MacBook Pro M1Max 16-inch: Clamshell mode doesn't work if connected to USB power?

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MacBook Pro M1Max 16-inch: Clamshell mode doesn't work if connected to USB power?

I have a 16" MacBook Pro M1 Max, and clamshell mode works fine if connected to the magsafe connector, but it doesn't work at all when connected to a USB charger instead of the magsafe connector. This means my previous charging configuration(with my charging cable being plugged into a hub and then only the cable from the hub being plugged into the computer) which required only one cable doesn't work. I can't see a technical reason why this wouldn't be allowed/enabled.

Are other people experiencing this? Is this the way Apple intends things to be? This is a regression(loss of functionality) if so, but it seems like an oversight on Apple's part.

MacBook Pro (2020 and later)

Posted on Nov 12, 2021 2:53 PM

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Answer 1

Best reply

Matthew Kinabrew Author

Level 1

5 points

Nov 13, 2021 2:10 PM in response to Matthew Kinabrew

I determined that the issue was related to the monitor in question not receiving a signal on its HDMI port. Although I had tried numerous HDMI cables and numerous adapters(mini-DisplayPort-to-HDMI adapter + HDMI cable, mini-DisplayPort-to-HDMI cable without extra adapters, USB-C-to-HDMI adapter + HDMI cable), in the end I switched the video port being used from the monitor's HDMI port to its DisplayPort port(a USB-C-to-DisplayPort cable), and that functions correctly in clamshell mode with the computer receiving power from any of the computer's USB-C ports.

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Answer 2

kamote0628

Community Specialist

Nov 13, 2021 1:57 PM in response to Matthew Kinabrew

Hi Matthew Kinabrew, We appreciate you reaching out to us. We understand that your MacBook Pro will not charge through a USB-C connector when in clamshell mode.

We’d like to gather additional details that may help us be in a better position to assist you.

Have you had the chance to try a different dock?

Have you had the chance to try a different cable?

Have you had the chance to try a different USB-C port?

Are you receiving an error message?

Are you only experiencing charging issues when in clamshell mode?

In the meantime, we recommend that you check if the issue persists when signed in on a different user account.

The article below can help if you do not have any other user account to test with.

Set up users, guests, and groups on Mac

Take care!

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MacBook Pro M1Max 16-inch: Clamshell mode doesn't work if connected to USB power?

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