MBP 2018 Not Charging mid CPU usage

Tex-Twil

macrumors 68020
Original poster
May 28, 2008
2,473
10
Berlin
Hi,
I have a 2018 15" MacBook Pro (2.6) and when the CPU is under usage (XCode compilation), the battery shows Not Charging.

I have the power supply plugged in via the original Apple USB-C cable directly into the mac without any adapters.

Is a 3000+ € laptop supposed to do that? :/

cheers,
Tex
 

LogicalApex

macrumors 6502
Nov 13, 2015
494
434
You need power to charge and power to run the laptop. Usually, you're not pulling in much to run the laptop so there is a lot of spare left over to use for charging (if needed). When you push the laptop to full tilt though you can pull in enough to not have any left over for charging and in rare circumstances you'll even need to dip into your battery to exceed the 87W in the power adapter.

since the MBP 2018 is USB-C if you have a 100W USB-C adapter I imagine it would be able to supply enough power, but Apple went with 87W to save weight since full tilt is probably more rare.

If I find spare time I will test this out since I have a 100W USB-C Power Delivery port on my Desktop that can be used to deliver maximum USB-C PD wattage to my 2018 MBP 2.6...
 

Tex-Twil

macrumors 68020
Original poster
May 28, 2008
2,473
10
Berlin
Hi,
thanks for your answer.

I'm just surprised that this is happening on a 2018 model while I never experienced this on my previous 2015 2.2 rMPB that came also with a 85W charger.

If this is "normal", I'm fine with it. I was just wondering if there is something wrong with the mbp

cheers,
Tex
 

LogicalApex

macrumors 6502
Nov 13, 2015
494
434
Hi,
thanks for your answer.

I'm just surprised that this is happening on a 2018 model while I never experienced this on my previous 2015 2.2 rMPB that came also with a 85W charger.

If this is "normal", I'm fine with it. I was just wondering if there is something wrong with the mbp

cheers,
Tex
Different chips. The 2018 MBP has more powerful chips drawing more power and giving off more heat.
 

mick2

macrumors member
Oct 5, 2017
66
58
UK
Surely the provided charger should be able to supply enough juice to fully power the laptop, even at times of high demand? I've *not* used a 2018 but have used most other generations before it and I've never seen any of them stop charging when running at full tilt for an extended time (gaming. rendering, compiling, sometimes for >2hrs at a stretch).

OP, I'd maybe try and wait for more anecdotes on this as it doesnt sound right to me that your charger cant keep up with demand.

I'm also doubtful that trying a more powerful 100w adapter will work, as the MBP EC communicates with the adapter and they agree on an ACPI power 'profile' to use; I'd imagine that the MBP doesnt have a >87w profile even if its used with an adapter capable of supply this.
 
Last edited:

LogicalApex

macrumors 6502
Nov 13, 2015
494
434
Surely the provided charger should be able to supply enough juice to fully power the laptop, even at times of high demand? I've *not* used a 2018 but have used most other generations before it and I've never seen any of them stop charging when running at full tilt for an extended time (gaming. rendering, compiling, sometimes for >2hrs at a stretch).

OP, I'd maybe try and wait for more anecdotes on this as it doesnt sound right to me that your charger cant keep up with demand.

I'm also doubtful that trying a more powerful 100w adapter will work, as the MBP EC communicates with the adapter and they agree on an ACPI power 'profile' to use; I'd imagine that the MBP doesnt have a >87w profile even if its used with an adapter capable of supply this.
The 2018 MBP supports USB Power Delivery which has profiles for 10, 18, 36, 60, and 100W I would imagine the MBP would use a 100W USB Power Delivery charger just fine. I have plugged it into my 100W PD port on my Windows Desktop and it detected it as 100W, but I didn't push it full tilt and compare it to the 87W wall charger to see if it will actually use the extra watts.

Additionally, my point about the charger not keeping up at full tilt is nothing new and goes back for eons with Apple laptops. Apple doesn't supply massive 100W and 160W power adapters with their laptops like manufacturers who expect their device to spend a lot of time at full tilt. So you can see the battery discharge if you're pulling extreme wattage as it will dip into the battery to get what it is unable to pull of the wall adapter.

https://apple.stackexchange.com/questions/307554/mbp-usb-c-charger-cant-keep-up-when-busy-is-that-normal