Something I've been wondering for a while is would be safe or bad for the laptop somehow to charge my 16" MBP M1 simply by plugging my MagSafe 3 charge cable's USB-C end directly into a wall outlet has a USB-C port on it. In essence, I'd just be using this cable.

Nominally, the port puts out 5V 3.3A. The desire to do this stems from the fact that I could eliminate that wall brick from the counter. I wouldn't charge the laptop in this manner while in use, just while in standby/sleep.

I've done the same thing with a Dell Precision 5560 but I cared about that machine a litle less. Just curious about thoughts here.


1 Answer 1


Your described use case does not harm your MacBook at all, rather the opposite. Charging the battery slower (i.e. lower wattage) means there is less heat, which is the main factor degrading your battery longevity.

You can also safely use your MacBook while connected to that outlet. As soon as your MacBook needs more power than whats provided by that outlet (in this case 16.5W) it will use the battery to provide whatever is still needed. For example: if your MBP needs a total of 30W, the battery will provide the 13.5W, since you only get 16.5W from the wall. Of course, the battery now discharges meaning, although connected to power, at some point your battery will run out of juice and your MBP shuts down.

The M1 Max and Pro chips are extremely efficient and depending on the workload can stay below that 16.5W power draw. Yet, this heavily depends on what you are doing with the machine.

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