Turn Your Old Laptop Charger Into USB-C Charger!

Have you ever wondered what to do with that old laptop charger gathering dust in your drawer? Before tossing it out or letting it rot away, consider this: that charger still has plenty of power — and potential left in it! In this tutorial, I will show you how to re-purpose your outdated laptop charger and transform it into a useful USB-C power supply. Whether you’re a hobbyist or just someone who likes to tinker, this project not only reduces electronic waste but also gives your old hardware a second life.

1x Fast Charging Module

1x Male-Male USB-C connector

1x Soldering Iron

1x Pliers

Old laptop chargers typically output 18 to 20 volts of DC power, which is too high for direct use with USB-C devices that expect 5V, 9V, or 12V. To safely convert this voltage, we use a fast charging module — an affordable, small device that steps down the voltage to a suitable level. In the video, we used a DC-DC fast charging module with a built-in USB-C output. This allows the laptop charger’s higher voltage to be converted into a stable 5V or 9V USB-C signal, perfect for powering or charging modern electronics.

First, identify the positive (+) and negative (-) wires coming from the laptop charger. Take as reference picture above but always double check with multimeter. Carefully strip and prepare the wire ends for soldering or secure connection. Then, connect these wires to the input terminals of your fast charging module, making sure to maintain proper polarity. Once the power supply is connected, plug in a USB-C cable and use a multimeter to check the output voltage before connecting any devices.

Re-purposing electronic devices requires attention to safety. Always double-check your voltage levels, polarity, and ensure there are no short circuits. If the converter gets too hot or behaves unpredictably, disconnect it immediately. It’s also a good idea to house the entire setup in a plastic or 3D printed enclosure to prevent accidental contact with exposed wires. By taking these precautions, you’re not only protecting your devices but also ensuring your own safety during and after the build.

Reusing an old laptop charger is not just a cost-saving hack — it’s also a great introduction to electronics. You’ll learn about voltage regulation, power supplies, and USB standards in a hands-on way. Plus, you’re actively reducing e-waste by giving new purpose to a device that would otherwise end up in a landfill. It’s a rewarding project for beginners and a practical one for makers who need a reliable power source for Raspberry Pis, Arduinos, or even as a quick phone charger.

The final result is a versatile, portable USB-C power brick that can be used around your home, in your workshop, or taken on the go. Whether you're charging phones, powering microcontrollers, or creating custom power solutions, this small project demonstrates how old electronics can be turned into something useful, educational, and eco-friendly. So next time you consider throwing away that charger, think twice — it might just become your next DIY project!