Recently (ok it was November 2017...end of the year is always busy for a magazine journalist) Pi Supply sent me a PiJuice to play with.
Disclaimer Yes Pi Supply sent me this unit free of charge as a loan device. I have not been asked to edit or alter this review so what I say is what I experience and the truth :)
The elephant in the room
Ok PiJuice is a crowdfunded project, and I am one of the backers. The Pi Juice project was announced at the Raspberry Pi Birthday Party in March 2015, and I still have the press release email in my inbox.
This project has been dogged with delays and issues, and nearly three years later we are just starting to see the unit being readied to ship. So this project may not have been smooth sailing for the team, in fact there were a few bumps along the way, but at least it is not vapourware.
What is it?
PiJuice is a power solution for all 40 pin GPIO models of the Raspberry Pi (B+ to Pi Zero W) it provides an interface (software and hardware) to monitor battery status, in this case a common Motorola Lithium Ion battery, commonly found in mobile / cell devices. Pi Juice fits conveniently on top of the Pi, while still enabling access to all of the GPIO pins.
- Onboard 1820 mAh “off the shelf” Lipo / LiIon battery for ~4 to 6 hours in constant use! (with support for larger Lipo Battery of 5000 or 10,000 mAH+ to last up to 24 hrs +)
- A Full Uninterrupted / Uninterruptable Power Supply solution.
- Designed for the Raspberry Pi A+, B+, 2B and 3B but also compatible with Raspberry Pi Zero v1.3 and Wireless.
- Integrated Real Time Clock
- Onboard intelligent on/off switch
- Low power deep-sleep state with wake on interrupt/calendar event
- Programmable multi-coloured RGB led (x2) and buttons (x3) with super simple user-configurable options
*Hardware watchdog timer to keep your Raspberry Pi on and working in mission-critical remote applications
- Full power management API available to Raspberry Pi OS with auto shutdown capability when running low on batteries
- Raspberry Pi HAT compatible layout, with onboard EEPROM for easy plug and play operation
- Low profile design to fit inside lots of existing Raspberry Pi cases!
- Enhanced graphical user interface (GUI) available for easy install (via APT)
- Customisable scripts for enhanced flexibility and full report of battery status
- All GPIOs available via stackable header for ease of expandability and connectivity
- Charge via on-board micro USB or via the Raspberry Pi micro USB (or from onboard pin headers)
- Batteries can be charged from different type of sources and voltages
- Replace the battery without downtime. Compatible with any single cell LiPo or LiIon battery
How do I use it?
First of all screw in the standoffs, these will ensure minimal chance of the GPIO pins being bent. Then place PiJuice over all 40 pins of the GPIO and press down firmly. If you have a battery...and you should, then insert it into PiJuice before the next step.
Insert your micro USB cable / power supply into the PiJuice connector and your Pi will power up and you will see the PiJuice charging LED flash to life.
On first boot you will need to open a terminal and update your repositories, then install the PiJuice software.
sudo apt update && sudo apt install pijuice
Software installed and ready to go!
PiJuice installs a background application (a service) that monitors the health of the battery, power supplies in use, and enables the user to setup custom scripts to launch at the press of one of three buttons located on the left side of the board.
The user interface can be accessed using the Raspbian menu, or via the system tray icon in the top right, just right click and select configure to see the many tabs of options.
Here we can see the status of the battery and power supplies.
Does what it says on the tin :)
Watches the health of the power supplies / batteries and provides a means to tweak the settings of minimum charge and wakeup the device when the charge reaches a certain state...handy for conserving power.
Here we can trigger scripted events, existing or user created and have them run them when certain conditions are triggered.
Each User Func points to a user created script that is stored ready to run with a System Event or if the user presses a button, which is handled by the Configure HAT button in the HAT tab.
In Configure HAT we can control what happens when one of the three buttons are pressed, change the built in LEDs to show a colour, change profiles for the battery, and update the device firmware.
Can I fit a HAT board on top?
I went to the box of many boards and pulled out Pimoroni's Displayotron HAT, with the Pi turned off I placed the HAT on top of PiJuice and I saw rainbows!
Off grid power
Pi Supply also sent me two solar power units which use a micro USB connection to the PiJuice board to supply power.
6W Solar Panel
I tested the 6W solar panel in the bright but cold January sunshine and I used a UNI-T UT658 USB Tester to monitor the current draw from a #pounderland USB LiPo battery. This gave me 3.15V at 150mA, not bad.
40W Solar Panel
A much bigger solar panel! I had problems securely placing it in the test suite...the wall to my neighbours house. Here I recorded 3.50V at 110mA.
Both of these panels failed to provide enough voltage to charge a battery, in fact the lowest level that the PiJuice charge IC (a BQ24160RGET) will accept is 4.2V. The low voltage levels are not the fault of the panels, rather they are the fault of the January sunshine. I'm sure that if I repeated this test in summer then I would get much better results. Oh and one last thing about this panel, it produced a rather irritating "buzz" when the panels were opened, this was due to the USB interface box inside the panels. Not loud, but when you hear it...you keep hearing it.
So what do I think?
PiJuice is quite a good platform for those makers / hackers that want to use battery power with their Pi. The ability to connect PiJuice to external sources of renewable power via micro USB means that a Pi based project can be powered "off the grid" and keep going for a considerable amount of time. In fact using a Pi Zero W would increase the amount of time immensely!
Installation is a breeze and the GUI is easy to use, all be it with a few bugs at this time but don't worry as these will be ironed out soon!
Access to the CSI (Camera Interface) and DSI (Display Interface) is awkward as PiJuice does not have any cutouts on the board to facilitate cable routing, but with care and a long enough ribbon cable you will be able to use them with PiJuice.
The starting price for PiJuice is £47.99 for the board itself, not a bad price especially when compared to existing products such as the S.USV PI Advanced board which retails for €54.99
I reviewed this board in Issue 214 of Linux Format
On to the solar panels, and these are not strictly necessary so I shall omit them from my verdict. The 6W solar panel is an additional £42 and the 40W panel a whopping £139.50! If you seriously need off grid power, or a form of UPS (Uninterruptible Power Supply) then these will no doubt be much needed purchases.
As for PiJuice, the board is definitely worthy of investigation, but it is a rather niche product.
Ease Of Use
Value For Money
Features / Performance
Does the job with no issues, the price of the board is good, the addons are a little expensive but the majority of users will not need them. Great to have access to all the GPIO pins, but tricky cable routing for the camera and display ports may put off some users.
So where can I buy it?
Head over to Pi Supply and pre order a unit