Lately – I’m not sure when this stated, my Nexus 7 (running 4.4.2) has been charging absurdly slow. I’m talking 20%-30% in a span of 24 hours. It’s like it’s hooked up to a trickle-charge. I’ve tried 2 different OEM cables and 2 different OEM chargers (I had the one that came with it, and I ordered an official Asus OEM replacement charger with cable as well, to have as a spare).
I downloaded Battery Monitor Widget and while it sees it as plugged in via AC, the charge rate is -9ma (in other words, while plugged in, running nothing but the battery monitor, instead of actually charging, it simply reduced the discharge rate from negative 718ma to negative 9ma).
The only thing I can think of is this: as I understand it, USB AC adapters capable of “fast charge” (2ma) first test the device to see if it’s compatible, to avoid potentially over-charging the unit. Perhaps my device is not properly responding to this test? Perhaps that’s why it’s not providing enough juice?
Or maybe someone else has some better insight and can educate me. I’m certainly open to learning. Any ideas?
WraithTDK said:
The only thing I can think of is this: as I understand it, USB AC adapters capable of “fast charge” (2ma) first test the device to see if it’s compatible, to avoid potentially over-charging the unit. Perhaps my device is not properly responding to this test? Perhaps that’s why it’s not providing enough juice?
Or maybe someone else has some better insight and can educate me. I’m certainly open to learning. Any ideas?
Click to expand...
Click to collapse
[apologies in advance for a long-winded reply; hopefully some of it will be useful to you]
The OEM charger should be capable of 2 A (not 2mA).
Dumb chargers don't "talk" to the tablet. (Well, except for Apple USB dumb chargers - Apple violates the USB spec with their proprietary hardware, and that raises the meaning of "dumb" to a whole new level).
The tablet tries to draw what it wants, and if the wall charger is capable of supplying that current, everything will be fine - meaning, that the output voltage of the charger will be stable (near to 5V). If the tablet tries to draw more current from a charger than the charger is designed for, what usually happens is that the output voltage of the charger will start to droop down. (Sometimes, even worse things can happen, such as the voltage coming from the charger will start to oscillate.) This will have the effect that the voltage drops down to the point where it is barely larger than the voltage from the battery, and so the current flowing out of the charger gets limited that way.
But you shouldn't have this problem as you have at least two OEM chargers, and more than one cable, suggesting that your difficulty is with the tablet somehow.
I note (from your post) that you can observe the actual charging current; this suggests that you have a custom kernel on your tablet, as the stock kernel doesn't have the BQ27541 patches which allow current monitoring (only battery voltage and percent charge).
Here's the reason why I mention this. (Oh boy, get yourself a beverage, this is a long story).
I was going to be making some long drives (>13 hr) and I wanted my N7 in the vehicle, WiFi tethered and active (Google Nav and so forth) As you have observed, when you have the tablet running and are poking away at the screen, it can draw anywhere from 300 mA to more than 1000 mA, depending on how many cores are alive, which CPU frequency is in use, the screen brightness, streaming activity, etc.
And unfortunately...I was in a hurry: I couldn't wait for a car charger to be delivered following an online purchase. And all the local electronics stores seem to only sell high-capacity car chargers that are "Apple Compatible", which is marketing speak for "violates the USB spec". The N7 expects compliant behavior from chargers.
So, I bought two of those "Apple Compatible" car chargers from different manufacturers, and also bought a micro-USB cable that I could hack. I opened up the cable, clipped the D+/D- wires, connecting them together on the "Nexus 7" end of the cable, and left them open on the charger side (open but insulated of course). This has the effect of preventing the N7 from thinking there is a data connection present - the Apple chargers twiddle those D+/D- lines a little bit, and that prevents the (USB spec-compliant) N7 from thinking there is a dumb charger on the other end of the cable.
I wanted to be sure that what I had was actually working correctly, and if either of those two car chargers really would provide enough current, so I installed a dev kernel that has the BQ27451 battery current monitor patches in it. I think several of the dev kernels have this; I used M-kernel.
OK, so far so good.
The next step was to crank both the min and max CPU clock limits way down (300 Mhz iirc), turn on the "performance" governor and turn the screen brightness all the way down. I may have even used Trickster Mod to set Max_Cores to only 1. This was done so that the tablet would draw a smallish and constant current. That way, when I plugged in the car charger, I would actually know what the total charger current was - the sum of the (absolute) values between the unplugged state (discharging) and plugged in (charging)** If you leave the CPU frequency controls in their normal state, the amount of current the tablet draws can jump all over the place depending on tablet activity, and then it would be hard to know the total current the charger is actually producing. (It is the SUM of the battery current displayed plus whatever the tablet is drawing).
When I did the above, my N7 (grouper, WiFi off) was drawing just under 300 mA of current from the battery in the unplugged condition.
Still with me? (it gets better, trust me).
So, what I observed was that, yes, one of the two chargers was better than the other; I could get get the monitored battery charging current up to 1400 mA with one, and maybe 1100 mA with the other. (That's total current from each charger of about 1.7A or 1.4A respectively after adding in the 300 mA the tablet is drawing)
Finally though, an explanation of why this is relevant to you:
When the tablet was plugged in to either charger, the current would not immediately jump up to the maximum value; instead, it would sometimes takes minutes or more for the current to jump up to that maximum value!
It would, however immediately jump up to about 800 mA total current right after plugging the charger. That's better than a 500 mA computer USB connection, but if the tablet is active, it's no guarantee that the tablet will gain any charge - as in your situation.
So why the delay? To be honest, I don't really know. In my panic to get ready for my travel, I only spent a little bit of time fooling with it - for a while I had a hypothesis that the kernel was doing *something* that made the current pop up to its full 1.7A value only after the tablet had left a deep sleep state. The good thing was that once the current stepped up to the full value, it would stay there despite the level of activity on the tablet.
[size=+1]The point is that the maximum charging current condition seems to be dependent on some condition(s) happening which is under control of the kernel - it is not just an "analog" behavior that happens as soon as you plug the charger in.[/size].
So I suppose it is possible that you simply have a configuration where the operating trajectory that your tablet passes through does not trigger the right conditions in the kernel to command the SMB chip (USB interface controller) to max the current out close to the 2A limit.
You might want to try an experiment where you:
- Observe the charging rate with the tablet completely turned off. Should be about 100% in 150 minutes (2.5 hrs) or about 6-7% every ten minutes. Note that because the battery is 4.235 A-h capacity, that works out to a charging current of at least (4.235 A-hr / 2.5 hr) = 1.7 A. (It is probably greater than that due to charging losses).
If your tablet charges at about this rate when it is off, then nothing is wrong with your charger, cable, battery, or SMB chip, and it points a finger at your kernel's code - and possibly other things like applications holding wakelocks which prevent the tablet from entering deep sleep.
I won't go so far as to claim that it is "coming out of deep sleep" that triggered the M-kernel to twiddle the SMB chip so it would draw 2A; in all my experimentation, I couldn't faithfully reproduce the behavior. The good news was that that it would eventually (within a few minutes, possibly due to the tablet sleeping) ramp completely up and then stay there.
Anyway, I hope this gives you some food for thought and maybe some experiments you can run to narrow down the problem.
- What kernel are you using?
- Does your tablet ever enter deep sleep? (I don't mean simply that the screen is off - it is a state where the hardware is placed in a low-power state where even the memory bus is no longer operating. A wakelock might prevent this from happening, but in any event you should be able to observe this in the kernel log - the clock values get wonky and you might see a message about "G" state)
- Does your tablet charge even a little bit when the screen is off?
** I sort of recall that that "Current Widget" app always displays a positive value for current, but changes the display color red/green depending on whether the tablet is discharging (red) or charging (green). Something to watch out for.
.
Kernel: It's rooted, but otherwise completely stock. Battery Monitor Widget doesn't seem to have an issue display the charging rate (and yes, I meant 2A, not 2ma).
Sleep mode: It should; I have one of those cases whose covers are supposed to put it in sleep mode. It DOES charge; but it does it at a snail's pace; a battery info app has it at 30% over the span of 24 hours with it never being touched during that time.
I turned it completely off 3 hours ago at 37% and I just turned it on to 76%
Unfortunately, Current Widget is not compatible with the N7.
WraithTDK said:
Kernel: It's rooted, but otherwise completely stock. Battery Monitor Widget doesn't seem to have an issue display the charging rate (and yes, I meant 2A, not 2ma).
Click to expand...
Click to collapse
It actually displays instantaneous current? Maybe I should restore a 4.4.2 ROM and see if the newer stock kernel has those BQ27541 patches.
WraithTDK said:
Sleep mode: It should; I have one of those cases whose covers are supposed to put it in sleep mode.
Click to expand...
Click to collapse
Well, "screen off" is not equal to "deep sleep". The tegra3 has multiple low-power modes, but the one I am thinking of is really low power - kind of like a "suspend" state for PCs. If there is an application holding a wakelock, the tablet will never enter deep sleep. (As I mentioned, the "deep sleep" mode is very near to the tablet being completely off - the lpRAM is still drawing a little bit of current (it is in self-refresh mode) ). When my N7 sleeps, it charges nearly at the same rate as when it is turned off. (But, see below; in light of that I don't think this is your problem)
WraithTDK said:
It DOES charge; but it does it at a snail's pace; a battery info app has it at 30% over the span of 24 hours with it never being touched during that time.
I turned it completely off 3 hours ago at 37% and I just turned it on to 76%
Click to expand...
Click to collapse
39% in 3 hrs? Hmmm. If things were linear, that would be: 0.39*4.235 / 3 = 551 mA.
You are right, that isn't very good at all. Your tablet will discharge if you are using it even though it is plugged in.
Well - that "tablet off" charging test is pretty diagnostic - the kernel and OS are not even running, so they can't be altering anything. So maybe they can't be blamed for anything either.
But, that Summit Microsystems SMB347 chip is sitting there acting as the battery charger, even when the tablet is "off". Maybe it has something stateful in it (like a few non-volatile memory registers) that could have been altered by past activity on the tablet. Summit doesn't allow datasheet downloads without a NDA, so I don't know.
When the N7 is fully turned off, there is still something tiny running - otherwise, how would that "charging animation" get painted on the screen when you plug the tablet in when it is off? I don't know if that is something in the tegra3 miniloader or just a low-power personality of the bootloader; hard to know really. I guess I am speculating whether something in the bootloader could have "programmed" the SMB chip, but the only thing I remember seeing here (on XDA) is a toggle via a fastboot OEM command that causes the tablet to boot up as soon as power is applied - the guys who do car installs use that.
Well, I'm sort of out of ideas. It sounds like you have tried the obvious stuff already. Do you have any reason to believe the USB port has an intermittent connetion? Or maybe that the battery itself has an intermittent or resistive connection at its power connector?
cheers
Had a very similar problem on my s3 and the problem was the microusb port on the phone
Sent from my SPH-L710 using Tapatalk
WraithTDK said:
Lately – I’m not sure when this stated, my Nexus 7 (running 4.4.2) has been charging absurdly slow. I’m talking 20%-30% in a span of 24 hours. It’s like it’s hooked up to a trickle-charge. I’ve tried 2 different OEM cables and 2 different OEM chargers (I had the one that came with it, and I ordered an official Asus OEM replacement charger with cable as well, to have as a spare).
I downloaded Battery Monitor Widget and while it sees it as plugged in via AC, the charge rate is -9ma (in other words, while plugged in, running nothing but the battery monitor, instead of actually charging, it simply reduced the discharge rate from negative 718ma to negative 9ma).
The only thing I can think of is this: as I understand it, USB AC adapters capable of “fast charge” (2ma) first test the device to see if it’s compatible, to avoid potentially over-charging the unit. Perhaps my device is not properly responding to this test? Perhaps that’s why it’s not providing enough juice?
Or maybe someone else has some better insight and can educate me. I’m certainly open to learning. Any ideas?
Click to expand...
Click to collapse
You might have an issue with your USB on your device. Mine was starting to charge slow but not quite to the degree as yours. I also found that my device would no longer communicate to any computer. If you have tried different cables & charger then you may have to RMA your device.
Asus Nexus 7 draining while plugged in to charge
My Nexus 7 was totally dead. Hit the power button and five blinks of a white LED. Plugged it in it went to 68% then next day it was 28% - 19% and on down. Before it got to zero I turned it off and took off the back. I noticed with the aid of a magnifying glass, that the soldered connections of the mini USB charging port were very possibly fractured. Having had experience at soldering, I added solder and reflowed the connections (about 4 or 5). I then plugged it in. For the first time since the beginning of this mystery I saw the battery icon actually indicating that it was charging. It was 100% within three hours. Haven't had a problem since.
I have been searching all over and found many ideas from - try another charger to - install another charging board. When you think about it, that connecter sees a lot of push and pull. If it is not soldered well and sturdy it's no wonder that it will fracture. I don't think there was enough solder on there to begin with.
If you do not know someone who can solder on a very small scale and want to brave this yourself, make sure you have a very small tip on the iron, not more than 700 degrees and some extra flux. You will most likely bridge a few connectors but keep brushing the tip of the iron away from the connections with flux added. You will get it eventually. Just don't burn the board. And clean it all with a brush and alcohol. Good luck.
Related
Guys, I'm hoping someone familiar with LiPo battery charging can give me some insight. I've done some diagnostics, and I'd like your take...
- Nexus 7 3G, purchased a few weeks ago. 4.2.1, not rooted, stock charger and cable
- Battery life seems good, fully charges and discharges 'normally'
- I usually charge with the device powered off (ie: blocky battery icon in the middle of the screen).
However....
- On two occasions now, I've left it on the charger for a long time (>15 hours) and have come back to a dead device.
- Pressing the power button doesn't bring up the blocky battery icon.
- Holding the power button for 30+ seconds brings the device back back.
- It has otherwise never failed to boot properly during normal use.
Out of curiosity, I was wondering if there was something wrong with the charging process causing this, so
- I plugged the stock charger into my Kill-A-Watt last night to monitor the charging current.
- Even 8 hours after the device finished charging (via the blocky icon), the current never dropped to zero - it stuck around 10mA on the AC side (ie: ~1.2W).
- My first N7 (sent back for a bad speaker and dead pixels) went to zero after charging. My iPad does the same.
QUESTION(S):
I know modern LiPo batteries have internal circuitry to prevent overcharging, but does it sound like that circuitry might be defective on mine such that I should be worried about overcharging? Could that be the reason for my lockups?
I really don't want to go through the return process again if I don't have to. I'd rather just live with it if I can prevent damage by taking it off the charger when complete. Thoughts? Opinions? Have any of you done this test, and if so, does yours go to zero?
Thanks for any insight!
developer_john said:
However....
- On two occasions now, I've left it on the charger for a long time (>15 hours) and have come back to a dead device.
- Pressing the power button doesn't bring up the blocky battery icon.
- Holding the power button for 30+ seconds brings the device back back.
- It has otherwise never failed to boot properly during normal use.
Click to expand...
Click to collapse
That might be a possible cause... Leaving any device plugged in the charger for long periods of time is not recommended. Anyway have you tried charging the tablet with another charger with a higher output? If it refuses to turn on even after holding the power button for 30 seconds you might be able to "wake" it up by using a higher output charger. Thats what I did on my Nexus 7 when the battery level went too low.
cr0wnest said:
That might be a possible cause... Leaving any device plugged in the charger for long periods of time is not recommended. Anyway have you tried charging the tablet with another charger with a higher output? If it refuses to turn on even after holding the power button for 30 seconds you might be able to "wake" it up by using a higher output charger. Thats what I did on my Nexus 7 when the battery level went too low.
Click to expand...
Click to collapse
Hmmm...everything I've read has indicated that Lithium Ion/Polymer batteries can be left on a charger without damage since they have internal circuitry to prevent overcharging (although I realize a constant topping off is probably not wise in the long run). As for a charger with a higher output, I thought the stock charger was 2.1A....I've never heard of a 3A or 4A USB charger. Can you clarify what you mean?
Also, as I said, on the two occasions it has locked up, holding the power button has brought it back, so I'm not really asking about how to get it back if it locks up - I'm asking if the behavior (locking up, charge current not dropping to 0) is indicative of a battery that has faulty overcharge protection.
Thanks though!
The "charger" IC inside the N7 not only charges the battery but at the same time powers the device - it should allow use of a N7 with no or a faulty battery. I've never looked at the standby settings on the N7 but I would suggest that is where your 1W is going. The only info about the IC I know is http://www.summitmicro.com/prod_select/summary/SMB347/SMB347.htm
Added I think this is an identical TI version of the chip http://www.ti.com/lit/ds/slusaw5a/slusaw5a.pdf
peterk-1 said:
The "charger" IC inside the N7 not only charges the battery but at the same time powers the device - it should allow use of a N7 with no or a faulty battery. I've never looked at the standby settings on the N7 but I would suggest that is where your 1W is going. The only info about the IC I know is http://www.summitmicro.com/prod_select/summary/SMB347/SMB347.htm
Added I think this is an identical TI version of the chip http://www.ti.com/lit/ds/slusaw5a/slusaw5a.pdf
Click to expand...
Click to collapse
Thanks - that's good info. However, since I have been charging with the device off, it would seem to me that it shouldn't be drawing any standby current...unless just the act of charging puts the unit in a form of standby. It also still doesn't explain why my first unit went to 0A a while after charging completed, while this one doesn't. I'm now wondering if I may be looking at roundoff error. The resolution of the kill-a-watt is .01A - which is what I'm seeing. It could just be that both units drew some current after charge completion, but this one pulls marginally more.
So, my question still stands. Does anyone familiar with LiPo technology know if this sounds like my overcharge protection circuitry is faulty? Is it normal for a device that has completed charging to draw SOME current, and if so, how much? Would someone else with a Kill-A-Watt be willing to try this and let me know what you see?
Thanks again for the help guys...
Just in case anyone is still following this thread, I have some new info. I charged my N7 last night POWERED ON.....and after charging was complete, the AC current draw went to 0A. I'm starting to wonder now whether the 1.2W constant power I saw when charging powered off is the power needed to keep the charging circuitry alive while the tablet is powered off. When the device is powered on, maybe this circuitry is running off the battery allowing the AC draw to go to 0A. I have absolutely nothing to support this, so it's just a guess/hypothesis, but at least I know my N7 is behaving the same as my first one. I also loaded Simple Battery Logger while doing my last charge and all looks normal....it charged up to about 4.208V, indicated 'full', then the voltage start dropping off - which tells me that it stopped charging. It also maintained a temp of about 23C throughout the process. I'm running a battery test right now and it doesn't seem to have been damaged by my overnight charging episodes...if anything, the battery life is better than when I first got it.
I'm going to let it go here and assume all is well. If anyone does any experiments with theirs, I'd be interested in seeing the results.
Thanks again!
When I am at home using my laptop, I normally plug in the charging cable and take out the batteries. Now for some obscure reasons, I want to be able to do the same thing with NST (or any other eInk eReaders). Is it possible? If not, why not? Can we do something to make it a possibility?
This can be useful for instance for when I am at home... Whenever I know I want to use the NST in USB host mode (as an eWriter, Android tablet, gaming, playing music, GPS whatever), I'd like to take out battery and use it while directly plugged into wall charger or laptop usb port. Possible?
Why take out the batteries? They are doing no harm.
If you want to hang the Nook permanently on the wall, Ok.
If you patched u-boot.bin, you could get the Nook to boot without a battery.
You could also do hardware mods to the Nook to make it work that way.
See:
Curent drain on the Nook
Measuring battery current accurately
Nook Simple Touch - DOA Wont charge/turn on
Renate NST said:
Why take out the batteries? They are doing no harm.
If you want to hang the Nook permanently on the wall, Ok.
If you patched u-boot.bin, you could get the Nook to boot without a battery.
You could also do hardware mods to the Nook to make it work that way.
See:
Curent drain on the Nook
Measuring battery current accurately
Nook Simple Touch - DOA Wont charge/turn on
Click to expand...
Click to collapse
It was exactly that post of yours (and the other one you referred me to) which gave me this idea. It might be just emotional but I want to preserve my batteries as much as I can, when I am on wall charger, so I'll take batteries out. It's been mentioned that for Li-ion batteries you can safely leave batteries in while charging, but... oh well, me being me I guess!
I'm interested to know both how to do u-boot patching AND hardware modding for this purpose. I guess I have so much to read.
You're the man, oops, ehem... woman, dear Renate.
idoit said:
When I am at home using my laptop, I normally plug in the charging cable and take out the batteries. Now for some obscure reasons, I want to be able to do the same thing with NST (or any other eInk eReaders). Is it possible? If not, why not? Can we do something to make it a possibility?
This can be useful for instance for when I am at home... Whenever I know I want to use the NST in USB host mode (as an eWriter, Android tablet, gaming, playing music, GPS whatever), I'd like to take out battery and use it while directly plugged into wall charger or laptop usb port. Possible?
Click to expand...
Click to collapse
I assume you want to preserve your batteries. You will only affect this type of batteries life/effectiveness by constant charging at 100%. Even then it will take a long while to notice. Many newer laptops (last 3-4 years) will give you bios option to charge up to only 80%. This is the sweet spot for charging life.
That said leaving your battery in your laptop/nook gives you some serious benefits. The amount of power surges, brown outs and rf noise on power lines can seriously screw with your system. That click of turning a light switch on goes through to your computer. Ok motherboard will have some filtering etc but I'd still rather have a battery protecting me. As to brown outs and surges these can cause corruption. I get a lot of power cuts and I wish there was a minimum power off length. e.g. If power is disrupted it must be off for at least 2 seconds. This lets devices power off and then switch on. The problem is where power dips for 0.5 second. This is enough time to affect your system. Possibly affect contents of your active memory and harddrive cache. Your system keeps on running and slowly overtime gets shredded.
Bottom line how much does a battery cost? Any battery for laptop is going to be <£50. How much does your laptop cost?
As to a device bursting into flames if you use a third party battery or charger its a possibility otherwise very unlikely.
Crispy3000 said:
I assume you want to preserve your batteries. You will only affect this type of batteries life/effectiveness by constant charging at 100%. Even then it will take a long while to notice. Many newer laptops (last 3-4 years) will give you bios option to charge up to only 80%. This is the sweet spot for charging life.
That said leaving your battery in your laptop/nook gives you some serious benefits. The amount of power surges, brown outs and rf noise on power lines can seriously screw with your system. That click of turning a light switch on goes through to your computer. Ok motherboard will have some filtering etc but I'd still rather have a battery protecting me. As to brown outs and surges these can cause corruption. I get a lot of power cuts and I wish there was a minimum power off length. e.g. If power is disrupted it must be off for at least 2 seconds. This lets devices power off and then switch on. The problem is where power dips for 0.5 second. This is enough time to affect your system. Possibly affect contents of your active memory and harddrive cache. Your system keeps on running and slowly overtime gets shredded.
Bottom line how much does a battery cost? Any battery for laptop is going to be <£50. How much does your laptop cost?
As to a device bursting into flames if you use a third party battery or charger its a possibility otherwise very unlikely.
Click to expand...
Click to collapse
Thanks once again for your comprehensive well-thought-about response.
About the bottom line, you're absolutely right. I read somewhere that the most killing factor for laptop is heat and one part that heats up most is batteries. One of the reasons I took it apart was this. I have to admit that I'm not electrically knowledgeable enough to claim anything. Just trying to be as green and liberally conservative as possible.
By the way, worth a watch: http://www.youtube.com/watch?v=MD6AiWP2VsY
hey guys i bought my niece a 2012 nexus 7 it has the axus charge with different usb cable but it charge so slow
i was wondering if there is a rom with better charging speed
i havent root and is wifi version
What does "so slow" mean? As in, how many minutes to change 10% in charge?
One thing you can do to troubleshoot things is to see how long it takes to charge the tablet when it is completely shut off. It should be pretty obvious that "the ROM" has absolutely nothing to do with that scenario. Wait till the tablet is discharged to about 10%, shut it off, and charge it for 90 minutes. If it is charging normally it will be close to 70% charge when you boot it back up.
If your tablet charges slowly in that case, then there is a problem with the charger, cable, or battery in the tablet - not the ROM. So, you should surely check that out first before you start worrying about software.
A nominal N7 (2012, WiFi) will charge from 5% to 100% in about 150 minutes: 2.5 hours. That's with a STOCK ROM. If you look at the battery capacity, that works out to a minimum 1.73A charging rate. (4.325 Amp-hours / 2.5 hours = 1.73 A). It's actually higher than that because a certain amount of charging current is "lost" to heat generation while charging.
The tab will ALWAYS charge slower than that if it is in use, especially if the screen is on and the owner is doing things like streaming data or playing games. If it is under heavy use, the tablet itself could easily dissipating 1.0 A of current... so in that case the 2.5 hour charging time would be over twice as long: over 5 hours.
The "fast charge" ROMs are not what you are thinking. "fast charge" there means "fast charge under conditions normally restricted to low currents when data transfer is taking place". If you are using a charge-only cable (such as the OEM charger and cable), the tablet should always be able to draw close to 2A of current with ANY ROM - there is no data connection present, and the tablet is not restricted in the current it can draw.
The ROMs don't really throttle the battery charging rate except in that very specific condition: when there is a data connection present. So, worrying about which ROM is installed really only applies to people that want to use a Y-cable and a live USB data connection (tethering or an OTG gadget attached) - for instance in car installs or maybe with data tethering via USB.
good luck
bftb0 said:
What does "so slow" mean? As in, how many minutes to change 10% in charge?
One thing you can do to troubleshoot things is to see how long it takes to charge the tablet when it is completely shut off. It should be pretty obvious that "the ROM" has absolutely nothing to do with that scenario. Wait till the tablet is discharged to about 10%, shut it off, and charge it for 90 minutes. If it is charging normally it will be close to 70% charge when you boot it back up.
If your tablet charges slowly in that case, then there is a problem with the charger, cable, or battery in the tablet - not the ROM. So, you should surely check that out first before you start worrying about software.
A nominal N7 (2012, WiFi) will charge from 5% to 100% in about 150 minutes: 2.5 hours. That's with a STOCK ROM. If you look at the battery capacity, that works out to a minimum 1.73A charging rate. (4.325 Amp-hours / 2.5 hours = 1.73 A). It's actually higher than that because a certain amount of charging current is "lost" to heat generation while charging.
The tab will ALWAYS charge slower than that if it is in use, especially if the screen is on and the owner is doing things like streaming data or playing games. If it is under heavy use, the tablet itself could easily dissipating 1.0 A of current... so in that case the 2.5 hour charging time would be over twice as long: over 5 hours.
The "fast charge" ROMs are not what you are thinking. "fast charge" there means "fast charge under conditions normally restricted to low currents when data transfer is taking place". If you are using a charge-only cable (such as the OEM charger and cable), the tablet should always be able to draw close to 2A of current with ANY ROM - there is no data connection present, and the tablet is not restricted in the current it can draw.
The ROMs don't really throttle the battery charging rate except in that very specific condition: when there is a data connection present. So, worrying about which ROM is installed really only applies to people that want to use a Y-cable and a live USB data connection (tethering or an OTG gadget attached) - for instance in car installs or maybe with data tethering via USB.
good luck
Click to expand...
Click to collapse
thanx man now i get it it won charge fast like the note 3
i was playing fifa 14 and didnt charge at all it was loosing power
mrej201 said:
hey guys i bought my niece a 2012 nexus 7 it has the axus charge with different usb cable but it charge so slow
i was wondering if there is a rom with better charging speed
i havent root and is wifi version
Click to expand...
Click to collapse
Get a better cable. I was using a third party cable on my Nexus 7 for a while and realized it was only charging about 10-15%/hr.. Changed the cable out for a better one and it charges at the normal rate now, 30%/hr or so.
Do check for loose connections for both battery connector and usb ribbon connector (under speakers). I’ve opened the back cover to check after slow charging problems and was solved by opening and clipping back the usb ribbon connector. Charging's back to normal now.
http://androidforums.com/nexus-7-20...esting-while-diagnosing-charging-trouble.html
Lim Wee Huat said:
Do check for loose connections for both battery connector and usb ribbon connector (under speakers). I’ve opened the back cover to check after slow charging problems and was solved by opening and clipping back the usb ribbon connector. Charging's back to normal now.
http://androidforums.com/nexus-7-20...esting-while-diagnosing-charging-trouble.html
Click to expand...
Click to collapse
thanx bro
If your battery isn't charging properly, don't immediately assume your phone charger or your battery is broken.
Based on personal experience, the problem and solution may be much simpler than you think.
If your phone or tablet isn't charging properly or at all, take a look at these 12 ways to fix a phone that won't charge.
Why a phone doesn't charge
The problem occurs in various degrees. Either your phone won't charge at all when it is plugged in, or it will only charge very slowly (sometimes barely faster than it is discharging). It’s a very common complaint, so here are a few solutions.
1. Do-It-Yourself USB port fix
The quickest, easiest, and often most successful solution, is to do a little DIY repair on your actual hardware. The problem is often that the metallic surfaces inside the USB port and the micro USB charger are not making good contact, either through a manufacturing defect or because of the continual plugging and unplugging of the charging cable.
All you need to do is shut down your device, remove the battery if possible and use something small, such as a toothpick, to 'lever up' the little tab inside the USB port on your Smartphone or tablet. Do so very carefully and gently, then reinsert your battery and plug it in again. Nine times out of 10 this is all that is required.
2. Remove lint, candy and dust
Do you keep your phone in the pocket of your jeans? If so, lint could be the culprit: we've lost track of the number of times the reason for unreliable USB charging turned out to be lint from the pocket of our Levis.
We've seen phones with charging ports choked with chocolate after they were chucked in a handbag alongside a packet of sweets. A can of compressed air can blow out the offending irritants and get your USB connection back to normal.
3. Switch cables
The flimsiest part of a charger is the cable, not the adapter that plugs into the wall socket. Apple users are particularly vulnerable here because Apple's proprietary (and expensive) Lightning cables appear to have a life expectancy of around 15 minutes. But all cables have a tough life, and endless flexing and curling can take its toll. Substituting a random USB cable for the one that came with your phone is another shortcut to an unenjoyable charging experience.
The easiest way to diagnose a faulty cable is to try a different one and see if that works properly with your device. If it does, you know the original cable was at fault. If it doesn't, that's another potential villain we've ruled out.
4. Diagnose a dodgy adapter
If the cable doesn't seem to be the problem, check the wall plug adapter – especially if it's one where the charging cable can be removed. We've encountered issues in multiple chargers where the USB port becomes a little loose after endlessly plugging in and unplugging the cable.
Also check whether the same charger/cable combination works on a different device because this will help you eliminate the possibility that it is your device at fault, rather than the cable or charger. You should also make sure there isn't a problem with your wall socket.
5. Remember – safety first
Don't charge your phone near water or in excessively hot or humid conditions. Also, if you're replacing a charger or cable, be wary: the internet is stuffed with reports of cheap third-party chargers that went bang in the middle of the night or turned smart phones into toast. As with any electrical equipment, make sure that anything you buy complies with all the relevant safety standards.
To give you an idea of how much energy is stored in your battery, check this video out (but don't try it at home).
A previous version of this article warned users of charging devices overnight, but I want to clarify that this is not because you can overcharge your device. Modern smartphones have measures in place to prevent damage when batteries continue to be charged at 100 percent capacity.
That said, charging a battery does generate heat and, if a smartphone is in a tight space – like under a pillow or inside a case – there is a chance it could become too hot. Essentially, if you're going to charge your phone overnight, just make sure it's out in a safe place.
6. Replace the battery
Batteries don't last forever, and after a couple of years they start to struggle to hold a charge. The more often you discharge and recharge them, the sooner they'll need replacing. If your battery's busted after just six months, it's probably faulty and you should make a warranty claim for a free replacement, but if the battery's older than two years, it's probably approaching the end of its lifespan.
Some defective batteries are easy to spot because they start to bulge or leak fluid. If nothing like that is obvious from the outside, remove your device's cover and inspect the battery (if you can; some devices have sealed battery compartments).
If the cover doesn't come off, you could try laying the device on its back and spinning it. A bulging battery will deform the case – you might not be able to see this bulge, but it might be enough to allow your phone to spin. If you suspect your battery might be swollen or leaking, get your phone to a repair shop and buy a reputable replacement.
7. Charge from the right source
Charging from a wall socket will always be faster than charging via PC or laptop, because computers' USB ports don't deliver very much power. A wall socket can deliver twice as much power as a USB port, and fast chargers it can deliver as much as five times the power – which means much, much faster charging. So if your phone is charging slowly and you're connected to a laptop: there's your problem.
If your wall charger doesn't appear to be delivering the goods, check that it's appropriate for your device. A charger from another phone might not deliver the right amount of juice — for example, a charger for a Bluetooth headset won't put out as much power as one designed specifically for smart phones. In the case of recent high-end phones, you might have a phone that supports fast charging but a charger that doesn't deliver it. Read the fine-print.
8. Update or roll back
Software updates and new Android versions can wreak havoc with your battery life, especially when upgrading an old device to current software. Newer devices are often optimized to take advantage of the latest software, whereas a two-year-old device can struggle when it gets updated.
If this happens to you and you can't troubleshoot the problem, consider rolling the device back to an earlier Android version; though be warned that this carries security risks. The latest software versions are always recommended to keep your device protected, and while the risk of keeping your smartphone on an older version is often negligible, it’s worth noting.
Similarly, sometimes device battery life can be significantly improved by an update, so if you think you might be way behind on your Android software version, head to Settings > About phone to check for an update.
9. Switch it off
Using battery-intensive apps/features while you are charging your device will affect how quickly it gains battery life. If you are charging while Skyping somebody at 100 percent brightness, the device will naturally take longer to charge than it would with its screen, Wi-Fi and 4G turned off.
Switch the device to airplane mode, or off completely, when you are charging if you want to see the fastest energy injection. Think of it making your device take a power nap.
10. Calibrate your battery
Sometimes the battery level your device 'thinks' it's at is wrong. The effect of this is that your phone may function differently, including limiting performance before it needs to or taking an hour to chew through the last two percent of battery.
We’ve already written an extensive guide on how to calibrate your Smartphone battery, so I won’t retype it all here, but this is a thing to try before completely ditching your defunct power pack.
11. Check your battery pack's voltage and amperage
This tip was pointed out in the comments below by Patrick and it can help you quickly identify a defective cable. Download the free Amperage app from the link below and open it. Now, connect your charger and the interface should go green and the text at the top should say "measuring". If you don't see this, or nothing happens, it means there is no current going to your device.
If it identifies a current, the app will now show the charging statistics for that charger, including the minimum and maximum load levels (in milliamps), voltage and maximum current. This is also a great way to find out which of your chargers is performing best.
Try connecting the different charge packs you own, including portable battery packs, to see which has the highest maximum charge value, or the highest average (the app makes it fairly easy to get an idea of this). It's not an exact measurement but it's an indication if nothing else and the app is completely free.
12. What about water damage?
A number of people in the comments asked about battery problems caused by water damage. If your phone fails to charge after falling in water you don't have many options: your best bet is to try and replace the battery – if that's even possible.
You should, however, try to prevent this from ever happening. Read our article explaining what to do when you drop your phone in water to find out the first steps you should take when trying to rescue it.
If all else fails, double-check that you have the power point switched on. That is the first thing they will ask you if you call your manufacturer for help, which might need to be your next step if none of these solutions has worked for you.
This guide is not specific for Honor 5X. This is for all mobiles.
Hi,
i use a Nook Simple Touch as typewriter with an usb-keyboard,
which works great thanks to the usb host mode app, or, automated:
an old version of tasker with a plugin to deactivate charging and activate hostmode ( and fastmode...) via shell command after booting.
The problem is, this mode drains the battery really fast,
and charging while using the keyboard, so nececessarily with OTG cable attached, is a bit of a pain in the neck,
because there is only 1 possible sequence of actions how you can enable charging with more than around 100 mA (which would be way too low in this case) while the keyboard is active,
which requires a 16k resistor between GND and ID pin, rebooting, temporarily disconnecting some wires via switch, tapping around etc etc,
(and also does not work well when the nook is completely off ),
so i decided to leave the usb port exclusively for the keyboard,
an remove the internal battery an replace it with a external big 7000mAh or so 1S li-ion pack,
which is charged externally with a lipo module
(while charging, the nook is powered by an ac adapter, power source switching is realised with a relay and a really big capactior to avoid any more complicated possibly failing electronics)
which works great and is very easy to handle,
BUT i really dont like li-ion batterys of any kind because of the fire hazard,
nimh eneloop cant be used because charging in parallel is not a good idea,
so i would like to use lifepo4 chemistry instead,
which has a working woltage between around 3 and 3,6 volts,
but the nook powers down at around 3,65 volts.
A boost/buck converter isnt possible because as the battery drains, the voltage must sink slowly for the nook to make a normal shutdown
and not crash, damage the file system etc, (and also a converter drains quite much battery even if the nook is completely off.)
Question: it would be VERY kind if anyone who has a clue about this could share his opionion on that:
is it possible (if the hardware itself can handle it) to lower the android/nook shutdown voltage to about 3 volts with some rom/software modifications ?
threshold not treshold
Wow, this all seems a bit complicated.
I had never heard of this 16K resistor stuff.
As far as I could tell, the ID pin is only sensed high or low..
Unless I'm mistaken the OMAP3621 ULPI registers only indicate high/low.
The TPS65921B (which is the actual PHY) list 90K as the typical break point.
Of course, there could be a circuit completely external to the ULPI/PHY.
Where did you find out about 16K?
Changing the voltage of everything seems the difficult way to go.
You'd have to modify uboot as well as the charger daemon.
A note: The USB charge pump is pretty inefficient, 55%.
If you were to load the USB to the maximum speced 100mA with a 3V battery, it would be drawing 303mA from the battery!
5V × 100mA / 3v / 55% = 303mA
Oh, you got me confused with your two posts.
When you were talking about ID and 16K did you mean the ID on the battery pack or the ID on the USB OTG?
Renate NST said:
Where did you find out about 16K?
Click to expand...
Click to collapse
wired a 50k pot between gnd and id pin,
in the usb mode app tapped "host" and watched if the led goes an stays on,
if not, lowered the resistance, tried again etc,
as soon it stayed on (at 16k at my device ) used this value as permanent fixed resistor.
with that otg mode keyboard use is possible,
but also at the same time the nook doesnt really believe its in otg mode so charging with 500mA is possible,
if done in this order:
- feed 5v to the + - of the usb cable
- reboot (not always required)
- remove an reinsert usb plug
- hit "host" 2 times, keyboard works and charging with around 500mA works (measured it)
but charging doesnt work when nst ist powered off,
and automount of the keyboard at startup via shell is not possible,
and cable acrobatic is required,
and as you say, usb charging is inefficient.
the other solution with an external battery (at the nst batt terminals) with external charging logic with a relay is a much easyer way,
but depends on a li-ion cell because of the 3,7-4,2 voltages the nook can use,
a lifepo4 ( or 2s li titanate + diode) would be safer and has more cycles but would require the nook
to work with 3 to 3,7 volts, which seems too complicated, changing demons etc whatever that is...
after some research it seems its not really an issue, the newer sanyo/panasonic, samsung, sony, lg powertool/ebike cells seem to be quite safe, as far as youtube shortcircuit etc tests demonstrate.
thanks for the orientational infos
Renate NST said:
Oh, you got me confused with your two posts.
When you were talking about ID and 16K did you mean the ID on the battery pack or the ID on the USB OTG?
Click to expand...
Click to collapse
sorry, i should have used one thread, i suggest ignoring the other one,
where the only request was if the nook battery terminals can survive up to 5v,
here was the request if the nook can be modified to accept at the battery terminals a voltage down to 3v and stay on.
so 3v too complicated, 5v too dangerous,
so i stick with the relay and the li-ion cell, no problem, i was just curious if an improvement would be easily possible.
the battery id resistors have nothing to to with all that, 10k and 30k work fine,
i meant the 5 pin micro usb otg connector, not shorted zero ohms as usual, but 16k.
(but thats obsolete now)
another observation: in some thread you mention you charge the nook while using an usb keyboard,
i tested it and with a normal otg cable, and the usb mode app set to 500 mA oder 1,5 A,
and a 50% charged normal internal battery,
the device draws around 250mA, and the battery gets charged very slowly, or not at all, depending on cpu usage etc.
and if the battery reaches 100% , it continues to draw around 250 mA, which is strange,
because when using a normal, non-otg usb cable,
the device draw only around 100mA when the battery had reached 100%,
so the difference must be used for heating purposes somewhere or overcharge the battery,
which might be a reason for swelling lipos.