Kobo Chargers and Charging Times

[Aleron Ives]

I'm wondering what people are using to charge their Kobos: do you use a computer's USB port, a standard 10W phone charging brick, or a fast charger, and how long does it take you to charge your Kobo?

I know the Libra 2 is supposed to support 10W charging, but a computer's USB port probably won't supply that much; it takes me about 4 hours to do a full charge via my PC, which isn't exactly speedy. In theory a fast charger should be safe, as the reader won't use more than 10W even if the brick can deliver more, but I'm curious what kind of charging performance people have with their various Kobos and the specs of the chargers they're using.

[Sirtel]

I use a Kindle charger I bought in 2011 with my first ereader. The output is 5.0V - 0.85A. Not sure what it is as W, but IMO it does charge faster than my PC, although I have never measured the actual charging time.

[mbovenka]

Originally Posted by Sirtel

I use a Kindle charger I bought in 2011 with my first ereader. The output is 5.0V - 0.85A. Not sure what it is as W, but IMO it does charge faster than my PC, although I have never measured the actual charging time.

That's 4.25W (5 x 0.85). A USB2 port is rated for 0.5A (2.5W) and a USB3 port for 0.9A (4.5W). So if your computer has USB2 ports, that fits. If it has USB3 ports, it should be as fast as your Kindle charger.

I use whatever I have to hand to charge my Sage, from your run-of-the-mill 5V/1A chargers to my 80W OnePlus charger from my phone (which can do 20W at 5V I think). I must admit I have never paid much attention to charging times, I just let it charge overnight.

[Sirtel]

Originally Posted by mbovenka

That's 4.25W (5 x 0.85). A USB2 port is rated for 0.5A (2.5W) and a USB3 port for 0.9A (4.5W). So if your computer has USB2 ports, that fits. If it has USB3 ports, it should be as fast as your Kindle charger.

Hm. My computer has USB-C only. So possibly it isn't slower, I've just thought it is. I rarely charge my ereaders from my computer.

Thanks for explaining.

[John F]

I use whatever. I'm charging a Sage with a USB-A port on an electrical outlet. I'm charging a Clara 2E with a USB-A cable (I don't know the specs of the wallwart).

[meeera]

Originally Posted by Aleron Ives

I know the Libra 2 is supposed to support 10W charging, but a computer's USB port probably won't supply that much; it takes me about 4 hours to do a full charge via my PC, which isn't exactly speedy.

Mine seems to charge much faster than that from my laptop, though I haven't run it all the way down and timed the charge. I just leave it on an extra 15 minutes or so when I load a new book. But my laptop ports are Thunderbolt; I don't know what yours are.

[twowheels]

I charge with whichever USB power source is available to me at the moment -- I don't have a dedicated Kobo charging spot since I charge it so infrequently.

Under my desk I have an older 40W 5 port charger by Anker held in place by peel and stick velcro with a micro, lightning, and C cable ready for whatever I want to charge at that moment.

I have no idea how long it takes to charge the Kobo, nor do I care -- I typically plug it in when it gets down to about 40% at a time when I don't have time to read anyway.

[Quoth]

Originally Posted by mbovenka

That's 4.25W (5 x 0.85). A USB2 port is rated for 0.5A (2.5W) and a USB3 port for 0.9A (4.5W). So if your computer has USB2 ports, that fits. If it has USB3 ports, it should be as fast as your Kindle charger.

Officially, or originally. Apple was first with a higher current USB-A port that did USB 2.0 speed and 1A or more for a DVD writer or something similar.
Then there is the compatibility issue. Quite a few standards for the gadget to measure the D- & D+, or communicate and then decide what current can be taken. The 0.5A (=500mA) is a common default if it makes no sense, but it used to be 0.1A (100mA).

[Aleron Ives]

Originally Posted by meeera

my laptop ports are Thunderbolt; I don't know what yours are.

I'm using the convenient USB2 ports on the front of the case, which are connected to the mainboard with flimsy wires that probably can't carry much juice. I would probably get faster charging if I used the USB3 ports on the back, which are connected directly to the mainboard, but using a wall wart would be more convenient.

[JSWolf]

I mostly use the USB port on the sofa or the 100W USB charger. One is a USB-A port and the other is a USB-C port.

[Frogm4n]

Lithium batteries use a ramp charge, where they charge the first phase at the high power you often see a device/charger rated at, and then lower the power they draw to reduce heat build up. That's why so many things advertise a "quick charge" feature these days. A high power charger will get through the first phase more quickly, but you'll always have that slow charge "top off" that it backs down to as it fills the battery. Slower/lower power chargers generally are better for the longevity of the battery because it won't get as hot while charging.

It's akin to running the tap to fill a pot at full blast when you start and then progressively slowing it down as it gets closer to full so it doesn't run over, but managed automatically by the device.

Another thing to keep in mind is that "full" doesn't usually mean finished with a lot of devices. Quite a few of them (most, in my experience) switch to 100%/green/etc. even while they are still drawing some noticeable amount of power at the very slow part of the ramp charge. I often use an inline USB power meter when charging devices and I've seen devices still take charge power for an hour or more after turning the charged indicator on. Letting a device charge overnight gives it time to finish that last bit while cooling down from the bulk of the charge cycle and you aren't tempted to take it off the charger before it finishes, and may even help the charge controller built in to the device recalibrate where full should be if it hasn't had a truly full charge in a while.