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The Samsung Galaxy Tab 10.1 comes with a special charger which (I'm assuming) provides a higher current output than the USB standard. Without it, the device can actually die, even if the USB cord is plugged in to a USB port (albeit a little less quickly).

I'm looking for other (cheaper) AC and car adapters, but I don't know the minimum power they need to provide to power the device. Does anyone know the minimum current needed for a 5V USB connection for the Galaxy Tab 10.1, or perhaps a link that provides this information?

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5 Answers 5

up vote 7 down vote accepted

This turns out to be more complicated than just the amperage rating of the power adapter.

This XDA post says that the Tablet itself may 'step down' to 0.5A charging if it cannot detect the right support in the USB host. There are some additional details in this post but I don't grok them.

That thread led me to this slashdot comment which seems very useful and knowledgeable. If I understand the story correctly, unless the tablet can negotiate with the host device, the amount of power it can draw is limited. A physical "hack" (now part of a USB standard) in the adapter can make it clear to the USB client (the tablet) that there is no host device (its a wall wart), so it can charge faster. Without the hack, the device is limited in the amperage it can use.

More details on the USB charing spec are on wikipedia.

I just verified some of this with my Samsung Galaxy Tab 10.1 and the no-name 2A USB wall charger I have. If I plug my tablet into this "unapproved" USB adapter, then I get a little red "x" on the battery charge indicator in the system tray. Additionally, I get the "media scanner running..." alert (which I think means that the Tablet thinks it might be connected to a computer). I cannot tell at what rate (2.5mA, 500mA, 2A, etc) the tablet is actually charging at, though.

If I plug the tablet into the 'approved' wall wart, I get no such red "x", nor any "media scanner" alerts.

All that said, in practice, I've found that the tablet will charge up on my no-name USB adapter. I'm not sure if that's because I tend to turn the screen off (and I don't have 3G), and thus the power draw of the sleeping tablet is less than the 500mA, or if its actually getting the full 2A.

I think the upshot is that any reputable wall charger or anything labeled as "compatible" with an iPhone or iPad will probably support the USB charging spec, and thus will fast-charge a Samsung Galaxy Tab. But I'm just guessing. It would be nice if there was an official USB logo or label for chargers that supported this mode ...

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This makes sense, but I wish there was a specific technical article on this from samsung. Thanks! –  John Mar 29 '12 at 21:51
Oddly enough my Samsung travel power adapter only provides power at 500mA (though it's rated for 2A) my Tab shows the red X on the battery, very slow charging, even when powered down. But I got lucky, I have some Rocketfish power adapter, and the Tab is happily drawing 2A from that. –  Chris O Mar 13 '14 at 16:57

I have no idea if there's some kind of separate "minimum" spec for this, but the OEM charger is ~2A (so 4 times the USB2.0 spec's 500mA):

enter image description here

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The Apple high-power charging method is vastly different from the rest of the world (my HTC, the wife's Samsung, etc).

So DO NOT assume an Apple fast charger will work on anything but an Apple.

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Where is Apple mentioned in the OP's question? –  t0mm13b Dec 21 '12 at 17:28

5volts 2AMPS for samsung TAB 2-or look at the back of your tablet its there its also on the chargers specs, do remember the specs of the original charger and match it to the new charger.

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The tablet charging current is proportional to the voltage that the power adapter can supply. If the charger has a lower than average voltage output, the tablet takes less charging current. A 6 foot USB cable can drop half a volt or more when the tablet is charging at a high rate. So, if you use a long USB cable, the tablet also drops to a lower charging current. I saw another post that said that that tablets can't charge if the voltage into them is less than 4.5V, so half a volt is a big deal.

The latest tablet charging adapters are rated at 5.3V/2.0A!!! This allows them to charge fast even with a pretty long cable with a big voltage drop (i.e. 5.3V - 0.5V is 4.8V, a lot higher than the 4.5V limit)

USB 2.0 Switches are rated to deliver only 0.5A, as are the USB sockets on most desktop computers. If you plug in your tablet to these, they will only draw 0.5A. If you're watching video, surfing or gaming, the tablets can easily draw twice this amount, which means they will be taking half their power from the battery. USB 3.0 switches might be able to supply more.

If you have a laptop, it can supply 0.5A if plugged into the wall, or only 0.1A if running on batteries.

So, if you want to charge your tablet quickly:

  • Use a power adapter with a 2.0A rating, preferably with a higher than 5.0V output (warning: higher than 5.5V may damage your tablet)
  • Use a short cable
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