🔋 How to Make a DIY Wi-Fi Router UPS at Home

If your Wi-Fi router disconnects every time the electricity goes out, this project will solve it permanently. In this tutorial, you’ll learn how to build a DIY Wi-Fi Router UPS at home using easily available components. It provides three different outputs: 12V, 9V, and 5V, so it works with Wi-Fi Routers, ONU, ONT, Modems, Switches, CCTV, and other DC devices.

This powerful mini-UPS works from a 12V battery and instantly switches power when the main supply fails — without restarting the router.

Supplies

Step 1: Components Required

Main Components

1. IRF9540 – P-Channel MOSFET (automatic switching)
2. LM2596 Buck Converter – Adjustable DC buck (9V/5V output)
3. XL6009 Boost Converter – (Used only if boosting needed)
4. DC Socket 12V (Input/Output)
5. 1N5822 – Schottky diode (low voltage drop)
6. 220 µF Capacitor (Electrolytic)
7. 103 Variable Resistor (10k preset for fine control)
8. 12V Lead-acid / LiFePO4 / Li-ion battery (2S/3S)
9. Wires, heat shrink, screw terminals, PCB or Vero board

Step 1: ⭐ Features

1. ✔ 12V, 9V & 5V output for all Wi-Fi routers and ONU devices
2. ✔ Instant switching (router never restarts)
3. ✔ Uses IRF9540 MOSFET for automatic changeover
4. ✔ Uses LM2596 for DC buck conversion
5. ✔ Uses XL6009 for boost conversion (if needed)
6. ✔ Uses 1N5822 Schottky diode for low-loss rectification
7. ✔ Compact, efficient and long backup
8. ✔ Protects router from burn or voltage drop

Step 2: Safety Precautions

1. Never short the battery terminals.
2. Check polarity before powering.
3. Do not exceed converter voltage limits.
4. Use proper heat dissipation for buck converters.

Step 3: 🧠How the Wi-Fi UPS Works

1️⃣ Automatic Switch-Over Section (IRF9540)

The IRF9540 P-MOSFET works as an ideal diode.

When the main 12V adapter is present → router gets power from adapter.

When the main power fails → MOSFET instantly connects the battery output.

✔ No delay

✔ No relay click

✔ No router restart

2️⃣ Voltage Regulation Section (LM2596 / XL6009)

For OUTPUTS:

1. 12V Output → Direct from battery (optional diode protection)
2. 9V Output → LM2596 Buck Converter
3. 5V Output → LM2596 Buck Converter
4. Boost output (if battery drops below 12V) → XL6009

The 103 preset is used to fine-tune output voltage.

3️⃣ Protection Section

1. 1N5822 prevents reverse current
2. 220uF capacitor smooths voltage dips
3. MOSFET ensures fast switching
4. DC socket ensures polarity safety

Step 4: 🔧 Circuit Explanation

12V Adapter → IRF9540 MOSFET → Outputs

If adapter fails:

Battery → IRF9540 → Outputs

Charging Section (Optional)

If you add a battery charging module (TP5100, 2S BMS), it provides auto-charging.

Voltage Outputs

1. LM2596 → trimmed to 9V using 103 preset
2. LM2596 → trimmed to 5V using 103 preset
3. Direct 12V output
4. Optional XL6009 for boosting from 8–12V to stable 12V

Step 5: 🛠️ Building the UPS (Step-by-Step)

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Step 5.1 — Install the DC Input Socket

This is your Main 12V Adapter Input.

Label it: 12V IN.

Step 5.2 — Connect the IRF9540 MOSFET

Source → Adapter 12V

Drain → Output to Routers

Gate → Battery + through resistor

1N5822 → Across MOSFET for reverse current protection

The MOSFET ensures seamless switching.

Step 5.3 — Add the Battery Terminal

Use 2-pin screw terminal:

1. Pin-1 → Battery +
2. Pin-2 → Battery –

Connect battery negative directly to all module grounds.

Step 5.4 — Install the 220µF Capacitor

Place it across:

+12V line → 220uF → GND

This reduces voltage drop during fast switching.

Step 5.5 — Add LM2596 Buck Converter (9V Output)

1. Connect VIN+ to MOSFET output
2. Connect VIN– to Ground
3. Adjust output using 103 preset
4. Set to exactly 9.0V

Label output: 9V OUT

Step 5.6 — Add Second LM2596 (5V Output)

Repeat the same:

1. VIN+ → MOSFET output
2. VIN– → Ground
3. Adjust to 5.0V

Label output: 5V OUT

Step 5.7 — Optional: Add XL6009 Boost Converter

If you want:

1. A stable 12V even when battery drops
2. A long backup

Connect:

1. XL6009 VIN → Battery/UPS output
2. Adjust output to 12V fixed

Step 5.8 — Add 1N5822 Schottky Diode

Connect in series with battery or DC adapter depending on your design.

This prevents:

1. Reverse current
2. Over-voltage
3. Sudden spike damage

Step 5.9 — Final Output Sockets

Add 3 DC sockets:

1. 12V OUT
2. 9V OUT
3. 5V OUT

All from MOSFET-controlled output.

Step 5.10 — Final Wiring Check

Before powering:

1. Check MOSFET orientation
2. Check 1N5822 direction
3. Verify LM2596 outputs using multimeter
4. Ensure no short circuits

Step 6: 🔋 Testing the Mini UPS

Test 1 — Power from Adapter

1. Router should power from 12V IN
2. No current drawn from battery

Test 2 — Adapter OFF

1. Router should NOT restart
2. Battery takes over instantly

Test 3 — Measure Output Voltages

1. 12V → stable
2. 9V → LM2596 trimmed
3. 5V → LM2596 trimmed

Test 4 — Load Test

Connect:

1. WiFi router
2. ONU
3. IP camera
4. Switch

Step 7:

📦 Step 7: Final Enclosure

Use a plastic box with:

1. Cooling holes
2. Battery compartment
3. Sockets labeled (12V/9V/5V)
4. LED indicator (optional)

Step 8: Video Reference

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Step 9: 🎉 Conclusion

You have successfully built a DIY Wi-Fi Router UPS that provides:

✔ 12V Output

✔ 9V Output

✔ 5V Output

✔ Instant switching (zero downtime)

✔ Long battery backup

✔ Router safe from fluctuations

✔ Reliable operation using IRF9540 + LM2596 + XL6009

This UPS can power:

1. WiFi Router
2. ONU/ONT
3. Switch
4. CCTV
5. IP Cameras
6. Small DC devices