alphanumeric
Posts: 1538
Joined: Tue Jan 19, 2016 2:17 pm
Location: Sydney, Nova Scotia, Canada

Raspbian + Pi3B+ = low voltgae warning?

Wed Jun 13, 2018 2:50 pm

I just recently swapped out a 3B for a 3B+. Did up a fresh Micro SD card with the latest Raspbian, then did the usual sudo apt-get update and upgrade. Did them both twice actually. Everything seemed fine. Put that Pi away for a week or two.
I just fired it up again today and got the flashing lightning bolt? I hadn't noticed this after the original fresh install.
Checked my voltage at the GPIO and it was just a little under 4.9V. 4.86, 4.89 fluctuating a little bit. Power supply is 5V at 10A.
Scratching my head I did another sudo apt-get update and upgrade. No more warnings? So is this a glitch (false warning) in Raspbian for the 3B+ that's fixed by an update upgrade? If yes, any plans to roll this fix into a new release?
If there is a sticky on this I missed it, haven't found it yet?

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piglet
Posts: 878
Joined: Sat Aug 27, 2011 1:16 pm

Re: Raspbian + Pi3B+ = low voltgae warning?

Wed Jun 13, 2018 3:47 pm

alphanumeric wrote:
Wed Jun 13, 2018 2:50 pm
Power supply is 5V at 10A.
See comments here

Most likely the cable, or the supply not really being what it says it is.

alphanumeric
Posts: 1538
Joined: Tue Jan 19, 2016 2:17 pm
Location: Sydney, Nova Scotia, Canada

Re: Raspbian + Pi3B+ = low voltgae warning?

Wed Jun 13, 2018 3:59 pm

https://www.adafruit.com/product/658 plugged into this, https://www.adafruit.com/product/610. Then good quality USB cables feed my Pi and 7 inch touch screen via their respective micro USB power jacks. I had a 2B and 3B in there with no issues.
It's only happened after swapping the 3B with a 3B+ and redoing my SD card. And now that I have updated and upgraded, again, the warning has gone away?

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PeterO
Posts: 4259
Joined: Sun Jul 22, 2012 4:14 pm

Re: Raspbian + Pi3B+ = low voltgae warning?

Wed Jun 13, 2018 4:06 pm

The 3B+ needs the latest firmware as the way the low voltage detection circuity works has changed.
PeterO
Discoverer of the PI2 XENON DEATH FLASH!
Interests: C,Python,PIC,Electronics,Ham Radio (G0DZB),Aeromodelling,1960s British Computers.
"The primary requirement (as we've always seen in your examples) is that the code is readable. " Dougie Lawson

alphanumeric
Posts: 1538
Joined: Tue Jan 19, 2016 2:17 pm
Location: Sydney, Nova Scotia, Canada

Re: Raspbian + Pi3B+ = low voltgae warning?

Wed Jun 13, 2018 4:52 pm

I must have not been paying attention when I first set it up? I don't remember seeing any warnings? I had it on for a while too. I did all the usual keyboard, time zone, wifi setup etc. I do remember having to do the apt-get update twice in order to install xscreensaver. One run through wasn't enough for some reason? Just one of those things I guess. Seems to be fine now.
A 10A power supply may well be overkill but this is my bread boarding rig. A Pi 3B+, Pi foundation display, speakers and analog audio amp, and a few other odds and ends. I also have a 4A version of that same power supply I use some times. I wanted extra capacity to run multiple motors, servo's, LED's etc. The whole idea was to prevent said warning from ever showing up.
Anyway thanks for the feed back guys.

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