Raspberry Pi 4 & Touchscreen under voltage issues

Hey all,

This is not a Ropieee issue but I figured some one might have a few wise words for me.

I recently put together a Raspberry Pi 4, a Touchscreen, a Flirc USB receiver and RoPieee as a zone controller (no audio) but I have been having problems powering them without getting the under voltage Lightning Bolt!

I originally used micro USB plugged into the screen PCB as suggested in the instructions for the Touchscreen but no matter the cable / charger variations I always received the under voltage messages.

Next I tried USB-C directly into the Pi and that worked fine. I was using a USB charger from an iPad and a 1m usb to usb-c.

As the cable wasn’t quite as long as I needed I tired an Apple USB extension cable between the charger and the usb-c. Using this combo I received the under voltage message again!

I figured it may be an issue with the extension so ordered a 2m usb-c cable. It arrived today and that also gives me the under voltage messages!

What gives? It is the length of the cable? Is 2m too long? Maybe the quality of cable?

Any help / tips appreciated

Best Regards


IThe quality of the powercable has been questioned a lot on pi forums as to why you can get the under voltage issue but I tried loads and always got it when it booted up and occasionally during use. I think 2m is too long to expect it to keep up the voltage needed. I did find it better using gpio pins to power than the usb out from the screen to the pi itself. I had it most of the time with the bog standard 2.5a pi psu. I only got round it by using two supplies.

If you can, try turning the display brightness down slightly — a work-around admittedly — but solved my lightening bolt.

Edit: I only use the 3 with my screens, and I know the 4 requires more power, so my suggestion may not help.

The answer is probably a 5.25v 3 amp PSU. The extra .25v takes care of cable length and the 3 amps takes care of the requirements of a Pi 4 or a Pi 3 with a hungry HAT. You will find examples with micro USB, I’m not sure about USB C.

You can also use 2 separate power supplies. One connected to the RPi and one to the display. I used this method for quite awhile. Eventually I bought a 5 volt / 5 Amp power supply to replace them. The one I use (below) has plenty of current to go through a long cable. It has a micro USB connector, but I just snap on a micro to USB-C adapter when using a RPi4.

5 Amp power supply
USB micro to USB-C adapter

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Thanks guys. I’ll have a play around with some of those options. I was going for a discreet / single cable option as it will be semi portable as I want to move it around the room / into the next room.

Best Regards