MobileRead Forums - View Single Post - Can I charge my K3 using iPad's AC/USB adapter?

speedlever · 04-11-2011, 10:01 AM

I've always found this confusing.

Just to summarize, it doesn't matter what the power source is, the device will take the charge at its own rate, up to the limit the power source can supply.

So I can charge my K3 from my computer USB ports, the Kindle charger, or my iPad charger... just using the USB charging cable that came with the Kindle charger.

And I can charge my iPad from the computer USB ports, the Kindle charger, or the iPad charger... just using the USB charging cable that came with the iPad charger.

I'll get about the same Kindle charging time and rate from the Kindle charger (0.85A) or the iPad charger (2.1A), and a slower charge from the computer USB ports (0.1A) since the K3 charger only shows 5v/0.85A which is equal to or less than the output of the K3 charger and the iPad charger but more than the output of the computer USB port.

I'll get the fastest iPad charge time and rate from the iPad charger, the next fastest from the K3 charger, and the slowest from the computer USB port.

And all this can be accomplished safely because the device draws the power it needs to recharge, it is not force fed from the power supply. Basically, anything with a USB connection can be safely charged from any USB power source, but the charge time will vary considerably.

Do I have this right?

Edit: source: http://en.wikipedia.org/wiki/Usb#Power
A unit load is defined as 100 mA in USB 2.0
A maximum of 5 unit loads (500 mA) can be drawn from a port in USB 2.0

04-11-2011, 10:01 AM	#13
speedlever Fanatic Posts: 592 Karma: 138200 Join Date: Nov 2010 Location: NC, USA Device: PW2014, PW2012, iPad Pro	I've always found this confusing. Just to summarize, it doesn't matter what the power source is, the device will take the charge at its own rate, up to the limit the power source can supply. So I can charge my K3 from my computer USB ports, the Kindle charger, or my iPad charger... just using the USB charging cable that came with the Kindle charger. And I can charge my iPad from the computer USB ports, the Kindle charger, or the iPad charger... just using the USB charging cable that came with the iPad charger. I'll get about the same Kindle charging time and rate from the Kindle charger (0.85A) or the iPad charger (2.1A), and a slower charge from the computer USB ports (0.1A) since the K3 charger only shows 5v/0.85A which is equal to or less than the output of the K3 charger and the iPad charger but more than the output of the computer USB port. I'll get the fastest iPad charge time and rate from the iPad charger, the next fastest from the K3 charger, and the slowest from the computer USB port. And all this can be accomplished safely because the device draws the power it needs to recharge, it is not force fed from the power supply. Basically, anything with a USB connection can be safely charged from any USB power source, but the charge time will vary considerably. Do I have this right? Edit: source: http://en.wikipedia.org/wiki/Usb#Power A unit load is defined as 100 mA in USB 2.0 A maximum of 5 unit loads (500 mA) can be drawn from a port in USB 2.0 Last edited by speedlever; 04-11-2011 at 10:04 AM.