Aura H2O Kobo came without wall wart

Xen · 04-07-2015, 02:44 AM

12345

meeera · 04-07-2015, 03:14 AM

Yep. I've used my laptop's USB ports, Apple chargers, and a powerboard with builtin USB.

oren64 · 04-07-2015, 04:27 AM

In the kobo h2o user guide it said you can use a 5V 500mA microUSB adapter.

Xen · 04-07-2015, 12:14 PM

12345

DNSB · 04-07-2015, 10:46 PM

Quote:

Originally Posted by Xen

Thanks, I think all the USB wall warts are 5V (because that's what USB is) - so any of the chargers should be fine. Voltage matters - and the device should only draw however many amps it normally uses regardless of the maximum the wall wart can provide.

I don't know why I was thinking there might be a problem - I already knew that all USB based wall warts are going to draw the same voltage, and given voltage is the same, amperage only matters for a device that draws more current than the wall wart provides - and then only because it'll charge slower, LOL!

So we can use any wall wart intended for devices that charge over a USB connector for any of our devices.

My usual caution for aftermarket no-name USB power supplies: check the actual output voltage. I've been unpleasantly surprised a couple of times when the output was well outside the 4.75 - 5.25V (5V ± 5%) standard for USB 1/2.

Xen · 04-08-2015, 12:32 AM

12345

JSWolf · 04-08-2015, 12:41 AM

I've used a Sony Reader USB charger, an Apple iPad charger to charge my H2O.

rcentros · 04-13-2015, 05:22 AM

Quote:

Originally Posted by Xen

So we can use any wall wart intended for devices that charge over a USB connector for any of our devices.

Voltage has to be near 5 volts but it's really not as important as the amps. Anything (I guess within reason) above .5 amps (500 mA) is good. You can damage equipment when the amperage is below what's required in the specs. It's doubtful you have any USB wall warts below 500 mA but that's the main thing you need to worry about.

TechniSol · 04-15-2015, 04:39 PM

I beg to differ, both are of import. Depending on the circuitry, the accepted norm is +/- 5% 5Vdc and has been since the TTL days -now with 3.3Vdc circuitry things are a bit different, but if the device expects 5Vdc it may be picky about not getting it even if it is being regulated down to 3.3Vdc or less for the circuitry actually doing the work. Best to always stay within the specs for voltage and meet or exceed the demand for current supply.

Undervoltaging has the nasty habit of drawing excess current in certain devices(most!) as power, the product of current times voltage is the true constant. Said excess current occasionally leads to burnt out traces or other conductors if the PCB designer did not leave enough width(call it overhead or tolerance) and thereby current carrying capacity. Ask me how I learned these lessons low so many, many moons ago... and I'll steal a line from a certain red shirted character(ha, was he ever!) with a scottish brogue who at least once opined that a good engineer is always more conservative on paper! ;-)

04-07-2015, 02:44 AM	#1
Xen Connoisseur Posts: 87 Karma: 180000 Join Date: Aug 2013 Device: Kindle	Kobo came without wall wart 12345 Last edited by Xen; 08-24-2018 at 03:13 PM.

04-07-2015, 04:27 AM	#3
oren64 I need a chapter break Posts: 4,042 Karma: 56058267 Join Date: Mar 2015 Location: Israel Device: Kobo Glo	In the kobo h2o user guide it said you can use a 5V 500mA microUSB adapter. Last edited by oren64; 04-07-2015 at 09:46 AM.

04-07-2015, 12:14 PM	#4
Xen Connoisseur Posts: 87 Karma: 180000 Join Date: Aug 2013 Device: Kindle	12345 Last edited by Xen; 08-24-2018 at 08:18 PM.

04-08-2015, 12:32 AM	#6
Xen Connoisseur Posts: 87 Karma: 180000 Join Date: Aug 2013 Device: Kindle	12345 Last edited by Xen; 08-24-2018 at 10:17 PM.

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04-07-2015, 03:14 AM	#2
meeera Grand Sorcerer Posts: 5,808 Karma: 68407974 Join Date: Dec 2011 Location: Australia Device: Kobo Libra 2, iPadMini4, iPad4, MBP; support other Kobo/Kindles	Yep. I've used my laptop's USB ports, Apple chargers, and a powerboard with builtin USB.

04-08-2015, 12:41 AM	#7
JSWolf Resident Curmudgeon Posts: 79,587 Karma: 145863177 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	I've used a Sony Reader USB charger, an Apple iPad charger to charge my H2O.

04-15-2015, 04:39 PM	#9
TechniSol GranPohbah-Fezzes r cool! Posts: 1,056 Karma: 3151024 Join Date: Jul 2010 Device: Nook STRs, Kobo Touch, Kobo Glo	I beg to differ, both are of import. Depending on the circuitry, the accepted norm is +/- 5% 5Vdc and has been since the TTL days -now with 3.3Vdc circuitry things are a bit different, but if the device expects 5Vdc it may be picky about not getting it even if it is being regulated down to 3.3Vdc or less for the circuitry actually doing the work. Best to always stay within the specs for voltage and meet or exceed the demand for current supply. Undervoltaging has the nasty habit of drawing excess current in certain devices(most!) as power, the product of current times voltage is the true constant. Said excess current occasionally leads to burnt out traces or other conductors if the PCB designer did not leave enough width(call it overhead or tolerance) and thereby current carrying capacity. Ask me how I learned these lessons low so many, many moons ago... and I'll steal a line from a certain red shirted character(ha, was he ever!) with a scottish brogue who at least once opined that a good engineer is always more conservative on paper! ;-)

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