pila
Posts: 3
Joined: Fri Jan 06, 2017 9:11 pm

RPi 3 intermitent Power problem

Sun Apr 14, 2019 10:13 pm

RPi3 is working for years now. Ocassionally, it would blink ranibow square top right - power problem. I have 4 of them, and it happens from time to time on them. Then it dissapers for a year or so!?!

Currently they are powered by a strong 25W power adaptor with 4 USB ports which has no problem giving 5V 2A.. This just happend. I forgot to look at its red LED, my bad. It only has LED directly connected for the remote, LAN and HDMI cables. Only LibreElec Kodi is running.

1. Connected USB meter into another slot on the same adapter, 5,2V.
2. Move RPi power cable into the meter in this new slot - again problem. Meter says: 5,1V 0,3A
3. Change USB cable from the meter to the USB. Meter says: 5,1V 0,3A. Again problem.
4. Change entire power supply. Meter says bit belowe 5,0V. Again problem.
5. Change entire PS and plug it directly into the RPI3 PS. All OK.
6. Return it to the original cable in the original slot in the original multi usb pwoer adapter. Works perfectly.

Just added load to the free charger slot. 5,07V 1,9A and no problem anywhere. RPi did not notice and it is connected two slots away from 2A load.

What could cause such odd behaviour? This occurs seldom, say, on a yearly basis and goes away within minutes of me fiddling around doing basically nothing. Looks like the problem is in RPi.

pila
Posts: 3
Joined: Fri Jan 06, 2017 9:11 pm

Re: RPi 3 intermitent Power problem

Sat Apr 27, 2019 9:54 am

Seems nobody ever had such problem.

Andyroo
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Location: Lincs U.K.

Re: RPi 3 intermitent Power problem

Sat Apr 27, 2019 10:49 am

It may just be a voltage drop on your mains that impacts the charger.

I'll assume you have a mains 'charger' with it having 4 USB outputs - these can drop down to 4.2ish volts and 'phones are happy - Pis are not.

Also unless you are using decent quality cables the voltage drop can be significant over the length of the cable and the Pi is more susceptible to voltage than current.

I would splash out and by an official Pi adapter for one machine and see how that goes - its solved ALL of my issues with them.
Need Pi spray - these things are breeding in my house...

Ernst
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Location: Germany

Re: RPi 3 intermitent Power problem

Sat Apr 27, 2019 10:53 am

pila wrote:
Sun Apr 14, 2019 10:13 pm
What could cause such odd behaviour? This occurs seldom, say, on a yearly basis and goes away within minutes of me fiddling around doing basically nothing. ???? Looks like the problem is in RPi.
You did something, only you did not notice what you did that fixed the problem.

Repeat once a year: remove cable, re-plug a few times to clean contacts, insert cable, do this on each side of the cable.
The road to insanity is paved with static ip addresses

pila
Posts: 3
Joined: Fri Jan 06, 2017 9:11 pm

Re: RPi 3 intermitent Power problem

Fri May 17, 2019 5:01 pm

I measure power supply, they are all above 5v in all cases even with 2A load. I hav tried various pwoer supplies, they do not solve the problem. I do have good and thick cables (as much as I can measure, they are adverties as having thick wires - AuKey). At their end, I do not loose any power according to any devices I use to measure voltage.

If a power supplied causes a problem, I would expect red LED at RPi to twinkle, yet it is perfectly stably lit! At all the times, it never saw red power led at the RPi to react at all.

I am just now having the same problem on one RPi3. Different city, this one is connected to strong UPS. I changed it to the original ModMyPi RPi 2,5A power supply, it did not help. It got stuck. Therefore: change of power supply or cable do not solve the problem.

Just to mention: here I do have another RPi 2 connected to the same MultiUSB power supply using the same cable. At the same moment RPi 3 nas problems second one works normally and does not complain about power.

In all cases, problem goes away after I try to rotate few cables or power supplies. Then I return to the original cable and cable, and things will work fine from then on for months. Problem lasts for hours, not weeks.

The only thing I did not thry to exchange is the Sandisk 8 GB memory card inside the RPis. Could it cause such behaviour?

I feel like the problem is within the Pis, not with the external power. My RPi3 were all bought at ModMyPi, are now 3+ years old. One has 2 DVB-T tuners connected, another (one from my initial post, from different city) does not have anything connected. For Remote Control, I use pure LEDs directly connected to the pins.

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Imperf3kt
Posts: 2197
Joined: Tue Jun 20, 2017 12:16 am
Location: Australia

Re: RPi 3 intermitent Power problem

Fri May 17, 2019 9:55 pm

To clarify, you are using ONE 2A rated power supply to power FOUR raspberry PI 3s?
Although you mention the power supply you use is 25w, that is not 2A, but rather 5A.

This setup should be ONE 2.5A (12.5W) power supply to ONE raspberry Pi.

Also note that your micro usb cables matter, most are pretty pathetic at delivering power to a Pi.
I have one specifically rated for 2.4A and one specifically rated for 3A (this one has pretty fat wires, but I suspect it's mostly plastic shielding) and even when used on a known good 5A power supply (not phone charger) I get undervolt when using either cable.


The best solution really is the official raspberry Pi power supply, unless your project has special requirements (portability, for example)
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Skorium
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Location: Dublin, Ireland
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Re: RPi 3 intermitent Power problem

Fri May 17, 2019 10:43 pm

I have few questions and a couple suggestions:
- What your raspberry pi are doing exactly ?
- What software are you running on them ?
- Are they working at max CPU usage ? If yes, can you cook an egg on them ?

Monitor your CPU usage, RAM usage and temperatures to exclude anything related to your use (that because you seem so sure that the problem is not your PSU). If your RPi get hot, they may overheat, then slow down so much that it looks dead... and will need to cool down before accepting to restart. If remains powered on, even with restart if your services are restarting automatically, they will not cool down quickly. Multiple reboot by changing PSU, cable and things like this may be just enough to get them to cool down and sudently restart normally.

I had this exact same experience with my RPI and it took me a while to troubleshoot only because I had one of those ridiculous crap of heat sinks sold with some case or RPi kit. I ended up going overkill cooling by designing this : https://www.thingiverse.com/thing:2598644. This overkill system without any fan keep my RPi 3 at 50-55 degree C running at 100% 24/7 (motion software with 2 USB HD camera running as CCTV). Since I run with this no problem any more, even with non official RPi PSU. Temperature are going down to 30-35 with 40mm fan on top the heatsink.

So maybe double check your CPU is not overloading really slowly, pushing into its limit after a year, even more if your RPi are running 24/7 without interruption at all (you mentioned UPS, so I guess you need no interruption).
Last edited by Skorium on Sat May 18, 2019 9:27 am, edited 1 time in total.

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Imperf3kt
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Location: Australia

Re: RPi 3 intermitent Power problem

Sat May 18, 2019 7:57 am

A Raspberry Pi should not crash and reboot if it gets hot, instead, if working correctly, it will throttle its performance down in order to generate less heat and throttle back up once cool enough.
If you are experiencing crashes when the Pi gets hot, something else is causing it.
Google is ubiquitous - Try it today, it's free!
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Skorium
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Location: Dublin, Ireland
Contact: Website

Re: RPi 3 intermitent Power problem

Sat May 18, 2019 9:24 am

Indeed it wasn't crashing in my case (sorry if I caused a confusion in my previous post), but wasn't usable any more. It was throttling so much that the only way I could shut it down correctly was via it serial interface and performing login steps and calling "sudo poweroff" took about 10 minutes...
SSH was timing out. I never got patience to see what speed the CPU was going in these conditions. I only checked for temperature the Pi was doing it's best to stay below 90*C. Cooling it down made the difference. At the beginning it was looking like I had a power issue, no SSH possible, power led stable red, but looked nothing was working correctly.

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