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whack3r24

macrumors newbie
Original poster
Jul 25, 2022
17
9
Hello!
I upgraded my 13-inch 2015 MacBook pro to the MacBook14-inch pro 14inch M1. I'm out and about a lot and usually charge my iPhone (XS) via the MacBook but I've noticed it charges my iPhone A LOT slower compared to my old macbook. Does anyone know why this is? I would have thought USB-c would support fast charging? Does anyone know if the ports have different wattage outputs?
My phone fast charges using everything else. I'm using the official usb-c to lightning cables (have tried 2). All my devices are up to date.
Thanks in advance
 

iMacDragon

macrumors 68020
Oct 18, 2008
2,389
723
UK
From previous threads there seems to be a bug on ventura with xs/xr generation phones and slow charging, not sure if it's been fixed in 13.3 or not.
 

real_mon2

macrumors member
Mar 11, 2023
49
8
Windsor, Ontario, Canada
The macbook is not an unlimited source of energy to power your load (phone / ipad, etc.). That is, perhaps you are using the macbook without an adapter and charging your phone? It is very realistic for the design to throttle the max power at the USB C port so that your laptop battery is not depleted. While the designers could certainly allow for higher current (power) to the device being charged, you would then be left with a bad user experience since the main battery is now depleted and it would need charging. It is a balancing act.

Perhaps you will find the charge rate to increase IF the macbook is being charged by an external adapter AND then you are charging your phone. In this case, the burden of current sourcing is on the external power adapter and not the main battery.

USB C is all about power delivery. Intelligent packets of data fly back and forth between the source (adapter? battery?) and sink (internal battery to the macbook? your phone? your ipad?). The designers likely chose the max allowed current to be as you are observing.

If you wish to review the exact current draw for each case scenario - purchase a relatively low cost USB Type C meter. Apply that tool between your charge cable and the macbook and observe the digital display for the full details.
 

whack3r24

macrumors newbie
Original poster
Jul 25, 2022
17
9
The macbook is not an unlimited source of energy to power your load (phone / ipad, etc.). That is, perhaps you are using the macbook without an adapter and charging your phone? It is very realistic for the design to throttle the max power at the USB C port so that your laptop battery is not depleted. While the designers could certainly allow for higher current (power) to the device being charged, you would then be left with a bad user experience since the main battery is now depleted and it would need charging. It is a balancing act.

Perhaps you will find the charge rate to increase IF the macbook is being charged by an external adapter AND then you are charging your phone. In this case, the burden of current sourcing is on the external power adapter and not the main battery.

USB C is all about power delivery. Intelligent packets of data fly back and forth between the source (adapter? battery?) and sink (internal battery to the macbook? your phone? your ipad?). The designers likely chose the max allowed current to be as you are observing.

If you wish to review the exact current draw for each case scenario - purchase a relatively low cost USB Type C meter. Apply that tool between your charge cable and the macbook and observe the digital display for the full details.
Thanks for the response: I've tested it when the macbook pro it's plugged into the mains and it made no difference. I just find it odd that my 2015 macbook pro could charge my iphone much faster over usb a than a brand new macbook pro m1. I'll have a look at the thread posted my @iMacDragon as it seems like it might be a software issues which is the only thing that could make sense.
 
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