Pi Undervoltage/power issues: I had a strange lightning bolt/temperature symbol with an exclamation mark popup in my navbar, what does that mean?

Are you measuring the voltage from one of the two 5V GPIO pins to any ground pin while it's running?

It would be nice to know which Raspi we're talking about.

You may be onto something about using the micro USB port versus powering it via GPIO. I remember that Robo 3D got in a batch of Raspberry Pi 3B computers which had sloppy micro USB connectors, the plug never could get a tight fit and the 5V would make/break as a result. (Testing this then, hold the micro USB plug firmly in place with rubber bands and see if the problem goes away.) If you find that it's the loose micro USB connector, consider adding a slight crimp in the connector housing with a pair of needle-nosed pliers or powering it differently.

That doesn't mean it isn't getting temporary undervoltage- you can check the flags on vcgencmd to see if it is "now" vs "in the past". Measuring undervoltage independently- but if you are getting the flag, you have power problems.

hello, I am having throttling issues with under voltage at some specific times. I only find the UI confusing and not very practical. It would be better if the icon only appeared when there is a current issue going on and then time out after like 5 mins or manually set. I get my setup is not ideal, but is not bad either. I don't want to disable the icon so I can keep my interface neat, but how it is really encourages me to do so. Thanks for the time.

See if you can find a 5.2V 3A power adapter and the problem might go away for good.

I have one of 2,5A which gives a steady 4.96 V... it is where I need it to be and I am just seeing under voltage occur right at startup. I'm guessing it is not so fast to provide 2.5 amps from zero, maybe small caps? anyhow, I don't believe spending that money when my powersource which was kinda expensive works fine after booting. I believe that a timeout feature will make the alert much more useful on the long run. Specially if it is acompanied by a notification banner.

I've been printing for a couple years now and from Day 1 I plugged it into an APC brand UPS (I know, this sounds like a commercial). For many people, the problem starts at the wall (the wall voltage occasionally drops below some arbitrary threshold). And then the output side of the Raspi adapter is lower than what it is supposed to be (which then gets reported as < 4.64VDC).

So, begin at the wall and use a multimeter and sit there and watch it while opening your refrigerator door. The compressor then will kick in which wants lots of power and will drive the input voltage down to something ridiculous like 109VAC.

Seems to make sense. But still that would mean im stuck with this behavior. Im a student and built my printer from literally scrap, can't afford a UPS since it would probably end up costing up to half my printer total cost! haha
If the timeout was added, alongside with a banner notification upon new under voltages; it would make this feature so much more useful for people like me on a far from ideal setup.

Well, that's not really my decision since I didn't code OctoPrint.

What I do, though, is I buy used APC UPSs at flea markets or someone's garage sale. They're heavy since they include a 12V acid battery inside like you might find in a car so anyone is delighted to get rid of them for almost nothing (even free).

At about the five-year point, the battery needs to be replaced but you can get them locally for about $24 but they'll give you about $5 back as a core fee for the replacement battery you bring back to them. Replacing the battery is about the easiest thing you've ever done.