Hey guys - I've been dealing with a Tab charging issue for a few days, and finally solved it... but I thought I'd post the problem and solution here in case it can save someone else a load of frustration if they run into the same problem.
From what I've read, we know that the Tab only draws .5A power from a USB socket, but that it draws ~2A from the wall, and that it knows the difference by testing for a short on the TX/RX USB data wires. (Correct me if I'm wrong on the details, but that's the general impression I've gotten.) We also know that the iPhone/iPad/iPod uses a pair of resistors instead (per the USB spec) to determine the current-delivery capability of the source. (I'm no EE, so I'm a little fuzzy on how that works from a technical perspective.)
So to set the stage: I had brought the USB cable for my Tab with me, but had neglected to grab the USB->outlet adapter for the mains. Similarly, a friend who was on vacation with us had forgotten the charging cable for his iPhone. Thinking I was killing two birds with one stone, I bought an aftermarket USB charging cable for the iPhone which had a separate USB->outlet adapter. His iPhone charged swimmingly, and when I charged my Tab overnight (screen off, starting at ~89% charge) using my cable and the aftermarket adapter, it worked flawlessly. No problem, great solution, or so it seemed...
...until I got home. Suddenly, my Tab wouldn't do more than a trickle charge - the same charge it gets when connected to the USB port on my laptop. (I could tell this was the case because of the small red 'x' next to the charging symbol in the battery icon - which I hadn't noticed while on vacation.) A 2.5-hour car trip using Navigator (screen on the whole time), even with the car charger connected, killed the battery completely. No matter what I did - shutting down apps, rebooting the device, resetting every option I could find - I could not get a fast charge to happen. Even leaving the device plugged in overnight resulted in *less* charge than what I started with if I didn't turn the screen off. I called T-mobile, talked to Samsung tech support twice... and all they could offer was to have me send the Tab back for replacement.
I was at a loss. I nearly did a hard reset in frustration, thinking I had screwed something up royally.
Then I saw the resistors in the pictures in this post:
http://forum.xda-developers.com/showthread.php?t=845844&page=3
and something clicked. I had been assuming that the *cables* were the difference between the iPhone and Tab chargers... but there isn't enough room for resistors in the cables! (Well technically, there is, but regardless...) The resistors must live somewhere else... and, I reasoned, that somewhere must be inside the USB->outlet adapter. So I pulled out the 'proper' Samsung adapter, plugged in the Tab, and voilà... a perfect fast charge.
So this is why the Tab won't charge with an iPod (or Sony-Ericsson, as it turns out) mains USB adapter OR USB-port car charger: the circuitry to let the device know it's capable of a full 2A delivery doesn't live in the Samsung cables; it's only present in the adapter. If that's not there, the device thinks it's connected via USB (and will, in fact, say "USB Connected" every time the charger is plugged in) and won't charge more than a trickle.
So that's my story, and hopefully it can save someone else some pain and frustration. Thanks for giving me the floor.
mattcelt said:
Hey guys - I've been dealing with a Tab charging issue for a few days, and finally solved it... but I thought I'd post the problem and solution here in case it can save someone else a load of frustration if they run into the same problem.
From what I've read, we know that the Tab only draws .5A power from a USB socket, but that it draws ~2A from the wall, and that it knows the difference by testing for a short on the TX/RX USB data wires. (Correct me if I'm wrong on the details, but that's the general impression I've gotten.) We also know that the iPhone/iPad/iPod uses a pair of resistors instead (per the USB spec) to determine the current-delivery capability of the source. (I'm no EE, so I'm a little fuzzy on how that works from a technical perspective.)
So to set the stage: I had brought the USB cable for my Tab with me, but had neglected to grab the USB->outlet adapter for the mains. Similarly, a friend who was on vacation with us had forgotten the charging cable for his iPhone. Thinking I was killing two birds with one stone, I bought an aftermarket USB charging cable for the iPhone which had a separate USB->outlet adapter. His iPhone charged swimmingly, and when I charged my Tab overnight (screen off, starting at ~89% charge) using my cable and the aftermarket adapter, it worked flawlessly. No problem, great solution, or so it seemed...
...until I got home. Suddenly, my Tab wouldn't do more than a trickle charge - the same charge it gets when connected to the USB port on my laptop. (I could tell this was the case because of the small red 'x' next to the charging symbol in the battery icon - which I hadn't noticed while on vacation.) A 2.5-hour car trip using Navigator (screen on the whole time), even with the car charger connected, killed the battery completely. No matter what I did - shutting down apps, rebooting the device, resetting every option I could find - I could not get a fast charge to happen. Even leaving the device plugged in overnight resulted in *less* charge than what I started with if I didn't turn the screen off. I called T-mobile, talked to Samsung tech support twice... and all they could offer was to have me send the Tab back for replacement.
I was at a loss. I nearly did a hard reset in frustration, thinking I had screwed something up royally.
Then I saw the resistors in the pictures in this post:
http://forum.xda-developers.com/showthread.php?t=845844&page=3
and something clicked. I had been assuming that the *cables* were the difference between the iPhone and Tab chargers... but there isn't enough room for resistors in the cables! (Well technically, there is, but regardless...) The resistors must live somewhere else... and, I reasoned, that somewhere must be inside the USB->outlet adapter. So I pulled out the 'proper' Samsung adapter, plugged in the Tab, and voilà... a perfect fast charge.
So this is why the Tab won't charge with an iPod (or Sony-Ericsson, as it turns out) mains USB adapter OR USB-port car charger: the circuitry to let the device know it's capable of a full 2A delivery doesn't live in the Samsung cables; it's only present in the adapter. If that's not there, the device thinks it's connected via USB (and will, in fact, say "USB Connected" every time the charger is plugged in) and won't charge more than a trickle.
So that's my story, and hopefully it can save someone else some pain and frustration. Thanks for giving me the floor.
Click to expand...
Click to collapse
I've recently seen (somewhere) a usb pigtail cable that shorts the pins to make the tab (or any other usb chargable phone) think it's hooked up to a wall charger, rather than a trickle charging usb port.... I need to find that again and just order a few to have in my various cable bags.
If you do find it again, please post it here. Definitely something I'd like in my bag of tricks as well.
Just as an FYI, the 2A charger that came with my Nook Color charges the Tab just fine from mains, even indicates charging. Makes sense, since both devices have a 4000mAH battery.
It's also a nicer unit for travel, it's nicely rounded, the prongs fold into the body of the charger, and you can pick it up from Barnes and Nobles stores just about anywhere in the US. Still doesn't solve the Tab cable issue though.
Croak said:
Still doesn't solve the Tab cable issue though.
Click to expand...
Click to collapse
I'm planning on hacking apart a spare Tab cable so that it goes to a female microUSB; no more multiple cable types then. The stock Tab cable doesn't appear to have more than 6 pins, of which I'm sure a few are grounds.
Someone recently posted a link to the first cheap 3rd-party cables:
http://www.dealextreme.com/details.dx/sku.51931
Get those with a 6' USB extension cable and the Nook charger, and that may be a winning combination. I ordered four the the charging cables yesterday, and I'll try to remember to post whether or not they work out well.
Resonance, what are you planning on using for a car charger, if any? I really like the Navigator app, but it's just not practical if I can't keep the Tab charged while using it.
Does anyone know if there are any USB->12v adapters that have the right circuitry for the Samsung? For that matter, do any other devices use the same amperage detection setup the Tab does? It would be good to know what components are cross-compatible.
Thanks for the info.
How about a list of chargers that work fine on the GTab.
1. Garminfone charger (1amp - works great and I use it as my primary charger)
mattcelt said:
Resonance, what are you planning on using for a car charger, if any? I really like the Navigator app, but it's just not practical if I can't keep the Tab charged while using it.
Click to expand...
Click to collapse
A 12V inverter, attached to the standard wall charger. :/
I bought the Duragadget 12V->USB charger, since it was advertised specifically as a 2A charger for the Galaxy Tab, but it DOES NOT work as advertised (the Tab treats it like a any other low-current USB port, and even offers to mount mass storage, heh).
Using the inverter and the wall charger worked just fine, though it was a bit clunky and unstable (on mine, the prongs aren't tightly gripped, so it bends out of place easily).
Does anyone know if there are any USB->12v adapters that have the right circuitry for the Samsung? For that matter, do any other devices use the same amperage detection setup the Tab does? It would be good to know what components are cross-compatible.
Click to expand...
Click to collapse
I'd been contemplating giving the Duragadget charger with integrated cable a try, but having been burned once by Duragadget, I'm a bit hesitant to do so.
ResonanceZero said:
Someone recently posted a link to the first cheap 3rd-party cables:
http://www.dealextreme.com/details.dx/sku.51931
Get those with a 6' USB extension cable and the Nook charger, and that may be a winning combination. I ordered four the the charging cables yesterday, and I'll try to remember to post whether or not they work out well.
Click to expand...
Click to collapse
OMG...I bought a charger cable from amazon SOLD BY AMAZON marketed as OEM samsung charger and I got the same one in the deal extreme page. WTF...paid $12 for it too.
ResonanceZero said:
A 12V inverter, attached to the standard wall charger. :/
I bought the Duragadget 12V->USB charger, since it was advertised specifically as a 2A charger for the Galaxy Tab, but it DOES NOT work as advertised (the Tab treats it like a any other low-current USB port, and even offers to mount mass storage, heh).
Using the inverter and the wall charger worked just fine, though it was a bit clunky and unstable (on mine, the prongs aren't tightly gripped, so it bends out of place easily).
I'd been contemplating giving the Duragadget charger with integrated cable a try, but having been burned once by Duragadget, I'm a bit hesitant to do so.
Click to expand...
Click to collapse
looks like that car charger is the same as the one you bought with a USB cable included.
nacron said:
looks like that car charger is the same as the one you bought with a USB cable included.
Click to expand...
Click to collapse
Good eyes. I thought it was a different unit with an integrated cable.
Has anyone found a functioning 12v charger?
yes, the verizon store has a 12v charger for the galaxy tab, but that was the only place I was able to find one... other than online.
Hi,
Can anyone else confirm that the Nook charger works for the Tab?
I've tried other high current (2.0+ amp) chargers. Some designed for the ipad and some not, and I always get the trickle charge icon and it's treated as a computer USB connection (Mass storage device options, etc).
How much was the Verizon charger?
Thanks!
stock wall charger works for me.
knowthenazz said:
Hi,
Can anyone else confirm that the Nook charger works for the Tab?
I've tried other high current (2.0+ amp) chargers. Some designed for the ipad and some not, and I always get the trickle charge icon and it's treated as a computer USB connection (Mass storage device options, etc).
How much was the Verizon charger?
Thanks!
Click to expand...
Click to collapse
Google the gobatt 2 charger. It comes with a usb adapter that charges the tab on any charger.
texasreb said:
Google the gobatt 2 charger. It comes with a usb adapter that charges the tab on any charger.
Click to expand...
Click to collapse
Hi,
Thanks for the tip. I can't find much information about the Scosche GoBatt 2 charger, or the adapter that comes with it. Today I tried other Scosche chargers, including their iPad charger, and it didn't seem to work.
Can you give some more details on the adapter that comes with the GoBatt 2?
Thanks!
Got this travel adapter by ZipKord with 2 - 1 amp outlets. Works with the OEM cord and also the Gomadic tip made for the Galaxy Tab. Just need to be careful it's not the older version that only has the lower power outlets. Cheapest I could find was $13+, so if it's less, it's the lower power. With the Gomadic tip and reractable cord, it says it's charging.
EVO 4G 9292 - Travel Adapter By ZipKord
Also this Scosche battery pack seems like it would work. Has 2 - 1 amp USB ports. I ordered one and should get it tomorrow.
Scosche IPDBAT2 Portable Back Up Battery for iPad and iPod
Oops - can't do links. Just search in Amazon. It's where I got both.
Gomadic cord and tips from Gomadic. Love losing the excess clutter (cords).
galaxy tab 7 charging while turned on
can someone explain well how to build the adaptor for charge galaxy tab 7 while it turned on?
is it possible to have a scheme with picture and some photos which describe the work to do?
thanks. and excuse me for bad english.
mattcelt said:
Hey guys - I've been dealing with a Tab charging issue for a few days, and finally solved it... but I thought I'd post the problem and solution here in case it can save someone else a load of frustration if they run into the same problem.
From what I've read, we know that the Tab only draws .5A power from a USB socket, but that it draws ~2A from the wall, and that it knows the difference by testing for a short on the TX/RX USB data wires. (Correct me if I'm wrong on the details, but that's the general impression I've gotten.) We also know that the iPhone/iPad/iPod uses a pair of resistors instead (per the USB spec) to determine the current-delivery capability of the source. (I'm no EE, so I'm a little fuzzy on how that works from a technical perspective.)
So to set the stage: I had brought the USB cable for my Tab with me, but had neglected to grab the USB->outlet adapter for the mains. Similarly, a friend who was on vacation with us had forgotten the charging cable for his iPhone. Thinking I was killing two birds with one stone, I bought an aftermarket USB charging cable for the iPhone which had a separate USB->outlet adapter. His iPhone charged swimmingly, and when I charged my Tab overnight (screen off, starting at ~89% charge) using my cable and the aftermarket adapter, it worked flawlessly. No problem, great solution, or so it seemed...
...until I got home. Suddenly, my Tab wouldn't do more than a trickle charge - the same charge it gets when connected to the USB port on my laptop. (I could tell this was the case because of the small red 'x' next to the charging symbol in the battery icon - which I hadn't noticed while on vacation.) A 2.5-hour car trip using Navigator (screen on the whole time), even with the car charger connected, killed the battery completely. No matter what I did - shutting down apps, rebooting the device, resetting every option I could find - I could not get a fast charge to happen. Even leaving the device plugged in overnight resulted in *less* charge than what I started with if I didn't turn the screen off. I called T-mobile, talked to Samsung tech support twice... and all they could offer was to have me send the Tab back for replacement.
I was at a loss. I nearly did a hard reset in frustration, thinking I had screwed something up royally.
Then I saw the resistors in the pictures in this post:
http://forum.xda-developers.com/showthread.php?t=845844&page=3
and something clicked. I had been assuming that the *cables* were the difference between the iPhone and Tab chargers... but there isn't enough room for resistors in the cables! (Well technically, there is, but regardless...) The resistors must live somewhere else... and, I reasoned, that somewhere must be inside the USB->outlet adapter. So I pulled out the 'proper' Samsung adapter, plugged in the Tab, and voilà... a perfect fast charge.
So this is why the Tab won't charge with an iPod (or Sony-Ericsson, as it turns out) mains USB adapter OR USB-port car charger: the circuitry to let the device know it's capable of a full 2A delivery doesn't live in the Samsung cables; it's only present in the adapter. If that's not there, the device thinks it's connected via USB (and will, in fact, say "USB Connected" every time the charger is plugged in) and won't charge more than a trickle.
So that's my story, and hopefully it can save someone else some pain and frustration. Thanks for giving me the floor.
Click to expand...
Click to collapse
potential solution
found this on youtube, looks like it has great potential:
forum won't let me post url links, but this is the video code in you tube. We're all geeks here (I think) so you know where this goes :
=uPc-ZA3t5aY
hope it helps!
I just received my stash of charging gear for my Optimus 7 today, bought from DX. Having read everywhere that USB chargers are 5V +/- 10%, and seeing that the original LG charger outputs 4.8V, I thought my purchase was ok and that this charger would work.
Turns out it doesn't. When I connect the phone to the charger via USB, I lose control of the touchscreen and the system gains a mind of its own. I literally just hold my phone in my hand and stare while it randomly enters hubs and either opens an email message or dials someone. The physical buttons still respond correctly, and it's not until I disconnect the charger from the wall socket or the phone from the USB cable that I can regain control of the phone. My guess is it's a hardware fault and not software.
Granted this unofficial charger cost me around $1, but I got some similar 5V car chargers to go with it, and I've never had problems with other USB chargers.
Unofficial charger specs:
Input: 100-240V 0.15A (0.15A) 50-60hz
Output: 5V 1A
Does someone else have this issue? Is the Optimus 7 an uncommon device for requiring 4.8V input instead of 5V?
Your problem is NOT the charger, as that has nothing to do with the functions of the phone.
Your problem is that your LG Optimus 7 E900 is a DEMO unit, with a DEMO ROM. And until you flash a stock ROM onto your phone, you will experience the demo played out while connected to a power source.
You sure? Because I tried it with the 5V 1A car adapters and no problem, and the original 4.8V 1A charger gives me no problems either.
How do I check my ROM version? Firmware is 1.0.7.10, OS is 7.0.7008.0 after the February update.
Can you get us video on this?
Please excuse the ****ty video quality
That is most fascinating. I recommend you stop using that charger on your phone
So, obviously, you do NOT have the demo ROM as I suspected initially.
Since you say it works with another 5V 1A charger, then I think this specific charger may be sending unexpected, random data signals down the USB cable, resulting in the unresponsive and bizarre behaviour. Since the original charger works well, and charges pretty fast, just stick with that for now.
At least you got the update, here in Canada, we are still waiting for our first update.
And your English is so good, and without any accents...Are you sure you aren't from our here (North America)?
This is true magic Really I have no eplanation on this problem. It is only 0,2V
Yeah, and there I was thinking that the whole point of USB charging is that it's universal and totally compatible, no matter what adapter you buy and what cable you use, provided it connects well.
It seems this is not the case, and I'm weary of trying another third party USB charger, as I still cannot tell if this phenomenon is unique to the Optimus 7 or not. Sadly, the only other MicroUSB phones I have lying around don't actually support charging via this port, just data transfer.
i also admit that im "dazzled" by ur -smart-phone...
probably that adapter is"magical" somehow... did u try it on another phone??
+i also use different chargers but never had any abnormalities so far..
Though i use the original chargers that came with my blackberry 9700 and htc-desire, and just checked the blackberry output is 5v!! i cant read the htc...
So, probably that adapter of yours is a "mutant from another place"...
confirm, htc is also 5v...
ps2- i'm also on 7008, and havent got any issues with charging on both 7004 and 7008
The problem is in the charger, it's too chinese . I had this issue with other touchscreen phones, like SE X8, X10... Just change the charger, obviously it has some hum/noise...
lol...
too chinese? lol
im having the same issue when i use the lg power adapter.. it doesnt always happen but when it happen the touch screen just when berserk.
i always thought that it happens on all units. uh oh
To be honest, I thought you were crazy till I bought a Chinese adapter as well. Don't know the voltage, but I'll check it tomorrow. I think it might have to do with the way the unit is shielded, or not. The only time I wiggs out is when I leave it on the desk, but as soon as I pick it up and pull it a few inches away form the desk or any other object it works fine. But as soon as I put it back down, the screen does the same thing.
I have a usb plug that I plug into the computer that didn't do that at the same desk, I'm going to bring in my other charger and see if it rule out the outlet / interference or just the cheap a$$ adapter....
The only part that worries me, and the only reason I might stop using it, is it takes a bit from the time I unplug it to the time the phone realizes it's unplugged and the charging icon stops. Which doesn't happen with any other charger.
I had this problem too.. until I realized it affected my other touch screen devices too (Galaxy S, Galaxy Tab)... Turns out the 5V charger was the problem. Replaced it with a 5V charger of Philips/Belkin/Samsung/LG and all worked..
The unbranded 5V chargers don't work well with capacitive screens as they seem to be letting off some extra current.
Hello everyone. I just want to start off saying that this is NOT a question about USB charging. I know about the trickle charge/lack of voltage stipulations. This is about the factory A/C adapter and USB cord I got with my transformer.
About 80% of the time I plug in my tablet to the A/C adapter, literally nothing happens. The screen doesn't turn on while in sleep mode like normal, the battery in the bottom corner doesn't change to a little lightning bolt, and most disturbingly, my tablet will not charge. The weirdest part is that it connects to the computer through USB no problem. I can move files and such, but no charging. Any ideas?
the charger construction is marginal at best and may need to be wiggled to get a good connection. also the usb connector an be plugged into the charger incorrectly. remember the usb connectot on the supplied cord does not comply s
with the usb spec. Also chev
ch the country ac side adapter ther are also unreliable
My cable went screwy and now it only trickle charges, regardless of what it's plugged into. I've got an RMA for it, but since I have to send them the cable to get a replacement, I'll have a paperweight for a few days at least.
Are you sure yours isn't trickle charging? There wouldn't be a lightning bolt, but I does charge.....very slowly.
Unplug the AC adapter from the wall for about 20 minutes. Plug it back in. Plug in TF.
Charging now?
unplugging it for a while seems to work better than anything. I'm pretty sure there isn't any trickling going on.
You can also try using the charger for your phone if the plug is a USB type. There have been a lot of problems with these charges documented in other threads.
Unplugging it definitely isn't a solution for me. When it first started happening I could do that and after a little while it would start working properly again, but now, it has charged at normal rates in about 3 weeks. I'm going to send it in with the RMA, but I have no idea what the turn-around time is. I'm going to be without any way to charge for that time, which pisses me off just a little bit.
Hey all, quick question.
I have my Nexus 7 installed in my car. Originally it was getting power from a 500mah USB car charger, but it didn't provide enough power to the tablet when running GPS/maps, etc.
So I bought an "8Ware Dual USB Car Charger 5V/2A" to try. I plugged it in, and the tablet doesn't detect it or charge from it. However I can plug my Galaxy S3 into it and it charges fine.
Really confused about this - it makes no sense.
Any ideas?
Thanks in advance!
I understand your frustration and it sucks!!
But sometimes even when it says UNPLUGGED and NOT CHARGING, just leave it there for 30-60 minutes. You might see that your battery actually increase... This happens with my Griffin PowerJolt Dual USB car charger also.
You can either blame the device or you can start blaming other issues like the charger, the usb cable etc but for me, I blame primarily on the device.
- Charles
chaddeus said:
I understand your frustration and it sucks!!
But sometimes even when it says UNPLUGGED and NOT CHARGING, just leave it there for 30-60 minutes. You might see that your battery actually increase... This happens with my Griffin PowerJolt Dual USB car charger also.
You can either blame the device or you can start blaming other issues like the charger, the usb cable etc but for me, I blame primarily on the device.
- Charles
Click to expand...
Click to collapse
Thanks for that. I tried plugging it in for a while but it definitely didn't get a charge.
Hey All.. I looked forever to find a solution. The Targus 2A car charger has a small (3") adapter cable that comes with it purportedly for Galaxy Tab. That little cable with the data wires shorted on the device end allows the N7 to be charged from ANY 2A car charger. I'm using the adapter with a Scosche dual 2.1 Amp Car Charger
Adapter picture
Targus Charger
Edit: I just built a usb cable with the data wires shorted on the Nexus end (cut, strip, short micro usb end green and white, remake connections red to red and black to black, insulate splices individually, wrap all in electrical tape or heat shrink for strength and beauty) and it works with all chargers. Took about 20 minutes.