MobileRead Forums - View Single Post - Basic kindle

Quoth · 08-06-2023, 10:59 AM

Both ends have to support fast charging. Most ereader USB-C connections are simply the same signals as on micro or mini or USB-B.

Usually an entire USB-A to USB-C cable is cheaper and more reliable than than an adaptor, but most are USB 2.x not USB 3.x. However only high speed devices 3.0 such as an external drive use USB 3.0 and needs a USB-C or USB-A host port that has USB 3.x mode and connections. An adaptor can only fully adapt on a USB-A USB 3.x connection to USB-C host. All the adaptors I have came with USB-A USB 2.x cables for the gadget end (mini, micro, USB-C and Apple lightning) so none support USB 3.x nor fast charging, but will go at 1.5A if the gadget and charger both agree thet support that (by dumb sensing).

The Kobo is USB 2.x, but like many USB gadgets not all host USB ports and not all 2A chargers will charge at the 1.5A of some newer Kobos. The 1.5A isn't "Fast Charging". A regular USB 1.x or USB 2.x port with a USB-A socket (regular USB host on PC, laptop, or charger port) is measured by the gadget on the D- and D+ pins and then the gadget decides what current to take and it's always 5V.
USB-C client to a USB-A with USB 3.x or to USB-C with USB 3.x uses serial communication to ask for voltage (which is 5V by default but up to 20V) and the charger & gadget negotiate on the current. If no communication is established the gadget then uses the old static voltage/resistor scheme on the D- and D+ of USB 1.x & USB 2.x, which can be as low as 0.1A and not higher than 1.5A (originally) and only ever 5V.
Even if the host can do 20V at 5A, in the absence of communication the gadget will only charge at maybe 0.1A or 0.5A at 5V. Like if the cable is a secure charge only kind with no D+ and D- wires.

I've 2A chargers that only go at 0.5A on my gadgets and others that deliver the 1.5A maximum my phone, tablet and newest Kobos can take, even with same USB-A to USB-C cable.
The PC USB-C and USB-A ports that do USB 3.x just go faster than the the other USB 2.x USB-A ports. They all only 0.5A, so take x3 longer to charge. I've not tested the ports on my newest laptop.

Edit:
I only use adaptors now on the Cigar to 5V USB-A charger with its coiled cable, so as to have only one cable in the car.

08-06-2023, 10:59 AM	#8
Quoth Still reading Posts: 14,450 Karma: 107078855 Join Date: Jun 2017 Location: Ireland Device: All 4 Kinds: epub eink, Kindle, android eink, NxtPaper	Both ends have to support fast charging. Most ereader USB-C connections are simply the same signals as on micro or mini or USB-B. Usually an entire USB-A to USB-C cable is cheaper and more reliable than than an adaptor, but most are USB 2.x not USB 3.x. However only high speed devices 3.0 such as an external drive use USB 3.0 and needs a USB-C or USB-A host port that has USB 3.x mode and connections. An adaptor can only fully adapt on a USB-A USB 3.x connection to USB-C host. All the adaptors I have came with USB-A USB 2.x cables for the gadget end (mini, micro, USB-C and Apple lightning) so none support USB 3.x nor fast charging, but will go at 1.5A if the gadget and charger both agree thet support that (by dumb sensing). The Kobo is USB 2.x, but like many USB gadgets not all host USB ports and not all 2A chargers will charge at the 1.5A of some newer Kobos. The 1.5A isn't "Fast Charging". A regular USB 1.x or USB 2.x port with a USB-A socket (regular USB host on PC, laptop, or charger port) is measured by the gadget on the D- and D+ pins and then the gadget decides what current to take and it's always 5V. USB-C client to a USB-A with USB 3.x or to USB-C with USB 3.x uses serial communication to ask for voltage (which is 5V by default but up to 20V) and the charger & gadget negotiate on the current. If no communication is established the gadget then uses the old static voltage/resistor scheme on the D- and D+ of USB 1.x & USB 2.x, which can be as low as 0.1A and not higher than 1.5A (originally) and only ever 5V. Even if the host can do 20V at 5A, in the absence of communication the gadget will only charge at maybe 0.1A or 0.5A at 5V. Like if the cable is a secure charge only kind with no D+ and D- wires. I've 2A chargers that only go at 0.5A on my gadgets and others that deliver the 1.5A maximum my phone, tablet and newest Kobos can take, even with same USB-A to USB-C cable. The PC USB-C and USB-A ports that do USB 3.x just go faster than the the other USB 2.x USB-A ports. They all only 0.5A, so take x3 longer to charge. I've not tested the ports on my newest laptop. Edit: I only use adaptors now on the Cigar to 5V USB-A charger with its coiled cable, so as to have only one cable in the car. Last edited by Quoth; 08-06-2023 at 11:06 AM.