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Pi 3 Under voltage solved  

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JMcK
 JMcK
(@jmck)
Reputable Member
Pi 3 Under voltage solved

I’ve been usingOctoPi on a pi 3 for a long time, powered by a 15w iPad charger. Always there’s an under voltage warning in the Octoprint UI. It never caused problems, (well, maybe some that I can’t prove yet.) but it’s irksome so I wanted a fix.

I’ve been meaning to replace the iPad charger with a more “official” power supply, but on a whim I replaced the USB cable, and I haven’t seen the warning since.

So, PSA: The cable matters. Neither of mine is a “cheap” cable; the one that works is actually the less expensive one $6 vs $8. So price is not an indicator; you might need some trial and error. The “good” cable is noticeably thicker, so probably better wire gauge inside, but without cutting the cables open I can’t prove that.

When someone asks you if you're a god, you say, "YES!"...
Posted : 04/03/2020 10:57 am
Clemens M.
(@clemens-m)
Prominent Member
RE: Pi 3 Under voltage solved

Trial and error helps there a lot - USB-cable for powering up of the raspberry pi is critical - cable cross section and length - and then there is sometimes a problem - it is the electrical contact at the plug. You can have some sort of oxidation on the contact surfaces which regard to undervoltage (especially when leaving the cable plugged in for a very long time).

Best regards, Clemens 

Posted : 04/03/2020 12:27 pm
bobstro
(@bobstro)
Illustrious Member
RE: Pi 3 Under voltage solved

I think the thicker gauge cables are key. I've always had the best luck using the official RPi, Adafruit or Canakit power supplies for my RPi projects. Those are also bumped up slightly in output voltage to compensate for the cable length.

 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 04/03/2020 4:03 pm
bobstro
(@bobstro)
Illustrious Member
RE: Pi 3 Under voltage solved

I think the thicker gauge cables are key. I've always had the best luck using the official RPi, Adafruit or Canakit power supplies for my RPi projects. Those are also bumped up slightly in output voltage to compensate for the cable length.

 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 04/03/2020 4:04 pm
Clemens M.
(@clemens-m)
Prominent Member
RE: Pi 3 Under voltage solved

@bobstro

A realy important message - has to be posted twice 😉

Best regards, Clemens

Posted : 04/03/2020 4:08 pm
Chocki
(@chocki)
Prominent Member
RE: Pi 3 Under voltage solved

One of those USB power meters can really show up poor cables, I ended up throwing numerous cables away over the years as they simply could not deliver the power required to higher powered devices, I bought this after one cable tried powering my phone running GPS navigation in the car, and the cable actually got hot! and the phone got flat, so after testing all my then owned cables, about half went into the bin.

These power meters are also good for testing charger compatibility with fast charging. If you do decide to get one, make sure you get one that can go to the higher voltages.

I bought one from portapow .

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 04/03/2020 4:44 pm
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