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?


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 ...

  • 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):

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The Galaxy Tab 10.1 original charger provides 2A. But providing 2A is not all it takes to make your tablet happy.

In order to use the 2A, the tablet needs to recognize the charger as a charger and not a computer's USB port. The tablet is not allowed to draw more than 0.5A from a USB port. So if the tablet thinks it is connected to a real USB port, it will display a red cross on the battery and charge slowly at best.

A Samsung charger will signal it is a charger and not a data port by shorting the data lines D+ and D- and pulling these 2 lines up to ~1.2V.

A third party charger is likely to leave the data lines disconnected, so the tablet will assume it is a normal USB port and use only 0.5A, even if the charger can provide 2A or more.

I believe Apple chargers short D+ and D- but without setting a specific voltage for this line. An "Apple compatible" charger might not work.

To charge a Galaxy Tab using a non-compatible charger or any 5V source, you can reproduce the behaviour of a Samsung charger by adding the following USB adapter between the charger and the USB cable:

Third party charger adapter.

I tested this on a P7510. It probably works also with other Samsung devices. Note that if you use this to charge your tablet from a PC there could be a risk of frying your USB port. And of course, it blocks all data transfer.

  • Is there a way I can charge my tablet in the pc. Right now discharge faster than charge if Im using the tablet. – Juan Carlos Oropeza Dec 20 '16 at 0:41
  • I don't think so. The problem is that a standard PC USB port doesn't provide 2A. Only 0.5A I believe. – Florian F Dec 21 '16 at 11:09
  • Once I have one usb hard drive, and I bought a cable with two usb input to connect in two usb port in the pc and feed twice teh Ampers. I wonders if microusb has a similar one. – Juan Carlos Oropeza Dec 21 '16 at 13:58

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

protected by Matthew Read Mar 20 '16 at 18:52

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