Jeufdfuaass
Posts: 5
Joined: Sun Aug 11, 2019 5:31 pm

Is my pi 3B throtteling due to undervoltage? [solved]

Sun Aug 11, 2019 5:36 pm

I have had trouble for a while with my raspberry 3B. Its being used as a small instance for Homeassistant and Pihole.

I only recently discovered that my raspberry seems to receive too less power. In the GUI/console output via HDMI, the yellow bolt symbol was shown all the time, so i swapped the power adapter. I once used an Ikea charger which should be able to provide 2,4A and now i switched to a 5 port pretty much overkill power supply with 2,4A per port too. The raspberry has no peripherals attached and has GUI disabled.

After switching to the new power supply, the yellow bolt disappeared. Yet the pi's vcgencmd tells a different story. Still while idle, i almost always get both throttled=0xd0000 and throttled=0xd0005.

I tried to research this online and it seems as my CPU frequency never goes above 600Mhz, not even under load. Here's a quick stresstest.

Code: Select all

pi@ZZZZ:~/output $ while true; do vcgencmd measure_clock arm; vcgencmd measure_clock core; vcgencmd measure_temp; vcgencmd get_throttled; vcgencmd measure_volts core; sleep 10; done& stress -c 4 -t 900s
[1] 5708
stress: info: [5709] dispatching hogs: 4 cpu, 0 io, 0 vm, 0 hdd
frequency(45)=600000000
frequency(1)=250000000
temp=53.7'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=55.3'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=55.3'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=55.8'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=56.4'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=56.4'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=56.9'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=57.5'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=56.9'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=58.0'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=58.0'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=58.0'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=58.5'C
throttled=0xd0005
volt=1.2000V
frequency(45)=1400000000
frequency(1)=400000000
temp=58.0'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=58.0'C
throttled=0xd0000
volt=1.3750V
frequency(45)=600000000
frequency(1)=250000000
temp=58.5'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=59.1'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=58.5'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=59.1'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=59.1'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=59.1'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=59.1'C
throttled=0xd0005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=59.6'C
throttled=0xd0005
volt=1.2000V
I tried 2 different power supplies and 2 different cables.

Could there be something other wrong, or might it just as well be my apparently too weak power supplies?

Thanks!

Cael
Posts: 96
Joined: Sat Jul 07, 2012 7:08 am

Re: Is my pi 3B throtteling due to undervoltage?

Sun Aug 11, 2019 6:29 pm

i had better luck w/ a 3A PSU w/ my 3B and 3B+, do you have a USB Load tester? (its a lil device you can use between the source n target and see the load) if you got one test to see if the Pi's pulling sufficient power, if not you might of blown something. or just poor quality cabling on the chargers

like this https://www.amazon.com/UNI-T-Digital-Mu ... ial&sr=1-4 for a tester, that should give you an idea if its in the in-between the Pi and power supply.
Last edited by Cael on Sun Aug 11, 2019 6:39 pm, edited 1 time in total.

Andyroo

Re: Is my pi 3B throtteling due to undervoltage?

Sun Aug 11, 2019 6:37 pm

Have you tried a power supply or a charger?

The Pi supply provides 5.1v via nice thick cables where chargers can drop down to 4.3v or so normally through thin cable.

Jeufdfuaass
Posts: 5
Joined: Sun Aug 11, 2019 5:31 pm

Re: Is my pi 3B throtteling due to undervoltage?

Sun Aug 11, 2019 7:29 pm

Andyroo wrote:
Sun Aug 11, 2019 6:37 pm
Have you tried a power supply or a charger?

The Pi supply provides 5.1v via nice thick cables where chargers can drop down to 4.3v or so normally through thin cable.
Yes, like i said above, i tried 2 different chargers :)
Cael wrote:
Sun Aug 11, 2019 6:29 pm
i had better luck w/ a 3A PSU w/ my 3B and 3B+, do you have a USB Load tester? (its a lil device you can use between the source n target and see the load) if you got one test to see if the Pi's pulling sufficient power, if not you might of blown something. or just poor quality cabling on the chargers

like this https://www.amazon.com/UNI-T-Digital-Mu ... ial&sr=1-4 for a tester, that should give you an idea if its in the in-between the Pi and power supply.
uhh, i had too less imagination to think about that. Yes, i have one of these load testers and tested it right away.
I gotta say, this is quite frustrating. Even under the stress test, the Pi only draws a maximum of 0,7 A, but as your instincts were correct, voltage drops down to 4,90V under load and to 4,96 - 4,98V in idle. So apparently the pi is quite salty about those few millivolts.

Its a shame, because i thought i could save some money buy not buying that 10€ power supply - and Amperage is not even the problem.
Do you have any experience with USB chargers which can be used with the raspberry pi? i feel like i am overspending 10€ for one port with low Amp draw when i can have 4 ports for 15€ or so. I recently saw this post, he uses and Amazon Basic power plug, but those are not available in my country unfortunately.
https://www.reddit.com/r/homelab/commen ... _so_i_did/

Thanks for the help!

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mahjongg
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Re: Is my pi 3B throtteling due to undervoltage?

Sun Aug 11, 2019 7:56 pm

chargers, unlike power supplies often lack the electronics to closely regulate their output voltage, and are more optimized to output a lot of current. computers, like the PI need precise 5V on their inputs, and are only guaranteed to work with a typical tolerance of 5%, that is plus or minus 0.25V. Such power suppies contain much better, and more costly electronics, and $10 for a good supply that can supply this amount of current with an absolute stable 5V output voltage is an absolute steal.

applying a bit more voltage is normally not a big deal, as long as you stay well below 6.0V. As most stuff you connect will survive that, but if you go below 4.75 V equipment is not guaranteed to work! Voltage received by the PI is dependant on the current flowing through the cable, and the regulating qualities of the supply, and as the current might vary rapidly the voltage might change rapidly too.

The PI itself is a bit more tolerant to voltages below minimum, but note that the dips below that 4.75 Volt can be very short, and still cause trouble in most 5V powered equipment (USB and other stuff like HDMI).

Most PI's have a detector with a trigger-point of about 4.65 Volt, below which, even for nanosecond long dips, it will report under-voltages.

Because the PI itself will normally keep working these events can be reported, (showing under-voltage icons) but memory bits, (in PI memory or in connected devices) can sometimes flip, (from one to zero, or from zero to one) and this can cause filing problems that express themselves in SD-card corruptions, and crashes later on, or peripherals that stop working.

If the dip goes low enough, it may also effect the 3,3Volt supply, and thus directly affect 3V3 powered stuff, like the SD-cards themselves.

this can have effects like causing flash write fails, which can cause the sd-card controller to switch to read only, as it thinks its flash memory is starting to fail. It becomes read only to protect the "photo's" it already contains, and its hard (sometimes impossible) to convince the controller inside the card to turn read/write mode on again.

Jeufdfuaass
Posts: 5
Joined: Sun Aug 11, 2019 5:31 pm

Re: Is my pi 3B throtteling due to undervoltage?

Sun Aug 11, 2019 8:20 pm

mahjongg wrote:
Sun Aug 11, 2019 7:56 pm
chargers, unlike power supplies often lack the electronics to closely regulate their output voltage, and are more optimized to output a lot of current. computers, like the PI need precise 5V on their inputs, and are only guaranteed to work with a typical tolerance of 5%, that is plus or minus 0.25V.
applying a bit more voltage is normally not a big deal, as long as you stay well below 6.0V. As most stuff you connect will survive that, but if you go below 4.75 V equipment is not guaranteed to work!

The PI itself is a bit more tolerant, but note that dips below that 4.75 Volt can be very short, and still cause trouble in most 5V powered equipment (USB and other stuff like HDMI).

Most PI's have a detector with a trigger-point of about 4.65 Volt, below which, even for nanosecond long dips, it will report under-voltages.

Because the PI itself will normally keep working these events can be reported, (showing under-voltage icons) but memory bits, (in PI memory or in connected devices) can sometimes flip, (from one to zero, or from zero to one) and this can cause filing problems that express themselves in SD-card corruptions, and crashes later on, or peripherals that stop working.

If the dip goes low enough, it may also effect the 3,3Volt supply, and thus directly affect 3V3 powered stuff, like the SD-cards themselves.

this can have effects like causing flash write fails, which can cause the sd-card controller to switch to read only, as it thinks its flash memory is starting to fail. It becomes read only to protect the "photo's" it already contains, and its hard (sometimes impossible) to convince the controller inside the card to turn read/write mode on again.
But to put that into perspective. My power supply seems to deliver steadily >4,96V in idle, yet i get "throttled=0x50005" in idle too. Either the pi really "cuts off" at just below 5V via software, or the power supply is not my problem. Do you know what i mean?

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mahjongg
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Re: Is my pi 3B throtteling due to undervoltage?

Sun Aug 11, 2019 8:31 pm

No, and I don't understand why the CPU should throttle due to under-voltage, AFAIK it throttles because of overheating, not undervoltages, but an RPI engineer might be able to give you a more definitive answer.

without an oscilloscope, measuring at the point of load, you cant say much about a PSU's capability to react well to rapidly varying loads, only the under-voltage indicator may give you some clues. Static output voltages might not say much at all. Especially if only measured at the end of a disconnected PSU cable.

All I can say that experience teaches us that unexplainable problems are often caused by the power supply used, or by the thickness (resistance) of the power cable, it must use short and thick copper cables, or its resistance becomes a problem.

Cael
Posts: 96
Joined: Sat Jul 07, 2012 7:08 am

Re: Is my pi 3B throtteling due to undervoltage?

Sun Aug 11, 2019 8:50 pm

Jeufdfuaass wrote:
Sun Aug 11, 2019 7:29 pm
Andyroo wrote:
Sun Aug 11, 2019 6:37 pm
Have you tried a power supply or a charger?

The Pi supply provides 5.1v via nice thick cables where chargers can drop down to 4.3v or so normally through thin cable.
Yes, like i said above, i tried 2 different chargers :)
Cael wrote:
Sun Aug 11, 2019 6:29 pm
i had better luck w/ a 3A PSU w/ my 3B and 3B+, do you have a USB Load tester? (its a lil device you can use between the source n target and see the load) if you got one test to see if the Pi's pulling sufficient power, if not you might of blown something. or just poor quality cabling on the chargers

like this https://www.amazon.com/UNI-T-Digital-Mu ... ial&sr=1-4 for a tester, that should give you an idea if its in the in-between the Pi and power supply.
uhh, i had too less imagination to think about that. Yes, i have one of these load testers and tested it right away.
I gotta say, this is quite frustrating. Even under the stress test, the Pi only draws a maximum of 0,7 A, but as your instincts were correct, voltage drops down to 4,90V under load and to 4,96 - 4,98V in idle. So apparently the pi is quite salty about those few millivolts.

Its a shame, because i thought i could save some money buy not buying that 10€ power supply - and Amperage is not even the problem.
Do you have any experience with USB chargers which can be used with the raspberry pi? i feel like i am overspending 10€ for one port with low Amp draw when i can have 4 ports for 15€ or so. I recently saw this post, he uses and Amazon Basic power plug, but those are not available in my country unfortunately.
https://www.reddit.com/r/homelab/commen ... _so_i_did/

Thanks for the help!
the fact its only drawing .7A is a little troubling, the voltages look to be within Spec, and you said you tried others and it still only draws 0.7A (700mAh) something doesnt seem right. you said it was working fine before this became an issue? i wonder if something did blowto cause such low amperage draw. its a real longshot, if you've had this pi for along time and been in various enviromental conditions get a cheap thing of contact cleaner and get at the MicroUSB power connectortake a USB Cable you dont particularly care about and plug it in and out a few times (yes i know that micro USB has a "Loosey goosey wear factor after awhile.) and let it sit to dry. Again it's a longshot, but if the contacts are dirty, it might not be able to draw what it needs.

if you know your stuff, grab a multimeter and look to see if the USB Fuse on the input side is showing normal or if its out of spec. i'm no engineer but just a quick look at the Schematics, F1 looks to be the input line's Fuse, and Q3 seems to be the USB input power management chip. i guess these would be suspect. a Pi engineer on the forums or by contacting them, would likely be able to tell you better where to test to find out.

Jeufdfuaass
Posts: 5
Joined: Sun Aug 11, 2019 5:31 pm

Re: Is my pi 3B throtteling due to undervoltage?

Sun Aug 11, 2019 9:18 pm

mahjongg wrote:
Sun Aug 11, 2019 8:31 pm
No, and I don't understand why the CPU should throttle due to under-voltage, AFAIK it throttles because of overheating, not undervoltages, but an RPI engineer might be able to give you a more definitive answer.

without an oscilloscope, measuring at the point of load, you cant say much about a PSU's capability to react well to rapidly varying loads, only the under-voltage indicator may give you some clues. Static output voltages might not say much at all. Especially if only measured at the end of a disconnected PSU cable.

All I can say that experience teaches us that unexplainable problems are often caused by the power supply used, or by the thickness (resistance) of the power cable, it must use short and thick copper cables, or its resistance becomes a problem.
Unfortunately i have no oscilloscope lying around here :( For my part, CPU throttling seems completely plausible if too low a voltage is detected, but thats concerning the core voltage not the input voltage.
Easiest method to test it is switching power supplies and cables again. That will be next on the list.

As for temperatures. Well it has been at a good 50°C and above for a while now with cooling elements but without fan. Nothing much i can do about it with 27°C room temperature.


edit, i just checked, it is not thermal throtteling.

Code: Select all

throttled=0x50005
volt=1.2000V
frequency(45)=600000000
frequency(1)=249999000
temp=32.2'C
throttled=0x50005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=32.2'C
throttled=0x50005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=32.2'C
throttled=0x50005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=32.2'C
throttled=0x50005
volt=1.2000V
frequency(45)=600000000
frequency(1)=250000000
temp=31.1'C

Cael wrote:
Sun Aug 11, 2019 8:50 pm
Jeufdfuaass wrote:
Sun Aug 11, 2019 7:29 pm
Andyroo wrote:
Sun Aug 11, 2019 6:37 pm
Have you tried a power supply or a charger?

The Pi supply provides 5.1v via nice thick cables where chargers can drop down to 4.3v or so normally through thin cable.
Yes, like i said above, i tried 2 different chargers :)
Cael wrote:
Sun Aug 11, 2019 6:29 pm
i had better luck w/ a 3A PSU w/ my 3B and 3B+, do you have a USB Load tester? (its a lil device you can use between the source n target and see the load) if you got one test to see if the Pi's pulling sufficient power, if not you might of blown something. or just poor quality cabling on the chargers

like this https://www.amazon.com/UNI-T-Digital-Mu ... ial&sr=1-4 for a tester, that should give you an idea if its in the in-between the Pi and power supply.
uhh, i had too less imagination to think about that. Yes, i have one of these load testers and tested it right away.
I gotta say, this is quite frustrating. Even under the stress test, the Pi only draws a maximum of 0,7 A, but as your instincts were correct, voltage drops down to 4,90V under load and to 4,96 - 4,98V in idle. So apparently the pi is quite salty about those few millivolts.

Its a shame, because i thought i could save some money buy not buying that 10€ power supply - and Amperage is not even the problem.
Do you have any experience with USB chargers which can be used with the raspberry pi? i feel like i am overspending 10€ for one port with low Amp draw when i can have 4 ports for 15€ or so. I recently saw this post, he uses and Amazon Basic power plug, but those are not available in my country unfortunately.
https://www.reddit.com/r/homelab/commen ... _so_i_did/

Thanks for the help!
the fact its only drawing .7A is a little troubling, the voltages look to be within Spec, and you said you tried others and it still only draws 0.7A (700mAh) something doesnt seem right. you said it was working fine before this became an issue? i wonder if something did blowto cause such low amperage draw. its a real longshot, if you've had this pi for along time and been in various enviromental conditions get a cheap thing of contact cleaner and get at the MicroUSB power connectortake a USB Cable you dont particularly care about and plug it in and out a few times (yes i know that micro USB has a "Loosey goosey wear factor after awhile.) and let it sit to dry. Again it's a longshot, but if the contacts are dirty, it might not be able to draw what it needs.

if you know your stuff, grab a multimeter and look to see if the USB Fuse on the input side is showing normal or if its out of spec. i'm no engineer but just a quick look at the Schematics, F1 looks to be the input line's Fuse, and Q3 seems to be the USB input power management chip. i guess these would be suspect. a Pi engineer on the forums or by contacting them, would likely be able to tell you better where to test to find out.
i actually find this very plausible if i compare numbers with this website:
http://www.pidramble.com/wiki/benchmark ... onsumption
My WiFi is turned off, i do not use any USB devices, GUI is turned off so only console output on HDMI which is not in use. No GPIO ports used. Plus: Its underclocked all the time at 600 MHz which saves a good amount of current.

Although i have a multimeter, i have a particularly shitty one. I will keep my distance from more invasive tests for now and simply try a new power supply. As i do not have one handy, i will buy one and get back here in a couple of days. If the problem still persists, then i might have a real problem on my hands :(

As to the "it was working before". I don't really know that honestly. I have had troubles now for weeks after a particular software update of home assistant. Influxdb would always periodically ramp up the CPU load and basically block the system (pihole does not respond, so my whole network is dead for 2min every few minutes).
This led me to further investigation up until this point today. (yes, i was a bit lazy as the problem occured at very random times. Problems like these you tend to procrastinate as they were not reproducable and the home assistant community was _0_ help at all)

Jeufdfuaass
Posts: 5
Joined: Sun Aug 11, 2019 5:31 pm

Re: Is my pi 3B throtteling due to undervoltage?

Fri Aug 16, 2019 11:05 pm

Hi guys,

so i changed the power supply and it was indeed the cruelpit. I get no error or warning codes now, even under stresstest.
Thanks all!

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