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I'm going on holiday soon and we planned to take a USB hub to charge all of our devices rather than take several wall adapters, however when I checked that my 7" Samsung Galaxy Tab 3 would charge, I found that it didn't. After investigating, I found that my iPad charger wouldn't charge it either and in fact the only that would charge it was the USB wall adapter that came in the box with the tablet, even though the port on the USB hub and the iPad charger are rated at 2.1 A (5 V).

When I plug the tablet into to a non-Samsung adapter powered off however, the screen flashes lighter and darker but nothing else happens which seems odd behavior to me.

What is the reason it will not charge by any other means, and is there a solution?

Andrew T.
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Andy
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  • It is not a duplicate actually, as the problem is in the charger. The "duplicate" post speaks about cable differences. Please someone un-duplicate this question. – Florian F Apr 09 '15 at 16:35
  • By the way, an explanation of the why can be found at http://android.stackexchange.com/questions/21144/how-much-power-does-a-galaxy-tab-10-1-charger-need-to-supply . It explains the problem for the Galaxy Tab 10.1 at least. – Florian F Apr 10 '15 at 12:23

2 Answers2

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There is more to an adapter than just the current, although kudos to you for knowing that much. The problems arise due to the fact that the USB-2 spec is for a maximum of .5 A at 5 V without some extra handshaking to ascertain that the device wants and can handle more. For Apple devices, this is done in a certain way according to their "standard", which is different than PCs. So, for a PC, you normally need a driver, and it sets up the port for the correct voltages.

Most aftermarket USB chargers are designed to work with Apple devices, and seem to have some differences that make them either more or less compatible with Android devices, but usually require what's called a "charge-only" cable or adapter, that shorts together certain pins of the connector to make the device charge at the higher rate. These can be bought on Amazon from companies like Mediabridge. But it's not 100% certain if any particular adapter will work with a particular device. Unfortunately, some Samsungs won't work at all with some chargers, and work fine with others (I have an 8" Galaxy Tab 3).

If the tablet recognizes the charger at all, it will probably work with the charge-only cable/adapter, I think. I have one charger where it doesn't even register that it's connected, and it won't work no matter what I do. But it does work with most adapters, including the one I use for my wife's iphone.

With the tablet powered down (not standby), it should charge at .5 A, which will take much longer. I'd try the charge-only adapter if you have time to get one before you leave. Otherwise, you may just need to bite the bullet for now and bring an extra one for the tablet.

Marty Fried
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    Thanks for your answer. This has made a lot of things more clear for me, especially why Apple devices don't charge when connected to the computer until the driver is installed... Also, through experimenting and after reading something online, I can make it charge by only pushing the USB cable in part way. Is this related to the pin idea? I did read that there is some kind of chip in the Samsung USB wall adapter. – Andy Aug 02 '14 at 18:25
  • I would guess that there is either a chip or some passive circuitry to set the voltage levels of the control wires to something other than simple shorting pins together. FWIW, I have an LG G2 phone that charges fine from the Samsung charger, and every other charger I have, including iphone. So, it's possible to be more universal, but Samsung may not desire this. This is one reason I probably won't buy any Samsung phones/tablets in the future. Oh, and I don't know about pushing the cable in part way, except that it doesn't make sense to me or my electronics mind. Sounds like a defect. – Marty Fried Aug 02 '14 at 20:16
  • Yeah, this certainly sounds like it's something Samsung have done to make sure they get as much money as they can with us. The person on the Internet who said that pushing the cable in part way would work suggested it was something to do with the two longer pins at the sides of the USB socket which Samsung use in what I can only describe as their detection mechanism. I don't know if this explanation holds any truth - I'm more interested in software, but what I do know is the method works with several different leads. It's not a fluke. – Andy Aug 02 '14 at 21:03
  • I don't really even know which cables were the original ones, so I don't know. But maybe it's somehow shorting the same two pins together that the charge-only adapter does. Anyway, I never heard that particular rumor. But I have found that the charge-only cable works with some chargers, but not all of them. – Marty Fried Aug 02 '14 at 22:01
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Check the power output of your Galaxy Tab 3's wall adapter and see if the power output is greater than the 5V 2.1A power output of iPad charger.

If the Tab 3's USB wall adapter power output is greater than the iPad charger's USB wall adapter then that's likely why the non-Samsung power adapters aren't charging your Tab 3. The non-Samsang adapters aren't putting out enough power for the Tab 3.

I own the Galaxy Tab Pro tablet. The power output of its USB wall adapter is 5.3V 2.0A. My Tab Pro doesn't charge when I use my Galaxy Player 5.0's USB wall adapter, which outputs 5.0V 0.7A.

You could take the Samsung USB wall adapter with you and use it to charge both your Tab 3 and iPad while you're on the road. I only use the USB wall adapter for my Tab Pro to charge both the Tab Pro and the Player 5.0.

Ray Santos
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  • Thanks for your answer but the power output of the Samsung charger is 5V 2.0 A, which is what has been confusing me. – Andy Aug 02 '14 at 18:28
  • I have a galaxy tab 2 and an iPad. The galaxy tab doesn't charge from the iPad charger and vice-versa. It might be different with newer models. – Florian F Apr 10 '15 at 12:22