Hi. I’ve recently purchased a PiJuice HAT online from your store for my Raspberry Pi 4B which has 4GB RAM. I am having doubts as to whether or not it would be advisable to go ahead with my original plan or not given the following information: My original plan was simply to attach the HAT to the Pi motherboard and install the recommended software and thus to have a kind-of UPS for my Pi, but my doubts are that I have both Recalbox and Raspberry Pi OS installed on the same microSD card and use both operating systems frequently (though obviously not at the same time). I don’t know whether my plan would work if I were using Recalbox at the time of a power surge or failure, or even if I were logged on to the Raspberry Pi OS partition at such a time - given this possibly unusual set-up for a Raspberyy Pi with a PiJuice HAT. Of course, there is the possibilty that, in additon, something else could go wrong - something I, with my limited knowledge, am not, as yet, able to foresee. As a last resort, I am willing to return to just using Raspberry Pi OS and ditch the Recalbox partition. Do you have any advice, please?
What is the intended purpose of the PiJuiceHat though?
Is it to keep the Pi running in a power out state?
You power the Hat, the Hat powers the Pi.
If power to the Hat drops, the Pi keeps doing exactly what it was doing as it has continuity of power until such a time as the battery is exhausted, then it either just stops running the Pi or does a safe shutdown.
It doesnt matter what OS you have, the PiJuiceHat will run the Pi.
The only issue that you might have is if your power outage to the Hat exhausts the battery and the Pi shuts down, then the power is restored and the Pi reboots, then it wont know how to determine what OS to boot into.
Im not sure as to what you use the Pi for, or why the two OSs, however they have little bearing on the operation of a UPS hat, it will work just fine, but this does depend on what your intentions were for getting it.
Good information from @AndrewBG.
The thread below has some posts I did in relation to using a larger LiPo for the Pi Juice. It all came down to calibrating the Pi Juice correctly for the battery. I eventually got it to work but it took some time.
I mention this because a fully charged Pi Juice with standard battery lasted about 2 hours connected to a Pi 3B on idle. The Pi Juice battery is large enough to keep the Pi going so it can shutdown nicely or will run during short power outages. I wanted the Pi to run for a few hours on just battery.
The Pi is only used to configure the Pi Juice, after that the Juice just does it thing regardless of what it connected to it.
Many thanks, Andrew. You’ve answered my question. Yes, the intended purpose of the PiJuice HAT is to keep the Pi running in a power out state. I use one OS, in the main, for retro-gaming (Recalbox OS), and the other OS, in the main, for programming (Raspberry Pi OS).
Thanks Jim, too: “The Pi is only used to configure the Pi Juice, after that the Juice just does its thing regardless of what is connected to it” answers part of my question as well. In short, problem solved.
Yes, the PiJuice can be used as a relatively simple UPS HAT which is its main function, the PiJuice software just allows you to modify profiles to increase rates of charging based on cell capacity, what type of thermistor the battery has on board to monitor temp, etc. Their README is fairly extensive:
Many thanks, Bryce. However, it is perhaps of interest to note that the ReadMe says
“Note: Turning on the Raspberry Pi via the onboard intelligent switch only works when the power is provided to the micro USB on the PiJuice.”
which appears not to be the case, for I have tried turning on the Raspberry Pi both when the power is provided to the micro USB on the PiJuice and when it is provided to the USB C on the motherboard of a Raspberry Pi 4 Model B (with a PiJuice HAT attached to it) and this, for me, has worked in both instances.