MacBook Pro 2018 battery drain while plugged in

gopnick

macrumors regular
Original poster
Oct 17, 2007
199
9
I have a 2018 MBP (15" Core i7). I travel a couple times a month, but most of the time it's on my desk, plugged in. I tried using it without my big 27" Apple display (Thunderbolt) for a few months. When I do that it sometimes makes me feel like I can't get work done without it, and I get less productive on the road. So I tried to trick my brain by just always using the built-in display. Long story short, I failed that. I need my bigger monitor so I can be more productive when I'm at my desk.

So here's the current setup:
87w Apple power adapter plugged in to the MBP (USB-C, of course).
27" Thunderbolt Display plugged in via a USBC to Thunderbolt adapter.
Nothing else drawing power except a tiny USB backup hard drive for Time Machine, which isn't running all the time of course...
And my BT keyboard/Magic Trackpad.

That's it.

Nothing super processor intensive. Just Outlook, Mail, Safari, Chrome, Slack, and MS Office apps.

And yet after putting in 11 hours today (not a long day for me) it died. Literally drained the battery to 0% and went off during a video call with no warning.

It's pretty clear that the display is somehow draining the battery... I assume because discreet graphics are being utilized.

This seems like a pretty core design flaw. If you can't use a computer with an external monitor all day using the manufacturer-supplied power adapter... yikes... I don't know what to say.

Any suggestions? Can I somehow limit the amount of power it uses? Is there a way to safely deliver more power via USB-C?
 

BuCkDoG

macrumors 6502a
Jun 13, 2013
535
178
The issue most likely occurring here is that the power draw is more than the 87W USB C Charger is delivering to the computer. Apple really should include a 100W USB C Charger since that is the maximum amount of power USB C can handle and when using Intel Power Gadget, I have seen sometimes where it draws more power than the 87W is currently supplying, hence not charge equilibrium.
 

gopnick

macrumors regular
Original poster
Oct 17, 2007
199
9
The issue most likely occurring here is that the power draw is more than the 87W USB C Charger is delivering to the computer. Apple really should include a 100W USB C Charger since that is the maximum amount of power USB C can handle and when using Intel Power Gadget, I have seen sometimes where it draws more power than the 87W is currently supplying, hence not charge equilibrium.
I was afraid of that. Is it possible to buy a 100w adapter that would be safe to use on the 2018 MBP?
 
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BuCkDoG

macrumors 6502a
Jun 13, 2013
535
178
I was afraid of that. Is it possible to buy a 100w adapter that would be safe to use on the 2018 MBP?
It is possible yes, Amazon gladly will sell you one. Is it safe? Of course its safe since USB C can already handle that lol. It's just like using an iPad charger for your iPhone, faster charge.
 

gopnick

macrumors regular
Original poster
Oct 17, 2007
199
9
Thank you.

I'm now second-guessing myself. I've been working for two hours so far today and I'm still at 100%. No clue what happened yesterday! Maybe it was a fluke.
 

Patcell

macrumors 6502
Aug 8, 2016
433
182
Bergen County, NJ
It would be extremely strange for the battery to drain during the workflow you described above. I have a 2017 15" that I very often use at my dest connected to two external 4k monitors and I have never, like ever, seen the battery drop below 100% while plugged into power. If it keeps happening, maybe an issue with the power adapter? Just guessing...
 

Ruskes

macrumors regular
Jan 4, 2019
135
37
Hi
Did you check the Power consumption for last 12 hours showing the biggest consumer.
Open Activity Monitor and check.
 
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fokmik

macrumors 601
Oct 28, 2016
4,007
3,227
USA
Are you on Mojave? on H Sierra, the default version that 2018 15" came, had some battery drain under full load when plugged but Apple fixed the problem