Higher-End 13-Inch MacBook Pro Models Can Use an 87-Watt Power Adapter, but Won't Charge Any Faster

[konqerror]

I’m not sure that’s how it works. I am pretty confident that the input power charges the battery and the battery runs the computer, don’t believe it can bypass battery

How it usually works is that there's a common bus, to which the battery via a pass transistor (to control charging), DC input (via a DC-DC converter), and system load regulators are all connected.

In normal use, the DC-DC maintains the bus at some maximum voltage, the system consumes the current it needs, and the charger regulates the current flow into the battery to a safe level. When demand exceeds the input limit, the system allows current to flow from the battery to satisfy the remaining need.

In some older systems, there is no input DC-DC converter, so the system has to be throttled to never exceed the maximum wattage of the charger. But all USB-C laptops require an input DC-DC, so it isn't relevant anymore.

 

[dannys1]

Even if you could take advantage of a higher wattage charger, it probably wouldn't be good for the battery long term.

You didn't read the article did you...

 

[incoherent_1]

I'm confused. I thought that USB-C charging made it safe to plug in any size charger to any device without fear of it hurting the device. So, for example, I *think* I can take my MBP 16's charger and plug it into my wife's MacBook Air to charge it without harming it. Am I wrong?

I think this is true of USB C that follows spec, but I know some devices (like Nintendo Switch) are off-spec, so plugging in something else could fry it (why so many people had bricked Switches with third party docks I think).

That said, and more to your point, one would assume Apple is on-spec so yes you’d assume any charger would work...

 

[BGPL]

To a certain extent, but there's the issue of short circuits and fault current. The device needs to be able to safely interrupt the maximum current supplied by the source. That's why the British use fuses in their plugs; they have hefty 32 A ring circuits and they want to be able to use devices and cords rated for much less. It's also why the US 20 A socket is compatible with 15 A plugs, but the 30 A socket is not.

Yes, thanks for pointing that out. You'll see them in Christmas lights with very thin awg wire that can't handle more than a few amps. In a malfunction an overage of current with set the wire on fire.

 

[casperes1996]

I’m not sure that’s how it works. I am pretty confident that the input power charges the battery and the battery runs the computer, don’t believe it can bypass battery

Doesn't really matter how it's wired up for the logic of what I was saying. - Whether it goes through the battery or not, if the charger is only just delivering enough power for the maximum grunt of the computer it won't have much more capacity to charge up the battery - whether the power the computer is actively using is coming from the battery or the power adapter, if it's eating the power as fast as it can be delivered to it or to the battery the result is the same. Increasing the power overhead means the battery will always be able to charge even if it also needs to output a lot to the components

 

[high heaven]

The cpu has a TDP of 28w. say with turbo boost that gets it up to 35w. in what scenario could anyone really go beyond 61w on a 13" MBP?

Dont be fooled by Intel. They can consume much more than their TDP value.

 

[Nicky G]

Same reason I often charge my Nintendo Switch with my 61W brick but it charges at the same speed it always does.

FYI if you ever want more info than you ever thought you could want, but then you'll still get sucked into immensely, on the best approaches to charging the Switch, I hiiiiighly recommend the appropriately-named switchchargers.com.

 

[mofoliar]

I have a MB Air 2019 I use a 45W usb c to charge my MB.

 

[G4-power]

Dont be fooled by Intel. They can consume much more than their TDP value.

Yep, you can see it in their document here: https://www.intel.com/content/www/us/en/support/articles/000055611/processors.html

What is the maximum power consumption for my processor?

Under a steady workload at published frequency, it is TDP. However, during turbo or certain workload types such as Intel® Advanced Vector Extensions (Intel® AVX) it can exceed the maximum TDP but only for a limited time

So as long as the cooling solution is adequate and the computer is not limiting power to the CPU, usually you can sustain Turbo Boost (above published "base" frequency) speeds for long periods of time, meaning you are going over TDP.

Anyhow, like already mentioned, there's a lot more in the computer consuming power than the CPU, you can have peripherals, and also may need headroom for charging the battery at the same time.

 

[Mojo1019]

I was also wondering if an iPhone can be plugged to the MacBook Pro 16inch charger. It is also rated for 5.2V--3A...

 

[ijbond]

I am pretty confident that the input power charges the battery and the battery runs the computer, don’t believe it can bypass battery

No!
With input power my MacBook works normally even though its battery is complety destroyed. Without input power the MacBook runs not even a single second and is immediately dead.

BTW, Apple does not pay anything to the extremly high repair costs even though it is only slightly older than two years.

 

[theluggage]

I'm confused. I thought that USB-C charging made it safe to plug in any size charger to any device without fear of it hurting the device. So, for example, I *think* I can take my MBP 16's charger and plug it into my wife's MacBook Air to charge it without harming it. Am I wrong?

Yes, the article (particularly the title) is... confused. Plugging a 60W MBP into a 100W Apple charger has never been a problem (even back in the MagSafe days). Even with an old-school dumb power brick you'd be OK as long as the voltage was within range.

USB-C has a "smart charging" protocol that negotiates the voltage and maximum current according to what the device, the charger and the cable can handle. It has always been safe* to plug any USB-C charger into any USB-C device, the worst case is that - if the power supply is too 'small' - it just won't work, or the battery will charge very slowly.

What the article is trying to say is that the new MBP can potentially take advantage of larger-capacity power supplies by drawing 86W (4.3A @ 20.2V) instead of the usual 61W (3A @ 20.2V) - but doesn't use it to charge the battery faster. Maybe it means that the battery can still charge when the CPU is under heavy load. maybe it means that it can power more external equipment or maybe it just means that the hardware is physically capable of drawing more power with some hypothetical future firmware update, so it has to go on the ratings plate.

*Unless you've got a fake power supply or cable, of course...
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This is because a device, machine, motor, etc only draws what it needs. You could connect a 13" MBP to a 20V charger that can do 100 amps and it won't hurt it...

Quite true of traditional "dumb" power supplies - USB-C goes even further with "smart" power supplies that negotiate the correct voltage and safe maximum current for the device/cable/psu combination.

 

[A Hobo]

I’m not sure that’s how it works. I am pretty confident that the input power charges the battery and the battery runs the computer, don’t believe it can bypass battery

This is not correct, MacBooks can run from the charger just fine when the battery is removed or failed in some way.
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BTW, Apple does not pay anything to the extremly high repair costs even though it is only slightly older than two years.

Should they? Seeing as you didn’t buy the extended warranty and it’s now undoubtedly YOUR property, why would they help pay for it?

 

[yurc]

Just to want to chime in, I always charging my MBP with my Wacom Mobile Studio 100W adapter without any issue, battery holding is still good shape, and it fast, by any means I can get 100% less than one hour from 40% battery percentage (always plugging charger when battery depleted around 40~50 percentage)

 

[Falhófnir]

have you seen that happen in real life? exceeding 61w?

Yeah it's less a concern for a machine like the 13", it's usually ones with a power hungry dGPU like the 2014 15" with GTX 750m - it's notorious for discharging while plugged in under heavy load...

 

[satinsilverem2]

have you seen that happen in real life? exceeding 61w?

I have seen my Mac exceed 60 watts couple of times. I have had instances when Ive been charging both my iPad and iPhone from my Mac while editing in FCPX and it will start to discharge. The max draw I have seen in istat is 73 watts with the most input I have seen is 57 watts using a 87 watt charger.

 

[CheesePuff]

Is the more powerful power adapter bigger/heavier?

How can you buy a high end 13" and avoid getting a clunky adapter? Which models are included?

You're not understanding the point of the article. The 13" still comes with the same 61 watt charger it has for years. The 2020 13" model accepts higher amperage input from a larger charger (such as the 87 watt or 96 watt of the 15" and 16" models) but it will not charge faster, only allow for more power to the machine + steady charging simultaneously.

 

[magbarn]

I was also wondering if an iPhone can be plugged to the MacBook Pro 16inch charger. It is also rated for 5.2V--3A...

You can, I do it all the time. Apple's USB-C chargers are very versatile. With exception of the original Apple USB C charger for the MacBook 12, it has very limited voltages and is an issue when trying to use it non-Apple devices. I've used my MacBook 16's charger to charge my Nintendo switch, iPad Air 2, iPhone 11, MacBook 12, 2020 MacBook Air, and a Dell computer of all things!

 

[calstanford]

Such a crap statement.
”Higher-End 13-Inch MacBook Pro Models Can Use an 87-Watt Power Adapter, but Won't Charge Any Faster”

You could always do that. For years and years and years.

 

[[AUT] Thomas]

I guess this is more software than hardware limited... there are a few points to it that need to be considered:

• The article says absolutely nothing about the charging circuit itself, especially not how much Amps its able to send to the battery... For now the charging circuit seems to stick with a certain wattage, but that could be changed in software theoretically.
  Keep in mind the iPhone charging circuit has ~20W.
  The Macbooks seem to charge at around 30-40W (https://9to5mac.com/2018/09/25/60w-usb-c-charger-good-for-all-macbooks/ assuming a 20W average system consumption).
• With a stronger PSU the Macbook could likely supply the charging circuit with full power even when the macbook is under load (in theory, see next points).
• The Macbook may supply USB-C equipment with power, which can also sum up to a considerable amount.
• TDP of the CPU has nothing to do (anymore) with the power draw of the CPU, especially not peak power consumption. At Boost the CPU may for a short time easily draw 100W. Plugged in, this will actually discharge the battery even when on AC. (Smartphone CPUs can act similar, but are usually restricted by software, see also Apple CPU throttling on iPhones, peak power support in settings.) Here's an article on the latest desktop CPUs that explain it in more detail (and the challenges that that causes): https://wccftech.com/intel-core-i9-...e-desktop-cpu-65w-tdp-224w-power-consumption/
  GPUs also use thermal boost technology, so they can also draw a lot of power, not an issue in the 13" model though.
• A limiting factor in chargin can also be temperature. Macbook Pros are known to get quite hot, so if the charging is thermally throttled to like 30W that would make sense as well (too hot/cold charging of batteries should be avoided, also the VRMs for the charging circuit may reach critical temperature).
  Condlusion: if the system is running a lot of load (high power drain) and thus can be considered hot, you don't want to put addition stress (such as fast charging) on the battery anyway. As such the combination of high load (=likely high temperature) and fast charging isn't really a desirable situation anyway, which practicaly more or less eliminates the scenario of needing a lot of power for the CPU/GPU AND charging for an extended period.
• There might still be a limit on how much "input power" the macbook can handle... Input power could also be limited in software. Question is what the DC-DC circuits can handle (temporarily und sustained, this may as well be thermal throttled at some point to like 60W).

 

[VictorTango777]

Such a crap statement.
”Higher-End 13-Inch MacBook Pro Models Can Use an 87-Watt Power Adapter, but Won't Charge Any Faster”

You could always do that. For years and years and years.

You wouldn't believe the amount of ignorance in these forums over this subject, with some people vehemently arguing that using a higher wattage power adapter will somehow damage the laptop. Those people seem to think that using a higher wattage power adapter is the same as force feeding electricity from the power lines directly into the battery. Their lack of understanding is compounded by Apple's tendency to ship different wattage power adapters for each laptop model, rather than standardizing on a single power adapter across all their laptops. Standardizing on a single power adapter for all laptops would simplify manufacturing for Apple. It would simplify inventory for stores so they don't have to stock adapters for multiple Mac laptops. It would simplify things for businesses and people who own different size Mac laptops. The difference in size between the Apple 60W and 87W is not that great. And since they are all the same price, it would make more sense to buy the most compatible.

I think this photo shows the iPad, 13 inch MBP and 15 inch MBP adapters.

 

[[AUT] Thomas]

@VictorTango777 I guess the bean counters did their math on it... power bricks are still quite expensive, especially good ones. Even with GaN becoming more widely adopted I think a 60W adapter will still be significantly cheaper than a 90W adapter. The stupidy on the power adapter is that it comes with only a single USB-C port and no USB-A port (those iPhones are still delivered with a lightning to USB-A cable!). Because that way the adapter could have doubled as port replicator without any additional equipment or dongles necessary and that would have added almost zero cost. can't innovate my...

 

[magbarn]

You wouldn't believe the amount of ignorance in these forums over this subject, with some people vehemently arguing that using a higher wattage power adapter will somehow damage the laptop. Those people seem to think that using a higher wattage power adapter is the same as force feeding electricity from the power lines directly into the battery. Their lack of understanding is compounded by Apple's tendency to ship different wattage power adapters for each laptop model, rather than standardizing on a single power adapter across all their laptops. Standardizing on a single power adapter for all laptops would simplify manufacturing for Apple. It would simplify inventory for stores so they don't have to stock adapters for multiple Mac laptops. It would simplify things for businesses and people who own different size Mac laptops. The difference in size between the Apple 60W and 87W is not that great. And since they are all the same price, it would make more sense to buy the most compatible.

I think this photo shows the iPad, 13 inch MBP and 15 inch MBP adapters.

View attachment 912951

The size and weight difference between the different adapters is definitely noticeable. My wife complained when she had to use my MBP 15's 87 watt brick when she lost her 29 watt adapter for her Macbook 12.
I've gone to ravpower USB-C adapter for my MacBooks. Much smaller than the Apple equivalent with the same wattage. Even the 90 watt model has 2 USB C ports which come in handy as I can charge iOS devices along with my MacBook when on the road.
Starting from upper left going clockwise:
1. Apple 30 watt from 2020 MBA
2. Ravpower 61 watt Gan - smaller and lighter than Apple's 30 watt adapter!
3. Apple 96 watt from MBP 16
4. Ravpower 90 watt Gan with 2 ports - about the same size as Apple's 60 watt - slightly smaller

 

[827538]

I guess system usage + battery charging + PD over USB must exceed 61W.
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@VictorTango777 I guess the bean counters did their math on it... power bricks are still quite expensive, especially good ones. Even with GaN becoming more widely adopted I think a 60W adapter will still be significantly cheaper than a 90W adapter. The stupidy on the power adapter is that it comes with only a single USB-C port and no USB-A port (those iPhones are still delivered with a lightning to USB-A cable!). Because that way the adapter could have doubled as port replicator without any additional equipment or dongles necessary and that would have added almost zero cost. can't innovate my...

Pretty sure iPhones are delivered with a USB-C to lightning cable now, not USB-A.

 

[shamino]

Unfortunately, very few people (aside from electrical engineers) understand how electricity and power supplies work.

Most power supplies are "constant voltage" supplies. They put out one voltage (in the case of USB, one out of several possible choices, selected by the attached device, supplying 5v if nothing is negotiated) at however much current the device tries to draw.

Good quality supplies include a current limiter, which will monitor the current (amps) drawn and either shut down or lower the voltage if the attached device tries to draw more than the supply is designed to put out. Cheap junk supplies don't have a current limiter - if the device tries to draw more than it is rated for, then it will overheat and fail. Maybe even catch fire if it is especially poor quality.

But in no case will a power supply somehow force more current into a device than the device is trying to draw. That's just not the way electricity works. The only way for a power supply to deliberately up the current is to increase the voltage, which they won't do because the results would simply damage the device it is trying to power.

Even if you could take advantage of a higher wattage charger, it probably wouldn't be good for the battery long term.

On any modern device (especially those with lithium ion batteries), battery charging is strictly controlled by a special circuit. This is either built-in to the battery pack or on the motherboard. It strictly regulates the voltage and current that flows into and out of the battery in order to maximize its life and prevent overheating (which will shorten its life and may cause a fire).

If a higher power charger will charge the battery faster, then the motherboard and battery were designed to work with the higher current. If they're not, then the charging circuitry won't draw the power, regardless of what the charger is capable of supplying.

Same reason I often charge my Nintendo Switch with my 61W brick but it charges at the same speed it always does.

Yep. Again, your device is drawing the current it needs. As long as the charger can supply everything the device is drawing, it works. If the charger is capable of supplying more (at the correct voltage, of course), it has no effect.

- - -

When I needed to buy spare power bricks for my laptops (my old iBook and a few different MagSafe devices), I always bought the biggest one Apple would sell. For some reason, they were all sold for the same price. They wouldn't charge my device any faster, but I always figured that I could migrate it to new computers in the future that might require more power. (And then Apple stopped shipping computers with MagSafe, so it all became moot. 😡 )

I also assumed that a higher capacity power supply would run cooler. That drawing 45W from a 45W charger would make it heat up more than drawing 45W from an 87W charger, because the 87W device has 42W of additional headroom and is designed to dissipate more heat without burning up. I don't know if that assumption is right or wrong, but since an extra large power supply can't hurt and Apple charged the same price, there was no disadvantage to doing so (aside from it being slightly larger and heavier).