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Be careful with the idea that the charger is just a regular USB-C charger. These laptops will draw 3-4 amps at 20 volts. Most phone chargers are designed for 1-

by guelo 10y ago

Be careful with the idea that the charger is just a regular USB-C charger. These laptops will draw 3-4 amps at 20 volts. Most phone chargers are designed for 1-3amps at 5 volts, so they would only provide a trickle of charge to these laptops. Older chargers (and computers ports!) can be damaged by these higher power draws. Also, the USB-C cable the Macs come with is rated up to a hefty 5 amps. Some of the cheap phone cables out there could actually pose a fire danger if they were to handle 5 amps.

Waterluvian 10y ago
Are the MacBook USB-C ports special in some way that makes them USB-C and also a non-standard charger port? If not, then they must be compliant USB-C ports and therefore would not be supplying an incorrect voltage. As far as I understand the fundamentals of electricity, current doesn't matter. A 5v USB power source that can supply 100 amps would still only supply whatever the device was designed to draw when charging. But all of that is moot if the MacBook ports are "special" USB-C ports and somehow they negotiate a voltage higher than 5V.
- snuxoll 10y ago
  The USB Power Delivery (USB-PD) spec allows devices to negotiate up to 20V - the key word, however being "negotiate", means this is no different than how older USB charging solutions work (start at 5V+100mA, negotiate to whatever the client device can handle and what the host will allow). I'm always amused by how uninformed many people are about USB and power supply, if devices can't negotiate something that works for both ends they just stop. It's a shitty situation to be in if your device fails to charge, but devices that follow the USB-IF rules will never draw more current than the power source can supply, and the power source will never supply more than the device has requested.
  - Waterluvian 10y ago
    So if I plug a dumb device into it that only makes electrical contact, it won't make that negotiation. So, so long as Apple's MacBook USB charger is compliant, it won't destroy anything USB that I plug into it, so long as those devices are also compliant. Right?
    - snuxoll 10y ago
      A "dumb" device that doesn't negotiate will get the minimum 5V@100mA that the USB spec allows, dedicated chargers often decide to not drop the power after the negotiation window is over but a proper host device (laptop, etc.) will drop all power if a device fails to negotiate. So yeah, if you plug something into the Macbook charger it will either not charge (dunno if it supports traditional USB power specs since it's a type-C only charger) or charge as any other charger already does.
      - deleted 10y ago
        [deleted]
      - kalleboo 10y ago
        Re: "dumb" devices, this is how it's supposed to work, yes, but I don't think I've ever seen a charger that won't happily dump 1A into a resistor wired over the power pins - including brand name (Apple) chargers and yes, the USB ports on a MacBook Pro. I've never seen a modern device supply only 100 mA. For devices that DO attempt to negotiate, yes in those cases usually you'll see it work according to spec. I haven't tried USB-C yet, it would be interesting to see if devices have gotten stricter.
  - nicky0 10y ago
    Isn't there also a spec for passive power supply over USB, used by chargers. Something about combinations of resistances across the pins to signal current requirements.
- marcus_holmes 10y ago
  USB-C is a collection of standards rather than one standard. As others have pointed out, two USB-C devices can use the same standard yet not operate together. The standard covers both 20V and 5V power supply. If the device needs 20V and only gets 5V, there is nothing that says it must work, or even inform the user that it, in fact, is not working.
ianburrell 10y ago
Only chargers that don't follow the spec can be damaged by the power draw. That is the problem with adapters and USB-A cables that use wrong resistor and USB-C device will pull 3A from USB-A charger that can only provide 2.4A at most. Also, the charge cable is electronically marked for 5A. Regular USB-C cables only do 3A, which limits them to 60W with USB-PD.
madeofpalk 10y ago
Heh. Was amused by this line > I’m sure it’s only a matter of time until Amazon is flooded with cheap versions of this idea that tweak it just enough to avoid patent issues. I look forward to buying $3 breakaway USB-C cables in the future. Has this guy not seen what's going on with Amazon and the cheap USB-C cables that are flooding it[0]? They're literally destroying people's laptops by drawing too much power and frying either end. [0]: http://www.theverge.com/2016/2/4/10916264/usb-c-russian-roulette-power-cords http://www.theverge.com/2016/2/4/10916264/usb-c-russian-roul...
- kalleboo 10y ago
  This author doesn't know what he's talking about "It’s not the Nexus’ fault that my MacBook got fried — it was just doing what it was supposed to do: ask for as much power as it can get. It’s not the MacBook’s fault either — its ports weren’t designed to handle delivering that much juice nor to know that they shouldn’t even try. It is the fault of the cable, which is supposed to protect both sides from screwing up the energy equation with resistors and proper wiring." This is simply not true. Both the device that is supplying and receiving power should be regulating. The cable should just be "dumb". I've done a bunch of testing on various chargers using cheap USB power meters and 2A USB dummy loads. For instance iPhones/iPads will monitor the voltage of the charger and if it starts sagging will reduce the amperage they draw. (my own testing has only been with "classic" USB type A stuff though) The only cable I've heard of that actually fried anything was one that was wired completely wrong putting power on the data pins or something like that.
  - madeofpalk 10y ago
    Are you familiar with Benson Leung (Google hardware engineer working on the Pixel) work reviewing various USB-C cables and accessories? He's extensively demonstrated that there are USB-C cables on the market that are dangerous. https://plus.google.com/+BensonLeung https://plus.google.com/+BensonLeung https://docs.google.com/spreadsheets/d/1wJwqv3rTNmORXz-XJsQaXK1dl8I91V4-eP_sfNVNzbA/edit https://docs.google.com/spreadsheets/d/1wJwqv3rTNmORXz-XJsQa... https://www.amazon.com/gp/pdp/profile/A25GROL6KJV3QG/ref=cm_cr_rdp_pdp https://www.amazon.com/gp/pdp/profile/A25GROL6KJV3QG/ref=cm_... http://www.theverge.com/platform/amp/2015/11/5/9674462/usb-type-c-google-engineer-third-party-cables http://www.theverge.com/platform/amp/2015/11/5/9674462/usb-t... www.theverge.com/platform/amp/2015/11/16/9742360/oneplus-usb-type-c-cable-adapter

by guelo 10y ago

Waterluvian 10y ago

Are the MacBook USB-C ports special in some way that makes them USB-C and also a non-standard charger port? If not, then they must be compliant USB-C ports and therefore would not be supplying an incorrect voltage. As far as I understand the fundamentals of electricity, current doesn't matter. A 5v USB power source that can supply 100 amps would still only supply whatever the device was designed to draw when charging. But all of that is moot if the MacBook ports are "special" USB-C ports and somehow they negotiate a voltage higher than 5V.

snuxoll 10y ago
The USB Power Delivery (USB-PD) spec allows devices to negotiate up to 20V - the key word, however being "negotiate", means this is no different than how older USB charging solutions work (start at 5V+100mA, negotiate to whatever the client device can handle and what the host will allow). I'm always amused by how uninformed many people are about USB and power supply, if devices can't negotiate something that works for both ends they just stop. It's a shitty situation to be in if your device fails to charge, but devices that follow the USB-IF rules will never draw more current than the power source can supply, and the power source will never supply more than the device has requested.
- Waterluvian 10y ago
  So if I plug a dumb device into it that only makes electrical contact, it won't make that negotiation. So, so long as Apple's MacBook USB charger is compliant, it won't destroy anything USB that I plug into it, so long as those devices are also compliant. Right?
  - snuxoll 10y ago
    A "dumb" device that doesn't negotiate will get the minimum 5V@100mA that the USB spec allows, dedicated chargers often decide to not drop the power after the negotiation window is over but a proper host device (laptop, etc.) will drop all power if a device fails to negotiate. So yeah, if you plug something into the Macbook charger it will either not charge (dunno if it supports traditional USB power specs since it's a type-C only charger) or charge as any other charger already does.
    - deleted 10y ago
      [deleted]
    - kalleboo 10y ago
      Re: "dumb" devices, this is how it's supposed to work, yes, but I don't think I've ever seen a charger that won't happily dump 1A into a resistor wired over the power pins - including brand name (Apple) chargers and yes, the USB ports on a MacBook Pro. I've never seen a modern device supply only 100 mA. For devices that DO attempt to negotiate, yes in those cases usually you'll see it work according to spec. I haven't tried USB-C yet, it would be interesting to see if devices have gotten stricter.
- nicky0 10y ago
  Isn't there also a spec for passive power supply over USB, used by chargers. Something about combinations of resistances across the pins to signal current requirements.
marcus_holmes 10y ago
USB-C is a collection of standards rather than one standard. As others have pointed out, two USB-C devices can use the same standard yet not operate together. The standard covers both 20V and 5V power supply. If the device needs 20V and only gets 5V, there is nothing that says it must work, or even inform the user that it, in fact, is not working.

ianburrell 10y ago

Only chargers that don't follow the spec can be damaged by the power draw. That is the problem with adapters and USB-A cables that use wrong resistor and USB-C device will pull 3A from USB-A charger that can only provide 2.4A at most. Also, the charge cable is electronically marked for 5A. Regular USB-C cables only do 3A, which limits them to 60W with USB-PD.

madeofpalk 10y ago

Heh. Was amused by this line > I’m sure it’s only a matter of time until Amazon is flooded with cheap versions of this idea that tweak it just enough to avoid patent issues. I look forward to buying $3 breakaway USB-C cables in the future. Has this guy not seen what's going on with Amazon and the cheap USB-C cables that are flooding it[0]? They're literally destroying people's laptops by drawing too much power and frying either end. [0]: http://www.theverge.com/2016/2/4/10916264/usb-c-russian-roulette-power-cords http://www.theverge.com/2016/2/4/10916264/usb-c-russian-roul...

kalleboo 10y ago
This author doesn't know what he's talking about "It’s not the Nexus’ fault that my MacBook got fried — it was just doing what it was supposed to do: ask for as much power as it can get. It’s not the MacBook’s fault either — its ports weren’t designed to handle delivering that much juice nor to know that they shouldn’t even try. It is the fault of the cable, which is supposed to protect both sides from screwing up the energy equation with resistors and proper wiring." This is simply not true. Both the device that is supplying and receiving power should be regulating. The cable should just be "dumb". I've done a bunch of testing on various chargers using cheap USB power meters and 2A USB dummy loads. For instance iPhones/iPads will monitor the voltage of the charger and if it starts sagging will reduce the amperage they draw. (my own testing has only been with "classic" USB type A stuff though) The only cable I've heard of that actually fried anything was one that was wired completely wrong putting power on the data pins or something like that.
- madeofpalk 10y ago
  Are you familiar with Benson Leung (Google hardware engineer working on the Pixel) work reviewing various USB-C cables and accessories? He's extensively demonstrated that there are USB-C cables on the market that are dangerous. https://plus.google.com/+BensonLeung https://plus.google.com/+BensonLeung https://docs.google.com/spreadsheets/d/1wJwqv3rTNmORXz-XJsQaXK1dl8I91V4-eP_sfNVNzbA/edit https://docs.google.com/spreadsheets/d/1wJwqv3rTNmORXz-XJsQa... https://www.amazon.com/gp/pdp/profile/A25GROL6KJV3QG/ref=cm_cr_rdp_pdp https://www.amazon.com/gp/pdp/profile/A25GROL6KJV3QG/ref=cm_... http://www.theverge.com/platform/amp/2015/11/5/9674462/usb-type-c-google-engineer-third-party-cables http://www.theverge.com/platform/amp/2015/11/5/9674462/usb-t... www.theverge.com/platform/amp/2015/11/16/9742360/oneplus-usb-type-c-cable-adapter