---------------------------------------------------------------------- Message-ID: <reoh3j$1ble$1@grapevine.csail.mit.edu> Date: 16 Jul 2020 03:21:23 +0000 From: "Garrett Wollman" <wollman@bimajority.org> Subject: Re: Pay no attention to that man behind the charger In article <0fc4b088-b15a-8c93-9995-613645f44451@billhorne.com>, Bill Horne <malQassRimiMlation@gmail.com> wrote: >Why, I wonder, has this particular phone started demanding to go home >to suck juice from it's mama's tap? Why, I wonder, does this happen >after five years of fault-free service while charging from a USB cube? >Could it be that Verizon has decided I've been away from their store >too long? This is going to blow your mind: every USB-C plug has an embedded microprocessor, and with it an X.509 digital certificate that it uses to authenticate itself to the device it's plugged into. USB-PD ("USB Power Delivery") uses this mechanism to allow (among other things) the device being powered to negotiate with the dock, cord, and power supply how much current it can draw. When you're drawing 95 watts at 5 volts, that's a lot of amps over that tiny little connector and cable. The authentication mechanism was allegedly introduced to allow devices to warn users about nonstandard, counterfeit, or even dangerous chargers. Of course it's impractical for the USB Implementers Forum to actually enforce this by revoking counterfeiters' certificates, and many rather darker explanations have been suggested. -GAWollman -- Garrett A. Wollman | "Act to avoid constraining the future; if you can, wollman@bimajority.org| act to remove constraint from the future. This is Opinions not shared by| a thing you can do, are able to do, to do together." my employers. | - Graydon Saunders, _A Succession of Bad Days_ (2015) ------------------------------ Message-ID: <renfol$kan$1@dont-email.me> Date: 15 Jul 2020 12:52:19 -0500 From: "GlowingBlueMist" <GlowingBlueMist@blackhole.io> Subject: Re: Pay no attention to that man behind the charger On 7/15/2020 12:01 PM, Bill Horne wrote: > > My wife has an LG "flip" phone, a basic voice and text device that > serves her needs. > > We've always charged it from a cube USB power converter plugged into a > wall outlet, with a USB cord connecting to the phone. Up until > yesterday, that worked fine. > > Yesterday, she got a notice that she had to use the charger that came > with the phone, and also that the unit would no longer charge from the > power cube. > > I don't know where the charger that came with the phone is - no doubt, > somewhere in the "wall of warts" that decorates my ham shack tool > bench, each with two prongs for an AC outlet, and a cord dangling down > to a connector that only fits one particular (battery charger|alarm > clock|router|walkie-talkie|clapping monkey). I was able to combine a > different USB cord with a different USB cube so that the phone stopped > refusing to charge, but we'll see if the complaints start up again. > > Why, I wonder, has this particular phone started demanding to go home > to suck juice from it's mama's tap? Why, I wonder, does this happen > after five years of fault-free service while charging from a USB cube? > Could it be that Verizon has decided I've been away from their store > too long? I would suspect the 5-volts from the charger now has a problem. It could be sending Low voltage or is no longer a clean DC signal. A USB cable can become partially defective as well. Either one can trigger this kind of response from a cell phone. ------------------------------ Message-ID: <7d3b6f43-4d73-689c-072a-5745c0b0a18c@ionary.com> Date: 16 Jul 2020 12:36:33 -0400 From: "Fred Goldstein" <fred_qrm@ionary.com> Subject: Re: Pay no attention to that man behind the charger On 7/15/2020 1:01 PM, Bill Horne wrote: > Yesterday, she got a notice that she had to use the charger that came > with the phone, and also that the unit would no longer charge from the > power cube. It is most likely a result of an aging battery or charging circuit in the phone. I have the same issue with a 5-year-old Dell laptop. Using its original charger, it gives a warning that it is not connected to the original charger. It is, but the battery is not keeping a charge very well, and that is probably causing it to give the bad charger message. So the LG phone is probably behaving the same way -- batteries do not last forever. -- Fred R. Goldstein k1io fred "at" ionary.com +1 617 795 2701 ------------------------------ ********************************************* End of telecom Digest Fri, 17 Jul 2020