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I'm having an issue,and seems not just me,that I can't charge the Tab via usb connected on a laptop or a Mac book (pro).
I'm wondering if its firmware related, I've tried JID and JI6 same issue.
Are you guys having the same?
If someone is not having this problem can please be so nice to tell me the firmware version?
Thanks
no, you cannot charge the tab from a PC usb slot cause of some minimum power requirements which was the same way with ipad
chowdarygm said:
no, you cannot charge the tab from a PC usb slot cause of some minimum power requirements which was the same way with ipad
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Click to collapse
No is not the same than ipad, ipad is possible to recharge with new macs (that what apple says on the web site, the don't say how new though). But is true the iPad has 2A battery versus the Galaxy Tab that has 4000mAh, I was hoping that there was a way to recharge it (slowly but at least to keep it alive when is connect)
zerocool76 said:
No is not the same than ipad, ipad is possible to recharge with new macs (that what apple says on the web site, the don't say how new though). But is true the iPad has 2A battery versus the Galaxy Tab that has 4000mAh, I was hoping that there was a way to recharge it (slowly but at least to keep it alive when is connect)
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Click to collapse
no idea on that. i didn't keep my tab connected so long to pc but whenever i connect it to pc it shows on battery with cross mark on charging symbol. may be will test it this weekend
charging
hi guys,
mine is also showing the non-charging-sign but it charges slowly - get juice plotter and try it your self
Can I recharge the Tab in the car sigarette ligther socket with USB adapter?
Portos61 said:
Can I recharge the Tab in the car sigarette ligther socket with USB adapter?
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Click to collapse
check this out, they have the adaptor for cigarette...
http://www.thinkgalaxytab.com/universal.html
I found the link above on google, but I've seen other around the web.So I think you can
hipath said:
hi guys,
mine is also showing the non-charging-sign but it charges slowly - get juice plotter and try it your self
Click to expand...
Click to collapse
Mine is the same guys... I left my AC charger at work over the weekend and have been charging it via USB the whole time... Slow but it gets there if you leave it on over night!
Mine won't charge unless I use the power adapter from Samsung
Mine does charge but slowly from USB.... you should also know that different PC boards and laptops have different power outputs.... in most cases, your tab should charge very slowly on USB power. Mine charges and has BT and Wifi on also... but with heavy use and plugged in to my laptop, it may offset and drain ever so slightly....
Same thing goes for car chargers... if not rated for higher output, it will charge VERY slowly. The original Samsung car charger has a much higher power output. If you can find one that has the same aftermarket USB car adaptor for Ipad charging, that should work too
eskasi said:
The original Samsung car charger has a much higher power output.
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Click to collapse
Indeed (yet it is very compact and doesn't get hot).
Related discussion here:
http://forum.xda-developers.com/showthread.php?p=9172163#post9172163
I tried my iPad charger - output rating looks to be the same - but it didn't work very well.
brucewilsonpa said:
I tried my iPad charger - output rating looks to be the same - but it didn't work very well.
Click to expand...
Click to collapse
The contacts on mine are upside down compared to an iPad/iPod/iPhone charger. The blade on which the contacts sit is also higher in the charger slot than an iPad charger. How did you get it to fit without breaking something?
Some PC:s (motherboards) have so weak power output via USB, that they just barely provide a mouse and a keyboard but nothing more.
So anyone should not expect it to be enough for charging Tab.
Tab's own power supply gives 2 Amps out!
My experience about car-usb-adapters: one can charge Tab, other quite similar for some reason not. However, both charge Galxy S fine.
Just something to keep in mind as an option... Usb 3.0 will give more juice to usb cables than current usb ports. Apple has "cheated" and already increased the power to the regular usb ports on their newer laptops on par/better with usb 3.. So... If you get usb 3 cards installed you'll have a port with enough amps to charge the tab. Easier/cheaper to just buy a pdmi cable but if you are about to upgrade to usb 3 its more incentive to do so.
Sent from my SCH-I800 using XDA App
Regarding the ipad charging you can use the below link to to download an ASUS program that will boost the USB power for Windows this works for the ipad and it's showing as charging when connected to my PC this may also work for galaxy tab
http dlcdnet.asus.com/pub/ASUS/misc/utils/AiCharger_V10006_XpVistaWin7.zip
Charging using usb on my mbp does take a long time. I timed it and it took at least 6 hours to charge from completely empty to full. Its ok since I plug it in when I'm about to go asleep and by the time I'm up its fully charged.
essahar said:
Regarding the ipad charging you can use the below link to to download an ASUS program that will boost the USB power for Windows this works for the ipad and it's showing as charging when connected to my PC this may also work for galaxy tab
http dlcdnet.asus.com/pub/ASUS/misc/utils/AiCharger_V10006_XpVistaWin7.zip
Click to expand...
Click to collapse
Careful with that.
Seems it has the not-uncommon tendency to screw up USB drivers to the point that mice and keyboards won't work either, especially on Win7 and Vista X64 machines. It got me, had to do a system restore to fix it. Neat idea though.
pdiddypdiddypdiddy said:
Apple has "cheated" and already increased the power to the regular usb ports on their newer laptops on par/better with usb 3.
Click to expand...
Click to collapse
USB port should give at least 500mA. But anything more is OK. So Apple can make their USB ports to give anything over 500mA and it is well within the standard. Actually it is good for everyone because if Apple port can give 2A you can use non powered hubs and have power for lots of USB devices.
Actually the Tab charges fine (albeit slowly) from a USB, you just have to be aware of a few things. Firstly as mentioned above some USB ports provide more power than others. Try the different ports on your machine and you'll soon figure out which ones work best. Secondly, while the Tab will display the "Connect your charger" message, it is actually charging. Go into Settings, About Phone, Status and watch the battery level. It'll take a while but will creep up. Finally, it charges faster when the Tab is switched off. ie: if you're actually using it, you won't get a charge, if you have it in standby with screen off, it'll charge slowly (takes most of a day for a full charge) and if the Tab is switched off, it'll go a lot faster (though still not as fast as with the power adapter.)
This is good to know as you can plug it in to your computer and let it set on your desk at work all day and know that it is slowly trickle charging.
I also found that plugging the USB cable into an Apple adapter (from an iPhone) brought up the same "Connect your charger" message, but did charge the Tab, faster than a USb but not as well as my samsung plug.
Just reading up on USB chargers, and I found somewhere in a thread here about phones defaulting to smaller ma when charging via USB if the connector didn't have the data pins shorted or something.
So, I was wondering a couple of things:
1) If the default charger supplies 700ma, do you think that is the most the Nexus S can draw? Does anyone have one of these shorted USB chargers? Does it charge the NS faster?
2) If it does charge faster, how hard would it be to do something similar to shorting the data connections? I have a generic AC-USB cable which I currently use for my iPod touch.
3) Is there a way to check if it is already shorted out? The USB charging port looks similar to ones on my computer, but I'm not sure what to look for.
Thanks for any help! Maybe if we can sort out this stuff, we can provide a solution for those looking for faster charging!
it does work safely, i'm using a 1000 mAh charger at home, and a 2000 mAh charger in the car both are from aftermarket eBay/DealExtreme charges.
no overheating
and charges faster than stock
AllGamer said:
it does work safely, i'm using a 1000 mAh charger at home, and a 2000 mAh charger in the car both are from aftermarket eBay/DealExtreme charges.
no overheating
and charges faster than stock
Click to expand...
Click to collapse
Ok thankyou for that AllGamer, I'll think of possible ways I could mod the charger now
The only reason it is slow is because of the USB charging brick instead of just a charger.
Sent from my Nexus S using XDA App
I know it's a wrong thread, but anyone has any pointers as to how to short a regular USB cable to make the phone think it's a power adapter cable?
XBOHDPuKC said:
I know it's a wrong thread, but anyone has any pointers as to how to short a regular USB cable to make the phone think it's a power adapter cable?
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Click to collapse
Nah it's not the wrong thread that was one of my questions! I'm not sure exactly where you would do it, but maybe if you skinned the wire, then cut the data lines it would work?
Not sure which end you would do it on however, but that may not matter. Any other ideas?
The two center pins in the USB carry the data. If you pull them out, the cable won't be able to connect to the computer.
Sent from my Nexus S
Wow - you don't need to do this and you wouldn't want to in a computer anyway.
The USB specification says that 500ma (@ 5v) of current should be available from a computer's USB port. Of course, the actual wires can carry much more than this, so manufacturers can tell their phones to takes as much current as is offered.
Almost all computers limit their USB power output accordingly - this is why some opld usb-powered external hard drives needed 2 USB plugs to get enough power. The only computers that I am SURE emit significantly more than 500ma on their USB ports are first and second generation MacBook Airs.
Some phones, the N1 and every other HTC specifically, look for a specially shorted cable to "know if they are plugged into the wall adaptor" as opposed to a computer USB port. In reality, this is just a way to make you specifically buy HTC chargers as opposed to third-party off-brands, because plugging one of these phones into an off brand charger will limit the current draw to about 450ma.
If you want to know if your Android phone thinks that it is in "USB" mode or in "AC" mode, just plug the phone in, open the dialer, enter *#*#4636#*#* and then select battery info. If your phone is one that cares (not all do), it will say USB if it thinks it should be in USB charging mode, or AC if it thinks it should be in AC charging mode.
I would not try shorting out the middle pins in a cable and then plugging it into the computer. First, most will probably just disable the USB port completely, shutting off even power you could draw. Second, if it doesn't shut down, you run the risk that a badly-built USB port might not properly limit the current to 500ma - and since they are not designed to furnish more current than that, you might melt something expensive or start a fire. third, if you make a mistake, you risk shorting out either your phone or your computer, which might ruin your day, week or month, depending on your financial means to replace the system that cooks itself.
I would just run out to your local store, pay 15 bucks for a 2A third-party usb charger brick, and go to town. That will work perfectly - this is what I use, and it probably cuts the charge time by 30-40%. Obviously, this indicates that the NS is not capable of drawing a full 2A - I have not put a meter on it, but I would bet that it limits itself to somewhere just under an amp in.
I have recently bought both a 2A wall charger and car charger and my phone does not recognise either of these as anything more than a 500mA source.
Is it really just a case of opening the car charger up and shorting out pins 2 & 3? they are currently not connected to anything in the charger.
If it's indeed a matter of shorting the data lines, then I think you can skin the wire as suggested by others, but then cut the data lines, short the end that leads to the phone, leave the end to the computer open. I think it's the phone that tries to determine whether the data lines are shorted.
Edit: Can someone measure the continuity between the data pins with the stock charger? I wonder if they are shorted. I'm still waiting for my Nexus S to arrive, so can't test it.
Yup, the data lines in the stock Nexus S charger ARE shorted.
I just modified a cheap 1A car charger by popping it open, soldering the 2 data lines together and putting it back.
The report on the Nexus S before I did this (*#*#4636#*#*) said "USB", and afterwards it now says "AC".
I will report back after I make a road trip if this improves the GPS + Pandora + Screen in car situation. I suspect it will.
----------------
Yup, the car charger seemed to actually maintain and increase the battery this time. Seems good.
The NS supports chargers output to a max of 1000mA, as it says on the back of it, where the battery resides.
I got the 16GB Touchpad few days ago and since i got the one with an american charger i cant charge it yet (till i get the traveler kit).
My actual problem is that it doesn't charge through the USB port too. I left it for like 24-30 hours charging through the USB port (with the cable that came with the touchpad) and when i try to turn it on, it shows me an icon of an empty battery.
Is my usb cable problematic or it just that the touchpad cant charge through the usb port from a PC?
ps: every time i plug the usb it get a message telling "to reliably charge please use the charger and cable that came with this device"
I have the same issue with a 32 GB one. I received it brand new, factory sealed today and it is going back to HP. I called HP, the cable is fine, works with my HTC phone, it's the USB port on the Touchpad, it's loose and losses connection. HP is sending a box with prepaid shipping label and doing a warranty repair.
I really love the Touchpad and I am a bit disappointed with receiving a new device with a loose USB port. HP has great support and I can't wait until I get it back.
Sent from my HTC Sensation 4G using Tapatalk
Unfortunately thats not an option for me (returning it to touchpad), since i bought it from Ebay (thats the only way possible for me to buy a touchpad from my country).
You had the same issue with the charger plugged in the usb cable as well?
What sort of power source do you use, if not the charger.
I've tried to use a computer, but it does not look like it's charging, but data transfer work.
I tried with an iphone charger, that sort of work. It complains about not getting enough power (iphone charger is 5,0V while the hp charger is 5,2V)
Bottom line. Use the original charger, just buy an us adapter. It works great.
There is another thread here sonewere discussing chargers for non US owners.
Sent from my M9 using Tapatalk
Jon (aka nle) said:
What sort of power source do you use, if not the charger.
I've tried to use a computer, but it does not look like it's charging, but data transfer work.
I tried with an iphone charger, that sort of work. It complains about not getting enough power (iphone charger is 5,0V while the hp charger is 5,2V)
Bottom line. Use the original charger, just buy an us adapter. It works great.
There is another thread here sonewere discussing chargers for non US owners.
Sent from my M9 using Tapatalk
Click to expand...
Click to collapse
Im trying to charge it through my PC using the original cable that was in the box (tried it in a USB 2.0 port) and im getting the 'try a reliable recharging source like the USB cable and the charger that came with your touchpad'.
I also tried charging it with a 5.0V 200mA phone charger but it didnt work either.
Shouldnt it charge even a bit with the cable? im trying to charge it for 2 days now
Varemenos said:
Unfortunately thats not an option for me (returning it to touchpad), since i bought it from Ebay (thats the only way possible for me to buy a touchpad from my country).
You had the same issue with the charger plugged in the usb cable as well?
Click to expand...
Click to collapse
Yes, tried the wall charger, then pc, a different usb cable, all had the same result. When I plugged in I could feel the USB port loose in the Touchpad itself, it had a bit of play and if I played gently on it, it would begin to charge or connect to the pc. When i let go, it disconnected from my pc and then gave me the charging error message. I purchased mine from an e bay store and it has a warranty for 1 year.
I would be happy to help you with yours, if you want to ship it to the US, it has a warranty from the factory. Pm me if you'd like help. I am certain that shipping to and.from US could be costly but I am willing to help.
Sent from my HTC Sensation 4G using Tapatalk
Mine will only will charge from official HP chargers. This is much like my old iPhone 3g before all the generic manufacturers caught up. I suspect that the voltage and amp requirements are tighter than the USB specification, so it will be a crap shoot if you use non HP chargers.
With that said, HP has 30% off all touchpad accessories right now. Combine it with the cupon SAVE15HP
-W
Sent from my I897 using XDA App
wpp105 said:
With that said, HP has 30% off all touchpad accessories right now. Combine it with the cupon SAVE15HP
Click to expand...
Click to collapse
Ya unfortunatelly i could order anything since i dont live in the US/UK regions
Varemenos said:
Ya unfortunatelly i could order anything since i dont live in the US/UK regions
Click to expand...
Click to collapse
Don't worry over that, I can get what you need and ship it to you.
Also, in speaking to HP, any USB charger in the US works, they're considered universal.
Sent from my HTC Sensation 4G using Tapatalk
you cant charge the touchpad using a computers usb ports. it doesnt draw enough power. the voltage of the charger doesnt really matter, it needs at least 2 amps or it wont charge the touchpad. cell phone chargers usually only draw 1 amp or less and usb ports only .5 amps.
cachookaman said:
you cant charge the touchpad using a computers usb ports. it doesnt draw enough power. the voltage of the charger doesnt really matter, it needs at least 2 amps or it wont charge the touchpad. cell phone chargers usually only draw 1 amp or less and usb ports only .5 amps.
Click to expand...
Click to collapse
That is absolutely not the case.
I have only charged mine once with the AC-USB thing and I have been using it since I got it the first day of the sale. I use mine all day long and only charge it occasionally via USB to PC connection. I use the original cable from HP and another one from my Samsung Mythic (work and home).
The message that you get when you plug it in is misleading but normal on a stock TP. However there is a patch in PreWare that changes it to just default to charge and not bug you. Anyone who intends to use this thing at all with WebOS needs to get PreWare installed. In fact, some time spent at precentral.net would benefit any new owners. You will learn A LOT more about these little jewels. I spent a few hours reading stickies and interesting threads and learned a great deal.
If it is really plugged in (and you will know because your PC will tell you) and you get no charge, you have a problem. It should charge on or off while plugged in - mine does.
nunjabusiness said:
That is absolutely not the case.
I have only charged mine once with the AC-USB thing and I have been using it since I got it the first day of the sale. I use mine all day long and only charge it occasionally via USB to PC connection. I use the original cable from HP and another one from my Samsung Mythic (work and home).
The message that you get when you plug it in is misleading but normal on a stock TP. However there is a patch in PreWare that changes it to just default to charge and not bug you. Anyone who intends to use this thing at all with WebOS needs to get PreWare installed. In fact, some time spent at precentral.net would benefit any new owners. You will learn A LOT more about these little jewels. I spent a few hours reading stickies and interesting threads and learned a great deal.
If it is really plugged in (and you will know because your PC will tell you) and you get no charge, you have a problem. It should charge on or off while plugged in - mine does.
Click to expand...
Click to collapse
The problem is, its plugged, i get the warning but its not charging at all (while the touchpad is turned out cause its out of battery the past 2 days).
Varemenos said:
The problem is, its plugged, i get the warning but its not charging at all (while the touchpad is turned out cause its out of battery the past 2 days).
Click to expand...
Click to collapse
Now to be completely honest - the first charge I made out of the box was with the AC adapter and I left it in overnight like I had been told.
But since then I have never used the AC plug and I have let it get down to about 20% or so but no lower.
It very well may be that from a DEAD state, it requires the extra amps to jump start it, but as long as you have that initial charge it is covered by the lower amperage of the direct USB-to-PC connection. I'm guessing it came with a fair charge and you burned through it without ever plugging it in to the USB.
Bear in mind that not ALL USB ports on a PC are powered the same either. Older USB 1.0 and 1.1 are crap for power. Front or top-mount ones also may not have as much juice as the ones in the back directly off the motherboard. Look at portable hard drives, some come with a double-header cable to use two low-powered ports. I know my top-mount ones will not power my 1TB 2.5-inch drive, but the ones in the back do.
However, I am really surprised you can't pick up a standard plug in USB adapter for your country for a few dollars (equivalent) for wall. Jeez they sell them at the dollar stores here now. I don't know if a car adapter would output enough to do it but that is another idea. If you can get one, you should be able to bring it back easily enough. The 2 amp adapter does charge a lot faster.
---------- Post added at 11:15 PM ---------- Previous post was at 10:53 PM ----------
LOL, I am really in a rare mood as this question has bugged me a little. So I decided to find some straight poop. Here is the best description I have seen anywhere.
http://www.maxim-ic.com/app-notes/index.mvp/id/3241
If you don't want to read it, the gist (as I understand it) is:
At 5V, the USB ports in a PC have to be able to source (provide) at least 500 mA (.5 AMP). However, depending on how your motherboard is provisioned (MOSFETs and diodes) that is limited/controlled.
The spec though, does allow as much as 5A to be provided. In fact, 2A is not uncommon if the other ports are not loaded.
So you could try unplugging all your other USB stuff or try another computer's USB ports.
Varemenos said:
Im trying to charge it through my PC using the original cable that was in the box (tried it in a USB 2.0 port) and im getting the 'try a reliable recharging source like the USB cable and the charger that came with your touchpad'.
I also tried charging it with a 5.0V 200mA phone charger but it didnt work either.
Shouldnt it charge even a bit with the cable? im trying to charge it for 2 days now
Click to expand...
Click to collapse
Given that the HP charger has a 2A output, odds are that anything much below around 500mA isn't going to charge the device, or at least not at a rate that'll offset the drain while it's running.
The USB ports on laptops often won't supply enough current, particularly if there's other devices on the same bus. If you plug it into a powered USB hub then you should be in business as they should supply more like around 1A generally.
My Touchpad charges from my laptop USB port, however it is slow. I am getting about 8 - 10% charge per hour. The screen needs to be off though, otherwise there is no noticable charging happening.
Mine is not charging with USB laptop at all. Need to use wall charger
I have XRON VB2.8 on my two touchpads and both show battery charging symbol when they are connected to computer via USB and yes the they charge very slow.
FYI, can't remember if WebOS / Govnah tells you what the current amps being used is, but if you are on Android tools like Elixir 2 tell you how many amps you are either discharging (-) or charging (+). So depending on what you are using (wifi, bluetooth, # of widgets, running applications, screen brightness, overclocking, underclocking, etc.) YMMV on whether or not you can charge via usb connected to your computer.
So if you are discharging at a rate of -750 mA connecting to a usb port on your computer will still have you discharging at a rate of -250:
Code:
[COLOR="Red"]-750 mA[/COLOR] + 500 mA = [COLOR="Red"]-250 mA[/COLOR]
mine charges in the usb port, but only if I turn off the screen or turn off the touchpad completely. my ports only provide 500mA, and with the screen off, the touchpad draws about 50mA, so it can charge at about 450mA. With the screen on, it draws about 760mA, so even when it's plugged in the USB, it is discharging at a rate of about (760-500=260mA).
So this is my first motorola and I had heard of the issues they have with non motorola chargers. Now I am experiencing it first hand. With the same ac charger I have charged many phones with and is capable of 1 amp output (D4 charger is only rated at 850 mA) my D4 struggles. With the device off it charged painfully slowly. While on it cannot even charge. It discharges while plugged in despite the charging indicator and reporting "charging (AC)" in status.
How does it know it is not a moto charger? Is it just about the resistance between the data pins? For most other phones shorting the data pins on the charger indicates to the phone that it is a high current charger and not a computer USB port. Is there a similar trick for motorola phones? I would rather not have to purchase an overpriced moto oem car charger. I have a perfectly fine 1.2 amp car charger soldered directly into my car's 12v system behind the dash. Can I make it work?
Thanks!
On a regular basis I successfully charge my D4 using both a charger from a Samsung Reality feature phone and from a B&N Nook Simple Touch, in addition to the one that came with it. I've also used a variety of car chargers.
Sent from my DROID4 using XDA
Actually, so far I have only one charger that had any trouble charging the phone (it was a $3 charger with 2 USB ports), but the $3 charger with ONE USB port works fine, as does the Nook Color charger, Blackberry charger, and Samsung charger I have tried it with, as well as both my old car charger and Lenovo's always-on charging port on their laptops.
JKingDev said:
So this is my first motorola and I had heard of the issues they have with non motorola chargers. Now I am experiencing it first hand. With the same ac charger I have charged many phones with and is capable of 1 amp output (D4 charger is only rated at 850 mA) my D4 struggles. With the device off it charged painfully slowly. While on it cannot even charge. It discharges while plugged in despite the charging indicator and reporting "charging (AC)" in status.
How does it know it is not a moto charger? Is it just about the resistance between the data pins? For most other phones shorting the data pins on the charger indicates to the phone that it is a high current charger and not a computer USB port. Is there a similar trick for motorola phones? I would rather not have to purchase an overpriced moto oem car charger. I have a perfectly fine 1.2 amp car charger soldered directly into my car's 12v system behind the dash. Can I make it work?
Thanks!
Click to expand...
Click to collapse
Not sure how it knows one way or the other. I've successfully used a few LG chargers to charge my D4. The only really hickup I've ran into is the usb cables from those lg chargers won't sync data to the phones when plugged into a computer, they'll still charge off the usb port but won't read as a usb connection to the computer.
Heh, captcha is trynply.
Every charger I've used, including an old charger for an EN-V, kindle, supplied, and various other phone chargers works just fine with this phone. Probably have a bad charger, guy.
Thanks for the replies. I guess I was wrong. My modded car charger works just fine. I guess its just time to retire the old charger that I have been using. I think it might be my old nexus one charger.
A more important question would be does the thing charge over computer-bound USB ports?
When you're without a charger, but there's a USB cable that fits your phone, sometimes a regular USB data port is the only that is around... even though it might take a really long time.
Try a computer bound USB port, then try your actual charger, again. Or do the hard reset (vol down plus power, hold until it actually does it), which is just like pulling the battery.
See how that goes.
Chris
RueTheDayTrebek said:
A more important question would be does the thing charge over computer-bound USB ports?
When you're without a charger, but there's a USB cable that fits your phone, sometimes a regular USB data port is the only that is around... even though it might take a really long time.
Try a computer bound USB port, then try your actual charger, again. Or do the hard reset (vol down plus power, hold until it actually does it), which is just like pulling the battery.
See how that goes.
Chris
Click to expand...
Click to collapse
It does in fact charge via USB port. In fact, it has a 'charge only' mode. Depending on how much juice your port puts out, and what you are doing with the phone, it will charge slowly/not at all, though.
from my experiences, the droid 4 will not accept lg microusb cables, the charging bricks work tho. i use a blackberry microusb on mine along with a Logitech and the stock moto ones. 1.2 amps is a bit high but not crazy sounding. personally, I charge at 1 amp.
Background
Hi all, I, for a very short period of time was suffering from the problem of my phone DISCHARGING while it was charging. This made no logical sense to me until I did some research, which I will detail below.
How USB Power works (Roughly)
Firstly let's discuss USB power provisioning. Strictly speaking, the specifications say that any given USB port should provide a maximum of 500mA (or 0.5A) at 5 volts. *Don't shoot me electronics guys, I'm simplifying for ease of explanations sake*. Imagine that ampage as the actual force of the charger, how quickly it can ram power into your phone. Like the rate of flow on a pipe.
The beginning of the problem
This was all fine and dandy when all USB was really used for was Keyboards, Mice, Memory, etc, low current draw devices. Something else I should mention here is that the Ampage that a port CAN provide is not the Ampage it DOES provide - the device draws a certain Ampage and if the USB controller agrees it outputs said Ampage. Later, when USB was beginning to be used for more power hungry applications, ie External hard drives, these required more power than the port could (In theory) provide. However, most more modern motherboards/USB controllers were more than capable of supplying plenty more Ampage if it was requested. This was breaking the specification but not in any massively dangerous way so as such nothing bad happens.
This is where we get to the actual issue people are experiencing here. The Nexus 4 is a standards compliant device in the respect that it seems to only draw 500mA from any USB port no matter what it's potential, unless it's an AC Wall wart. If you're experiencing problems with wakelocks (see XDA) and other things, this causes your phone to draw more than 500mA which means your phone actually discharges while it's charging! Terrible!
This is quite easy to get around, but again I'm going into detail so let's explain how the phone tells the difference between a dumb wall wart and a USB controller. Easily! The USB controller obviously makes use of the data pins found within the USB cable, whereas a wallwart just (almost always) shorts them out. The Nexus 4 can detect this short, and as such draw more power *While still in quotation marks staying in spec*.
The root problem is not with how the N4 is charging, it's with the wakelock you're experiencing which is causing the phone to draw so much power while the screen is off. While the screen is off and the phone is in Deepsleep (A CPU state where it uses very little power) - it should draw no more than 50mA leaving 450mA for charging the battery, but you guys are probably experiencing a wakelock of some sort.
Solutions to the problem or How to break a specification for the good of mankind
The simple solution is to install this app: https://play.google.com/store/apps/details?id=com.rootuninstaller.batrsaver
This forces the device into a Deep sleep when the screen goes off by killing applications and turning off all internal chipsets that have wakelock capability, most commonly networking on the Nexus 4. This will allow your phone to charge (slowly) off USB without an issue. Another common wakelock is when the device is picked up by your desktop as a media device. The USB controller inside the Nexus 4 forces a wakelock which keeps it from charging. Stupid design, I know.
* A more hackish solution is to install Francos kernel, buy his app, and tick the Fast charging option in the kernel settings dialog. This will force the phone to think that everything is an AC adaptor and will force the phone to draw as much current as it can from the USB port (which on most modern motherboards is fine, and results in extremely quick charging).
* An even simpler solution than all this is to just use a 'USB Charging cable' - this is simply a cable that does not have the Data pins, and as such does exactly the same as what enabling USB fast charge above does. http://www.ebay.co.uk/itm/Micro-USB...487076?pt=PDA_Accessories&hash=item51a465d124
If you live near a Poundland store here in the UK they sell a 4 in one USB cable type thing which turns 1 USB port into Ipod sync connector, Nokia connector, MicroUSB and MiniUSB, and this doesn't have the data pins and as such is excellent.
One final point, an excellent app for monitoring whether your device is actually charging or not and how quickly is Current widget: https://play.google.com/store/apps/details?id=com.manor.currentwidget&hl=en
This widget will tell you how much Ampage is going into or leaving your battery. If the battery icon is green, then it's discharging, if it's black/white then it's charging. The bigger the number, the faster the discharge/charge. This is an extremely easy way to test speed of chargers too.
Recommendations
Another solution, just use an AC Wall wart - they're cheap as hell and the one supplied with the Nexus 4 is an extremely fast charging one. Shame I've gone and lost mine.
A way to roughly monitor charging current draw
I'd also recommend you install https://play.google.com/store/apps/details?id=com.manor.currentwidget&hl=en and monitor, if the battery is green while charging it's discharging and you need a more powerful charger/to figure out what's causing your phone to use so much power.
General good values in Current Widget
I generally saw a max draw of about 750mA for charging (not including draw for powering the device, the Nexus 4 can draw more power to charge and power the device) on my old Rev10 first generation Nexus 4. On my new Rev12 board I'm noticing this increase to about 850mA.
Are higher amperage chargers any benefit to anyone?
Yes and no. You will not notice faster charging unless you use your device while charging. Your nexus will draw as much power as it needs to power the phone while charging at the fastest rate. For example on the stock 1.2a charger
1200mA | 800mA goes to charging 400mA goes to powering the phone idling
Let's say you start a stability test. Your phone will obviously be using a lot more power so this will happen
1200mA | -600mA goes to charging and 1800mA goes to powering the phone stability testing
That minus value above may look strange! Let me explain. If the phone needs more power than the charger can supply, it will draw from the battery. That's the minus number.
If you have a higher ampage charger like for example a 2.5a charger
2500mA | 800mA goes to charging 400mA goes to powering the device
Stability testing
2500mA | 700mA goes to charging 1800mA goes to powering the device
Can you see the difference?
DISCLAIMER: I am not an electronics engineer nor do I claim to be, I am simply a hobbyist and this is what I've found to be the case. Please correct me if I've made any mistakes, I want to learn.
Thanks!
Thanks so much for this post. It's very helpful.
kn100 said:
Another common wakelock is when the device is picked up by your desktop as a media device. The USB controller inside the Nexus 4 forces a wakelock which keeps it from charging. Stupid design, I know.
Click to expand...
Click to collapse
This isn't true for everyone then as mine connects and charges just fine off of my laptop and desktop when connected as a media device. In fact its on my laptop right now charging, gone from 68% to 81% in about 30 minutes and it shows connected as a portable media player.
Great info! Thanks for writing this!
In certain use cases the Nexus4 discharges faster than it charges and this is a very useful guide.
I use my phone for navigation in my car and having the GPS on and the screen at high brightness
drains the battery faster than the 0.5A car chargers can supply. Car chargers rated for 2.0A work well.
I haven't tried a 'USB charging cable' with the data pins shorted, it may work as well.
-Mindroid- said:
Great info! Thanks for writing this!
In certain use cases the Nexus4 discharges faster than it charges and this is a very useful guide.
I use my phone for navigation in my car and having the GPS on and the screen at high brightness
drains the battery faster than the 0.5A car chargers can supply. Car chargers rated for 2.0A work well.
I haven't tried a 'USB charging cable' with the data pins shorted, it may work as well.
Click to expand...
Click to collapse
was over in Nexus 7 forums and the 4.2.x kernel should have solved the problem at least for having to use shorted cables. have to wait and see if 4.2.2 brings any more changes.
http://forum.xda-developers.com/showthread.php?t=1984838
Section 6 in this link is about power supplied through USB
http://en.wikipedia.org/wiki/Universal_Serial_Bus
I can't tell if we have an updated kernel allowing faster usb charging as I'm limited by the power output of the usb port in my laptop. The output (5V at 500mA max) is controlled by the laptop (USB Standards) and it doesn't matter what the phone or cable is capable of as that's the max it will give out and that's about what I'm charging at. If I had a dedicated charging port in my laptop then it would be different and I could see if its able to draw more power. I have a 1.0 amp port in my car and it does charge at the higher amperage, I would assume it would do the same thing if I had a 2 amp usb port in the car. So I think the stock kernel has the fast usb charge built in it just depends upon if you have a usb port capable of providing a faster charger, it has nothing to do with the cable as I'm using a standard unmodified micro usb cable and its able to draw the max a usb device is able to put out.
thanks
thanks for a great detailed post!!!
I have the same trouble with my N4 when I was charging while using my phone...
I find it very slow... I guess I've been spoiled by my previous iPhone (which charges fairly fast)....
i might be stating the obvious but I find the phone charged "a lot" faster when it's OFF
if you are running low with your battery and need a quick 10 min charge, just do yourself a favour by turning off your phone...
the difference is quite significant!
kzoodroid said:
This isn't true for everyone then as mine connects and charges just fine off of my laptop and desktop when connected as a media device. In fact its on my laptop right now charging, gone from 68% to 81% in about 30 minutes and it shows connected as a portable media player.
Click to expand...
Click to collapse
Yup, me too. It only discharges while charging when I am playing like NFS most wanted.
Sent from my Nexus 4 using xda app-developers app
The issue with cables is with the LG usb wall charger as the one supplied isn't capable of getting the 5 volts at 1.2 amps that the charger is rated at, mine is getting around 300 - 400 mA. The micro usb cable I have in my car and use with my laptop (for charging and data transfer) is able to handle the higher amperage, it gets around 1 amp with the LG plug. There are no specs on these cables so I can't list a definitive difference and I would assume that the cable mod in the OP might help with the LG cable. It also might just be simpler to only buy those cables capable of handling higher amperage as obviously they are out there from my experience.
The cable I'm using is an RCA coiled charging/syncing cable model AH732CBR (has data pins). The maximum I'm getting from this is about 870 mA regardless of the amperage of the usb port, I've tried a 1.0, 1.2 and 2.1 and they are all around 870 mA on current widget. I would suppose if I could find a strictly charging cable I could get higher (link to ebay in OP is outdated) but this is still 2x that which I'm getting from the LG cable supplied with the phone which only puts out 300-400 mA. Our phone also has Qualcomm's quick charge which is supposed to improve battery charging times by 40%.
http://www.droid-life.com/2013/02/1...allows-your-device-to-charge-up-to-40-faster/
How do you measure how much mA the device draw from the charger?
Sent from my Nexus 4 using Tapatalk 2
omrij said:
How do you measure how much mA the device draw from the charger?
Sent from my Nexus 4 using Tapatalk 2
Click to expand...
Click to collapse
current widget, link is in the OP
kzoodroid said:
The cable I'm using is an RCA coiled charging/syncing cable model AH732CBR (has data pins). The maximum I'm getting from this is about 870 mA regardless of the amperage of the usb port, I've tried a 1.0, 1.2 and 2.1 and they are all around 870 mA on current widget. I would suppose if I could find a strictly charging cable I could get higher (link to ebay in OP is outdated) but this is still 2x that which I'm getting from the LG cable supplied with the phone which only puts out 300-400 mA. Our phone also has Qualcomm's quick charge which is supposed to improve battery charging times by 40%.
http://www.droid-life.com/2013/02/1...allows-your-device-to-charge-up-to-40-faster/
Click to expand...
Click to collapse
Bit of a late reply but please bear in mind the Nexus will NOT draw anything more than about 800mAh from the wall for charging alone. That is the absolute max and is a hardware limit - If the cable is transmitting that and it's showing in current widget you've got a good setup. See the added section in OP for more info on higher amperage chargers.