Is there any way to check how long a 2020 M1 MacBook Pro has been connected to an AC adapter? (I have a charger that I think is periodically disconnecting and reconnecting.)

I'd like something like Terminal "uptime" but for this purpose it'd print something, for example, "On AC Adapter for H hours M minutes).

  • Why is this important info to have? The SMC (what handles charging) will connect and disconnect mains periodically to maintain a certain level of charge in the battery especially when “optimized charging” is enabled. What this means is, you could potentially get a message that it was on mains for 5 minutes and it has full charge. What problem are you looking to solve?
    – Allan
    Commented Mar 2, 2023 at 22:17
  • I think my charger is disconnecting/reconnecting. I hear the occasional beep from the laptop like it's being plugged in again. I'd like to confirm before I "retire" the charger - it is a nice one.
    – user489817
    Commented Mar 2, 2023 at 22:19
  • 1
    Check your household current first. Plug into a UPS and if that behavior stops, you’re having small power drops or brown outs. If it continues, then you likely have a bad charger. Confirm by trying a different charger; even an inexpensive one.
    – Allan
    Commented Mar 2, 2023 at 22:21

1 Answer 1



Use the built-in macOS command line tool pmset to see a log of power events. The log should include switches to and from AC power:

pmset -g log

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