5 ms·

That's the case already with USB Power Delivery Standard: The dream of "One Wall adapter and one car adapter" to charge all your devices (phones, laptops, batte

by ce4 10y ago

That's the case already with USB Power Delivery Standard: The dream of "One Wall adapter and one car adapter" to charge all your devices (phones, laptops, battery driven accessories). Actual situation: not really. Examples: Apple's MacBook 12 charger delivers non-standard 14.5V and the Dell XPS 13 only accepts 19V. USB PD however allows 5-12-1USB and on top of that the old USB Battery Charging standard with 5V@2A. Additionaly USB-C allows methods to authenticate peer devices. We will for sure get DRM'ed chargers and whitelisting for some accessories...

gumby 10y ago
> Examples: Apple's MacBook 12 charger delivers non-standard 14.5V and the Dell XPS 13 only accepts 19V. Actually Profile 5 allows anything from 5 to 20 volts so they are both compliant.
edraferi 10y ago
I actually wouldn't mind a little white listing. Folks like Underwriters Laboratory could serve as CAs, issuing certificates for compatibility with different profiles / standards. Then chargers could refuse to throw current at unproven devices. Of course then you need the ability to boot your charger into some kind of "promiscuous" mode for development or backwards compatibility purposes. To get REALLY ambitious, your charger could have an Internet connection and monitor a blockchain for certificate information. Some careful protocol design could let users override the DRM at will without letting cheap chinese crap factories ship exploding devices.
- madeofpalk 10y ago
  > your charger could have an Internet connection
  - witty_username 10y ago
    Quoted out of context > To get REALLY ambitious
    - MertsA 10y ago
      Honestly we already have standards for tethering over USB... Still crazy, but it could actually work.
- corndoge 10y ago
  the day when chargers monitor a block chain for certificate information is the day I retire
userbinator 10y ago
IIRC the Apple adapters are variable voltage and will increase up to "18.5V" depending on the load current, but the laptop itself is perfectly happy to receive full voltage --- and slightly more --- all the time. In fact, laptops that have a 19V adapter will be fine with 20V too, and may actually run slightly cooler because of the lower current draw. I suspect all the funny voltages is just to create differentiation and a sense of lock-in, but the underlying engineering and tolerances on components mean that a 19V adapter may actually be in the range of 18-21V depending on load. It's amusing to find laptop adapters claiming 18.25, 18.75, 19.6, and a bunch of other "why!?" voltages which are technically all in the same tolerance range. I've written about this before too: https://news.ycombinator.com/item?id=7594383 https://news.ycombinator.com/item?id=7594383 Some further discussion on MacBook-PSU-related details here: http://www.eevblog.com/forum/repair/replacing-apple-magsafe-85w-charger-with-a-normal-laptop-psu-possible/ http://www.eevblog.com/forum/repair/replacing-apple-magsafe-... http://www.eevblog.com/forum/projects/apple-magsafe-power-brick/ http://www.eevblog.com/forum/projects/apple-magsafe-power-br... (last post is enlightening) The real obstacle with the "one adapter for all laptops" is the proprietary DRM-ish ID schemes that a lot of them have, where they may complain/warnin and/or won't charge the battery with just pure voltage input.
- nerdponx 10y ago
  Couldn't this DRM-esque stuff be a more innocent reflection of different manufacturers having different protection circuitry on their batteries?
  - userbinator 10y ago
    Batteries are behind the charge controller which does have its own way of communicating with and authenticating the battery pack. The term "laptop charger" is a misnomer; it's just a power supply without any battery charging circuitry.

by ce4 10y ago

gumby 10y ago

> Examples: Apple's MacBook 12 charger delivers non-standard 14.5V and the Dell XPS 13 only accepts 19V. Actually Profile 5 allows anything from 5 to 20 volts so they are both compliant.

edraferi 10y ago

I actually wouldn't mind a little white listing. Folks like Underwriters Laboratory could serve as CAs, issuing certificates for compatibility with different profiles / standards. Then chargers could refuse to throw current at unproven devices. Of course then you need the ability to boot your charger into some kind of "promiscuous" mode for development or backwards compatibility purposes. To get REALLY ambitious, your charger could have an Internet connection and monitor a blockchain for certificate information. Some careful protocol design could let users override the DRM at will without letting cheap chinese crap factories ship exploding devices.

madeofpalk 10y ago
> your charger could have an Internet connection
- witty_username 10y ago
  Quoted out of context > To get REALLY ambitious
  - MertsA 10y ago
    Honestly we already have standards for tethering over USB... Still crazy, but it could actually work.
corndoge 10y ago
the day when chargers monitor a block chain for certificate information is the day I retire

userbinator 10y ago

IIRC the Apple adapters are variable voltage and will increase up to "18.5V" depending on the load current, but the laptop itself is perfectly happy to receive full voltage --- and slightly more --- all the time. In fact, laptops that have a 19V adapter will be fine with 20V too, and may actually run slightly cooler because of the lower current draw. I suspect all the funny voltages is just to create differentiation and a sense of lock-in, but the underlying engineering and tolerances on components mean that a 19V adapter may actually be in the range of 18-21V depending on load. It's amusing to find laptop adapters claiming 18.25, 18.75, 19.6, and a bunch of other "why!?" voltages which are technically all in the same tolerance range. I've written about this before too: https://news.ycombinator.com/item?id=7594383 https://news.ycombinator.com/item?id=7594383 Some further discussion on MacBook-PSU-related details here: http://www.eevblog.com/forum/repair/replacing-apple-magsafe-85w-charger-with-a-normal-laptop-psu-possible/ http://www.eevblog.com/forum/repair/replacing-apple-magsafe-... http://www.eevblog.com/forum/projects/apple-magsafe-power-brick/ http://www.eevblog.com/forum/projects/apple-magsafe-power-br... (last post is enlightening) The real obstacle with the "one adapter for all laptops" is the proprietary DRM-ish ID schemes that a lot of them have, where they may complain/warnin and/or won't charge the battery with just pure voltage input.

nerdponx 10y ago
Couldn't this DRM-esque stuff be a more innocent reflection of different manufacturers having different protection circuitry on their batteries?
- userbinator 10y ago
  Batteries are behind the charge controller which does have its own way of communicating with and authenticating the battery pack. The term "laptop charger" is a misnomer; it's just a power supply without any battery charging circuitry.