DIY Portable (Cordless) Variable Bench Power Supply

In this project, I’ll show you how to build a DIY Portable Bench Power Supply — a compact and reliable power source for all your electronics projects.

This power supply can deliver variable voltage and current (0–36V / 6A, up to 120W max), making it perfect for testing circuits, powering microcontrollers, and prototyping anywhere you go.

The design is built around an SK-120 DC-DC converter module, enclosed in a 3D-printed custom case featuring banana jacks and a car lighter socket for extra versatility.

The SK-120 module can also be used as an MPPT solar charge controller. For testing purposes, I added a 2-pin pluggable terminal block connector to easily connect a solar panel. This feature is optional — if you don’t plan to use solar input, you can simply omit this part.

It’s a great addition to any workbench — and even better when you can move it easily around your table, workshop, or carry it with you wherever you need power!

For this project, you’ll mainly need an SK-120 DC-DC converter module, a Makita (or compatible) tool battery, and a few other components listed below.

You’ll also need 3D-printed parts for the battery adapter and housing to complete the build. You can find the STL files for all the 3D-printed parts included with this project. These files can be used to print the battery adapter, enclosure, and other mounting parts.

SK-120 Power supply Module x1 Nos

Car lighter socket x1 Nos

Banana Sockets(Red & Black) x1 Pair

10A Fuse Holders & Fuses x 2 Nos

10A 3Pin on-off-on Rocker switch x1 Nos

Digital Voltmeter (2 Wire, 0.36", 4.7~32V)

Makita or Makita compatible tool battery

2-pin pluggable terminal block connector x1 Nos (Optional)

Note:

Designed for Makita or Makita-compatible lithium-ion tool batteries (18V / 21V).

Not compatible with G-Series batteries or 18V NiCd batteries.

If you’d like to use another brand or model of battery, you’ll need to modify the STL file accordingly.

The first step in building this project is to 3D print all the required parts.

I used ABS and PETG filament materials for better strength and heat resistance. PLA is not recommended, as it can soften or deform under heat.

Print settings may vary depending on your 3D printer model and filament manufacturer, so feel free to adjust layer height, infill, and print speed to suit your setup.

Follow the steps and simplified wiring diagrams shown in the video to assemble the power supply.

You can also see some of the tests and performance checks I performed at the end of the video.

Based on my tests and experiments, this power supply performs very well within its range and is suitable for most DIY or Arduino hobby projects.

It’s easy to build, with no complicated wiring or setup required.

Overall, it makes a great secondary power supply for your workbench — reliable, portable, and practical for everyday electronics work.