Thinkpad tablet slow charge analyzed - Thinkpad Tablet General

I have TPT for 10 days now.
I have usual iisue with USB charging. When used like standard smartphone = put it to charger overnight. Not usable anyway. Charge rate about 5% per hour, which means 20 hours per full charge???
I even consulted it with local technical support. I was adviced to buy docking station with external power adapter .....
So ... I took regulated power supply, made a USB socket connected to it and started to measure
.. and look what I found
When device is switched on, usb power oscilates sligthly under 1000 mA. It is NOT using all available power of 2 Amps of stock power adapter!!!!!
But ... when I power the device off using power button. The current goes down to 300mA for about 5seconds and then raises to full 2 A!
Conclusion? It seems like control issue of the charging ciurcits. What if we can enable full 2A power even when turned on? SW issue?
Is there any chance, how to instruct internal power circuity to use all available power? ADB?

Well I guess that explains the slow charging that people have been reporting. I picked up a dock for my tablet from amazon for about $30 shipped. Now I just put my USB charger in my bag for when I am out and about and dock it when I get home. That being said when I was charging via USB before I had the dock, a full charge seemed to take about 6 hours or so.
As for your question regarding modifying the input charging rate while powered on, I am not sure that can be done via ADB. I am taking a stab in the dark here, but I wouldn't be surprised if the charging rate was hard coded into the power circuit. Which would make some sense so as not to draw to much power if someone wanted to try and charge their tablet while having it plugged into a laptop or USB hub. I am not sure if it has an auto sense capability to determine whether or not it is charging via USB from a port or from the power adapter. I do know when I hook it up to my computer to transfer files it offers me the option to charge via USB, but I think that is a software thing and not hardware. I could be wrong. Maybe if we had access to the board schematics I could figure out. I can read schematics and might be able to figure it out.
Any chance you could get a proper reading via the docking port on the tablet? I would be curious to see if it is always at 2A. I haven't counted the pins but I don't see why you would need more than VCC+, VCC-, GND and maybe a sense line. But I know there are more than 4 pins.
Sent from my ThinkPad Tablet using xda premium

I would say this is a SW issue. Maybe if we had the kernel source code someone could cook up a custom kernel with that control feature tweeked.

Temetka said:
~
Any chance you could get a proper reading via the docking port on the tablet? I would be curious to see if it is always at 2A. I haven't counted the pins but I don't see why you would need more than VCC+, VCC-, GND and maybe a sense line. But I know there are more than 4 pins.
~
Click to expand...
Click to collapse
The best thing to use is a watt meter if anyone wants to pursue this.
My findings indicated that the dock has a similar issue as the USB charger when the TPT is on.
Maximum current allowed at the dock connector was measured at just over 1A . Dock should charge the battery at a maximum rate of just over 1% per minute provided the battery charge level is below 70%. So if you discharge the battery to around 50% and compare charge rates you should see the difference between TPT on/off.

Related

how to enable high power usb charge

anyone knows?
possibly need to write a custom oem_misc.dll. if some one can, then we can have TV out too ...
i heard it is just a reg change
anyone knows pls?
Don't know the reg change in this case, but guess won't really work.
For instance, for enabling FM radio without headset, changing the headset state in reg won't work. I would be happy to be proven wrong though
leobox1 said:
anyone knows pls?
Click to expand...
Click to collapse
Hi leobox1,
Not sure that there is a way to enable this. Charge rate is determined by battery voltage and available current from the charger, not by software (other than the simple battery management chip in the battery). So if your battery is low and you have high power USB connection, it will take as much charge transfer as the battery will accept, provided the supply voltage can keep up. I don't think that the charger circuit can recognise the difference between low power USB, high power USB, or charger USB connection.
mike.waters said:
Hi leobox1,
Charge rate is determined by battery voltage and available current from the charger, not by software .... I don't think that the charger circuit can recognise the difference between low power USB, high power USB, or charger USB connection.
Click to expand...
Click to collapse
I don't think so. When HD is on, the current consumed at a given battery level of charge for a given (same) voltage is higher with wall charger than computer USB. Don't have the values that I measured once... But this doesn't seem to be the case when HD is switched off.
So there has to be some kind of monitoring going on by the CPU.
The charger has the two data pins connected together so the handset knows it is receiving power from the charger and not a USB port. The device will then charge with as much power as the charger will allow, up to 1000mA
The amount of USB power definately changes the speed at which this recharges. I purchased a 3amp car charger and it will charge my Touch HD in half the time it charges from the wall charger. My laptop puts out a small USB power supply and it take all day to charge my phone. My old Pocket PC had the selection for fast or slow charge, this one seems to handle it on it's own.
hmm so in short it is beyond our control?
leobox1 said:
hmm so in short it is beyond our control?
Click to expand...
Click to collapse
In short - Yes
backdoc94 said:
I purchased a 3amp car charger and it will charge my Touch HD in half the time it charges from the wall charger.
Click to expand...
Click to collapse
3 Amps? Are you sure, I don't know if I would want to connect my Touch HD to a 3A supply. Where did you buy it from?
Picked it up from ebay. It works really well, no overheating. The phone only takes what it needs, the charge is controlled by the phone not the charger.
Oh, I know the phone will only pull the power it wants, that is not the issue. A 3 amp power supply would cost quite a bit if it was a decent regulated one, and I would not use anything but a regulated power supply.
So I was guessing you were using a 3A unregulated supply. Which is something I would be very wary of, the risk of a voltage spike is going to be higher than with a lower amperage.
the only reason that the phone charges faster using the htc charger is so that people like us spend more money on official htc accessories.
its not just htc that do this.
why do you even think they have this extusb instead of a normal usb port?
a normal usb port on a pc is rated to give out 500mA (half an amp) of current.
that doesnt mean that a normal usb socket cant accept more than that though. just think back to the old htc devices that charged much faster.
wake up guys
http://www.nuerom.com/BlogEngine/
I think theres something interesting there
chrisque1 said:
http://www.nuerom.com/BlogEngine/
I think theres something interesting there
Click to expand...
Click to collapse
what is it for?

Faster USB charging?

Just got a new motheboard which has high output USB charging for iPhones, pads etc.
Can this work on N1 ?
http://gigabyte.com/MicroSite/185/on-off-charge.htm
edit: driver link is at the bottom for all the hackers. Hopefully its just changing string from apple to android hehe
kazprotos said:
Just got a new motheboard which has high output USB charging for iPhones, pads etc.
Can this work on N1 ?
http://gigabyte.com/MicroSite/185/on-off-charge.htm
edit: driver link is at the bottom for all the hackers. Hopefully its just changing string from apple to android hehe
Click to expand...
Click to collapse
Hopefully not, I dont want my nexus one to be iphone.
But as you know nexus one is using qualcomm motherboard.
But aslong cyanogen and fm transmitter is working there is no problem wiith your phone.
Dear lord what a crappy reply. Stick to disney mate.
It should, it basically just converts the USB port from .5 amps to 1 amp, like a wall charger.
elkyur said:
Hopefully not, I dont want my nexus one to be iphone.
But as you know nexus one is using qualcomm motherboard.
But aslong cyanogen and fm transmitter is working there is no problem wiith your phone.
Click to expand...
Click to collapse
WTF??? May want to lay off the halucinogenics
elkyur said:
Hopefully not, I dont want my nexus one to be iphone.
But as you know nexus one is using qualcomm motherboard.
But aslong cyanogen and fm transmitter is working there is no problem wiith your phone.
Click to expand...
Click to collapse
lol I seriously hope this is a joke!
I agree with JCopernicus, it should definitely work.
I installed the software in the first post but it still charges very slow compared to wall outlet
Slightly OT, but I've got a USB adapter that plugs into the wall that came with my iphone and when I plug the N1 USB cable into this to charge the N1, it still charges very slowly compared to using the proper wall adapter, why is this? Does this iphone adapter restrict the voltage or something?
Generally, "charger detected" is a circuit that has USB data pins shorted together. So when the phone's USB device probes the lines and detects them shorted, it knows it's connected to a power supply.
But since USB max current spec is 500mA, the current draw is restricted - either by the phone or by the supply.
There might be some other connectivity trick that allows the phone to know it can draw x2 current from the socket and won't damage anything. Most phones probably don't limit the current draw and count on the board to do it. Some boards don't limit the current output, or limit it higher. And the fast chargers provide pulsing voltage - which isn't like USB.
So for the board to be able to charge the device, it needs to detect a device that can use pulsing voltage, and enable such voltage on the socket. It doesn't detect Nexus as such a device, I believe, and that's why the charging is slow.
Faster charging with USB
Building on Jack_R1's response, I believe that the phone is limiting the charge rate. You can make the phone "realize" it is connected to a charger rather than a data connection by shorting the 2 middle USB pins together. I have done this in several car chargers, and the N1 About/Status shows charging (AC), which is the faster charge mode. While you can short the pins in the larger end of a dedicated USB cable, if you can disassemble the connector, I found it much easier to open the charger itself to short the pins.
i also have a gigabyte mobo that has this feature but i havent gotten around to test it out yet. I dont think it would work because the feature is software based and will only bump up the voltage if the program detects an iphone connecting to your computer. Gigabyte doesnt want to be liable if they bump up voltage on every device you plug in and fry something.
btw I have tried charging my n1 from my computer and its extremely slow. started charging at around 5pm on sunday and at 11pm it went from about 23%-97% lol.
Yes, USB charging is very slow. It's actually good for the battery, though.
Maybe someone with some know how can look at the driver files for this 3x tech and see how it checks if its an Apple device. Then fool the check and presto!
Shame I don't know how to do any of this
There is a simple hardware (don't worry, it's on the cable) mod for faster charging; however, make sure the phone has good air vent (it means NO CASE when charging).
1. modify your microUSB cable, disconnect the data connector the A (host) plug, then shorten the data connector to the B plug. (This can charge N900 properly, and speed up n1 charging).
2. modify your powered (with AC adapter plugged) USB hub. Simply shorten the #2 and 3 connectors on USB jack. Make sure you cut the copper strip going to the chip or malfunction may occur.
These modification can greatly speed up the charging, but phone will produce a lot of heat (that's why you must have the phone "naked").
I don't understand this. If the phone + battery are capable of being charged at 1000 mAh from the wall charger then why need extra cooling when asking for 1000 mAh from a PC USB socket?
Mine's still defo getting only 500 mAh from the PC USB despite it being able to give up to 2700 mAh for iPad!!! All I want is my 100 mAh charge.
Because what he suggests isn't a proper charging but rather removal of slot power control, and will damage the battery / phone, if succeeds.
Proper charging at 1000mAh requires pulsing voltage - his hack doesn't provide that. Your MB does, but it requires SW intervention to turn it on.
So can someone brew the intervention ?
martinl1030 said:
i also have a gigabyte mobo that has this feature but i havent gotten around to test it out yet. I dont think it would work because the feature is software based and will only bump up the voltage if the program detects an iphone connecting to your computer. Gigabyte doesnt want to be liable if they bump up voltage on every device you plug in and fry something.
btw I have tried charging my n1 from my computer and its extremely slow. started charging at around 5pm on sunday and at 11pm it went from about 23%-97% lol.
Click to expand...
Click to collapse
They are not doing anything to the voltage, simply allowing more current to pass.
And as said in this thread, any typical data USB cable will charge very slowly. And most standard USB ports charge well less than the max specced 500mAh, in fact my subnote at work I found charged my old phone at around 150mah one time when I was dead and needed to top off and it's all I had available.
i'm not sure of the pinout on the micro USB port but i'm pretty sure that that the Mini USB-B port that was used on phones like the G1 used shorting the -Data pin to the unused 5th pin (actually pin 4 on the connector pinout) to activate AC charge mode. some devices actually require a resister of a certain value to be placed across them to work(i know older motorola phones did like IDEN's)
one thing people often forget but should not forget is that current is drawn from the device using power. its not forced on the device. voltage is forced on a device and while a variance is usually ok for devices depending on how they were designed generally its not a good idea to exceed +1.5v on any low power DC device. 120V AC devices are designed to actually work in a much wider range like 100-130V but thats because of the power supply/nature of AC power. it always varies and in japan they use 100v 60hz AC so many electronics power supplies are designed to work in the full range to save costs and only have to make 1 unit for all (same deal with 220-240 switches on PC power supplies)
the reason why you don't want to do this mod is you could damage you PC's motherboard by pulling too much current from its circuits. USB spec is 500ma. performing this type of mod on a power adapter (car or AC) that does not get recognized as an AC charger by the phone is a safer way to go. worst case senario is you break the charger (unless you mess up on the pinout then you could damage you phone too though)

Battery charge current help needed

Long story, but I bought a used Fascinate without the stock charger.
Could someone install, or hopefully already have, the "Battery monitor Widget". Then plug their Fascinate into the stock AC charger or stock car charger (NOT the USB on a PC), and let me know what the usage (ma) reading is on the widget.
More of the story. Basically, I know that at least on older HTC devices they would pull more charge/operating power from a non-USB connection. Actual USB is limited to 500ma load, so they had a system that kept the current low on USB and bumped it up for non-USB. All of the non-stock cables that I have show a very low charge rate on the Fascinate. It in fact runs the battery dead while on charge and I use the phone with GPS software.
i can tell you the factory charger is putting out 5v at .7a(700ma).
Mylt1 said:
i can tell you the factory charger is putting out 5v at .7a(700ma).
Click to expand...
Click to collapse
Thanks, it is good to know that they stick with 5V. But it just means that it can put out up to 700ma. I suspect it is using about half of that.
If you can cut open the wires and insert and ammeter in series, that is what I need to know.
edit: nvm ...
Found it. I have been searching for this for a couple of weeks and just now stumbled on the right search keywords.
For anyone that wants to know.
The Fascinate appears to pull about 350ma from the 5 volt supply normally. But, if you short out the USB D+ and D- lines in the charge connector, the charge current goes up to about 600ma.
That will help me not have a dead battery when using the GPS.
Oh, as an added bonus, you don't get the USB / Debug notification.

Impossible to charge sg2 in car

Hi all, just came 3 days ago from an htc hd2, and so far I am more than happy with it.
I have only one complaint and maybe you guys will help me sharing your experience : I can't charge this phone in my car while using gps.
It seems that the power adapter is not powerful enough to charge the phone screen on.
The car charger has a 5v 1000ma output, more than the regular wall charger provided by Samsung and it was working well before with my HD2 so I have no clue about this problem.
Did you experience that issue too, else can you share what car charger do you use?
try to buy new standard car charger with micro plug.. 13 eur and you will be saved..
Sent from my GT-I9100 using XDA App
Charger doesn't matter unless the phone is dropping into USB charging mode - phone limits to around 600-650 mA by default.
Custom kernels can bump this limit up for I9100 users. I777 users are screwed - we've got a crippled charger chip.
I had the same problem, I used the samsung one, useless, so I used my iPad charger, which is 2A, and charges the iPad quick, still useless. We drove from Bathurst NSW, down to Melbourne, about 10 hour drive, plugged in all the way using GPS, and about an hour from home, the connect to charger warning came on!! So once I stopped GPS, it started taking charge. Looks like when the phone is in use, it draws more then it takes charge, plus I read somewhere on here the phone is limited on the charge it takes, so using the 2A does nothing different then the stock 500mA charger.
I always had this problem with my Nexus One, although they are different phones, the problem is the same, uses more power then it can recharge in USB mode.
After trying 3 or 4 different charges I remember that I found one ultra-cheap 'made in taiwan' from a street seller that worked very well.... so it's kind of a lucky shot!
good luck!
Im using a genuine Samsung SGS2 charger and I can charge and run Sygic just fine. I started my journey with 80% and 40mins later I was up to 91% when I stopped and got out. (not in aeroplane mode..)
Very interesting feedbacks... So that confirm that is clearly not a matter of output amperage power.
It is now the same problem on the galaxy tab 10.1, for quickly charge this tab you need the Samsung compatible usb adapter.
It can be likely with a tab bringing a proprietary plug, but I didn't thought it will be the same with a Samsung phone bringing a regular micro usb plug. Quite frustrating and disappointing!
I will search around a micro plug car charger as suggested by redzion, but actually I don't clearly see the difference with my usb charger + a micro usb cable.
Double post, sorry.
If I use the usb cable from my cd player I have the same problem but if I use the official Samsung car charger Ithe only problem I have is the phone getting stupid hot
Sent from my GT-I9100 using xda premium
Oh Samsung, when you will understand?!
Samsung DOES follow the USB charging standard - it goes to its highest current setting when a charger that follows the standard is connected.
Note that iPad/iPhone chargers do NOT follow the standard - Samsungs will treat these as USB hosts and limit to 450 mA instead of 600-650.
Modified kernels can increase both of these values on I9100s.
The only thing Samsung really did **** up is counting screen/CPU current usage against the charge current limits - that's just stupid.
So the charger has smarts. On the i9000 factory chargers, the data pins were bridged. Bridging these pins manually on a USB cable when connecting to a USB source (such as a PC) enabled full current charging. You can see this in Settings -> About; it will say either USB or AC charging.
Do you think this is the case with the i9100?
I don't condone testing this theory on your i9100. Increasing the max current via custom ROM may be a safer solution.
I had the same problem. Two things fixed it for me:
1) I bought this charger: Sony Ericsson AN300 Micro USB 10€
2) I am using a custom kernel now
Any charger that is rated at 1000mA or more (per port) will do just fine. The problem is the cable - you need a quality microUSB cable, or it won't provide all the juice you need. I had the same issue, and I swapped three chargers until I found the real culprit.
Try with the charger you have now and the mUSB cable that was in the phone box - it should work well with that one.
I just press the power button to turn the screen off. when i need the sat nav i press the power and it still tracks you so there is no delay. With the screen off it does charge.
same problem
Duffman19 said:
I just press the power button to turn the screen off. when i need the sat nav i press the power and it still tracks you so there is no delay. With the screen off it does charge.
Click to expand...
Click to collapse
You are right, but even if it is better than nothing the charging time is still a big problem.
Yesterday I drove for at least 40mn phone off. Arrived to destination, I turn the device on: it charged only from 0 to 5%
I would like to test the mariusi theory concerning the Samsung micro usb cable, unfortunately on my SgsII box I just have a wall charger, no a microusb-usb cable.
Entropy512 said:
Samsung DOES follow the USB charging standard - it goes to its highest current setting when a charger that follows the standard is connected.
Click to expand...
Click to collapse
Is there a way to know before buying if the charger respect this charging standard?
I have some cheap usb chargers here and no one is a fast as the one provided by Samsung.
Entropy512 said:
The only thing Samsung really did **** up is counting screen/CPU current usage against the charge current limits - that's just stupid.
Click to expand...
Click to collapse
Maybe for safety purpose? Gps phones can become very hot behind the car glass.
Samsung are trying to "encourage" you to buy only their official accessories. To do this they've wired something differently in their chargers and cables. This "problem" exists on the Galaxy Tab too and can be solved with this adapter...
http://www.ebay.co.uk/itm/USB-car-w...ccessories&hash=item2c5c07736b#ht_3084wt_1163
It's cheap and turns a trickle charge into a full charge. I don't know the specifics of what they've done, but their USB charging just isn't the same as most others manufacturers.
Archer said:
It's cheap and turns a trickle charge into a full charge. I don't know the specifics of what they've done, but their USB charging just isn't the same as most others manufacturers.
Click to expand...
Click to collapse
Great find.
Pretty sure it just bridges the data pins.

Charge from USB

I figured I would share this since I have not found another thread with this info.
The Galaxy Note 10.1 will charge from usb.
I find this interesting because no tablet, at least none I have known, will do this. They all need to be actually plugged into a wall outlet to charge. However, my note 10.1 has charged from around 13% to 32% plugged into USB. Now, mind you , it doesnt charge very fast, but it does charge.
For some this won't matter. In my case, that 3 ft cord doesnt go from the floor outlet to my desk at work too easily, but the usb will plug in very easily and reach where I need it too. At the very least, it will add a little more time to the length of the batter. I work a 10 hour shift, not adding in the hour for lunch, and I can usually made it about 8 hours. So this may get me the extra two hours I need...hopefully.
phoenixbennu said:
I figured I would share this since I have not found another thread with this info.
The Galaxy Note 10.1 will charge from usb.
I find this interesting because no tablet, at least none I have known, will do this. They all need to be actually plugged into a wall outlet to charge. However, my note 10.1 has charged from around 13% to 32% plugged into USB. Now, mind you , it doesnt charge very fast, but it does charge.
For some this won't matter. In my case, that 3 ft cord doesnt go from the floor outlet to my desk at work too easily, but the usb will plug in very easily and reach where I need it too. At the very least, it will add a little more time to the length of the batter. I work a 10 hour shift, not adding in the hour for lunch, and I can usually made it about 8 hours. So this may get me the extra two hours I need...hopefully.
Click to expand...
Click to collapse
Hmm, I think mine claims not to (it puts an X on the battery icon), but I didn't leave it plugged into my computer long enough to see whether it charged or not. I think all tablets can potentially charge via USB port on a PC, it's just that most disable it out of the box but eg. for the Galaxy Tab 10.1 custom kernels could enable charging over USB.
iofthestorm said:
Hmm, I think mine claims not to (it puts an X on the battery icon), but I didn't leave it plugged into my computer long enough to see whether it charged or not. I think all tablets can potentially charge via USB port on a PC, it's just that most disable it out of the box but eg. for the Galaxy Tab 10.1 custom kernels could enable charging over USB.
Click to expand...
Click to collapse
Mine also puts the RED X over the battery icon whether I try to charge it through a PC USB port or other USB charging port other than the Samsung adapter (Goal Zero 150 usb port and Panatech 10000mah external USB battery pack). The tablet shows that it is charging when i view it using GO POWER MASTER app. Watched it for 5 minutes but with WIFI off, it still dropped from 88% to 87%. I am however using the stock kernel.
It charges faster if you have the screen off. The usb gives more or less what you need to keep it running with the screen on.
Skickat från min GT-I9300 via Tapatalk 2
Mine put the red X on the battery icon as well, but still charged. I had to have the screen off.
I had mind plugged into my USB 3.0 port (which should really make a difference) to transfer some files, and then just left it plugged in and it charges. Its definitely a trickle charge, but I am glad to see it does this, as my a500 did not.
When I transferred 40Gb of data to the mSD via MTP (screen off) and called up the batt-graph after disconnection it showed me a fair charging rate. Not stunning but at least a noticeable charge ( from 63% to 82% in three hours).
So it does charge the battery, in spite of the red X?
Yes it does, albeit very slowly.
You guys are misinterpreting the red x. Just got off the phone with Samsung. The x stands for "extra awesome charging". I swear.
Sent from my GT-N8013 using Tapatalk 2
phoenixbennu said:
I figured I would share this since I have not found another thread with this info.
The Galaxy Note 10.1 will charge from usb.
I find this interesting because no tablet, at least none I have known, will do this. They all need to be actually plugged into a wall outlet to charge. However, my note 10.1 has charged from around 13% to 32% plugged into USB. Now, mind you , it doesnt charge very fast, but it does charge.
For some this won't matter. In my case, that 3 ft cord doesnt go from the floor outlet to my desk at work too easily, but the usb will plug in very easily and reach where I need it too. At the very least, it will add a little more time to the length of the batter. I work a 10 hour shift, not adding in the hour for lunch, and I can usually made it about 8 hours. So this may get me the extra two hours I need...hopefully.
Click to expand...
Click to collapse
Interesting, because every tablet I've owned (Tab 10.1 and Nexus 7) behaved like this.
They will charge VERY slowly on USB - and will likely not charge at all if the screen is on due to the total unit power consumption being >500 mA.
Entropy512 said:
Interesting, because every tablet I've owned (Tab 10.1 and Nexus 7) behaved like this.
They will charge VERY slowly on USB - and will likely not charge at all if the screen is on due to the total unit power consumption being >500 mA.
Click to expand...
Click to collapse
Same here. iPads, nook color, Samsung tablets, all say not charging but do trickle charge if you are doing anything to drain it faster than thenusb can supply. It takes around 8 to 10 hours to charge my gt101 through regular USB 2.0.
mitchellvii said:
You guys are misinterpreting the red x. Just got off the phone with Samsung. The x stands for "extra awesome charging". I swear.
Sent from my GT-N8013 using Tapatalk 2
Click to expand...
Click to collapse
Bwahahaha... A friend of mine posted on twitter that Apple should make something that lets iDevices charge each other... Ours actually can because of USB host! I actually lost the usb host adapter for my old galaxy tab so I need to get a new one but I had one for my gs3, and it does charge my tablet. But the reverse is clearly more useful.
Sent from my SCH-I535 using Tapatalk 2
Tested again when attached to Notebook by USB:
Screen on at max. Brightness and working: batt charge stays level
Screen off: batt charges approx. 5% per hour
Tested on GNote charger (1A output)
Screen on : charging very slowly (approx. 3% per hour)
Screen off: charging approx. 8% per hour
Tested on iPad charger:
Slower than original charger although max. Output:
The more items you have attacht to your computers USB the less power it has to allow your tablet to draw for charging.
donec said:
The more items you have attacht to your computers USB the less power it has to allow your tablet to draw for charging.
Click to expand...
Click to collapse
I don't think this is the case. The USB ports provide a set power output, and not variable by available power supply type of output.
phoenixbennu said:
I don't think this is the case. The USB ports provide a set power output, and not variable by available power supply type of output.
Click to expand...
Click to collapse
You are correct they are not variable but they only have a given amount ofpwer available and if you are drawing the max and add another device that needs more power to charge the power will not be available.
donec said:
You are correct they are not variable but they only have a given amount ofpwer available and if you are drawing the max and add another device that needs more power to charge the power will not be available.
Click to expand...
Click to collapse
Of course, everything has a limited power availability, USB ports being no exception, whether having their own psu or bus powered or whatever your setup may be, but unless you are doing something beyond practical use or have a poorly designed setup, than this should not be a problem. I know some systems out there, the mac book pro for example, specific limits USB power output between ports by design (you may even call it variable haha...but by design). However, in a general sense, you should not have a power output issue with simply plugging in for usb charging., even if all other ports are used up as well. So don't daisy chain, or do anything like that. Practical use should be fine. I personally hook my usb charged devices, like my phone, to my monitor at work. It was a few usb ports on the side, and it works great. Also, it keeps me from having to deal with all the annoying security popups that go with plugging it into the actual computer.
In a probably unfunny but still remotely amusing anecdote, I remember the massive work I put my a500 through. I used to have a usb hub attached with 2 1tb portable hard drives, a keyboard, a mouse, my phones, and more all charging directly from USB. Never had trouble with power issues, aside from quicker draining of the battery. lol.
does anyone know if charging is possible when you use an Y adapter on USB-OTG to hook up an external harddrive and a charger at the same time?
cproaudio said:
does anyone know if charging is possible when you use an Y adapter on USB-OTG to hook up an external harddrive and a charger at the same time?
Click to expand...
Click to collapse
Barring any specific device hardware limitations, it is possible to do data transfer and power transfer at the same time using a y cable. Its essentially the same thing as using a usb hub, except you only have two ports instead of 4 or more.
As for actual practical use on the note, I have not tried it out, and I am not aware of any limitations built into software or hardware to prevent it. So, I do not see you having a problem with it.
Almost all tablets can charge through regular USB2 if they're sleeping (or better - powered off).
USB has power limits (USB1.1 is 100mA, USB2.0 is 500mA and USB3 is 2A) BUT these are the 'minimum maximums', if you will. That is, these are the current source *required* for certification. It's entirely permissable for a USB port to provide as much current as it wants - it just can't be limited to *less* than these amounts.
USB 2.0 and later ports are also supposed to implement 'overcurrent' warnings if the device is taking more current than the port can provide..
That's why, for example, some ports can drive a CDROM or external HD drive without a problem - while other ones can't.
The Note 10.1 needs a little over 2A @ 5V to charge at a reasonable rate.
One other note, if you let your battery drain very low, then the lower current of most USB 2 ports won't be enough to charge it even if it's off. The charge current curve isn't linear.

Categories

Resources