The real story behind MagSafe, USB-C PD, and why you need a 20W AC charger

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Comments

  • Reply 21 of 43
    citpekscitpeks Posts: 193member
    MplsP said:
    Nice article - it explains a lot. It still doesn’t explain why the MagSafe connector couldn’t use the older 2.0 protocol to get higher power delivery. Strictly limiting bit to the 3.0 protocol that’s less than a year old means relatively few people are going to have a compatible charger. If it’s not clearly documented, many more people will never know why they are not reaching the full potential of their device. 

    PD 3.0 takes a different approach than PD 2.0.  3.0 is dynamic, and proactive, and takes into account variables that 2.0 cannot.  2.0 is still bi-directional, but more passive, in a more "take it or leave it" manner.  Think of it as the difference between ordering from a set menu, as opposed to having a chef tailor dishes to your taste.

    There is backward compatibility, but due to the paradigm shift, it operates according to the newer approach, and the old one is only kept as a fallback.

    Would it surprise you to learn that one of Apple's first full USB 3.1/3.2 and PD compliant devices, the iPads Pro, only support a lowly standard 7.5W charge level when not connected to a non-PD adapter?  They don't even support Apple's own 12W/2.4, but do have that minimum baseline level capability, but only as a backup, not as the primary, which is all in the PD basket.
    Alex1NMplsP
  • Reply 22 of 43
    Super interesting article [nerd emoji]
    If the MagSafe puck and the AC adapter can't negotiate the 9V and 2.22 amps, USB Power Delivery will default to the highest common mutually compatible voltage and amperage that it can, not to exceed that 9V or 2.22 amps.

    So, would an 18W PD3 charger be able to supply 9V 2A to the puck then, albeit at <15W output?

    And if you are using an 18W PD2 charger are you saying it would default to 10W input (ie 5V 2A) and this would give correspondingly less output (7.5W?)
    edited October 2020
  • Reply 23 of 43
    Mike WuertheleMike Wuerthele Posts: 6,550administrator
    citpeks said:
    "if you don't want to buy Apple's USB-C AC adapter, any USB-PD 3.0 one will do to get that faster charging speed, and a lesser one, won't."

    Is that really the case?  Apple's 96W adapter, released in 2019 with the MBP 16", has been tested to result in only a 10W level with the MagSafe.  Presumably, it's PD 3.0 compliant.

    I think there is a distinction to be made -- 1) an adapter must be PD 3.0 spec, and 2) it must be able to successfully negotiate the new/oddball (for now) 2.22A/20W profile that Apple has created.  The latter is far from certain, even with a PD 3.0 adapter.  PD 3.0 introduced better handshaking and accounts for more variables, but when the source and the sink don't agree, it will default to the next lowest step.

    Another distinction that hasn't been noted in this new "-gate" controversy, and that's what it is -- is that these quirks apply not only to the MagSafe, but to the iPhone 12 as well.  That's made clear in Apple's support documents.  Everyone is testing against MagSafe, but that introduces another variable in the wireless coupling.

    What people should be testing against is the iPhone 12 itself, where the only negotiation is between the adapter and the phone itself, which eliminates all the potential quirks that exist in the wireless coupling negotiation as well.

    On the surface, non-proprietary standards like USB PD should prevent a lot of issues.  But underneath the surface, there are plenty of deviations and proprietary games being played, which only get noticed in situations like this.  Apple is not alone in playing these games.

    Many fail to see the bigger picture that the MagSafe and iPhone 12 have new requirements, and it will take time for 3rd parties to adjust and adapt with new products to match.  But they will, and eventually the issue will fade, just like it did with Apple 2.4A, which saw scant support when it first appeared, but eventually became ubiquitous, despite not being an official USB spec.
    it is not PD 3.0. PD 3.0 is backwards compatible with PD 2.0, 1.0, and USB 3 charging, so I'm not sure what you're wondering about with "quirks" on the iPhone 12.

    In no way is this a "gate" by any definition, and that's a ridiculous assertion. This is a matter of spec compliance, and nothing else.
    edited October 2020 jdb8167Alex1N
  • Reply 24 of 43
    Mike WuertheleMike Wuerthele Posts: 6,550administrator
    webweasel said:
    Super interesting article [nerd emoji]
    If the MagSafe puck and the AC adapter can't negotiate the 9V and 2.22 amps, USB Power Delivery will default to the highest common mutually compatible voltage and amperage that it can, not to exceed that 9V or 2.22 amps.

    So, would an 18W PD3 charger be able to supply 9V 2A to the puck then, albeit at <15W output?

    And if you are using an 18W PD2 charger are you saying it would default to 10W input (ie 5V 2A) and this would give correspondingly less output (7.5W?)
    Depends on what's negotiated by the hardware. Probably 7.5W.
    Alex1N
  • Reply 25 of 43

    it is not PD 3.0. PD 3.0 is backwards compatible with PD 2.0, 1.0, and USB 3 charging, so I'm not sure what you're wondering about with "quirks" on the iPhone 12.

    In no way is this a "gate" by any definition, and that's a ridiculous assertion. This is a matter of spec compliance, and nothing else.
    I meant "-gate" in the sense of being a false, overinflated controversy,  I know exactly what is going on, and what's in play.

    But you fail to address my real point, at the point, there is no assurance that "any" PD 3.0 adapter will successfully negotiate the 2.22A profile with the MagSafe or the iPhone 12.  In theory, that should be the case, but in practice, has yet to be proven, or the available findings would confirm it.  Or do you plan to provide some empirical testing to back up that contention?

    And yes, 2,22 is a quirk, at least for now, or we wouldn't be having this discussion to begin with.
    Alex1Nsvanstrom
  • Reply 26 of 43
    citpeks said:

    it is not PD 3.0. PD 3.0 is backwards compatible with PD 2.0, 1.0, and USB 3 charging, so I'm not sure what you're wondering about with "quirks" on the iPhone 12.

    In no way is this a "gate" by any definition, and that's a ridiculous assertion. This is a matter of spec compliance, and nothing else.
    I meant "-gate" in the sense of being a false, overinflated controversy,  I know exactly what is going on, and what's in play.

    But you fail to address my real point, at the point, there is no assurance that "any" PD 3.0 adapter will successfully negotiate the 2.22A profile with the MagSafe or the iPhone 12.  In theory, that should be the case, but in practice, has yet to be proven, or the available findings would confirm it.  Or do you plan to provide some empirical testing to back up that contention?

    And yes, 2,22 is a quirk, at least for now, or we wouldn't be having this discussion to begin with.
    A video by Alvin Lim on youtube shows him pulling the same current as an apple 20w brick on two different third party PD 3.0 bricks, one being 120w and the other being 65w. Both support the 9V/3A standard output that any compliant USB brick 27w or over will provide.
    edited October 2020 jdb8167danncerAlex1N
  • Reply 27 of 43
    Mike WuertheleMike Wuerthele Posts: 6,550administrator
    citpeks said:

    it is not PD 3.0. PD 3.0 is backwards compatible with PD 2.0, 1.0, and USB 3 charging, so I'm not sure what you're wondering about with "quirks" on the iPhone 12.

    In no way is this a "gate" by any definition, and that's a ridiculous assertion. This is a matter of spec compliance, and nothing else.
    I meant "-gate" in the sense of being a false, overinflated controversy,  I know exactly what is going on, and what's in play.

    But you fail to address my real point, at the point, there is no assurance that "any" PD 3.0 adapter will successfully negotiate the 2.22A profile with the MagSafe or the iPhone 12.  In theory, that should be the case, but in practice, has yet to be proven, or the available findings would confirm it.  Or do you plan to provide some empirical testing to back up that contention?

    And yes, 2,22 is a quirk, at least for now, or we wouldn't be having this discussion to begin with.
    Good on the -gate thing. Apologies for misunderstanding. We are not the first to come to the conclusion that a suitable specced PD 3.0 charger will do the job, but we're the first (I believe) to explain specifically why, and address why 15W isn't sufficient. There is sufficient other proof on the internet that this is the case, but we will be looking into it further, as time allows.

    What you're looking for specifically is in the piece in regards to wattage, just not in the sentence you've quoted. I've clarified the language in that sentence a hair.
    edited October 2020 Alex1N
  • Reply 28 of 43
    Rayz2016Rayz2016 Posts: 6,957member
    After reading two pages of this, I ordered another lightning cable. 
    bikerdudeAlex1NMplsPmazda 3s
  • Reply 29 of 43
    Mike WuertheleMike Wuerthele Posts: 6,550administrator
    Rayz2016 said:
    After reading two pages of this, I ordered another lightning cable. 
    Truth be told, I'm not a giant fan of MagSafe here. I'm going to stick with my older Qi chargers, and Lightning.
  • Reply 30 of 43
    Good on the -gate thing. Apologies for misunderstanding. We are not the first to come to the conclusion that a suitable specced PD 3.0 charger will do the job, but we're the first (I believe) to explain specifically why, and address why 15W isn't sufficient. There is sufficient other proof on the internet that this is the case, but we will be looking into it further, as time allows.

    What you're looking for specifically is in the piece in regards to wattage, just not in the sentence you've quoted. I've clarified the language in that sentence a hair.

    It's early, and the dust has yet to settle, so it is good that you're trying to address the uncertainty by providing the facts, with some authority.

    Unfortunately, theory is not always consistent with practice, and that's what I wanted to note.

    There are standards, and they can be written on stone tablets and hoisted to the top of Mt. Everest, but that does not assure that they will be implemented properly, or not deviated from.

    We've seen this kind of thing before, from the fustercluck at the beginning of USB-C (ref -- Benson Leung), to the mishmash of Qi "fast" charging profiles.  The standards provide the foundation, but the companies still go and build houses to their liking that may not meet code.  It's the users who suffer, and it sows confusion and mistrust.

    Kamirose said:
    A video by Alvin Lim on youtube shows him pulling the same current as an apple 20w brick on two different third party PD 3.0 bricks, one being 120w and the other being 65w. Both support the 9V/3A standard output that any compliant USB brick 27w or over will provide.

    Can you provide the link?  I don't doubt that there are adapters available now that do work, and there will eventually be more.  But sorting the wheat from the chaff will still be a work in progress, until products with assured compatibility with the 20W level become more prevalent.

    And there is still the slim possibility that Apple could alter the rules, and retroactively handicap shipped products, as it did with iOS 7 and Lightning cables, or the "7.5W" non-EPP Qi chargers with 13.1.  One could argue that the latter was a matter of closing a loophole, but that doesn't help the users who find that their chargers won't charge as fast as before due to an iOS update.  Go back far enough, and Apple has done that kind of thing with RAM as well, after an OS update.
    Alex1N
  • Reply 31 of 43
    jdb8167jdb8167 Posts: 624member
    citpeks said:

    it is not PD 3.0. PD 3.0 is backwards compatible with PD 2.0, 1.0, and USB 3 charging, so I'm not sure what you're wondering about with "quirks" on the iPhone 12.

    In no way is this a "gate" by any definition, and that's a ridiculous assertion. This is a matter of spec compliance, and nothing else.
    I meant "-gate" in the sense of being a false, overinflated controversy,  I know exactly what is going on, and what's in play.

    But you fail to address my real point, at the point, there is no assurance that "any" PD 3.0 adapter will successfully negotiate the 2.22A profile with the MagSafe or the iPhone 12.  In theory, that should be the case, but in practice, has yet to be proven, or the available findings would confirm it.  Or do you plan to provide some empirical testing to back up that contention?

    And yes, 2,22 is a quirk, at least for now, or we wouldn't be having this discussion to begin with.
    Any PD 3.0 that supports 9 V 3 A will work. That’s the normal profile. You only need the 2.22 A if you want a 20 W charger. Apple isn’t doing anything odd here it is just the spec is pretty new and not widely adopted yet. 
    citpeks
  • Reply 32 of 43
    citpeks said:
    Kamirose said:
    A video by Alvin Lim on youtube shows him pulling the same current as an apple 20w brick on two different third party PD 3.0 bricks, one being 120w and the other being 65w. Both support the 9V/3A standard output that any compliant USB brick 27w or over will provide.

    Can you provide the link?  I don't doubt that there are adapters available now that do work, and there will eventually be more.  But sorting the wheat from the chaff will still be a work in progress, until products with assured compatibility with the 20W level become more prevalent.

    And there is still the slim possibility that Apple could alter the rules, and retroactively handicap shipped products, as it did with iOS 7 and Lightning cables, or the "7.5W" non-EPP Qi chargers with 13.1.  One could argue that the latter was a matter of closing a loophole, but that doesn't help the users who find that their chargers won't charge as fast as before due to an iOS update.  Go back far enough, and Apple has done that kind of thing with RAM as well, after an OS update.

    Alex1Ndanncerjdb8167MplsP
  • Reply 33 of 43
    Good video - I would have like to see one of the two black chargers used again at the end of the sequence, just for completeness (further verification of the temperature effect). Thanks :).
  • Reply 34 of 43
    citpekscitpeks Posts: 193member
    jdb8167 said:

    Any PD 3.0 that supports 9 V 3 A will work. That’s the normal profile. You only need the 2.22 A if you want a 20 W charger. Apple isn’t doing anything odd here it is just the spec is pretty new and not widely adopted yet. 
    Yes, ultimately, I think the simplest way to put it is that a PD 3.0 adapter, which incorporates PPS, and thus variable profiles is the requirement.  The article is correct.

    Unfortunately, that's not how PD adapters are commonly marketed, least of all by Apple.  Contrast that to QC, where the version number is often front and center, and where variability arrived with its v3.0 as well.

    edited October 2020 danncer
  • Reply 35 of 43
    USB-C is becoming a big PITA.

    That different connectors didn't fit different ports was, of course, a bit of a pain, but that people easily understood; but with USB-C people are standing there with stuff that fits perfectly, but they have to understand different profiles and standards that are practically invisible to them.

    If Apple had wanted to they could have made a better product by putting the smartness in the MagSafe device, which would have made it "just work" for everyone rn. 
    tobian
  • Reply 36 of 43
    noraa1138noraa1138 Posts: 31unconfirmed, member
    tht said:
    jagnut said:
    So, if we plug the MagSafe into any particular charger how do we know what is being delivered?  Is there any display on the iPhone that tells us what we are getting?
    There are many apps that will provide you this info. Just search for charging, amperes, battery, etc, in the App Store.


    The problem with those apps is they're not measuring the power being delivered directly - because said information is not being supplied by the OS. Instead, they determine average power draw/drain by measuring how quickly the battery charges over a period of time. The problem with this type of measurement is two fold - 1.) it's just an estimate and can't be nearly as accurate as a USB power meter, and 2.) there are a lot of variables that go into the calculation including the capacity of the battery (which is slightly different for every phone, and obviously changes with the age of the battery) and how much power is the phone using while idle (the apps require the phone to be idle for a more accurate measurement). In other words, these apps can only give you a rough estimate.
  • Reply 37 of 43
    noraa1138 said:
    tht said:
    jagnut said:
    So, if we plug the MagSafe into any particular charger how do we know what is being delivered?  Is there any display on the iPhone that tells us what we are getting?
    There are many apps that will provide you this info. Just search for charging, amperes, battery, etc, in the App Store.
    The problem with those apps is they're not measuring the power being delivered directly - because said information is not being supplied by the OS. Instead, they determine average power draw/drain by measuring how quickly the battery charges over a period of time. The problem with this type of measurement is two fold - 1.) it's just an estimate and can't be nearly as accurate as a USB power meter, and 2.) there are a lot of variables that go into the calculation including the capacity of the battery (which is slightly different for every phone, and obviously changes with the age of the battery) and how much power is the phone using while idle (the apps require the phone to be idle for a more accurate measurement). In other words, these apps can only give you a rough estimate.
    Thing is… a rough estimate can sometimes provide a single, clearcut, black/white, no-doubts-about-it, definite answer to the question asked; depending on the question asked, which in this case is at what level a specific charger is able to charge your phone. The relevant answer in this case is simply if the type of charger only allows charging at a certain level, and if a higher level of charging is found; then that's your very clear answer.
    tobian
  • Reply 38 of 43
    tundraboytundraboy Posts: 1,844member
    citpeks said:

    There is backward compatibility, but due to the paradigm shift, it operates according to the newer approach, and the old one is only kept as a fallback.

    Come on, that's not what paradigm shift means.  It's still the same old physics in use.  Going from Newtonian to quantum and relativistic physics, that's a paradigm shift.  Just saying.
    MplsP
  • Reply 39 of 43
    MplsPMplsP Posts: 3,700member
    Rayz2016 said:
    After reading two pages of this, I ordered another lightning cable. 
    I agree - I’ve never been a great fan of wireless charging. Slower, finicky, more prone to errors and it wastes power. Lightning cables are easy and reliable. Is it really that hard to plug in a lightning cable?
    mazda 3s
  • Reply 40 of 43
    thttht Posts: 4,618member
    MplsP said:
    Rayz2016 said:
    After reading two pages of this, I ordered another lightning cable. 
    I agree - I’ve never been a great fan of wireless charging. Slower, finicky, more prone to errors and it wastes power. Lightning cables are easy and reliable. Is it really that hard to plug in a lightning cable?
    It's like every other feature. If you find MagSafe convenient, it's worthwhile. So people, who have a desk job can have an inductive charging mat at their desks, and just keep their phones on it during the whole work day, and essentially have a fully charged phone for the evening. It really doesn't need to be fast for a use case like this. 2 to 3 Watts is basically all that is needed. Like with AirPods, not having a cord when you are continually picking up and putting down your phone should feel better to use for most people.

    MagSafe is like the Apple Watch magnetically latched inductive charger, but a little more evolved. Use your phone the whole day, charge while sleeping. The magnets will ensure optimal placement for inductive charging. You don't need a lot of power in this scenario either. 5 Watts will be fine. Well, it really should be the maximum power usage of the phone, so, something like 8 Watts, for people who are using their phone while charging, but Apple doesn't think this is too big of a market to address as the MagSafe charger has a short cable.

    On the other hand, if a phone lasts the whole day, a cable will be perfectly fine, and they'd be fine with a 5W charger, charging overnight. Yup. Perfectly fine, and probably the best way for most people.

    The fast charging, wired or inductive, is really only for a niche of people who use their phone hours on end, who don't charge daily, or is in a situation where they are using moe power than average, like by in a poor cellular coverage area. Would like to hear more from people on why they need to charge their phone so fast, and how they get to the point of needing to do that.
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