D-Licious
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Raspberry PI 3 "Under Voltage"

Tue Apr 24, 2018 8:41 pm

Hey guys, I'll post this again since my first post seems to have got deleted (unsure why?) but my raspberry pi 3 was working completely fine, now its suddenly coming up with an under voltage warning and not properly booting? Nothing has changed since it worked peripherals wise and I have tried multiple cables/etc. Any advice would be appreciated! (If this is going to get deleted could you pop me a quick message since Im new here and dont know what im doing wrong, sorry!) Thanks in advance!

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mahjongg
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Re: Raspberry PI 3 "Under Voltage"

Tue Apr 24, 2018 11:09 pm

Your first post wasn't deleted, it simply was not yet moderated (let through), also your third post was deleted as a duplicate of your second post (as far I can tell this is the second of three posts) your first I only got to see when I already had let this one through.

Sudden ondervoltage messages means that suddenly the PI receives voltage (dips ) under the 4.65V.

WHY?

I don't know, maybe your local mains developed brownouts, a refrigerator in the next room kicks in and causes brown outs, or a connector isn't making good contact, or you started running more power hungry software, or a hundred other possibilities.

Probably your supply has always been marginal, especially a cheap microUSB cable often causes voltage drops at the receiving end of the cable.
Try a really thick and short one, most cables you get which chargers are trash.

One other possibility is that the polyfuse on your PI has seen a steady current overload, and is on the brink of "blowing".
It might help to give the polyfuse a few days rest, so it can recover.

You should read the boot problem sticky (in trouble shooting).

D-Licious
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Re: Raspberry PI 3 "Under Voltage"

Wed Apr 25, 2018 7:00 am

Thanks for the reply, I only figured out it hadn't been moderated after posting so my bad! Only posted twice though (both about power). Thought I checked that sticky but looking at it now I must have seen something else so will be sure to look through that, sorry for not doing that first. Will read the sticky and if I can't fix it will try here again.

jahboater
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Re: Raspberry PI 3 "Under Voltage"

Wed Apr 25, 2018 7:25 am

The usual recommendation is to get the "official" Raspberry Pi3 PSU.
https://thepihut.com/products/official- ... o_s=gplauk

This has a really thick (18AWG) cable that it is fixed, so the voltage is specified at the end plug.

MaxK1
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Re: Raspberry PI 3 "Under Voltage"

Wed Apr 25, 2018 8:07 am

I have had couple of so-called PSU's go bad anywhere from an hour to a few days. (In other words, built to pass inspection, but not much else...) And as Mahjongg said - most inexpensive cables (even some of the spendy ones) are pure crap (thin wire, poor connectors) My preference is to power my Pi's (And my "other" SBC) via pins 2/6 with a 3A-6A power "brick" using short, heavy gauge wires whenever possible.
You are in a maze of twisty little passages, all alike.
When General Failure and Major Disaster get together, Private Parts usually suffers.

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mahjongg
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Re: Raspberry PI 3 "Under Voltage"

Wed Apr 25, 2018 9:17 am

MaxK1 wrote:
Wed Apr 25, 2018 8:07 am
I have had couple of so-called PSU's go bad anywhere from an hour to a few days. (In other words, built to pass inspection, but not much else...) And as Mahjongg said - most inexpensive cables (even some of the spendy ones) are pure crap (thin wire, poor connectors) My preference is to power my Pi's (And my "other" SBC) via pins 2/6 with a 3A-6A power "brick" using short, heavy gauge wires whenever possible.
Note that if you power through the GPIO header pins you are bypassing all security measures (polyfuse, overvoltage, shorting protection) that powering through the microUSB offers, you also can make costly wiring (polarity) mistakes.

In other words, I cannot recommend powering through the pin-headers.

Its also like shooting with a cannon at a sparrow, no need for such heavy handed measures.

drgeoff
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Re: Raspberry PI 3 "Under Voltage"

Wed Apr 25, 2018 12:13 pm

mahjongg wrote:
Wed Apr 25, 2018 9:17 am
Its also like shooting with a cannon at a sparrow, no need for such heavy handed measures.
The usual English expression is "Using a steamroller to crack a nut".

MaxK1
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Re: Raspberry PI 3 "Under Voltage"

Wed Apr 25, 2018 12:23 pm

I have a number of USB chargers, cables and power banks with uUSB connectors that just don't mate properly with any of my Pi's (Too loose) That's why I gave up using them. I have exactly 1 that does fit well, but it is connected to a 1.5A charger (for a tablet) so only usable on an older Pi . I almost gave up on the pi 6 years ago with my first model B because finding "bad" connectors and cables was a lot easier than finding good ones :D
Since then, I have used pins 2/6 on all my Pi's (15 I think, and my "Other board") with no problems. I know it bypasses a lot of circuitry on the Pi, but I have the ability to measure voltage, count pins,solder and see colored wire. (BTW - if you do this, don't rely on the red/black being the power wires in all USB connectors - I have also encountered a few powered USB supplies that had Red/Green (data) and Black/White (power)!
You are in a maze of twisty little passages, all alike.
When General Failure and Major Disaster get together, Private Parts usually suffers.

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rpdom
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Re: Raspberry PI 3 "Under Voltage"

Wed Apr 25, 2018 3:36 pm

MaxK1 wrote:
Wed Apr 25, 2018 12:23 pm
I have a number of USB chargers, cables and power banks with uUSB connectors that just don't mate properly with any of my Pi's (Too loose) That's why I gave up using them.
I have the opposite experience. Every charger/power supply/whatever with MicroUSB connectors have had no problems connecting to any of my Raspberrys. (Ok, so a couple were too weak to power them). On the other hand, I have only found a couple that will connect properly to my Samsung mobile phone and actually charge it.

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Re: Raspberry PI 3 "Under Voltage"

Wed Apr 25, 2018 4:15 pm

Interesting ...
You are in a maze of twisty little passages, all alike.
When General Failure and Major Disaster get together, Private Parts usually suffers.

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