PiJuice In & Out of 'Communications_Error'


I keep on getting ‘COMMUNICATION_ERROR’ every 30 seconds to a minute for about 10 seconds before resuming back to normal.

I am currently powering the Pijuice through the Raspberry Pi rather than the Pijuice because I read it can be powered from either ports. I have tried the micro-usb port too. Power source that is incoming is 5.1v stable.

Out of the box the battery it came with ‘BP7X_1820’ is also not connecting to the Pijuice. It looks perfectly fine as well as the pins on the PCB of the Pijuice - but it still says under battery status NOT_PRESENT.

I have also attached a photo of the information on the GUI when normal.

I am more interested in fixing the stability problem rather than the battery because I do not need the functionality of the battery, as I only need the RTC to work and of course be stable.

I have verified the Pijuice is correctly connected to my Raspberry Pi.

Your urgent help would be much appreciated.

Possibly a fault product.

Here is a photo of my GUI

Hi Samuil,

Could you include a picture of the setup / connections, and also confirm the voltage of the LiPo battery?

I’ve heard that a lot of times in my life, and I’d say 8/10 times it ends up being a mistake in setup somewhere. Never hurts to get a second pair of eyes over it - and often saves an awful lot of head scratching by everyone.


Hi, thank you for the quick response.

The battery is @ 3.94 volts, I have also attached a photo of the pins.

I have also taken a photo of the connections. I have also removed the Pi hat and reinstated multiple times, and even checked if I am getting power from both rail power GPIO pins.

The set up is just the raspberry pi 4 model B and the Pi hat on top. The OS is running off of a SSD as well.

I was just doing some googling of your error. Found this issue on the PiJuice Github:

Are you running the latest version of Pi OS? There’s an update in the kernel for some possible i2c issues.

sudo apt update
sudo apt full-upgrade

might fix your issues.

Thank you Oliver, I have run this command already with no luck, apologies I should have mentioned this. I have also verified it has the latest firmware version.

I also just rubbed the copper on the LiPo battery roughly and now it appears there is connection established to the board and the LiPo battery. I am getting a slow pulsating green light on the PiJuice while the Pi4 is still off.

I can confirm I have connection with the battery and the Pi 4 now. The only thing is I still am getting COMMUNICATION_ERROR popping up frequently.

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2.8A is a lot. Negative current is from Raspberry Pi to PiJuice.

You should not be seeing -2.8A, especially when your battery is already at 4.18V. Something is wrong there - a short circuit, or a high resistance on the current shunt maybe?

PiJuice/Software at master · PiSupply/PiJuice · GitHub

I cam currently powering via the raspberry Pi USB-C port. I ready that I am allowed to use either port. Could this be the reason for negative voltage?

How can I test why I am getting the negative voltage - It constantly fluctuates between -0.9V, -2V, -2.5V. Is this the voltage of the battery or my supply power?

You don’t have a heatsink under the Pi Juice do you? If it’s making contact that could definitely lead to issues.

I just checked the heat syncs and there is definitely plenty of room between them and the PiJuice PCB.

Hmm, well, can always try the old turn it off and on again.

If you use the BP7X battery, make sure your dip switches are configured correctly:

Then a do a dual long press of SW1 and SW2 for 20 seconds to reset PiJuice HAT configuration to default, and also be sure reset the software to default settings.

I unplugged the USB-C power connector from the Pi 4, and connected a Micro-USB connector into the PiJuice instead. This is now giving me a reasonable amperage reading:

I am still getting COMMUNICATION_ERROR at the same frequency mentioned earlier.

It looks like the USB-C power to Pi 4, which then powers the Pi Juice from GPIO pins, was the only circumstance where I was getting negative amperage readings. I read that powering the Pi Juice via the GPIO pins (which source power from the power supply via USB-C port) was a method use.

Thank you Oliver I will try this now, can you confirm what the dip switches are for?

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They’re for battery config. Have read through:



You shouldn’t get a negative voltage. Negative current is normal if powering from the Pi, but not negative voltage.

Ok my apologies, I accidentally wrote V instead of A. Correction: -0.9A, -2A, -2.5A*

Based on what you said getting negative current if powering from the Pi 4 itself, this is actually what I am doing, therefore it appears there is nothing wrong with the total voltage and current readings.

This does not explain the communication_error I am still receiving however.

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Hmm, maybe have a go at this - checking i2c devices and updating pijuice firmware.

I’m starting to run out of ideas if the reset didn’t work.