Database Develop

Charging NC for longest battery lifetime

( meaning how many months before the battery loses storage capability, as opposed to "battery life" - how many hours until you run out of juice )
There are a lot of battery/charger threads, and some bright person actually looked up the TI charger circuit documentation, but I don't see anyone who has looked up what a li-ion battery needs to have a long lifetime.
So, I found information at:
http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries
Interesting tidbits:
- Charging to 100% means that you can use the device longer the next day, but is not necessarily best for the battery itself. Frequent partial charges are just fine, and are actually better for the battery.
- It seems to be particularly important for Li-ion battery charging to be turned off when you get to 100%. The LED turning green in the NC cable shows that the system is taking care of this (so you can safely charge overnight without damaging the battery).
Connecting the NC to another system that does not stop applying current at 100% charged seems to definitely be a bad idea. So, don't use any system overnight, that the NC does not recognize as "charging".
This indicates that charging from a laptop USB may "work" but may be bad long-term for the battery. Here it depends on whether the TI charging circuit is sophisticated enough to adapt to the non-standard condition. Since the charging indicators do not indicate "charging" then the answer may be "no", and while you are getting the battery charged up, it may not be in the best way. (This seems to be an area for more research about the actual NC charging system.)
- The critical part is to not use a USB cable or other charging system that is not recognized by the NC, when the NC is close to 100% charge, to make sure that it doesn't overcharge the battery. As the article states:
Li-ion cannot absorb overcharge, and when fully charged the charge current must be cut off. A continuous trickle charge would cause plating of metallic lithium, and this could compromise safety. To minimize stress, keep the lithium-ion battery at the 4.20V/cell peak voltage as short a time as possible.
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- So, in summary, I think that a different brand of charger is okay as long as the NC recognizes it as "charging", and one should avoid charging in situations where you are "fooling" the NC by charging the battery when the NC is not noticing.

I honestly had no clue about this lol, thanks!
This might save a lot of headaches with "bad batteries" in the long run.

Thanks for this! Very interesting.

Well said, ADude. I'm so used to having to go onto forums and set people straight on the "myth's" of battery charging, but you hit it right on. The most important thing to remember is that overcharging drains your battery life (but most modern tech has auto off, in which it goes into a low power mode that allows for a stable current to just keep it around 99%), there is no benefit to letting your nook (or any other device) die completely before charging again, as there is not benefit to charging fully (or not charging fully) in the long run.
Thanks again!

LiIon likes being charged early and often... Don't run it down to 20-30% every time, it'll only shorten the overall battery. If it's down to 40-50% at the end of the night, put it on the charger.
Mine lasts 3 or so days before it gets near 40%.

Deciphering the Nexus 7 Automatic Input Current Limit (for chargers)

For the time being this is going to be in Accessories, but eventually it might get moved to Development as I get even more data. It's borderline at the moment.
It's been known for a while that the Nexus 7 is finicky about power supplies. In addition to the usual requirements for a power supply that complies with the USB Battery Charging Standard (D+ and D- shorted by the supply), which makes it VERY hard to find good supplies as most use Apple's nonstandard convention - The Nexus 7 seems to be VERY finicky about supplies which drop their voltage under load. Samsung tablet supplies will charge the N7 faster than the stock supply.
The charger controller chipset in the N7 is a Summit SMB347, same as found in a number of Samsung tablets. No datasheet is available for this chipset, but we do know it has an Automatic Input Current Limiting (AICL) feature - If the power supply "browns out", it will reduce current demand until the supply voltage raises to above the trip threshold.
Previously, I only had the ability to measure battery input current using CurrentWidget, but the top of my Christmas wishlist was an adjustable bench power supply. It has adjustable voltage AND an adjustable current limit - so I can limit the current delivered to the N7 and determine what voltage it settles at. If the voltage kept bouncing between two values, I recorded the voltage as the halfway point. E.g. if it bounced between 5.1 and 5.2, I recorded it as 5.15.
A picture of my setup is at:
https://plus.google.com/u/0/101093310520661581786/posts/gkbHaKKDnj6
Components:
Sinometer HY3005D from Mastech (Adjustable bench supply, 0-30v 0-5A)
22 gauge solid wire (the best USB cables I've seen are only 24 gauge - lower gauge = thicker wire)
Sparkfun MicroUSB breakout with D+ and D- shorted
Here are the results (Bear with me as I try to figure out how to properly format a table here on XDA... The HTML tag doesn't work as expected...):
HTML:
<table border="1">
<tr><td>Amperage Limit</td><td>Voltage</td></tr>
<tr><td>1.85</td><td>5.15</td></tr>
<tr><td>1.80</td><td>5.0</td></tr>
<tr><td>1.70</td><td>4.9</td></tr>
<tr><td>1.60</td><td>4.9</td></tr>
<tr><td>1.50</td><td>4.8</td></tr>
<tr><td>1.40</td><td>4.8</td></tr>
<tr><td>1.30</td><td>4.7</td></tr>
<tr><td>1.20</td><td>4.7</td></tr>
<tr><td>1.10</td><td>4.6</td></tr>
<tr><td>1.00</td><td>4.55</td></tr>
</table>
Below 1A, I think the tablet goes into a more severe AICL mode - it will drop to around 600-650 mA, the power supply will exit current limiting (back up to 5.1 volts), and current will not go up until the device is unplugged and replugged.
One observation here - If the voltage drops 0.2 volts, you lose 400 mA of charge current. Many previous efforts here put an ammeter in series with the power supply - many ammeters drop 0.1-0.2 volts under load! The ammeter used by those previous effort was having SIGNIFICANT effect on the results.

Reserved - future analysis of how various chargers behave under load. Do they REALLY meet their ratings?
May be posted in Hardware Hacking and linked from here instead.

Reserved for work on trying to change the SMB347 AICL behavior.

Even if the amperemeter drops 0.1-0.2 V under various loads, you can stick a voltmeter after the amperemeter (i.e. parallel to the device only) and you should have a pretty accurate reading of the voltage on the device alone since voltmeters are pretty high impedance. And to compensate for the loss, just increase the supply voltage a bit.

Entropy512 said:
Stuff.
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Click to collapse
I think you may be trying to read too far into this.
I charge my Nexus 7 off of a generic 2A/5V X4 output charger, and off the stock charger, and off the woman's kindle fire charger, and off a 2A car adapter. All of it works just fine.
I think the real problem comes from people using chargers that aren't able to produce enough current (thus the voltage drop you're trying to measure for). But honestly, this tablet lasts incredibly long on a charge, and takes almost no time to get back to 100%. Aside from if you're using it in your car as a long term audio/gps/hspa unit, all at once, why even bother taking out your meter?
TLDR: Buy a charger that is rated for 5V, 2A, and go back to having a good holiday instead of trying to measure it. Granted, I understand you're interested in finding out the how's and why's, but I haven't found any issue with charging the Nexus 7 on any charger I own, because I only buy ones that are rated for 2A or above draw. I won't get out the Fluke to test what it's pulling on each one, but it seems to charge very quickly on all of the above. 1%-100% in the time it takes me to not care, anyways.

bladebarrier said:
I think you may be trying to read too far into this.
I charge my Nexus 7 off of a generic 2A/5V X4 output charger, and off the stock charger, and off the woman's kindle fire charger, and off a 2A car adapter. All of it works just fine.
I think the real problem comes from people using chargers that aren't able to produce enough current (thus the voltage drop you're trying to measure for). But honestly, this tablet lasts incredibly long on a charge, and takes almost no time to get back to 100%. Aside from if you're using it in your car as a long term audio/gps/hspa unit, all at once, why even bother taking out your meter?
TLDR: Buy a charger that is rated for 5V, 2A, and go back to having a good holiday instead of trying to measure it. Granted, I understand you're interested in finding out the how's and why's, but I haven't found any issue with charging the Nexus 7 on any charger I own, because I only buy ones that are rated for 2A or above draw. I won't get out the Fluke to test what it's pulling on each one, but it seems to charge very quickly on all of the above. 1%-100% in the time it takes me to not care, anyways.
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Except that many chargers, even the ONE THAT COMES WITH THE DEVICE, aren't capable of delivering 5v 2A even if they may claim to do so. They may be capable of 4.8v 2A - but as the data I've taken shows, a charger that can only do 4.8v 2A will only charge the N7 at 1.4-1.5 amps. If the charger drops to 4.7v under load, it'll drop to only 1.2A or so.
More data (taken using CurrentWidget):
Idle load with screen at max brightness: 500 mA drain reported by CW
Current entering battery when screen at max brightness: 900-950 mA with stock Asus charger, giving approx. Since system drain under these conditions is 0.5A, that gives 1.4-1.45A into the device, consistent with a charger that is dropping to 4.8v under load.
Current entering battery with a Samsung Galaxy Tab charger: 1300 mA, giving a total of 1.8A into the device (almost the maximum the device will pull given a solid stiff rail)
Current entering battery with the power supply used in the tests above: 1330 mA, giving a total of 1.83A into the device (power supply itself reported 1.86 in this state).
The stock Asus charger that ships with the device underperforms by 400 mA when used with this device. Many "2.1A" chargers underperform even more (I'll run some tests with the Scosche reVIVE II later, but if memory serves me correctly, it's more appropriately rated 1A...)

gokalp said:
Even if the amperemeter drops 0.1-0.2 V under various loads, you can stick a voltmeter after the amperemeter (i.e. parallel to the device only) and you should have a pretty accurate reading of the voltage on the device alone since voltmeters are pretty high impedance. And to compensate for the loss, just increase the supply voltage a bit.
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Click to collapse
Yup. If I didn't have a bench supply with an adjustable current limit, I could've done this. Problem is even a few tenths of a volt difference makes a significant current difference - it's easier to adjust the current limit if you've got a supply that allows it.

Entropy512 said:
Except that many chargers, even the ONE THAT COMES WITH THE DEVICE, aren't capable of delivering 5v 2A even if they may claim to do so. They may be capable of 4.8v 2A - but as the data I've taken shows, a charger that can only do 4.8v 2A will only charge the N7 at 1.4-1.5 amps. If the charger drops to 4.7v under load, it'll drop to only 1.2A or so.
More data (taken using CurrentWidget):
Idle load with screen at max brightness: 500 mA drain reported by CW
Current entering battery when screen at max brightness: 900-950 mA with stock Asus charger, giving approx. Since system drain under these conditions is 0.5A, that gives 1.4-1.45A into the device, consistent with a charger that is dropping to 4.8v under load.
Current entering battery with a Samsung Galaxy Tab charger: 1300 mA, giving a total of 1.8A into the device (almost the maximum the device will pull given a solid stiff rail)
Current entering battery with the power supply used in the tests above: 1330 mA, giving a total of 1.83A into the device (power supply itself reported 1.86 in this state).
The stock Asus charger that ships with the device underperforms by 400 mA when used with this device. Many "2.1A" chargers underperform even more (I'll run some tests with the Scosche reVIVE II later, but if memory serves me correctly, it's more appropriately rated 1A...)
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Interesting.
Are you getting the same readings when the device is turned off, to ensure there isn't a possible software issue? Is this purely on the stock ROM/kernel, or are you using a custom one?
With the Droid X, there were some concerns that it was unable to charge a fully discharged battery if not on a stock ROM, because Moto implemented measures in the "bloat" that allowed it to do so when it would normally not be capable in pure Android. I remember people having to cut wires to charge batteries externally, if they ran out of juice while trying to flash a ROM that was not Moto based. The whole concept seemed absurd to me, yet that was clearly the case. A dead Droid X could charge normally, if on the Moto software, but could not charge at all, if on AOSP if the battery was completely discharged prior to the attempt.
Just throwing out some ideas. I don't have your level of equipment to test it out at home, but I could take mine into the EE lab and see what one of the students can discern.
Is it possible that some of this is because of the pogo connection, and that may not be sorted out well enough, as such causing complications to the circuit?
EDIT: What is the accuracy of Current Widget? I tried it on my Nexus 7, and it was reporting some absurd numbers that didn't appear to be accurate. I would be charging at normal speed, and it would show me as discharging. The Nexus 7 would go back to 100%, and the whole time it would read as if I was losing power. I uninstalled it, figuring there is a compatibility issue with either JB or the device.

bladebarrier said:
Interesting.
Are you getting the same readings when the device is turned off, to ensure there isn't a possible software issue? Is this purely on the stock ROM/kernel, or are you using a custom one?
With the Droid X, there were some concerns that it was unable to charge a fully discharged battery if not on a stock ROM, because Moto implemented measures in the "bloat" that allowed it to do so when it would normally not be capable in pure Android. I remember people having to cut wires to charge batteries externally, if they ran out of juice while trying to flash a ROM that was not Moto based. The whole concept seemed absurd to me, yet that was clearly the case. A dead Droid X could charge normally, if on the Moto software, but could not charge at all, if on AOSP if the battery was completely discharged prior to the attempt.
Just throwing out some ideas. I don't have your level of equipment to test it out at home, but I could take mine into the EE lab and see what one of the students can discern.
Is it possible that some of this is because of the pogo connection, and that may not be sorted out well enough, as such causing complications to the circuit?
EDIT: What is the accuracy of Current Widget? I tried it on my Nexus 7, and it was reporting some absurd numbers that didn't appear to be accurate. I would be charging at normal speed, and it would show me as discharging. The Nexus 7 would go back to 100%, and the whole time it would read as if I was losing power. I uninstalled it, figuring there is a compatibility issue with either JB or the device.
Click to expand...
Click to collapse
I can only confirm CW works properly on CM10. It is completely nonoperational in stock (as the code was disabled), and they did something in that area in 4.2 that I haven't taken a look at yet. I know the voltage value was off by a factor of 1000 in stock 4.1.
As to software issues - there are none other than whatever nonvolatile defaults are preprogrammed into the SMB347. If you look at the SMB347 driver for grouper you'll see that it does almost nothing in terms of configuring current limits and such, relying on the internal NV defaults. (Very different from Kindle Fire and Note 10.1, which perform quite a lot of configuration of the chip, not relying on internal NV defaults.) I've seen people report similar behavior on multiple kernels and firmwares.
Based on the Kindle Fire sources, there is at least one AICL setting that can be tweaked. However after looking at them further, I think that's the one that hits when the power supply droops to 4.5 volts. The question is whether the charger circuit is doing limiting before hitting that severe AICL threshold. When I get back from my holiday I'm going to try changing the threshold to 4.2 volts to see how things behave.

Entropy512 said:
I can only confirm CW works properly on CM10. It is completely nonoperational in stock (as the code was disabled), and they did something in that area in 4.2 that I haven't taken a look at yet. I know the voltage value was off by a factor of 1000 in stock 4.1.
As to software issues - there are none other than whatever nonvolatile defaults are preprogrammed into the SMB347. If you look at the SMB347 driver for grouper you'll see that it does almost nothing in terms of configuring current limits and such, relying on the internal NV defaults. (Very different from Kindle Fire and Note 10.1, which perform quite a lot of configuration of the chip, not relying on internal NV defaults.) I've seen people report similar behavior on multiple kernels and firmwares.
Based on the Kindle Fire sources, there is at least one AICL setting that can be tweaked. However after looking at them further, I think that's the one that hits when the power supply droops to 4.5 volts. The question is whether the charger circuit is doing limiting before hitting that severe AICL threshold. When I get back from my holiday I'm going to try changing the threshold to 4.2 volts to see how things behave.
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You're way above my pay grade.... Yet I'll speculate further.
If it's hardware based, to drop the amperage draw, based on a voltage drop, and can be replicated in CM, then it could be an intentional protection circuit in the Lion battery itself. There are many Lion batteries that use protection circuitry these days, yet I don't know of anyone using aftermarket replacements for the Nexus 7, and so testing it could very well be basing the tests purely on the battery itself.
Maybe try running the tests directly to the battery, removed from the Nexus itself, and that will at least exclude the software and the hardware of the Nexus.
I could crack open the body and check the manufacturer, but if it's Panasonic or Sony, there's a reasonable chance that there are built in circuits on the Lion itself.
If you get identical readings, while running leads directly to the battery, the issue will be known immediately. If you don't, we can rule out one of the three options (battery, hardware, software). And you already ruled out most of the software.

bladebarrier said:
You're way above my pay grade.... Yet I'll speculate further.
If it's hardware based, to drop the amperage draw, based on a voltage drop, and can be replicated in CM, then it could be an intentional protection circuit in the Lion battery itself. There are many Lion batteries that use protection circuitry these days, yet I don't know of anyone using aftermarket replacements for the Nexus 7, and so testing it could very well be basing the tests purely on the battery itself.
Maybe try running the tests directly to the battery, removed from the Nexus itself, and that will at least exclude the software and the hardware of the Nexus.
I could crack open the body and check the manufacturer, but if it's Panasonic or Sony, there's a reasonable chance that there are built in circuits on the Lion itself.
If you get identical readings, while running leads directly to the battery, the issue will be known immediately. If you don't, we can rule out one of the three options (battery, hardware, software). And you already ruled out most of the software.
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No way it's the battery itself. If you ran straight 5v into a LiIon/LiPo battery you'd blow it up (unless the protection circuitry kicked in). Running 5v straight into even a protected LiIon is an extremely bad idea.
It's something in how the SMB347 behaves - http://www.summitmicro.com/prod_select/summary/SMB347/SMB347.htm - Unfortunately there is no public datasheet, just a 1-2 page "product brief" with little detail, other than it does have some sort of automatic input current limiting. The SMB347 is the chip responsible for charging the battery safely, and basically anything related to charging the battery in the N7 is within that chip. Understand that chip and you understand everything about charging the N7.
The only technical detail we have about this chip resides in kernel source code for devices with the same chip - Samsung Note 10.1 and Kindle Fire both have a 347, and unlike the N7 which appears to use nonvolatile defaults burned into the chip, these devices touch the chip's registers. The KFire source has some info on how to change one of the AICL configurations.

Entropy512 said:
No way it's the battery itself. If you ran straight 5v into a LiIon/LiPo battery you'd blow it up (unless the protection circuitry kicked in). Running 5v straight into even a protected LiIon is an extremely bad idea.
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Without a doubt!
I would never suggest someone use the method for normal charging. You would have to be capable of limiting the current, and be very careful, if testing in that manner.

I don't know how useful this comment will be, since there's no technical data, just empirical evidence, but I've used a friend's Nexus 7 charger several times on my Xperia S, that has fast charging enabled by default, and it charges noticeably faster than the charger that was packed with it (850 mA).
So, I'm inclined to think the culprit is the SMB347 chip.

FenrirMX said:
I don't know how useful this comment will be, since there's no technical data, just empirical evidence, but I've used a friend's Nexus 7 charger several times on my Xperia S, that has fast charging enabled by default, and it charges noticeably faster than the charger that was packed with it (850 mA).
So, I'm inclined to think the culprit is the SMB347 chip.
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Click to collapse
It's the SMB347 combined with the power supply. The PS is drooping a little bit (not significantly), and the SMB347 is being exceptionally finicky about the droop.
Supplies that don't droop (Samsung Tab chargers - FYI, the Note 10.1 also has an SMB347) are OK, that supply is likely OK with less finicky devices.
Next on my project list:
While the setup used here (22 gauge sold wire that is only a foot or so long) is ideal for eliminating voltage drop in the USB cable, I need to whip up a "universal charging adapter" between my bench supply and a female USB port that uses Samsung tablet resistances (which are also OK for most standard devices). That way I can see how my Note 10.1 behaves with a current limited supply.
A power supply tester - PWM out of an AVR microcontroller into an adjustable constant current load, ramp up the current draw and monitor the supply voltage with the uC to get an output I/V curve for various supplies.

current widget
My apologies for reviving such an old thread, but I have been searching for information about how the nexus 7 charges and why of acts so different with different chargers. Your posts have been very informative. I have found that my Verizon car charger will charge my nexus considerably faster than any other charger I have, including the one which came with the tablet.
I am curious to know how you were able to use current widget on this device. I am running cm10. Which kernel has support for current widget so that I may flash it? I am using battery widget for the time being and while of does give me a rough estimate, I would really like a real time reading.
Thank you for your time.

Crystawth said:
My apologies for reviving such an old thread, but I have been searching for information about how the nexus 7 charges and why of acts so different with different chargers. Your posts have been very informative. I have found that my Verizon car charger will charge my nexus considerably faster than any other charger I have, including the one which came with the tablet.
I am curious to know how you were able to use current widget on this device. I am running cm10. Which kernel has support for current widget so that I may flash it? I am using battery widget for the time being and while of does give me a rough estimate, I would really like a real time reading.
Thank you for your time.
Click to expand...
Click to collapse
I actually stumbled on an answer myself.
Franco Kernel r65 for 4.2.2 on CM 10.1 Provides battery current information =)

Here's what I've learned from a hardware perspective...
Posting this in a few places hoping it stimulates an answer to the problem....
We're working on a hardware + firmware + software product that uses an Android tablet, which right now is specifically the Nexus 7. We have found that the standard charge rate of the battery is insufficient to support tablet operation with a few sensors enabled and high screen brightness. Therefore, even if plugged in to a power source, the Nexus 7 discharges during normal use. The charging system cannot keep up with normal power requirements. That is a TERRIBLE hardware design decision.
Rather than guess at what is happening, or jump to conclusions based on various apps that claim to report current, we connected an actual ammeter (current meter) in line with the USB cable plugged in to a 2012-era Nexus 7 and ran a lot of experiments to characterize its behavior.
A few basic things to keep in mind:
* The current rating on a power supply/charger is the max current that device can provide. The device being charged controls how much current is actually drawn from the supply. A higher-current charger cannot, simply by virtue of its higher capacity, force more current into the device.
* USB hardware specs very clearly define the max current that a Portable Device (PD, in this case an N7) can draw from various power sources. Earlier posts in this thread properly referred to the names of the various types of ports including the one that we need, a Charging Downstream Port (CDP), which supports both data and higher charging current. A CDP uses certain voltage levels on its D+ and D- pins to signal the availability of greater current; a "dumb charger" can just short the two data pins together to signal the same thing, but obviously this won't work if you also want to pass data and not just charge the battery. (The "shorted data pins" trick is a documented way to let cheap chargers inform the PD of higher current capacity without having to add intelligence to the charger.)
* USB software specs also define how the PD can negotiate with the upstream port (in our case, a CDP), essentially letting the N7 specify how much current it wants to draw and letting the upstream port respond with approval or disapproval. In this case, the hardware does its thing, and then the software on both ends talks back and forth to agree on a (potentially higher) current rate.
I'll cut to the chase: The N7 never draws more than 440mA. Ever. With any charger, with any cable, with any combination we've tried. This includes the Asus-labeled 5V 2100mA OEM charger and the Asus-labeled OEM cable that came with the tablet. We really, really want it to, but we have not been able to figure out how to convince it to use more current (and thus stop draining the battery while plugged in). Yes, I've read the other comments in this thread that report higher currents and I don't know how to explain what they're seeing. But in a laboratory environment, with real test equipment run by Engineers, 440mA is the number.
On the hardware side, our product has a dedicated 5A 2000mA+ power supply for the N7 connection. This is really clean power - it's a little switching power supply with great filtering that powers nothing but the USB connector. An oscilloscope shows an absolute flat line, no ripple, no noise, nothing, even under load. We have tested its current output capacity and it goes well beyond 2000mA with no degradation of the voltage level nor quality. This power is as clean as its gets. The power is there if the N7 wants it.
On the software side, the N7 does in fact do the "USB software negotiation" for current and we tell the N7 that 2000mA is available. Nevertheless, the N7 always requests 500mA (we've captured and analyzed the USB data), and in reality never draws more than the 440mA mentioned above.
We cannot short D+ and D- since we need to communicate with the N7. But there are other tricks supported by the USB spec, including specific voltage levels on the data lines to indicate that the port to which the N7 is connected is a CDP. Briefly, a PD which takes advantage of a CDP first performs "primary detection" by looking at D- for 0.4-0.8VDC. If a voltage in that range is found, "secondary detection" causes the PD to apply voltage to the D+ pin looking for a pulldown resistance of (nominally) 19.5K.
So we added circuitry to provide this environment, thus indicating we are a CDP. Result: No change at all. The N7 draws 440mA with or without the CDP circuitry.
We kept at it for a long time, because we thought it strange that Asus would ship a 2100mA charger when a 500mA charger would suffice. We figured that was proof the N7 could charge at a higher rate. But after hours and hours of analysis, testing, experiments, etc. we were forced to conclude that the N7 simply never draws more than 440mA. Presumably its onboard charging circuitry cannot handle higher current rates. This is a real shame, because it means the Nexus 7 cannot be used in kiosk mode - it cannot run indefinitely when plugged into external power. It will always require some "down time" to recharge its battery. That's fatal to a lot of applications for this tablet, including ours.
We have not yet tested a 2013 N7, but we're hopeful it has a better charging circuit.

SpokaneNexus said:
We cannot short D+ and D- since we need to communicate with the N7. But there are other tricks supported by the USB spec, including specific voltage levels on the data lines to indicate that the port to which the N7 is connected is a CDP. Briefly, a PD which takes advantage of a CDP first performs "primary detection" by looking at D- for 0.4-0.8VDC. If a voltage in that range is found, "secondary detection" causes the PD to apply voltage to the D+ pin looking for a pulldown resistance of (nominally) 19.5K.
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Click to collapse
I never saw this particular post of yours until trying to find this old post of mine.
N7 does not support CDP (Charging Downstream Port) detection. Few Android devices do. (N7 2012 most definitely does not, and I'm fairly certain N7 2013 doesn't either). If it sees a downstream port, it assumes it's an SDP (Standard Downstream Port) with 500 mA current limit. This is a fundamental requirement of the USB standard - don't pull more than 500 mA from a host unless you support CDP detection and detect a CDP.
N7 does support DCP (Dedicated Charging Port) detection. N7 will ABSOLUTELY pull more than 500 mA from a DCP (this includes the wall supply) when D+ and D- are shorted.
If you want to communicate with the device and supply more than 500 mA, you need either a device that supports CDP detection (rare) or you need to violate the standard. This can be done with kernel modifications that override the current limit when an SDP is detected - this is usually a HORRIBLE idea but is acceptable in a specific case like yours. (Some kernel hackers refer to this as "USB Fast Charging").

Sorry for posting on an old thread, but it is still an issue, and i am determined to find a fix.
I bought a thick 20awg cable, and that seems to do the job, but i don't use my n7 enough to see if it really does.
You referenced the kernel a few times in reference to the chip that controls the charging.
I was wondering if it would be possible to modify kernel sources to change the way the chip behaves, although i dont have many hopes, because i imagine it would have already been done
i was thoroughly engaged in this issue, and even resolved to build my own dock, and bought the pogo pins, but have never used them!
Even if there isn't a way the change the chips behaviour, i was wondering if there was another workaround on the kernel/software side, as i am certainly up for the job, even though not very able as a developer, and always needing to be pointed in the right direction.

[PSA] First Charge out of box is important for battery init

For those that experience long first charges, the first-charge charging time MAY be intentional.
I couldn't figure out why USB-500mA was taking so long to charge my phone, and wondered if the charging circuit wasn't correctly detecting the current rating (500mA) of my computer's USB. Charging shouldn't have taken more than 5 hours.
It took 20.
I'm getting ~>6hr screen on time now/charge and USB-500mA charging is snappy-- 3-5 hours or so. (albiet turned off all syncs except contacts and a few apps, app quarantine on facebook/drive/etc, and calibrated Lux for indoor lighting at 13-15% up to 150 Lux or so; and 1% for 0 Lux (at night); and Faux123's 003b3 kernel clocked at 1.6ghz and EcoMode and Snake Charmer ON in FauxClock (faux kernel control app).
TL;DR: the charging circuit wants the first charge to be slow. Don't worry if it takes long. It won't always take this long. Just for the first charge.

rancur3p1c said:
FYI, the first-charge charging time taking a super long time is actually intentional.
I couldn't figure out why USB-500mA was taking so long to charge my phone, and wondered if the charging circuit wasn't correctly detecting the current rating (500mA) of my computer's USB. Charging shouldn't have taken more than 5 hours.
It took 20.
I'm getting ~>6hr screen on time now/charge and USB-500mA charging is snappy-- 3-5 hours or so. (albiet turned off all syncs except contacts and a few apps, app quarantine on facebook/drive/etc, and calibrated Lux for indoor lighting at 13-15% up to 150 Lux or so; and 1% for 0 Lux (at night); and Faux123's 003b3 kernel clocked at 1.6ghz and EcoMode and Snake Charmer ON in FauxClock (faux kernel control app).
TL;DR: the charging circuit wants the first charge to be slow. Don't worry if it takes long. It won't always take this long. Just for the first charge.
Click to expand...
Click to collapse
i find it funny that you think the "charging circuit" knows when it's "the first time" :laugh:

altezza2k2 said:
i find it funny that you think the "charging circuit" knows when it's "the first time" :laugh:
Click to expand...
Click to collapse
why?

rancur3p1c said:
why?
Click to expand...
Click to collapse
firstly, the first time you go to plug in your phone to charge is not the first time it has been charged. it has been turned on and off multiple times during production. also, i don't know about you but my phone came charged 90%. how did that happen?
secondly, it's extremely improbable that extra circuitry was put in place to limit the charge rate just for the the first time charge. if for whatever reason they wanted to limit the first charge, it would be done in production with production equipment.
which brings me to my last point...what is the benefit of rate limiting the first charge cycle?

TL;DR
Phone normally charges at 1.2A, you feed it 0.5A it's going to take more than twice as long to charge.
Simples....

altezza2k2 said:
firstly, the first time you go to plug in your phone to charge is not the first time it has been charged. it has been turned on and off multiple times during production. also, i don't know about you but my phone came charged 90%. how did that happen?
secondly, it's extremely improbable that extra circuitry was put in place to limit the charge rate just for the the first time charge. if for whatever reason they wanted to limit the first charge, it would be done in production with production equipment.
which brings me to my last point...what is the benefit of rate limiting the first charge cycle?
Click to expand...
Click to collapse
hmm good thoughts. My phone came at 45%, which is right in line with what you should store a Lithium cell at, hence the start of my theory. Presumably, the cells get partially charged at the factory or are simply made that way-- have to be, because they won't recharge if they drop below 2.9-3v or so, charge has to start somewhere. 90%, probably not made that way though.
I doubt they have a lineup of USB-micro chargers at a dust/lint-free factory doing the charging for us, which lends credence to the notion they are _installed_ charged/factory conditioned.
Factory testing, would probably only take 15 minutes on the phone, if they even test everything (probably just basic stuff).
extra circuitry-- nothing extra physically besides the charging chip, the charging circuit for lithiums requires ability to sense charge current, because that's how you know when to stop charging (i.e. all lithium chargers have to be intelligent). So then you simply have to have a single 3-state flash or eeprom byte that starts at FF (programmed from chip factory), is initialized once to 0 on powerup in the chip (not android or even firmware, lower) code iff it's FF, and then gets written to "1" after the charging circuit gets shut off.
first charge cycle-- because if I thought they were doing it, I could see why they would (chemically). I guess they're not, so maybe I can't anymore. In theory, I could see why it COULD be good, something along the lines of running the car hard the first 1500 miles to ensure the piston seals wear/bed properly to the cylinder.

Charging through USB to your computer is always slower though. It was not intended to make the first charge slower and your battery results are mostly a result of your customizations.

rancur3p1c said:
FYI, the first-charge charging time taking a super long time is actually intentional.
I couldn't figure out why USB-500mA was taking so long to charge my phone, and wondered if the charging circuit wasn't correctly detecting the current rating (500mA) of my computer's USB. Charging shouldn't have taken more than 5 hours.
It took 20.
I'm getting ~>6hr screen on time now/charge and USB-500mA charging is snappy-- 3-5 hours or so. (albiet turned off all syncs except contacts and a few apps, app quarantine on facebook/drive/etc, and calibrated Lux for indoor lighting at 13-15% up to 150 Lux or so; and 1% for 0 Lux (at night); and Faux123's 003b3 kernel clocked at 1.6ghz and EcoMode and Snake Charmer ON in FauxClock (faux kernel control app).
TL;DR: the charging circuit wants the first charge to be slow. Don't worry if it takes long. It won't always take this long. Just for the first charge.
Click to expand...
Click to collapse
Just a warning to anyone reading this thread... ALL OF THE CHARGING INFORMATION IN THE OP IS COMPLETELY UNTRUE
It really makes no difference how you charge the phone, especially so for the first charge. The phone's systems will detect when the battery is at full capacity and stop charging as necessary. So nonsense like the OP makes absolutely no difference, as it simply stops charging once it reaches 100%. The reason your phone charged slow, is simply that USB provides (as has already been said), a much reduced current compared with the wall-socket chargers.

rancur3p1c said:
I could see why it COULD be good, something along the lines of running the car hard the first 1500 miles to ensure the piston seals wear properly in the cylinder.
Click to expand...
Click to collapse
You are comparing mechanical and chemical things here. like comparing wind and wave. Both can push things but driving force is absolutely different.

hmm..
im getting 5.5-6 hours screen on time without charging it at all when i just got it. and its first charge took just under 3 hours.

undercover said:
TL;DR
Phone normally charges at 1.2A, you feed it 0.5A it's going to take more than twice as long to charge.
Simples....
Click to expand...
Click to collapse
lol

undercover said:
You are comparing mechanical and chemical things here. like comparing wind and wave. Both can push things but driving force is absolutely different.
Click to expand...
Click to collapse
yes, different.
simms22 said:
hmm..
im getting 5.5-6 hours screen on time without charging it at all when i just got it. and its first charge took just under 3 hours.
Click to expand...
Click to collapse
that's interesting.

Dan1909 said:
Just a warning to anyone reading this thread... ALL OF THE CHARGING INFORMATION IN THE OP IS COMPLETELY UNTRUE
It really makes no difference how you charge the phone, especially so for the first charge. The phone's systems will detect when the battery is at full capacity and stop charging as necessary. So nonsense like the OP makes absolutely no difference, as it simply stops charging once it reaches 100%. The reason your phone charged slow, is simply that USB provides (as has already been said), a much reduced current compared with the wall-socket chargers.
Click to expand...
Click to collapse
nope, not completely untrue just mostly untrue.
I take most of it back though.
It's possible the ultra long charge was because I didn't have a SIM in, constantly running radio looking for service?

The engine burn in is an old wives tale as well. The engines are all tested at high rpm the same as transmission before final assembly. No need to drive hard when it is new unless you want your transmission to learn your aggressive shift patterns!
Sent from my Nexus 5 using Tapatalk

rancur3p1c said:
nope, not completely untrue just mostly untrue.
I take most of it back though.
It's possible the ultra long charge was because I didn't have a SIM in, constantly running radio looking for service?
Click to expand...
Click to collapse
Not having a SIM in wouldn't cause that effect. It'll still be connected to a network, as it has to allow emergency calls, it simply won't be allowing you to make/receive any calls/data/texts. It was just a slow charge as it was over USB, rather than the full power chargers.

Dan1909 said:
Not having a SIM in wouldn't cause that effect. It'll still be connected to a network, as it has to allow emergency calls, it simply won't be allowing you to make/receive any calls/data/texts. It was just a slow charge as it was over USB, rather than the full power chargers.
Click to expand...
Click to collapse
but nothing else explains a 20h charge. That's 10000mAh at 500mA/hr (USB). I checked the CPU state and it was 300mhz the whole time-- same as every night. Except now, it only takes 3-5hrs to charge (on the same 500mA usb slow charging)
maybe the battery did need conditioning... - .-

rancur3p1c said:
but nothing explains a 20h charge. That's 10000mAh at 500mA/hr (USB). I checked the CPU state and it was 300mhz the whole time-- same as every night. Except now, it only takes 3-5hrs to charge (on the same 500mA usb slow charging)
Click to expand...
Click to collapse
To be honest (and I don't mean to sound rude here, just explaining my thinking), I don't really believe that happened. It seems highly unlikely, and goes against pretty much everything about the way the batteries work. This is assumign the USB port was actually putting out the full 500 mA, and that the phone wasn't having any kind of extra drain at all (which wouldn't be that unusual on a new phone).
Even if for some strange reason the battery did take an exceptionally long first charge, it was just a random occurrence probably due to a minor error in your battery. That doesn't mean that all first charges will or need to take that long.

Elisha said:
The engine burn in is an old wives tale as well. The engines are all tested at high rpm the same as transmission before final assembly. No need to drive hard when it is new unless you want your transmission to learn your aggressive shift patterns!
Sent from my Nexus 5 using Tapatalk
Click to expand...
Click to collapse
really? that's weird. why do they say the exact opposite in the service manual (stay under 4k RPMs for the first 5-10k miles) if they've already broken it in? I saw some pics on a site from a guy who had people send him their 200k mile pistons and compared between those given the hard drive from day 1 vs. the soft drive break in method per manuf. spec. Those that were driven hard on purpose for the first 500 miles or so still had immaculate piston seals and zero carbon blowby/leakage. Maybe he was cherry picking results but the theory sounded good-- why else would they cross bore the cylinder? Might as well drive hard to help the piston seal as well!

of you are using your device when plugged into the usb, many times itll drain more battery juice than will be brought in. there are even live wallpapers that you can have running while plugged into tbe usb, and watch the battery drain right before your eyes. plus each usb device thst you have it plugged into could charge the device differently, some barely let a trickle in.

Dan1909 said:
To be honest (and I don't mean to sound rude here, just explaining my thinking), I don't really believe that happened. It seems highly unlikely, and goes against pretty much everything about the way the batteries work.
Even if for some strange reason the battery did take an exceptionally long first charge, it was just a random occurrence probably due to a minor error in your battery. That doesn't mean that all first charges will or need to take that long.
Click to expand...
Click to collapse
well, I will say that I can swear it happened because I plugged it in at ~8pm and it wasn't done the next day till like 5pm or something.
Only remaining theory (this actually makes sense more I think about it), is perhaps got confused and thought I was on USB 100mA. I was using a semi flakey USB cable that sometimes seem to have trouble detecting my phone is attached in Windows. Maybe that's what it was.
Additionally, the next day my battery exhibited some very peculiar discharge curves. After using for >5m screen on and turning the screen off, the battery % would rise about 3-5%. Additionally, I think I managed about 7 hours screen on time after that charge lending credence to my theory that slower charge curves store more energy.
Hm. I think I will try this again.

Teclast x98 air The still ongoing problems (and an ongoing hardware investigation)

So... like most of you, i have at least one problem with my teclast x98 air tablet, version C9J8, running only windows (8.1 pro/10 preview).
At this time i've constantly encountered the following problems:
- not turning on after being shut down. Pressing the power button doesn't do nothing. Sometimes it does this while charging, at the end of the charge, othertimes it... simply won't power on.
- huge battery drain in stand by. I've flashed ALL (yes... all) dual boot/single boot air/air 2 BIOS files i could get, in all versions. If it's got a .bin extension... yes, i've flashed that too. No change AT ALL!
- huge batterty drain... when powered off !?!?! Yes, that's the next level of awsomeness. You know your tablet is special when it sometimes discharges faster when turned off compared with it turned on. (@XDA, guys .. can you please add some facepalm smiley/emoji.. i wanted to use it about 30 times since i got this tablet)
- sudden shutdowns. Like when you use your tablet it simply dies in your hands with no apparent reason.
- battery meter stuck at 7% and only 1 cell reported. NOT fixed by the methods already known (flashing BIOS and letting it discharge then recharge with tablet turned off).
So.. i'm pissed off. I've disassembled the damn thing in search for some answers. I'll by posting some photos with the guts of this thing (c9j8 version).
First of all, I wanted to check the power draw directly from the battery, so i've desoldered the positive wire from the battery and inserted an amps meter to check the current flow.
For example, the stock charger will supply around 1.5-1.9 amps to the battery when charging (tablet off). For comparison a small 5V 1A, samsung charger supplied 1.1 amps in the same setup. Some other interesting facts, when on and booted to windows - the tablet draws about 1.1-2.2 amps (mostly depending on screen brigtness and cpu load). That's a total of 4-11 watts. If you lower the brigtness from full to low (bottom third of the slider) you effectively half the power consumption. As usual the display consumes more then 50% of the total power being drawn. Those who complain about huge power drain on standby will be surprised to know that the tablet draws 0.3-0.8 amps (it fluctuates) in standby. That’s HUGE. It should be 0.03-0.05 amps at MAXIMUM. 0.3 amps multiplied to a 3.8volts cell is 1.14Watts draw per hour at minimum in my case.
Leaving that aside, let's return to the above problems. The battery is connected to the motherboard by using a 3 wire connection (positive, ground and data bus/i2c or similar). The motherboard itself doesn't feature ANY protection/power management chip aside from a single ROHM controller located under a metal shield. Even if some data is passed between the battery and motherboard, you can simply decouple the battery and power the tablet with regular 18650 lithium cells or 3 AA alkaline batteries in series. The tablet is stupid enough not to notice any difference.
Let's go more deep in the start-up sequence.
When you press the power button, a half a second 500mA ramping to 800mA load is registered. The power management chip measures the voltage drop under that load and if it deems it to be "acceptable" it passes power to the rest of the motherboard. BIOS/firmware takes over from there but does a measurement of its own. If it results in an "ok" the boot sequence can the follow. If not, the BIOS would then power off the tablet. Here lies the first problem. The power management chip and BIOS thresholds for a "low voltage" battery are different. Very different. The chip itself considers the battery voltage to be ok if it's above about 3.45-3.5 volts and not dropping lower then 3.3v under a 500-800mA load. The BIOS/firmware (or whatever software part does this) won't accept a measurement below 3.65v. volts. So, when you pass the BIOS stage and boot to windows, the data you get when checking your battery comes from the power management chip. If you fully discharge the battery in windows (down to 2-3% or similar) and you are able to shutdown the tablet by yourself (it doesn’t cut power by itself) you could find that it cannot power back again because even if the power management ic gives the go ahead, the bios/firmware side refuses to go any further. The battery must be charged for some time before the bios will allow for booting.
The problem is that both power management IC and BIOS readings should be taken in same way and be of similar value. They are not. It’s not that Teclast couldn’t do this, but for whatever reason they decided to write the BIOS in that way. The 7% problem could originate in the fact that a what the BIOS considers a dead battery (0%) is actually charged to a degree and is different from 0% measured at the power management chip level. Overall the power readings are inconsistent in both measurement and reporting. It doesn’t seem to be a hardware problem.
Another problem is how „dumb” is the battery management hardware. In any modern portable computer (laptops, tablets, even phones – excluding some chinese products) you cannot simply disconect the data bus from the battery and simply feed some random 3-4 volts to power the thing. It’s like you would remove the battery from your laptop, check the label on it for the voltage rating and stick a bunch of wires on the contacts (2 of them) and expect the thing to boot. It won’t. Firstly because IT’S NOT SAFE. The battery or motherboard can’t report one to another if a fault is occuring and can’t accurately measure voltage/current consumption.
Yet another problem is that the same power circuitry does not compensate for large voltage/current swings. A simple experiment for you folks to try. Get a aa battery (a battery in general) measure it’s voltage as it’s sitting still then connect a small lightbulb/motor/led/whatever load runs on that battery and measure the voltage WHILE the battery suplies current to the load. You will find a voltage drop at the battery level. It’s normal, is how these things run. A complex electronic device must take that into account in it’s design. At idle/browsing web/viewing picture, the tablet draws about 1.1 amps from a battery that’s registering 3.87volts (at that test’s time in my case). Running a benchmark/video game produced a series of spikes to 2 – 2.1 amps and an aditional voltage drop to around 3.61 volts. Remember that some power rails require exact voltages (cpu core, main bus, 5volt usb bus etc). The power circuitry must provide those exact voltages regarding the input voltage swing. Noup... and that’s the main problem untill now. THEY DONT! I was shocked to see how the chinese engineers are pushing it right on the edge. If you desolder one battery pin and insert an ampere meter in series, that’s enough to induce the little voltage drop needed for the tablet to freeze under load or shut down alltogether. The ampere meter leads were rated to withstand 10 amps under load – and they do, yet the simple fact you inserted a piece of wire along the track is enough to disturb an already delicate balance. The thing is only barely capable of whitstanding it’s own battery voltage swing. In my opinion you can try to reduce the load by disabling turbo modes on cpu/gpu or whatever (and teclast tried with some bios/models of the x98 air) but you cannot fix this by firmware. It’s just bad hardware design. They cut costs on the power management side.
Those are my finds untill now. I’m thinking of adding some capacitance over the power rails to take the load over from the batteries when a large amount of current is drawn (spikes that occur under load). Other then that, there is not much to do about this.
Even so, i don’t know why the tablet still draws power while turned off. I wasn’t able to make it do that while measuring. Aditionally i don’t know why only one cell is reported in windows. More tests are required.
This is still an ongoing "project". Some of my conclusion could be wrong at this stage. Like i've said it's still a work in progress. It would be quite a thing if anyone with some knoledge about the BIOS code (or how it runs on this tablet) could step in and direct me to the right hardware to examine.

here are some photos with the guts of this tablet
As you can see, the C9J8 at least has some metal shield above the cpu area and some crappy thermal compound over it. Some older models lacked the metal shield.
Next we have the battery wires and their link to the motherboard. As you can see, left to the 3 wires there are 4 brown devices, mounted in parallel. Those are capacitors. Like i've said above I'm thinking of adding some aditional capacitance to further help the motherboard compensate for the voltage drops registered on high load scenarios. The chinese guys thought of that, added the 4 caps but deemed them enough. Noup, that's just barely doing it. In fact the whole design is made to a price point, that's to be expected.
For easier probing, I've disconnected the red positive wire, and added a piece of wire of my own, one end to the battery red wire the other to it's coresponding pad on the motherboard. At the end of my wire, i'm probing in series with an ampere meter.
And for the sake of it, here's a photo with the registered power consumption with the tablet on. 1.11 amps x 3.8 volts = 4.21W total power being drawn. Actually that's pretty good. I remember the days i was probing a htc hd2 for some cpu related problems. While doing a benchmark at full brightness that device draw a maximum of 5.5 W. Due to the recent advancements, now we see a tablet drawing only 4.2W (admited, it's not on full load, but the screen is also much larger).
Anyway let's get back to our problems.
1. The high power drain when the tablet was off can be solved in the same way as fixing the reported battery capacity. Like previous guides made, you need to fully discharge the battery and then charge for 8 hours with the tablet OFF (don't turn it on). I had to do this 2 times to get the thing to work.
2. 7% battery and 1 cell reported. Like i've said in my first post, i've tried to let the battery discharge and then recharge while turned off. It never work. However, after desoldering the battery wires from the motherboard and then soldering them back (power was cut off from the motherboard during that time) now after my first attempt to discharge/recharge the battery, the capacity and number of cells are reported correctly for the first time since i've had this tablet. I now have to discharge the tablet again to see if it will get stuck at 7% again but at least i get the capacity reported like it should.
2. The shutdown/freeze under load. This thing ocured to me several times in the past but for whatever reason the tablet doesn't do that anymore. Arghhh.... Anyway, if anyone has this problem and knows how to reproduce it in windows (i'm only running windows now) please do tell me in order to test some solutions to it. My first try is to add some capacitors over the main power rail. If this will work, i'll then design a capacitance multiplier circuit using some transistors since there is not enough space in the tablet to simply add capacitors.
3. High standby drain. In my best scenario, the tablet draws 0.3 to 0.5 amps in standby and that's huge. I've tried disconnecting various devices on the motherboard but all that power goes into the cpu area. It has to do with the cpu core voltage and stand by states. The cpu is simply not sleeping deep enough. However that should be fixable with a bios update if teclast should decide to bother with that. One problem though, it seems not all tablets have this problem. But since it's located in the cpu area, if it should be a hardware fault there is no practical diy fix for that.

Just to confirm, you have tried the 2.02 BIOS that was released with the Lollipop beta a few weeks ago? Several people have reported that this BIOS solved the Windows standby battery issues. I've avoided flashing it myself because many people have also bricked their tablets.

Edited post..
I did tried that, no change. I'm close to fixing my particular problem. I'm now at about 1% per hour.
I'll keep testing meanwhile.

this seems allot like my issues with a C5J6, mostly unstable while charging or shortly after charging, also restart/shutdown is a hit and miss, most of the times I need to hold the power button for 10 seconds after I do reboot/shutdown and start the tablet again.
I'm trying to contact the seller (got it from banggood) but they want a video, should not be that hard but I dunno what they can do about obvious design flaws.
Do you think you can ever get the tablet stable yourself? (I'm not completely sure it's part Windows issues or not)
btw, I only use Windows as I was not interested in another android tablet.

I also just picked up a X98 Air 3G from GearBest, it's the C5J6 version. I just ran into the battery charge stuck at 7% in windows. I'm going to try clearing hibernation data, turning off hibernate while low (powercfg -setdcvalueindex SCHEME_CURRENT SUB_BATTERY BATACTIONCRIT 0) and then fully draining (manual) and letting it charge while off overnight.
I'm very interested in what you have been finding, I would be more than willing to help out if you need any assistance. I have a mutli-meter, soldering iron and a desire to get this thing working like it should. It bugs the hell out of me that it has these silly problems. My Bios version is 5.6.5 with a BIOS build date of 1-16-2015.
Could this have something to do with the Intel Power Managment drivers? Does this 7% problem still continue under Android? I suppose I need to do more testing myself.
HWINFO shows 14432 Designed Capacity (half) current capacity is 1007 mWh (7.0%) current voltage 3.784 V
It's been working fine under Windows for the last week, I dont really use Android much though I will likely try RemixOS sometime soon. I was considering blowing out all the partitions (BTW is there a map of all the partitions and their functions/contents?) and going with straight Windows 10 Pro when its full final version is out.
Is there a list of all hardware revisions and their release date and changes/logs? C5JG,C9J8, wtc......) the naming convention seems to have no real correlation to revision date huh?
PS: I also have been getting forced hibernation under heavy load/heat. I wonder if switching to another version of Windows will change anything? Anyone have the 7% issue and shutdowns under Win7?

Hello liquidmass. The 7% problem happens for me in both windows and android. I haven't figured out what to blame but the hardware side "knows" how to measure the actual charge level, it's just that the reporting part is all wrong or the software is poorly written (BIOS, mostly).
Funny though, all my initial problems seem to have vanished. I cannot figure out why since i can't make the tablet to do those bugs again. The single most probable thing it could have made any difference was the fact that i desoldered the battery wires and short circuited the pads on the motherboard (all 3 of them together) during some initial testing. Since I cannot make the tablet to shutdown under load I can't test a capacitance multiplier circuit over the power rail in order to check for improvements. The damn thing just works now.
Yet, the battery gauge still is broken and since i don't know the software side of these things i cannot figure out why. I can let it discharge completely and it would work fine for some time but it will occur again and so i would have to do it again and so on. I guess i can live with that...

motoi_bogdan said:
Hello liquidmass. The 7% problem happens for me in both windows and android. I haven't figured out what to blame but the hardware side "knows" how to measure the actual charge level, it's just that the reporting part is all wrong or the software is poorly written (BIOS, mostly).
Funny though, all my initial problems seem to have vanished. I cannot figure out why since i can't make the tablet to do those bugs again. The single most probable thing it could have made any difference was the fact that i desoldered the battery wires and short circuited the pads on the motherboard (all 3 of them together) during some initial testing. Since I cannot make the tablet to shutdown under load I can't test a capacitance multiplier circuit over the power rail in order to check for improvements. The damn thing just works now.
Yet, the battery gauge still is broken and since i don't know the software side of these things i cannot figure out why. I can let it discharge completely and it would work fine for some time but it will occur again and so i would have to do it again and so on. I guess i can live with that...
Click to expand...
Click to collapse
I'm trying to figure out the 7% bug as well but I don't think it has anything to do with software. I might try and open it up to de-solder the battery wires and short the mainboard pins (if anyone else does this, make sure you do disconnect the battery and don't short the wires of the battery!!)
The shutdown under load might be my issues as well, but the most annoying thing probably is that reboot or shutdown don't work most of the time, it will just hang in a state that requires me to press the power button for 10 seconds and start it up again (with shutdown this isn't always obvious until you try and turn it on again)
I kinda hope things get a bit more stable with windows 10, else it's quite an expensive paperweight to be honest.

Hello,
I have several months a X98 Air 3G with id: C5J6. After two weeks I try install thunderbird and windows 10 collapse. I send several mails at Teclast with very little result. Such things as brushing in the language Chinese. After a while I try to reinstall windows via the UBS. After that my tablet has a black screen. I try to send the tablet back to china but that’s no option. I have experience that its never come back. With the USB flasher CH341A and a flash cable I flash the WINBOND 25Q64FW on board after disconnecting the battery. When I read it is flashed. So far so good? After loading with 5 volt and connecting the battery my tablet stays black. Now I put it in the box and put it far a way and buy something else. Never again in china.

My x98 is been stuck at 0% battery it wont turn on or charge...
I've disassembled the tablet and charged the battery externally, still not working. Any sugestion?

Hello, we have encountered similar problems with the Teclast Air III not turning on. Did you conclude anything?

Larterptx said:
My x98 is been stuck at 0% battery it wont turn on or charge...
I've disassembled the tablet and charged the battery externally, still not working. Any sugestion?
Click to expand...
Click to collapse
u should cut the red wire in the battery.. wait 5 minutes to reset then again solder the wire..
I encountered the same problem and above solution worked for me

I turned my tablet off last night and plugged the charger in. The tablet already had maybe 60 or 70 percent charge. This morning it wouldn't turn on or charge. I tried the above and desoldered battery etc but no luck. The charger is putting out 5v. The battery only read 0.05v. And when on charge it reads 0.38v. It's my battery dead and needs replacing it is It another problem.

Same problem not turning on after battery fully drained in win8, please help

The advice I found somewhere to check power management on drivers seems to have stopped power drain in standby (windows 10). in particular Sound controller>realtek I2S Audio Codec>Power management>untick "allow device to wake computer"
Now the thing doesn't drain too badly. Before the rapid drain also lead me to the power on issue which I can now 'solve' by getting a charge in before it drains.
Alos, needs at least 2.1amps charger to fire up after draining.
Still get that uncertain feeling as to whether it will turn on or not!, but the last week or so has been fine.

I can confirm the power drain issues. Our Chinese friends made no effort in stabilizing the power line.
I'm using my AIR 3 as a home automation / wall tablet. Because it was unstable as hell I disconnected the the battery-print from the battery, and connected a laptop charger (4.62a) with buck down converter to it. With some tinkering I made Android believe the battery was 100% full and always charging. This made it much stabler, but still every 2 days, it just dies on me. Keep in mind this is a wall tablet, the screen goes off, only wifi is at full-performance wake-lock. So it's doing absolutely nothing, ice-cold to the touch, and still dies in the middle of the night. It's not logging errors anywhere, so I suspect a hardware problem.
Pondering what to do because the tablet is already flush mounted and I would need a different tablet with the exact screen dimensions.
Absolutely no more Teclast for me...

Has anyone modded the Teclast X98 to work without battery. Plugging a cable directly to the battery connection inside?
I see someone used a laptop charger, but I dont have one. Is it possible to use a regular USB charger?
I just bought a new battery and even with it the drain is absurd. This tablet has become unusuable.
Sadly Teclast is absolute garbage

Dear friends....Be careful with this company....their items is totally un- trustworthy..After sales support is terrible, they dont respond to emails messages etc and generally they dont care about their customers....this is not only my opinion, read the XDA forum about teclast products...Too bad for this company. Try to find what you looking for to another brand.....https://forum.xda-developers.com/x98-air/general/teclast-warning-buy-t3161767

I have air 3g model C5J8, It is working quite well, but with 2.5 A power charger when working with both OS's on it, batery is draining, It means that it is impossible to work with tablet longer than 7-8 hrs even with power charger connected, Is it normal in this model?

I tried using the tablet without battery with a 3.1 amp usb charger, but the Air III powerpeaks are to much for it to handle.
Now with a laptop charger of 4.62 amps, it's mich stabler, but it still dies on me...
Teclast = crap. Don't waste your money on it.

Question about quick charge

Hello,
I have a few questons about my nokia 8 and quick charging.
I haven't had a phone that supports it before, so i'm not sure about how it's meant to behave. I've been reading mixed reports that the charging icon changes or a message pops up on the screen to say its quick charging. I haven't seen this on my phone. Does the nokia 8 have any indication it is quick charging?
I've also read varying people accounts on when it quick charges. Some say that phones will quick charge between 0 - 70%, is that true? I've also read people say that it only works when the screen is off?
I've just ordered a certified quick charge 3.0 charger, so will do testing when it arrives, but I thought the one in the box was meant to be QC 3.0 compatible?

The one that comes in the box is qualcomm qc 3.0 and the one you ordered should support qualcomm qc 3.0 also in order to work.
Indeed the phone quick charges only between 0-80% which is reasonable cause above this the battery should be charged at a lower rate in order to achieve maximum capacity, lower temperatures, better battery health and more charging cycles in it's life, because Lithium batteries "love" to be charged slowly (with low and constant current) and in low temperatures, not above 40°C for sure.
On your device now. Quick charging is heavily depended on software as well as hardware. So when your device is hot for some reason (heavy use etc) it will not quick charge and will charge regularly instead, in order to protect and avoid high temperatures in the battery.
On the other hand when your device is cool and your battery is bellow 80% when you plug and leave it for a few minutes, when you wake your screen, at the bottom of your lock screen it should display "Rapid Charging" at some point. But this can change in just "Charging" if the software detects that your device starts getting hot. In order to achieve constant "Rapid Charging" between 0 and 80% i would advise that you charge your device without a case and on a heat conducting surface (metal etc).
From my measurements and those things on mind my device charges from 0 to 100 in about 1 hour 50 minutes.
Although it should be mentioned that for better battery health you should never leave your battery drain bellow 25-30% and full charging to 100% is not to be preferred due to lithium ion battery behaving nature at very low and very high voltages.
So a great charging habit would be to keep your battery always charged between 30 and 90% and when charging your device be sure that it sits nice and cool and nothing is stoping it from dissipating the heat, that is generated from charging the battery, to the environment.
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