2019 macbook pro acting like the power cable is being unplugged and plugged back in while charging

CXK wrote:

We have two of these 15” MBP laptops from 2019. When we plug the USB C charger in (official Mac charger it came with) we hear the tone indicating it’s been plugged in. Almost immediately after, the screen dims, brightens and plays the tone again like it’s being plugged in again. This happens repeatedly, sometimes up to 20-30 times in a row. We have tried SMC reset and the pRAM reset. Tried different ports too, But it still occurs. It’s not every time we plug them in my it happens enough to be annoying especially considering the price of these.

I personally miss the MagSafe and was frustrated to find they brought them back after we bought these.

Is there anything left to try?

SMC is the power management controller...

I would be tempted to try again —Reset the SMC of your Mac - Apple Support

The user diagnostic is not definitive— to test your Mac

Use Apple Diagnostics to test your Mac - Apple Support

I would take it in if your issue does not resolve—

In or out of warranty you can get a free over the counter 'Apple Service Diagnostics' test /assessment

Make an appointment for a "hardware issue"

Genius Bar Reservation and Apple Support Options - Apple

Outside the USA

Contact Apple for support and service - Apple Support

If both these Macs are displaying the same issue on two different chargers I would suspect third party interference...

To trouble shoot further you can:

—Test issue in another user (or guest user) account Change Users & Groups settings on Mac - Apple Support

This will tell you if it a universal issue or isolated to your user/admin account. 

—A SafeBoot How to use safe mode on your Mac - Apple Support will sort many anomalies

does a quick disk repair before it fully boots up, and certain system caches get cleared and rebuilt, third party system modifications and system accelerations are disabled. a reboot will put it back to normal mode.

This test will tell you if third party interference; most* extensions etc are not loaded in safe boot mode.

The current stable release of Ventura including bug fixes, security updates is macOS Ventura 13.4

Keep your Mac up to date - Apple Support

Keep your Mac up to date - Apple Support

I had the very same issue for a few weeks, it was annoying, the computer was 99% of the time connected to the charger.

• everything was original: charger, cable, laptop
• I am the first owner, unpacked it myself from the sealed box, from the original Apple store
• the computer is from 2020, running Ventura 13.5.1
• I was thinking the cable was damaged by my cat, tried different cable - same result
• I've tried to do SMC reset, 2 times - didn't help
• I have another MBP (Apple Silicon M1) with more powerful charger (140W), so I've tried my original cable from personal MBP with that charger from M1 - and everything was working fine as expected
• so I started to suspect my 96W charger... I've used it with other devices to charge my phone, headphones, etc, everything that has USB C and it always was connected to the mains power
• so then I've thought maybe my 96W charger stuck with some kind of a "low power" mode and can't switch back to what MBP is demanding
• I've disconnected the charger both from mains and from MBP for a few minutes, then connected it to MBP, waited a minute and then connected it again to the mains power
• voila - now it works, Coconut Battery shows charging power 40+ Watts, in contrast to 5-9W before.

So it looks like it makes sense to disconnect the charger once in a while or not to use it with anything else except MBP it was designed for :)

If it occurs with two different laptops with two different sets of power adapters & charging cables, then it is most likely there is an issue with the electrical circuitry in your house. Try using another electrical receptacle especially on another circuit breaker including connecting directly to the wall/floor receptacle.

The other possibility is the charger is not correct for your laptop. Verify you are using at least the 87W charger (96W or 114W is also Ok).

Were both of these laptops purchased from the same person? If so, then there may be more going on here...and these laptops have been damaged. While rare, I have encountered times when one device (laptop or the external device) fails and damages the other item. Then when you test things by connecting the laptop or item to another one it causes that working item to fail as well. And it goes on & on....a tech's worst nightmare.

Or maybe the seller was just not honest about the condition of these laptops. I find that the 2019 model laptops seem to have a much higher failure rate of their Logic Boards. I would suggest returning them for a full refund.

FYI, I support thousands of our organization's Apple laptops and I find the USB-C port on the majority of them tend to have liquid damage (it only takes a single drop getting splashed into the port). While the USB-C ports on the 2019 models don't wear out as easily as the 2016-2017 model, I suppose you could still have a loose cable connection which would also produce this issue....keeping in mind any one of the following could be the source of a loose or damaged connection: laptop, charger, and charging cable.