Kobo's and charging

John F · 08-09-2015, 07:03 AM

Sorry if this was asked before.

My primary reader is a Glo HD. I have one charger that says 0.85A output and one that says 1.5A output. Will the 1.5A output charge the reader quicker?

Thank you.

frostschutz · 08-09-2015, 07:23 AM

The Kobos detect pure chargers (there is no "connect to PC" popup if you use them). So it's possible they will make use of higher charging currents as well, and thus charge faster - but I have never tried.

Charging should not take long either way. If it takes too long for you, let it charge more often. Running out of power is not good for the battery.

John F · 08-09-2015, 10:38 AM

Please define "too long."

On my Glo HD, charging takes a long time, probably 3-4 hours when the battery is at 30-40%. I almost always use the .85A charger. I think I was getting the same charging times with my other Kobos.

I charge so infrequently (once every 3-4 weeks), charging speed isn't all that important to me.

EndlessWaves · 08-09-2015, 12:10 PM

I'm not sure about the Glo HD but my Aura HD doesn't seem to charge any faster with a BC1.2 compatible charger and appropriate cable and the bundled cable wasn't capable of carrying much current when I tried it with a faster charging device. It seems unlikely that it'll either use the new Power Delivery spec or one of the nonstandard device specific signalling schemes from the likes of Apple and Samsung.

As you say, with charging being so infrequent it doesn't make a lot of sense for kobo to implement faster charging. It may even benefit long term battery life to charge more slowly.

MGlitch · 08-09-2015, 01:06 PM

According to the wiki, it should take 2-3 hours for a full charge for the Glo (not HD).

That gives with what I recall for other ereaders similar to the Glo. I can't imagine the charge time increasing much over that.

Have you tried the obvious checks to rule out everything else besides your Glo HD?

1) use a different cable
2) use a different adaptor
3) use a different outlet
4) turn your Glo HD off and back on after about 2 hours of it charging (I've seen some devices that don't update the charged percentage properly at first, usually this resolves itself after a power cycle or two.

John F · 08-09-2015, 01:41 PM

Quote:

Originally Posted by MGlitch

According to the wiki, it should take 2-3 hours for a full charge for the Glo (not HD).

...

Could you provide a link please? I found a wiki page for the Glo, but I didn't see any mention of charging. Thank you.

MGlitch · 08-09-2015, 01:44 PM

Just as an example, my H2O while charging off a USB port on my PC, which I believe is 0.5A, went from 68% to 89% in about 38 minutes. This was with me occasionally waking it to check the charge amount, I've the frontlight set to 20% though of course that's off when the H2O is sleeping.

The H2O was connected, but not mounted (I'd ejected it from the PC just left the cable connected).

edit- upon disconnecting it, it went to 100%.

And really with how long the charge lasts I'm fine with a charge period of four hours. Connect it when you're going to sleep, wake up and boom.

JSWolf · 08-09-2015, 02:02 PM

I've charged my H2O using an iPad charger at 2.1A. I suggest using the 1.5A charger are it will charge faster than using the .85A charger.

EndlessWaves · 08-09-2015, 02:36 PM

Quote:

Originally Posted by JSWolf

I've charged my H2O using an iPad charger at 2.1A.

I'd imagine the iPad charger won't deliver more than 0.5A to any non-apple device because it doesn't support the standard USB Battery Charging spec. I know the reverse is true.

Quote:

Originally Posted by MGlitch

edit- upon disconnecting it, it went to 100%.

Kobo's battery percentage indicator is worse than useless. It seems to be pretty much a linear attempt to convert a voltage reading into a percentage. So it'll be nearly flat at '30%' and read higher when the charger is connected than when you disconnect it. I usually charge 40-90%. Gives a long enough life and avoiding the extremes should keep the battery going for more charge cycles (which isn't likely to matter in the case of an eReader).

I couldn't find any capacity information on the GloHD's battery except that it was '1.5Ah'. If that's at 5V than four hours is about the expected charging time from a 5v/0.5A supply (Lithium Ion batteries have to charge more slowly when they get closer to full).

MGlitch · 08-09-2015, 11:10 PM

Quote:

Originally Posted by John F

Could you provide a link please? I found a wiki page for the Glo, but I didn't see any mention of charging. Thank you.

Apparently it's not the wiki, but Kobo's own help page

http://www.kobobooks.com/wifi_faq

adding further evidence that I need more sleep than I've been getting it the fact that it specifies the kobo wifi. However while batteries have improved I don't think the charge time should have changed overly much since then.

DNSB · 08-10-2015, 01:41 PM

Quote:

Originally Posted by JSWolf

I've charged my H2O using an iPad charger at 2.1A. I suggest using the 1.5A charger are it will charge faster than using the .85A charger.

I've used several adapters to charge my Kobos over the years and found that using an adapter that delivers over the rated charge current has little effect on the charge speed. My H2O charges at the same speed using a 5V/0.9A charger or a 5.1V/2.1A iPad charger. Using a 5V/0.5A standard USB charger does increase the charge time. The battery charge circuitry is very likely designed to maximize the battery life by controlling the charge current.

Ken Maltby · 08-11-2015, 04:50 PM

The reference design for ARM based ereaders is built around two major ICs, the iMX50 SoC (System on a Chip), and a Power Management IC (PMIC). The PMIC is very sophisticated and controls both charging and power usage. All Li-ion charge controllers limit the current drawn to a set of profiles for three stages and at the end shuts down all current draw, for charging. It is all highly managed and will not over draw, no matter any reasonable current available. (It couldn't handle a lightning strike.)

Luck;
Ken

DNSB · 08-11-2015, 06:54 PM

Quote:

Originally Posted by Ken Maltby

It is all highly managed and will not over draw, no matter any reasonable current available. (It couldn't handle a lightning strike.)

Personally, I wouldn't consider a lightning strike reasonable but maybe that's just me. But you bring up a point that many people seem to forget. As long as the voltage is in spec and the current meets the minimum requirement, the charging circuit will not allow more than the maximum safe charging current.

Though there are some interesting items about using lightning to charge your cell phone courtesy of Nokia and some scientists in the UK a few years back.

Kind of makes you wish for the Shipstone battery (Robert Heinlein, Friday) or the batacitor (Philip J. Farmer's Riverworld series).

John F · 08-12-2015, 11:57 AM

Quote:

Originally Posted by John F

... On my Glo HD, charging takes a long time, probably 3-4 hours when the battery is at 30-40%. I almost always use the .85A charger. I think I was getting the same charging times with my other Kobos. ...

I charged my Glo HD this morning and it took 2 hours to go from 30% to 100% using the .85A charger.

08-09-2015, 07:03 AM	#1
John F Grand Sorcerer Posts: 7,941 Karma: 70583139 Join Date: Feb 2009 Device: Kobo Clara 2E	Kobo's and charging Sorry if this was asked before. My primary reader is a Glo HD. I have one charger that says 0.85A output and one that says 1.5A output. Will the 1.5A output charge the reader quicker? Thank you.

08-09-2015, 01:44 PM	#7
MGlitch Wizard Posts: 2,855 Karma: 22003124 Join Date: Aug 2014 Device: Kobo Forma, Kobo Sage, Kobo Libra 2	Just as an example, my H2O while charging off a USB port on my PC, which I believe is 0.5A, went from 68% to 89% in about 38 minutes. This was with me occasionally waking it to check the charge amount, I've the frontlight set to 20% though of course that's off when the H2O is sleeping. The H2O was connected, but not mounted (I'd ejected it from the PC just left the cable connected). edit- upon disconnecting it, it went to 100%. And really with how long the charge lasts I'm fine with a charge period of four hours. Connect it when you're going to sleep, wake up and boom. Last edited by MGlitch; 08-09-2015 at 01:47 PM.

08-11-2015, 04:50 PM	#12
Ken Maltby Wizard Posts: 4,466 Karma: 6900052 Join Date: Dec 2009 Location: The Heart of Texas Device: Boox Note2, AuraHD, PDA,	The reference design for ARM based ereaders is built around two major ICs, the iMX50 SoC (System on a Chip), and a Power Management IC (PMIC). The PMIC is very sophisticated and controls both charging and power usage. All Li-ion charge controllers limit the current drawn to a set of profiles for three stages and at the end shuts down all current draw, for charging. It is all highly managed and will not over draw, no matter any reasonable current available. (It couldn't handle a lightning strike.) Luck; Ken Last edited by Ken Maltby; 08-11-2015 at 04:54 PM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Aura Charging the kobo	christopher22	Kobo Reader	16	01-01-2015 07:51 PM
Kobo not charging?	gonatgo	Kobo Reader	19	05-09-2014 02:49 PM
Kobo Charging Woes	Kboland	Kobo Tablets	3	01-12-2012 09:08 PM
Kobo not charging when plugged in	Robotech_Master	Kobo Reader	7	06-06-2011 05:54 PM
Kobo charging	The Terminator	Kobo Reader	4	01-15-2011 04:15 PM

08-09-2015, 07:23 AM	#2
frostschutz Linux User Posts: 2,282 Karma: 6123806 Join Date: Sep 2010 Location: Heidelberg, Germany Device: none	The Kobos detect pure chargers (there is no "connect to PC" popup if you use them). So it's possible they will make use of higher charging currents as well, and thus charge faster - but I have never tried. Charging should not take long either way. If it takes too long for you, let it charge more often. Running out of power is not good for the battery.

08-09-2015, 10:38 AM	#3
John F Grand Sorcerer Posts: 7,941 Karma: 70583139 Join Date: Feb 2009 Device: Kobo Clara 2E	Please define "too long." On my Glo HD, charging takes a long time, probably 3-4 hours when the battery is at 30-40%. I almost always use the .85A charger. I think I was getting the same charging times with my other Kobos. I charge so infrequently (once every 3-4 weeks), charging speed isn't all that important to me.

08-09-2015, 12:10 PM	#4
EndlessWaves Zealot Posts: 119 Karma: 38158 Join Date: Jan 2014 Device: Kobo Aura HD	I'm not sure about the Glo HD but my Aura HD doesn't seem to charge any faster with a BC1.2 compatible charger and appropriate cable and the bundled cable wasn't capable of carrying much current when I tried it with a faster charging device. It seems unlikely that it'll either use the new Power Delivery spec or one of the nonstandard device specific signalling schemes from the likes of Apple and Samsung. As you say, with charging being so infrequent it doesn't make a lot of sense for kobo to implement faster charging. It may even benefit long term battery life to charge more slowly.

08-09-2015, 01:06 PM	#5
MGlitch Wizard Posts: 2,855 Karma: 22003124 Join Date: Aug 2014 Device: Kobo Forma, Kobo Sage, Kobo Libra 2	According to the wiki, it should take 2-3 hours for a full charge for the Glo (not HD). That gives with what I recall for other ereaders similar to the Glo. I can't imagine the charge time increasing much over that. Have you tried the obvious checks to rule out everything else besides your Glo HD? 1) use a different cable 2) use a different adaptor 3) use a different outlet 4) turn your Glo HD off and back on after about 2 hours of it charging (I've seen some devices that don't update the charged percentage properly at first, usually this resolves itself after a power cycle or two.

08-09-2015, 02:02 PM	#8
JSWolf Resident Curmudgeon Posts: 79,741 Karma: 145864619 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	I've charged my H2O using an iPad charger at 2.1A. I suggest using the 1.5A charger are it will charge faster than using the .85A charger.

Advert

Advert