart UPS

Minimalist ESP8266-based controller for smart power management of UPS, inverters or any device with a power button.

The controller is typically installed inside the target device and connects directly to:

• the power button
• an ON/OFF feedback signal
• the battery voltage

UG56 Smart UPS can be controlled locally using a single button, or remotely over Wi-Fi via a built-in web interface.

It supports both station mode (connects to existing Wi-Fi) and access point mode, where the controller creates its own network for configuration and control.

The device periodically turns power ON and OFF to extend usable battery runtime during long outages, while keeping self-consumption low — without modifying firmware or relying on vendor-specific protocols.

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Visual overview

Project cover

Schematic

Breadboard prototype

Soldered version

PCB Designing

📂 The img/ folder contains more photos than shown above.

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Demo

Live web interface demo (no real hardware required):
https://universalgeek56.github.io/UG56-Smart-UPS/

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Why this exists

Most UPS and inverters are designed to stay ON all the time — even when the load doesn’t really need it.
During long power outages this wastes energy on self-consumption instead of useful work.

UG56 Smart UPS solves this in the simplest and most universal way: by automating the existing power button logic and adding timed power cycles.

In practice, you usually have to open the device:

• solder to the power button
• connect a feedback line
• install the controller inside the case
• bring the button, LED and optional switch to the front or rear panel

This is still a logic-level non-invasive approach: no firmware hacks, no reverse engineering, no proprietary protocols — just a controlled, repeatable button press.

Wi-Fi is used for remote control and configuration: cycle timings, thresholds and modes are set through the web interface,
while the controller continues to operate autonomously even without a network.

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Key features

• Modes: OFF / ON / Cycle (configurable ON & OFF times)
• One-button control
  • short press → change mode
  • long press → switch AP / STA
• LED feedback: mode indication + OTA progress
  (using onboard TX LED on ESP-01 or external LED)
• Battery protection: low-voltage cutoff with hysteresis
• Battery % estimation: separate charge & discharge curves (lead-acid)
• Offline-first: fully functional without Wi-Fi
• Web UI (optional): monitoring, control, OTA, Wi-Fi setup
• Power saving: Wi-Fi disabled automatically on critically low battery
• Persistent settings: stored in EEPROM

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Works with any device that has a power button, such as:

• UPS / inverter
• relay-based power modules
• generator controllers
• custom power devices

This is not limited to IT equipment. The controller can be used with any system that requires periodic operation, such as:

• heating or cooling elements
• lighting systems
• humidifiers and dehumidifiers
• aeration and ventilation
• mixers, pumps, and agitators
• other time-based automation tasks

The controller must know the current device state (ON/OFF) to operate correctly.
This is usually done via a simple feedback line connected to the device's power indicator or logic output.

No firmware changes or vendor-specific protocols are required — the controller simply:

• monitors the device state
• simulates button presses when needed
• applies timed power cycles autonomously

Supports any ESP8266/8285 module, including the tiny ESP-01.
ESP-01 requires a small hack to access the ADC (see https://github.com/universalgeek56/esp01-adc-hack),
while other boards (ESP-02 to ESP-12) already include an ADC, so no hardware hacks are needed.
On some boards, connecting pin 16 (wake-up) to RST allows ultra-low-power deep sleep and timed wake-ups.

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Hardware

• ESP8266 module (ESP-01, NodeMCU, Wemos D1 Mini, etc.)
• Voltage divider for battery sensing (typically ~20kΩ / 1kΩ)
• 2× optocouplers (or transistors):
  • power button emulation
  • device state feedback
• Designed for 12V lead-acid UPS / inverters

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Schematic & PCB

• 🧩 Schematic (EasyEDA): https://pro.easyeda.com/editor#id=ba064ebfc1004759837a427cbccaf71f Note: EasyEDA sometimes blocks direct navigation from external sites.
  If the link doesn’t open, paste it directly into the browser address bar.

• Wiring diagrams and photos:
  https://github.com/universalgeek56/UG56-Smart-UPS/tree/main/img

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Quick start

1. Click Code → Download ZIP

2. Extract the archive

3. Rename the src folder and main.ino to the same name, for example:

   Smart_UPS/Smart_UPS.ino
   

   ⚠️ Use Latin characters only, no spaces or special symbols

4. Leave all other files unchanged

5. Copy the project folder to Documents/Arduino/

6. Open Arduino IDE → select board and port → upload

PlatformIO / Git / GitHub Desktop users can clone and build the project as usual.

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License

MIT License
See LICENSE file for details.

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Related projects

• ESP-01 ADC Hack
  Reliable analog input on ESP-01
  GitHub - universalgeek56/esp01-adc-hack: