USB charging issue

[Smellmet]

I've got a 2017 iMac 27" 4.2ghz, Radeon 575, 24GB RAM running Big Sur 11.6 that I've had at work for a few years, and in all that time I've been using the USB ports to charge my Android phones (S7 Edge and now Samsung A71), albeit slowly without any issues.

This week however the charging has been cutting off and restarting in quick succession, almost as if the cable is damaged or something else loose, or just not charging at all. No problem, I'll just change ports, still does it, ok I'll order a new cable, and got an official Samsung one. Still does it. Ok, I'll try my colleagues iMacs (all similar age and spec), and again, doesn't work. All tests carried out with the two different cables.

The phone charges 100% fine on my Samsung brick at home with no issues too.

Anyone any ideas? Normally you can pinpoint issues like this but this just seems weird and points to the iMacs themselves, could it be some sort of firmware issue with Big Sur or something?

 

[Nguyen Duc Hieu]

Try turning-off the machine, unplug it from the power source and let it there for a couple minutes.
Then press the power button (still un-plug) several times to clear out the capacitors charge.

After that, plug it back in to see if it clear your issue.

 

[Fishrrman]

OP wrote:
"The phone charges 100% fine on my Samsung brick at home with no issues too."

If it was me (I realize that you ARE NOT "me"), I'd just get another standalone charger and use that at home. Problem.... solved.

 

[NoBoMac]

USB delivers a finite amount of power spread across all ports, so if you have something else plugged in drawing power, that can be causing the symptoms. Try disconnecting something and then plug in to see if charges.

 

[nambuccaheadsau]

Lash out and purchase a Samsung fast charger.

 

[Moonjumper]

I do see the appeal of being able to charge at work using the machine you have there, which won't be solved by a charger.

As I am a mobile game developer, I have iOS and Android devices connected to my iMac on a regular basis. Android can be finicky, but often works. Which makes me think of two points that could narrow down the potential solutions:

1. Did the change coincide with a macOS update?

2. Do iOS devices still charge?

 

[Smellmet]

I was at the end of my tether and a colleague walked in who isn't even particularly computer savvy just said the usual 'turn your phone off and on again' (which I laughed at as I turn my phone off every night) and hey presto it all works as it did before, even on the old cable.