Teardown of Apple 40w Dynamic Power Adapter with 60w Max
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The teardown of Apple's 40W dynamic power adapter with 60W max capability sparks discussion on design, efficiency, and the implications of fast charging technology.
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and it's barely past 10 votes.
Peak power tends to last about 10 minutes or so.
Or put another way, past ten mins it’s just as likely the phone will be plugged in for hours or overnight and the charge speed is irrelevant.
https://www.reddit.com/r/UsbCHardware/comments/1nfhctl/hands...
> The thermistor monitors the internal temperature and dynamically adjusts the power level to reduce output power when the temperature rises.
My guess is that it's dependent on the ambient temperature, but that's just a guess! I can't imagine what the restriction on peak power would be other than temperature rise, though...
Also while the US plug makes some pretty compact power adapters, the effect is largely ruined in the EU and UK with their wider more cumbersome plugs.
https://www.chargerlab.com/complete-pd-3-2-spr-avs-specifica...
Agreed. Seriously, am I missing something or are the compact chargers from various other companies at least as compelling as this? I've got a nice one from Lenovo with high output and a smaller form factor than this. (Several other manufacturers have a similar size and output so nothing special about Lenovo here). The Apple one, while maybe smaller then their usual, is still bigger and appears to be short and "fat" which can limit where you can plug it sometimes.
Or is just another "but this time it is from Apple" kind of thing. (All the vapor chamber talk from a few days ago had me scratching my head too.)
Having read the article, I’m a little surprised this hit the front page. It’s well done as a tear down. But that’s all it is.
Physically the design is pretty much the same as this new 60/40W version, so I would expect them to eventually offer a 60/40W folding pin UK charger too.
https://www.apple.com/uk/shop/product/MUVT3B/A/20w-usb-c-pow...
The Apple charger is mildly interesting because they made a slightly smaller than usual one that displays a dynamic behavior where it boosts up to 60W. That’s it.
(If you actually mean efficiency of energy delivered, and not time efficiency… the energy efficiency of charging your own personal phone is completely irrelevant to anything. You could save many times that amount of energy per year by switching to a heat pump water heater, or a heat pump clothes dryer, but most people haven’t.)
You don’t need some kind of special charger.
[0]: https://9to5mac.com/2025/09/13/iphone-17-pro-fast-charging-p...
https://photos5.appleinsider.com/gallery/65105-135925-Dynami...
I could definitely see maximum sustained charging speeds only being sustained with optimal supply voltages, which minimizes converter loss (and thereby heat, which is the actual limiting factor for fast charging these days) in the phone.
Apple simply says “For iPhone 17 models, you can charge up to 50% battery in around 20 minutes with a 40W adapter or higher.”
Sure, it would be fun to see someone do a thorough test on this. No, I don’t agree with all the posts that are fear mongering people into believing they need some super fancy charger to reach the charging speeds Apple claimed, when Apple themselves doesn’t claim that, and the original 9to5Mac article no longer claims this true. There is simply no reason to believe that AVS is required, and anyone saying that has the burden of proof here.
If you want to get technical, the difference in conversion losses between AVS at 13.3V@3A and a non-AVS 15V PDO @ 2.667A is going to be rounding error. Both need to be regulated down to about 3.5V to 4.2V by the phone's internal circuitry. A hypothetical buck converter that is just as efficient at 15V -> 3.5V as it is at 13.3V -> 3.5V would see no difference at all in heat generation. In the real world, such a small difference in input voltages at >1A would likely yield a less than 1% efficiency difference. 1% of 40W is 0.4W, but I repeat: I am saying less than 1%, not 1%. Based on tests I've seen in the past, previous iPhones could dissipate at least 4W of power continuously, forever, in normal ambient conditions. For a 95% efficient buck converter (which is probably conservative here), the total thermal load from charging at 40W is 2W. Unless the thermal load exceeds 4W, there should be no difference in charging speed potential. 2W + 0.4W would be 2.4W, which is well below the 4W threshold, and the buck converter on a high end smartphone is probably more than 95% efficient, while the difference in input voltages probably yields less than 1% difference in efficiency, so 2.4W is a very conservative number here. Keep in mind that phones can dissipate significantly more than 4W for brief bursts, and the charge curve on the battery isn't going to allow 40W charging for very long regardless of the thermals, so the phone likely has even more thermal headroom here in the real world. Even a 20V PDO @ 2A -> 3.5V should be perfectly fine here. I see no evidence that there is even a possibility of AVS making a difference here unless you wrap the phone in real insulation (not a phone case) or stick it in a toaster oven while charging.
Talking about how there might be an imperceptible difference under very specific extreme conditions is exactly what I would call fearmongering in a thread where someone was specifically asking for recommendations. It won't matter to anyone, ever, in any real world situation. This is not the thread to be contrarian for the sake of digging into minutiae. You're welcome to start a thread where that is the goal.
In summary: OP does not need to buy a fancy AVS-enabled charger. They shouldn't avoid such chargers, but there is no reason to get one. Unless you have material proof to the contrary that you want to present, but it seems like you don't.
Mainly, I'm trying to understand why AVS is supported by both the phone and the adapter if supposedly it makes effectively no difference.
It could be as simple as being a requirement for PD 3.2 wall adapters, of course, but that raises the question for why it's required as well, if it's supposedly that irrelevant.
Since I have shown through basic math that it isn’t related to the ability to charge the phone any faster, that possibility is obviously eliminated.
AVS is likely supported because there’s no reason not to support it. It is part of the newer USB-C PD specs, which Apple wants to support, and it continues to iteratively refine the energy efficiency of the charging process, which matters a small amount at a scale of billions of devices, but doesn’t matter at all for a single individual’s purchasing decision.
[1] https://www.amazon.co.uk/Apple-20W-USB-C-Power-Adapter/dp/B0...
0: https://www.amazon.co.uk/UGREEN-Foldable-Charger-Support-Com...
I'm guessing an Apple 40-60W UK version might come in somewhere in between in size?
There's also the Anker Nano 45W, at 49 × 49 × 34 mm: https://www.amazon.co.uk/dp/B0DPR2VYQF
https://a.aliexpress.com/_EuPD4j8
It can deliver 50 watts entirely to 1 port, unlike most others where they mean 25 watts per port.
$5.50 with free shipping.
That being said, Amazon isn't much better nowadays and I have been pleasantly surprised by some items from AliExpress. However one should not expect western quality standard for most things...
I seem to get the 'delayed delivery' coupon every time even if the delivery is on time for example, and sometimes that coupon is worth more than the item itself for low value items.
It doesn't matter much anyway; I stopped buying there because I am a bit tired of too random quality that doesn't make the "savings" really worth it. For example, I bought a connected outlet that was half the price of ones from an EU brand but the app is pretty bad (data logging and display is terrible) and build quality worse. I also bought various RCA cable for an old amplifier and all of them were producing noise, I got a good one from Amazon (made in Germany) and no problem.
You couldn’t pay me enough money to plug this into a building’s electrical distribution system, it’s drawing ~3A at 120V (60W at 5V plus inefficiency) and in a very small form factor, I sure hope the engineering and QA of that $5 charger is up to par. Did they include an internal fuse or did they forego that to save $0.03? Who knows!
Fire is more of a concern, but this is indeed internally fused and the IC has both overcurrent and overheat protection - both of which are effectively 'free', so there are no cost savings to not include them.
The triple built-in protections alleviate the rest of my concerns, my apologies for overreacting but I’ve seen people plug some scary things into receptacles.
https://youtube.com/playlist?list=PLfUGOPyKWwiriWhjmdtvjBw_J...
Older installations can be retrofitted but there is no requirement to do so.
Anyone know the switching frequency?
[1] https://regulatoryinfo.apple.com/en/eurocompliance
https://www.apple.com/shop/product/MGKN4AM/A/40w-dynamic-pow...
I wish there was something like this for Europlug chargers. Ironically, the most compact USB adapter for me so far is one with a US plug, combined with an US-to-Europlug adapter, which can be made very compact, but seem a bit risky at 220V, given that US plugs expose the prongs while connected.
Better than that. You just move the biggest (earth) pin and the other pins fold automatically with it (in the opposite direction!), via a perfectly weighted/sprung mechanical linkage. It's a very smooth, elegant, robust action. Whoever designed it should get some design awards!
Bu as the other responder implied, I’ll believe Bezos when his lips stop moving.
Just don’t buy from random listings with vendors named TREGARBLE or something. Inspect it upon arrival and send it back if it’s a problem.
How did you verify their authenticity?
https://9to5toys.com/2018/11/09/apple-and-amazon-deal-iphone... https://www.cnet.com/tech/mobile/apple-pumps-up-its-amazon-l...
(I think there may be a few other top-tier brands who get this special treatment from Amazon.)
USB-PD now has a standard for having sink devices request a particular current from the charger, meaning that you could actually remove a converter from the sink device side, because with a programmable source, the current limiting happens on the power supply side. Cool stuff especially for small electronics like wearables.
Generally though if you want to charge with USB-PD and accept all kinds of chargers, the sink device will have to have its own charge control PMIC.
All this negotiation happens over a side band via the "CC" pins on the USB-C connector.
Devices that support it can potentially charge more efficiently (and by extension more quickly, if they're limited by heat dissipation), but they can't rely on any USB-PD adapter supporting it.
It's also different from AVS (which Apple's adapter seems to support), which allows controlling the voltage in finer steps, but not limiting the current in the same way that PPS does.
More to your question the DIY solar community is torn between the benefits of float voltage which is a pretty low charging rate. I bought some cells (not for my house) and on the data sheet they were fine with .1C. They were more concerned with temperature and very high C rates hurting the lifespan. Since I was going to AC couple I was more worried about total system efficiency so similarly staying under a rate that heats the battery up and above the idle power of the inverter was my goal.
I would also have guessed the slow charging was better, but that is an uninformed opinion. I'd be quite interested in what people think.
An extra dilemma - often if I'm around the house or the office all day, I'll just plug in my phone every time I see it reach about 70%, and unplug when it reaches 80% (this is easier to spot if you have low-power mode on for an iPhone because the screen lights up at 80% when low-power mode is turned off). Is it worse to do that 2 or 3 times, compared to just charging to 100% and leaving it on the charger all day. Is being at 100% all day, but not using any (fractions of) charge cycles, worse than doing a few shallow discharges?
Of course, I don't think it really matters, but it's the kind of thing that I wonder and then do when I remember.
That said, my assumption is that most people want to charge overnight precisely because they do not want to have to remember to do a fast charge in the morning. Maybe that’s just me tho. Assuming you want to charge overnight, I totally agree that spending less time between 80% and 100% is good, and software that either prevents this or limits it is good. But whether you have such a device or not, for overnight charging a lower power charger seems prudent.
If a device charged overnight does not support limiting charging to 80%, a 5W charger means the device spends less time between 80% and 100% versus a higher wattage charger.
For a newer device that does support limited charging to 80%, I agree that there’s probably a little difference in battery aging between different speed chargers, however for overnight charging, where I really don’t care how long it takes to charge, I would still go with the lower power.
And batteries can charge pretty fast these days. Modern pocket supercomputers keep track of battery temperature to keep things within defined limits during charging.
AFAIK the real problem, longevity-wise, for these batteries in normal use is the time spent at extremes of charge (<20% or >80%, ish).
That all said: Sure, some phones have options.
My Samsung phone does some man-behind-the-curtain tricks to attempt to make it reach 100% just before it predicts that I'll unplug it (eg, when I wake up). The idea is to maximize the charge on the phone while also keeping it at 100% SoC for as little time as practical. This probably works great for people with regular schedules (which is to say: people who are not like me).
This phone also lets me explicitly disable various fast-charge modes. I think there's at least two different modes that I can turn off (but I leave them all turned on).
And there's also a mode that limits the maximum charge to 85%, to promote long-term battery health. I have this mode engage automatically when using wireless charging, which is something I only do with the wireless charging cradle on my car's dashboard. (I do want the phone to be powered while I drive, but I don't normally need anything to work extra-hard to cram that last 15% into the battery when I'm on a long drive. It's a good balance, for me.)
That being said...
I can't be the only person who consciously avoids fast-charging my phone. My whole apartment is full of wireless charging pads intentionally plugged into weak chargers (wireless charging avoids putting wear on the USB port). 60 watts can't possibly be healthy for a battery small enough to fit into a phone.
If you want to use the newer chargers, I’d think you’d want cooling and airflow. At some point, I want to build a MagSafe stand with a low RPM silent fan on it.
I really like Ikea's cheaper Smahagel chargers, by the way. They have very good electrical separation, they're cheap, and only run at 5W. The way they're shaped makes it easier to cram a bunch of them into a power strip, which is nice. Can't speak for the USB-C Ikea chargers though.
For me a year is nothing though, my phone is on its 4th year, my daughter has my old iphone X.
While I'm not an Apple engineer, I am an embedded systems engineer. I promise you, this kind of trickery is commonplace in consumer electronics. It's also far more common in expensive stuff (phones, laptops) than in cheap stuff (power banks, vapes). Cheap stuff could do this, it's not hard, but the people making those devices don't get paid enough to care.
Point being: A lithium ion battery's capacity is reduced every time you charge it - sometimes by only a couple mAh, but still. This is intrinsic to the chemistry. Your phone is doing things behind the scenes to mitigate that wear, but wear still happens. If you intend to keep your phone beyond its designed 2-3 year lifespan, it behooves you to keep charging current down.
Even LinusTechTips did a video that showed the length of charging doing more damage than fast charging. For the concern about thermal damage, most phones will throttle their charge if they become too warm.
Personally, I feel my wireless charger in the car does the most damage. It generates more heat and holds the battery in a charging state for longer
My previous phones never even got below 90% in their lifetime.
As a counterpoint, I've been using low-power wireless charging (5W adapters) with my phones for the last several years (three phones at least). The battery degradation was minimal, I was able to pass my phone to my kid after 3 years of use with near perfect battery.
The key here is to prevent heat buildup.
Linus is surprised that fast charging does not heat the battery as much as expected.
I interpreted that "length of charging doing more damage than fast charging" meant that slow charging was worse, because the battery spends more time charging, but I don't think this is stated in the video. In the video, Linus confirms that it is the high state of charge that does the damage and that trying to keep the state of charge as close to 50ish % is best. The conclusion that fast charging is better for the battery, is because you are more likely to do it when awake, and can stop the charging once it reaches whatever percentage you require (but the damage really starts to increase above 80%.
I work at a place with a huge phone fleet. We have interns study our telemetry and records because I kids like phones and they find ways to save us money. We allow for low friction replacements of phones at 12 months — the average replacement is ~27. The most common issues are cracked screens and excessive scratching on iPhone 16 and a Samsung I cannot recall. Batteries are only an issue for field devices subject to excessive cold or heat.
Unless you’re trying to keep the thing going 5 years, you’re likely seeing marginal benefits.
At work, the optimal cash flow is rapid replacement. We buy high volume so as long as I don’t use a lot of labor, we make money on the subsidy. I buy a phone for $1, and net $250 in trade in 18-20 months.
5-10 years means you want a wall phone. There’s nothing wrong with that, but it’s a contrarian position and the options on the market don’t support it well as a result.
As an individual, I generally keep my phones for at least five years.
Why should I spend $300 per year instead of $150 when the lower cost option works for me?
(I'm typing this on a 2020 iPhone SE; it runs the latest software. Although this year, that's not necessarily a good thing. Liquid Glass, Safari bugs.)
Actually no, that's not what it means at all. The phone I want a phone supports various smartphone features like GPS and NFC. It receives regular software and firmware updates, providing whatever new software functionality has been developed lately. It's built to last, without artificial barriers and compromises that prevent 5-10 of use.
The market may not support it very well, especially when looking at the major handset manufacturers. If that makes me a contrarian, fine. But let's not pretend that the "market" (a space dominated by just a few vendors) is optimizing for long-term customer satisfaction or any such things, or that the absence of something in the marketplace means that that things is silly.
I get that you're coming from a specific context, needing and wanting to turn hardware over quickly. But there are plenty of other people (who are generally quieter than tech enthusiasts) who don't have any such need or desire. A well-supported phone with enduring battery technology would be very welcome to me. The fact that the market doesn't meet our needs is reflective of the market-makers, not the would-be customers.
Not GP, but yes: that’s exactly what I’m trying to do. I think that people should generally expect 5+ years out of their devices. And in a world where user-replaceable batteries are decreasingly common, it makes increasing sense to change habits to preserve the built-in battery.
My last phone went for 6 years, and the only reason I replaced it is because one of my banking apps dropped support for Android 8.
Also I am using magsafe which due to the magnet alignment leads to a high efficiency transfer at least.
The sole benefit of AVS over PPS is that AVS goes beyond 100W. But these chargers only do 60W. And it would have cost Apple almost nothing to also add PPS to their phones and chargers.
Edit: hello fanboys :)
It would make more sense if they used it for their MacBook chargers, but AFAIK the sole charger they having going beyond 100W is the 16" Pro charger at 140W. Every other Macbook charger is between 45W-96W.
If this is true, then if you own a 3rd party charger that is up-to-date with the very latest USB PD specs, your charger is going to charge an iPhone 17/Air/17 Pro more slowly than buying Apple's new charger.
(I don't claim to know the technical details of whether AVS is part of the spec below 100W or not, I am just going by the comments in this thread and speaking of the hypothetical)
https://youtu.be/TYEqCgMnA8U
[0]: https://rollingsquare.com/products/supertiny-the-smallest-65...
Hot but not too hot
Many devices are made larger simply to have more surface area to spread the heat over to stay within the law.
I actually prefer pinch zoom than developers implementing accessibility features which often don’t test all hardware and get glitchy at certain zoom levels.
IMHO, it should be the default, I have never been in a situation where it caused a problem, but I have been in plenty of situations where it helped.
At my work, we have an X-ray machine for PCB reverse engineering. On Fridays we throw in random stuff from around the office, and sometimes make videos about what we find inside.
A few weeks ago we released an X-ray teardown of several other, older chargers. Very interesting to compare with these fancy new ones!
https://youtu.be/4h4qabPsPfI
A CT is, simplifying, an x-ray machine that takes lots of images in slices, then analyze them with certain algorithms to reconstruct 2D and 3D images of the interior of the 'subject'.
It's better explained visually (at least to me) :P
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