• After 15+ years, we've made a big change: Android Forums is now Early Bird Club. Learn more here.

Help My charger suddenly stopped charging, help using other chargers

M

MattKimura

Lurker
I've had my Samsung Galaxy Tab 2 since May 2013, and now my charger seems to have given up on me. The other day, I plugged it into a wall, and I heard a zap noise. When I plugged in my tablet like normal, it does not charge at all, not even a symbol.

I've done tests, and it's the adapter itself that gave up. The wire itself still works. I took a charger from an old Samsung phone and I plugged the USB wire into it, then plugged my tablet. it seems to charge, but VERY slow. I can see a red x symbol on the battery icon. And when I go into settings, it says not charging. I have to leave my tablet off while leaving it plugged in, to get a slow overnight charge.

Replacements cost $50, that's insane! So I ordered a $3 third party charger from a site called cellphonebatteries, that over 100 buyers mentioned it working just like the original. But what if the red x problem remains? I heard that you can reset the tablet by holding down the power button and volume buttons to bypass the red x symbol and charge like normal. But won't this make me lose all my data if I reset the device?

Why are these chargers so cheap, yet so expensive?!
 
Thanks for the reply, happy to see someone among the forums.
I was looking at an apple charger while at Office Depot, and it seemed to be enough to charge my Samsung Tab 2. But I wasn't sure if it would work, and I knew I wouldn't be able to return it. It cost $15, I guess it would've worked.

I already ordered this charger: Travel Charger For Samsung Galaxy Tab, Tab 2, Galaxy Note 10.1 - Samsung Galaxy Note 10.1

I heard by many comments that it worked, I really hope so because I spent a total of $7 (not much). I'll definitely consider that Anker charger, I really appreciate you finding that for me.
 
For future reference, the Apple side of an Anker charger will likely not give you a fast charge. I have an Anker 4.8 amp dual car charger and the documentation specifies that a Galaxy tablet will only charge at the 500ma rate on the Apple port. This is because that port, though willing to give up to 2.4 amps, is configured to emulate an Apple charger, which is incompatible with the Galaxy charging scheme.

When you have a charge symbol with the red X, that is the tablet telling you that it thinks that it is plugged into a standard USB port, such as your computer. Since it knows that USB 2.0 and less can only push 500 ma, that it's s as much as it will draw.

If the two data pins on the USB port are shorted together, then the device will think it is connected to a charger, and draw up to 1a of current.

From my research, I have learned that the Galaxy Tabs look for a voltage of approximately 1.245v on the two data pins (still shorted together), that would be an indication that it is connected to a high-amp charger, where it will draw something like 2a for a much faster charge.
 
After a little more research, and a morning reflection, I am thinking there is a third level of charging that we have not seen yet.

With the known scheme for charging Galaxy devices on third-party chargers (using a voltage divider to provide 1.2v to the data pins), the device only pulls at most around 1.2 amps of current (with the display on, then it drops to 1 amp).

I have an idea that the device will draw even more current under certain circumstances, but I have to perform an experiment or two. Unfortunately, I am out of town this week, so I will not be able to look into this further until next Sunday at the earliest.
 
Well, I did a little more exploration today, and found next to nothing new.

I did discover that it is more proper to say that the device (in this case, a Galaxy Tab 2 7.0, model GT-P3113) looks for a voltage drop of approximately 3.73v between the data lines and V+ .

Normally, it makes no difference of we say that we need 1.25v between the data lines and V- because we generally use a voltage divider across V+ and V- but my experiment today involved using a separate power supply to drive the data lines, and I found that I had to anchor that voltage source to the V+ line, otherwise the device treats the power supply(s) as a computer and only draws .5 amps.

My suspicion is that the Samsung OEM power source can provide supplemental current through the data lines for a faster charge.

Unfortunately, I failed to prove that using the test rig I built today-- the max current draw I got was around 1.1a with the screen on.

It just makes no sense that they provide a 2a brick of the device is only going to pull max 1.1a.

Sadly, I am using recycled parts for testing, and limited test equipment for these experiments... I need a four wire shielded USB breakout and a few digital ammeters at the very least to properly see what is coming out of this block (I am not going to break open my only power source, sorry).
 
More interesting information [ur=http://forum.xda-developers.com/showthread.php?p=55481080]here[/url].

Don't know when I will be able to experiment with the voltage changes...
 
You must log in or register to reply here.
Back
Top Bottom