Portable Power Supply (18650 Battery)

Every time, when you get a new idea and need to design a new electrical circuit, you want to test your idea as quickly as possible. The breadboard very helpful to us in such cases. There comes a moment when you need to power up your circuit and you start thinking...

"Where to get power for the breadboard prototype?",
"Maybe get the lab power supply from the garage? Too far..."
"Maybe this battery is suitable? Nope, too high/low voltage."

And that happens very often in my life.

So, I decided to make such a power supply, that has the following features:

• portable (not bigger than breadboard and no need external power)
• rechargeable (from USB port)
• adjustable output voltage
• has a display (to show output voltage and battery charge)
• easy to connect

You will need the following electronic components and tools to build this portable power supply.

Electronic components:

• J5019 Li-Ion Charging Module with Step Up Boost Converter x1
• Mini LCD Display voltmeter x1
• 2-Position Slide Switch x2
• 18650-Battery Holder x1
• 18650-Battery(> 1000mAh) x1
• 1 * 6 Pin Header Socket (2.54mm between pins)
• Wires

Other:

• M2 * 5mm bolts/screws x8

Tools:

• 3D-printer
• Soldering iron
• Wire cutters
• Screwdriver
• (Optional) Hot glue gun

Initially, I planned to use something like the TP4056 board, but then I found the J5019 board in my "parts for projects" collection and decided to use it in this project.

The J5019 board is perfect for this project's requirements:

• Charging over Micro-USB.
• Output voltage: continuously adjustable 4.3-27V
• Charging current: up to 1A
• Discharge current: the maximum 2A
• Output reference maximum current: 5V 1.4A, 9V 0.8A, 12V 0.6A

The schematic for this project is very simple:

• The positive output of the battery holder (BT1) is connected to the Bat+ output of the J5019 board through the first switch (SW1A). And the negative output is directly connected to the Bat- output.
• Vout+ and Vout- are connected to the 6-Pin Socket as you prefer. In my case, I connected Vout+ with two right pins and Vout- with two left pins.
• The Voltmeter negative input is connected directly to the Bat- output. The positive input is connected through the second switch(SW2A) to the Bat+ and Vout+, to be able to monitor the output and battery voltage.

The enclosure was designed in Fusion360. For a more convenient enclosure design, firstly, I designed all the components, chose the suitable position of the components, and finally designed the enclosure.

The enclosure was designed so that it could be easily printed on a 3D printer and accommodate all the components inside as compact as possible.

The enclosure was printed on my custom HyperCube 3D Printer. The whole print took about 1 hour and 26 minutes.

I used transparent PET-G filament with the following settings:

• Nozzle: 0.4mm
• Layer high: 0.15mm
• Infill: 25%
• Temperature: 230°C
• Cooling: enable
• Support: disable

Here you can find the .stl files for the enclosure.

Before wiring the parts together, I recommend putting all parts into the enclosure to select the right wire lengths.

The soldering plan should help you with this process.

Important points:

• DO NOT SOLDER THE BATTERY HOLDER! It should be soldered at the next step and at least 10mm longer, to be easier to solder when all other components already in the enclosure.
• I recommend soldering the wires to the switches and the 6-pin socket perpendicular to the pins. Otherwise, they will prevent fit these components inside the enclosure.
  (I made this mistake with the switches, so I had to bend the contacts a little to fit into the enclosure.)

Here you can find all the photos of how I soldered the components together.

The most exciting step of the project!

1. Prepare 8 screws for assembly (I used screws from old electronics)
2. Start inserting the soldered components into the enclosure from the J5019 board.
3. Run the wires for the battery holder through the enclosure.
4. Put the voltmeter in the place and screw it on.
5. Put the 6-pin socket in the place.
6. Put the switches in the place.
7. Screw on the upper part of the enclosure.
8. Check all components. If some of them seem wobbly, then fix it with the hot glue gun. In my case, everything holds tightly without glue.
9. Solder wires to the battery holder.
10. Screw on the battery holder with two screws.
11. DONE!

Insert the 18650 battery and the portable power supply is ready to go!

How to charge it:

• Plug micro-USB into the device and the red led will light up.
• When it is fully charged - the green led will light up.

Hope you like the project!