Lower Power mode and automatic sleep disabled but external SSD keeps disconnecting on battery

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Level 1

19 points

Lower Power mode and automatic sleep disabled but external SSD keeps disconnecting on battery

I have a MacBook Air (M4) running Tahoe 26.3. In settings, Low Power mode is set to "Never" and I have also enabled "Prevent automatic sleeping."

Despite all that, my external Thunderbolt SSD (which I use for Time Machine) keeps getting disconnected when I pull the charging USB cable. When I unplugged the Mac today, I even saw a notification pop up briefly about "Lower Power mode enabled"

Am I doing something wrong here, or is this a bug?

Posted on Jan 16, 2026 12:59 PM

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Answer 1

dwb

Level 7

33,372 points

Jan 16, 2026 2:17 PM in response to Pho3bus

If I’m reading this correctly, when you switch the computer from being plugged in to battery by yanking the charging cable your external SSD unmounts. My guess is that the SSD requires more power than the computer supplies on battery. If the SSD does operate normally while on battery it could be that it doesn’t like that momentary switch when you remove the cable. You might try putting the computer to sleep then pulling the plug and seeing if the SSD remains connected.

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Lower Power mode and automatic sleep disabled but external SSD keeps disconnecting on battery

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