Raspberry Pi UPS: A Comprehensive Guide on Building One

UPS often plays a crucial role in Raspberry Pi by providing emergency power when the mains power or input power source fails. Today, we will enlighten you on building a Raspberry Pi UPS using a PiJuice HAT and simple hardware. 

Why do You need a Raspberry Pi UPS?

UPS stands for Uninterruptible Power Supply. When working on a Pi project, you’ll need a UPS to ensure continued working despite occasional bumped AC adapter, power outages, or minor power fluctuations.

Others include;

  • Prevent SD card corruption

Unfortunately, you can corrupt your Raspberry Pi SD card every time you shut down the Raspberry Pi improperly. However, UPS can prevent the challenge. 

  • Projects that need to remain on all the time

Additionally, UPS enables the integrity of projects that involve running continuously, complex scripts that don’t restart when booted, streaming, data collection, and camera.

It can also serve various custom projects like Pi-Hole and OctoPrint. They can send safe shutdown commands or notifications if it has a low battery voltage. 

Raspberry Pi UPS Options

The two main options for constructing Pi UPS include:

  • Option #1: Power bank
power bank

(power bank)

It’s a simple process that requires you to plug your Raspberry Pi into a power bank with high output. Essentially, you hit the external battery pack into a wall, then hit the Raspberry into the battery pack. 

Important factors to consider 

Power output

The power bank should have a minimum output of 1A for Raspberry Pi Zero, 2.5A – Raspberry Pi 3B+, and 2A – Raspberry Pi 3. 

The condition means the power bank doesn’t draw power, or you have not plugged any peripherals into the Raspberry. 

Sadly, the Pi won’t always experience a safe shutdown since it’s unable to detect being on battery power. Also, portable power banks with the requirements are expensive and rare. 

Simultaneous discharge/charge

The power bank should output maximum power to one of the USB ports as it charges, i.e., simultaneous charge and discharge. 

Again, finding power banks with this feature is challenging because it needs additional circuitry. 

  • Option #2: Power management board

You will directly connect a battery and power management circuit to the Pi. Next, click the AC adapter to the power management board. 

If there’s power loss, the board still operates smoothly for a more extended period. Furthermore, the Pi can notify you when its power is low to initiate a safe shutdown and if it’s using battery power. 


You will use components like;

  • JuiceBox Zero – A cheap option for Raspberry Pi Zero UPS or
  • PiJuice – It is easy to set up and compact.

UPS Runtime

Start by connecting a large onboard BP7X 1820mAh off-the-shelf Li-Ion/LiPo battery to continuously run your Pi for 4-6 hours or a day. 

Lithium battery

(Lithium battery) 

The runtime mostly depends on the type of Raspberry Pi used, the external hardware it supplies power to, and the tasks it performs. To make work more accessible, you can also use a battery discharge calculator to know the project’s runtime. 

Install Raspberry Pi OS & Configure your Raspberry Pi

Usually, your Pi runs some software. So, depending on whether the project needs GUI or not, you can settle for a Lite or full version of Raspberry Pi OS. 

Shut Down Your Pi

Run the following command after connecting the Pi to the PiJuice to shut down the Pi while working safely. 

Connect the HAT (PiJuice Hardware)

Next up, cautiously press the PiJuice onto the GPIO header of the Pi, and secure it using plastic standoffs and screws. 

Note; Solder a header onto your Pi first if your hardware is Raspberry Pi Zero. 

Connect the Battery

A PiJuice package has a preinstalled off-the-shelf battery making it easy to replace or swap the battery in a powered Pi. If you find the battery, remove the clear plastic insulation tab on the battery.

There are circumstances where PiJuice doesn’t have a battery, or you need additional power capacity from a different Lithium-polymer/Lithium-ion battery. Here, solder a battery terminal on PiJuice, then connect the separate battery. 

Attach the PiJuice case (optional)

Omit the top of the case off PiJuice when it lacks a GPIO port/ slot or uses Raspberry Pi cases. Moreover, you can use the points designed for PiJuice, like a tall and short case for a full-size Pi, e.g., Pi-3. 

Steps; Slide off the case’s front, back, and top. Afterward, slide the PiJuice and Pi into their respective places to lock the whole assembly into slots on the case’s sides. Lastly, swap the top and sides, then connect the 4-rubber feet. 

Connect a Power Source and Power on the Pi

You can connect a standard Raspberry Pi power source to the Micro-USB port of the PiJuice. Then, press the small SW button near the flashing LEDs with a pin or paper clip to turn on your Pi. 

Safe shutdown; Hold and press the same power button on Pi for a minimum of ten seconds before releasing it. 

Unsafe shutdown; Hold and press the power button for 20 seconds. 

Additionally, install PiJuice software to enable your Pi to perform some commands on low power or undergo a safe shutdown. 

Automatically shut down if the Raspberry Pi UPS battery is low

We’re now in the last step that requires configuring PiJuice to shut down PiJuice at a low battery percentage/voltage. 

To achieve configuration;

In the PiJuice CLI

Use the command line to run the instructions below, then check and change the configuration options. 

In the PiJuice GUI

Use VNC or a keyboard to move from the menu, preference, to PiJuice settings, where you’ll change the option from Raspberry Pi OS GUI.

Afterward, press the system tasks tab, click the box on a minimum charge and insert 1 in the text input. Lastly, select Apply. 

For both CLI and GUI configuration options

Furthermore, you can directly edit the JSON configuration when battery capacity is low by;

Then add the following in the system_task object;

The configuration above will automatically shut down the Pi when the battery percentage reaches 1%. 


As we conclude, we hope the guideline in our post today was easy to grasp. However, if you still have burning queries or need assistance, kindly contact us. 

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Emma Lu
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