🔋 DIY Wi-Fi Router UPS With Auto Changeover

If you face frequent power cuts that disrupt your Wi-Fi or internet connection, this project is for you.

Build your own Wi-Fi Router UPS (Uninterruptible Power Supply) using a 2S 8.4V battery pack, XL6009 boost converters, and automatic changeover circuit.

This UPS instantly switches to battery backup when the main power fails, keeping your router and ONT online without reboot or delay.

⚙️ Project Highlights

1. Automatic Changeover – Zero delay
2. 2S BMS for battery protection and charging balance
3. 8.4V Li-ion Battery Pack (2×18650 cells)
4. 12V Input, 2A–3A
5. 4 Outputs – 12V, 12V, 9V, 5V USB
6. LED Indicators for Charging, Full, Power, and Battery Level
7. Compact PCB Design (EasyEDA/KiCad)
8. Designed for Router, ONT, CCTV, or IoT Devices

Components Required

1. XL6009 Boost Converter IC – 2 pcs
2. 18650 Li-ion Battery (3.7V, 2200–3000mAh) – 2 pcs
3. 2S Li-ion BMS Module (8.4V, 10A) – 1 pc
4. Schottky Diode (1N5819 or SS34) – 2 pcs
5. Electrolytic Capacitor 470µF/25V – 2 pcs
6. Electrolytic Capacitor 100µF/16V – 2 pcs
7. Resistor 10kΩ – 2 pcs
8. Resistor 100Ω – 2 pcs
9. LED – Red (Charging Indicator) – 1 pc
10. LED – Green (Full Charge Indicator) – 1 pc
11. LED – Blue (UPS ON Indicator) – 1 pc
12. DC Power Jack (5.5mm) – 4 pcs
13. USB Port (Type-A Female) – 1 pc
14. Slide Switch (ON/OFF) – 1 pc
15. 12V DC Adapter (2A–3A) – 1 pc
16. Heat Sink for XL6009 – 2 pcs
17. PCB Board (Mini Router UPS V4 Layout)

Input Voltage: 12V DC

Input Current: 2A to 3A

Power Adapter: 12V SMPS or Router Adapter

Battery Type: Li-ion 18650

Battery Count: 2 Cells in Series (2S)

Battery Voltage: 7.4V Nominal / 8.4V Full

Battery Capacity: 2200mAh to 6000mAh (depending on cells)

Battery Protection: 2S BMS Module

Output 1: 12V, 0.5A (Router 1)

Output 2: 12V, 0.5A (Router 2 / ONT)

Output 3: 9V, 1A (Switch / CCTV)

Output 4: 5V, 1A USB (Wi-Fi Dongle / Mobile)

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1. Power Input Section – The 12V adapter powers the circuit and charges the batteries simultaneously.
2. Battery Management Section – The 2S BMS ensures balanced charging, overcharge and discharge protection.
3. Boost Conversion Section – XL6009 ICs step up battery voltage (7.4–8.4V) to fixed 12V and 9V outputs.
4. Auto Changeover Section – Schottky diodes switch power sources seamlessly when the input fails.
5. Indicator Section – LEDs display charging, full battery, and UPS ON status.

1. Normal Mode (AC Power ON)
2. Router is powered directly from the 12V input.
3. Battery charges via BMS module.
4. LED shows “Charging” (Red) or “Full” (Green).
5. Power Failure Mode
6. Power automatically switches to battery (8.4V boosted to 12V).
7. Router and ONT continue running without disconnection.
8. LED shows “UPS Active” (Blue).
9. Auto Recovery
10. When mains returns, circuit switches back to input power instantly.
11. Battery charging resumes automatically.

This schematic includes two XL6009 boost converter modules, 2S battery pack, auto changeover diodes, and LED indicators for charging states.

The compact 2-layer PCB is designed with:

1. Dedicated DC jack outputs (DC1–DC4)
2. Separate tracks for input and battery
3. Easy solder pads for BMS, battery, and converter modules
4. Space for heat sinks and indicator LEDs

Step 1: Connect two 18650 cells in series (B+, B–).

Step 2: Connect BMS board between cells (B+, B–, BM).

Step 3: Connect B+ and B– from BMS to UPS board.

Step 4: Use a 2-pin JST connector for easy removal.

DC1: 12V Output (Router)

DC2: 12V Output (ONT)

DC3: 9V Output (Switch)

USB Port: 5V Output (Wi-Fi Dongle / Charging)

LED1 (Red): Charging

LED2 (Green): Full Charge

LED3 (Blue): UPS ON

LED4: Battery Percentage (Optional)

Use only matched 18650 cells of the same brand and capacity.

Ensure proper heat sinking for XL6009 converters.

Use Schottky diodes for fast switching and minimal voltage drop.

Insulate all terminals properly.

Avoid over-discharge below 6.0V.

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Input Voltage: 12V DC

Battery Voltage (Full): 8.4V

Battery Voltage (Cut-off): 6.0V

Backup Time (2×2200mAh): 2.5 – 3 hours

Backup Time (2×3000mAh): 4 – 4.5 hours

Changeover Delay: 0 milliseconds (instant)

Charging Time: 3 – 4 hours

Efficiency: 88% – 92%

Load Support: Wi-Fi Router, ONT, CCTV Camera, or IoT Node

Continuous internet connection during power failure.

Compact and easy to mount near router.

Automatic charging and cut-off protection.

Supports multiple DC voltage outputs.

Plug-and-Play design for home or office use.

This DIY Wi-Fi Router UPS is an ideal low-cost backup solution for routers, modems, and network devices.

With auto changeover, 2S BMS safety, and multi-output support, you’ll never lose your connection again.