low voltage warning

[Sinibotia]

hoping somebody can help me as I'm trying to do this project without a pi zero. I've wired up the pi hat exactly as according to the instructions for part 2 of the tutorial. I tried it with a pi 4 and the system functioned ok but I consistently had a low voltage warning. thinking it was the pi 4, I switched to a pi 3A+ which has lower power requirements but I still get the error (albeit with less frequency). as best I can tell both pi models are supposedly able to be powered by the 5v pins. any ideas on how I might resolve this or where the issue might be coming from? can this project just only be done with a pi zero?

 

[gbroadbridge]

hoping somebody can help me as I'm trying to do this project without a pi zero. I've wired up the pi hat exactly as according to the instructions for part 2 of the tutorial. I tried it with a pi 4 and the system functioned ok but I consistently had a low voltage warning. thinking it was the pi 4, I switched to a pi 3A+ which has lower power requirements but I still get the error (albeit with less frequency). as best I can tell both pi models are supposedly able to be powered by the 5v pins. any ideas on how I might resolve this or where the issue might be coming from? can this project just only be done with a pi zero?

Does it only happen once after reboot, or are you getting a lot when the system is running?

 

[theatrus]

What are you using as the 5V power supply?

Yes, the Pi can happily be powered by the 5V pins without issue, so any faults are going to be the power supply or any converters you've used.

 

[Sinibotia]

What are you using as the 5V power supply?

Yes, the Pi can happily be powered by the 5V pins without issue, so any faults are going to be the power supply or any converters you've used.

On adafruit: 12V DC 1000mA (1A) regulated switching power adapter

On digikey: DFR0379 (converter)

Does it only happen once after reboot, or are you getting a lot when the system is running?

Regularly while running. On the 3A+ it will go a little while between errors but its more than just on boot.

 

[theatrus]

Do you have some other 5V supply, such as a USB supply, you can use for testing?

Is anything else connected to the Pi?

 

[Sinibotia]

Do you have some other 5V supply, such as a USB supply, you can use for testing?

Is anything else connected to the Pi?

Had a temp sensor attached that didnt seem to affect the issue whether it was attached or not. But I'm wondering now if maybe the 1000mA supply is the issue when the supply is apparently supposed to be 2.5 or 3A minimum.

Ive used the official power supply for pi 4 previously and had no issue. This was my first time booting the 3A today and i only tried with the 9V supply

 

[Sral]

Had a temp sensor attached that didnt seem to affect the issue whether it was attached or not. But I'm wondering now if maybe the 1000mA supply is the issue when the supply is apparently supposed to be 2.5 or 3A minimum.

Ive used the official power supply for pi 4 previously and had no issue. This was my first time booting the 3A today and i only tried with the 9V supply

You have to include the voltage in that thought. 12V @ 1A is 12W, whereas the DC/DC step down converter has 5V @ 3A (peak) which is 15W.

So both are not far of each other and the step down converters typically range in the 80-90% efficiency. 80% of the 12V‘s power of 12W gives you about 10W, which is 2A continuous in 5V. Peak power might be higher on both.

So it might be either converter in my opinion. I would personally both try identical ones in case you have a faulty one and upping the 12V to 2A.

You could also try looking at strengthening the connection with better connectors and cables to rule out high cable or contact resistance, as well as increasing the 5V line to 5.1 or 5.2.

 

[bishoptf]

Just FYI, I have had and continue to have issues getting low voltage alarms when I have powered via pins vs the usb power in port. I know it shouldnt matter but I have powered both ways with the same power supply and seems to run better with power going into the usb power port.

I have also noticed that when using a buck converter to drop power that I have also seen more issues when using the cheaper buck converters, they do not seem to supply a constant voltage when under load etc...

Here are my logs for the last few weeks:

For whatever reason I cannot post my logs, I get a browser error, so friggen lame...

Here is a screenshot since I can't past the text for some reason:



And before anyone says anything about the power supply its a OEM power supply I've just been to lazy to re-do things with the power, since I need 12v to run other stuff its a 12v supply going through a buck converter.

 

[bishoptf]

I will add this, I tend to set my voltage on the buck's output to 5.1 but according to this exchange that the official rpi power supplies put out 5.25v, see the bottom posting of this thread - https://raspberrypi.stackexchange.com/questions/91493/get-reading-of-rpi-supply-voltage

I studied this official schematic diagram. It shows that all chips are powered from an onboard voltage regulator chip RG2 for 3.3 V. This means that the 5 V input voltage should not be very critical. The only other use of the input 5V is VDD_BAT1 to 4, which could be some sort of voltage measurement used to display the thunderbolt if the input voltage drops below 4.65 V. The chip used for RG2 is a NCP-1117-3.3V, with this datasheet. This ic has a voltage drop of min. 1.2V, so the input should be at least 3.3 + 1.2 = 4.5 V. Add a little margin and 4.65 V is a reasonable min. voltage to guarantee that all chips onboard of the RPi will function correctly. I do not see a problem of input voltages higher than 5 V. Of course, if the input voltage gets much higher, the dissipation of RG2 will increase, but there is no hard limit of e.g. 5 V + 5 % = 5.25 V. So e.g. 5.30 should give no problems.

This does NOT mean that every usb power supply would work. To charge a phone battery, it would not be a problem at all if the usb power supply has voltage dips. But for powering the chips inside the RPi, any voltage dip on the 3.3 V rail would be fatal, no matter how short this voltage dip would be. Translated to the 5 V usb input, this would mean that that input should NEVER drop below 4.65 V. So the official Raspberry Pi power adapter is not a regular USB charger; it is designed to NEVER drop below 4.65 V. It also has a slightly higher voltage, the nameplate voltage is 5.1 V, and I measured 5.25 V. In practice, there is always some loss of voltage in the cable and micro usb connector, so by starting at a slight overvoltage, the risk of ever getting below 4.65 V is minimal. Again, a slight overvoltage is not a problem at all, as all chips are at the 3.3 V level, and the overvoltage is dealt with by the RG2 voltage regulator.

For designing your own power supply, I got good results with a cheap 3 ampere switching regulator set to an output of 5.25 V and directly wired to the 5V and GND pins on the 20-pin RPi headers to eliminate voltage drop over a usb connector. In fact, the 5V header pins are directly connected to the usb power connector, except that the usb connector has a polyfuse, intended to avoid damage in case of a short circuit in a usb device fed from the RPi.

I am still puzzled about the exact power voltage measurement used to show the lightning bolt in case of undervoltage. I just guess that the VDD_BAT1 to 4 pins are used to measure the input voltage. I read about a APX803 (the power-monitoring device used on Pi 3) and GPIO26, but could not find anything about this on the schematic diagram. Any insight from more knowledgable people welcome.

I would be curious to hear what @Sral or @theatrus suggest setting the output from a buck for the input, maybe I will make some adjustments.

 

[Sinibotia]

Increasing the output to as high as 5.3 is something I have already tried with no success. I will try swapping out converter and power suppy to see what happens.

 

[bishoptf]

Increasing the output to as high as 5.3 is something I have already tried with no success. I will try swapping out converter and power suppy to see what happens.

Are you feeding power in via the GPIO pins or via the USB input? Also like I said if your using a buck converter to step down the power then it may be the buck converter that is the problem.

 

[Sinibotia]

Are you feeding power in via the GPIO pins or via the USB input? Also like I said if your using a buck converter to step down the power then it may be the buck converter that is the problem.

Via the 5V pin. I'm hoping it's not the buck converter, but I have a few spares to try.

 

[bishoptf]

Via the 5V pin. I'm hoping it's not the buck converter, but I have a few spares to try.

I have a bunch of these and I've had the issue repeated across supplies and for whatever reason I saw it as an issue with the cheaper buck converters not maintaining voltage but it also could be something with the power supply, I've seen more instances when feeding vi gpio vs the usb connection...something else to try also splice a usb cable from the buck converter going to the usb power port and see if that makes any difference.

 

[Sinibotia]

I have a bunch of these and I've had the issue repeated across supplies and for whatever reason I saw it as an issue with the cheaper buck converters not maintaining voltage but it also could be something with the power supply, I've seen more instances when feeding vi gpio vs the usb connection...something else to try also splice a usb cable from the buck converter going to the usb power port and see if that makes any difference.

This is the buck converter I'm using. Do you have a recommendation for a better one?

 

[bishoptf]

This is the buck converter I'm using. Do you have a recommendation for a better one?

@Sral and @theatrus would probably have better recommendations, I think most would say get a better quality supply that does a better job supplying constant voltage under load. I started using these which are way overkill but have had better luck with them XL4015 chipset

I have had this issue for sometime, I have some that have been running with the message for years though, ymmv...

 

[Sinibotia]

@Sral and @theatrus would probably have better recommendations, I think most would say get a better quality supply that does a better job supplying constant voltage under load. I started using these which are way overkill but have had better luck with them XL4015 chipset

I have had this issue for sometime, I have some that have been running with the message for years though, ymmv...

The 3A+ does seem to run fine despite the message, so if swapping parts around doesn't provide a quick fix I may just do an extended test run and see if it works despite the error.

 

[bishoptf]

Just adjusted my buck converter up to 5.2 and I still see the issue, whats odd is Mine seems repeatable, at the top of the hour, really odd and I'm sure its the power supply but not sure how you get a quality power adapter that you know will work. Note the times, once it gets to the morning I see lots more instances, some days worse than others:

Feb 28 03:00:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 04:00:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 05:00:13 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 06:00:11 octopi kernel: Under-voltage detected! (0x00050005)

pretty odd stuff...

Here is the rest of the day:

Feb 28 07:13:45 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:14:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:34:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:35:10 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:36:11 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:40:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:40:26 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:41:10 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:45:47 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:46:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:47:06 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:51:11 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:51:26 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:52:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:57:11 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:58:11 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 07:59:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:03:11 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:04:11 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:04:30 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:09:11 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:09:30 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:10:46 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:14:31 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:15:11 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:16:11 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:19:33 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:21:10 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:21:56 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:25:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:27:10 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:28:11 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:30:51 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:31:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:32:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:36:11 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:38:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:40:10 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:44:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:45:12 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 08:46:10 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 10:00:11 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 10:01:07 octopi kernel: Under-voltage detected! (0x00050005)

It's udder crap but been running this way for 2 years, maybe I need to look for a different power adapter and swap them out, currently running a 5a 12v power supply from netgear, lol.

 

[theatrus]

You can always dual run it - use the RPi power supply just for the Pi, and the existing supply and converter for the rest of the circuit. Just connect the grounds in one spot and you're good.

On another note, be cautious about dupont jumper lead wires. I've bought some (Amazon, random sellers) which effectively were 32 gauge or smaller (super tiny) wire, maybe not even copper, but looked more like a 24 gauge wire due to the massively thick jacket on them. Those wires are no good for carrying a few amps without voltage drops. If you have a multimeter, you can try to measure voltages under load (aka, Pi running) at various points to see how bad things are.

 

[bishoptf]

You can always dual run it - use the RPi power supply just for the Pi, and the existing supply and converter for the rest of the circuit. Just connect the grounds in one spot and you're good.

On another note, be cautious about dupont jumper lead wires. I've bought some (Amazon, random sellers) which effectively were 32 gauge or smaller (super tiny) wire, maybe not even copper, but looked more like a 24 gauge wire due to the massively thick jacket on them. Those wires are no good for carrying a few amps without voltage drops. If you have a multimeter, you can try to measure voltages under load (aka, Pi running) at various points to see how bad things are.

Yeah agree, I am using 22 awg wire for my connections running to and from buck but I am also using JST connectors so I can disconnect things etc, I know I have always had the issue and have tried lots of things...

I mean for me it appear to happen at the top of the hour, pretty bizarre

Feb 28 10:00:11 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 10:01:07 octopi kernel: Under-voltage detected! (0x00050005)
Feb 28 11:00:11 octopi kernel: Under-voltage detected! (0x00050005)

 

[bishoptf]

So would a meanwell adapter be better suited something like this one - https://www.mouser.com/ProductDetail/MEAN-WELL/GST60A12-P1J?qs=odmYgEirbwzBCeXKJrW1mg==

sorry @Sinibotia didn't mean to thread jack but I have had the same issue and would like to find a better solution, should I be looking at defferent power supplies or different buck converters..inquiring minds want to know

Here is the one I am using, UL listed etc...