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.
Click to expand...
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.
Click to expand...
Click to collapse
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.
Click to expand...
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...)
Click to expand...
Click to collapse
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.
Click to expand...
Click to collapse
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.
Click to expand...
Click to collapse
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.
Click to expand...
Click to collapse
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.
Click to expand...
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.
Click to expand...
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.
Related
Simple widget that shows power draw from a charger in mA. There is an update button on the widget, you can set auto refresh intervals and record logs.
- download zip in third post
- extract APK to SD root
- install
- apply widget.
Thanks to rm9, pgwipeout and Orel Bob, for creating the orginal Nexus one version. link
Thanks to ytj87 for finding the file to read and TDO for show the Nexus Version of the Widget link.
Last but by no means least, thanks to grennis for moding the app to work with the vibrant.
(see next post)
Here ya go... the file is attached.. enjoy!
I think you will need to first uninstall the current one, if you have it. I could not sign the apk with the same key the author used since he did not make it available (rightly so)
I think there is actually a bug in the APK, it should be handling this situation, but it's using a slightly wrong filename. I contacted the author already.
Grennis. thanks will change title of thread from think tank.
Works for me. Thanks. Please note that for the Vibrant it looks like the current displayed in the file is 2x the actual. Few data points to support it right now, but it makes sense (e.g. USB number ~800 in file, measured around 400mA).
See here - http://forum.xda-developers.com/showpost.php?p=8009138&postcount=73
Showing 854mA from my PC. 1022mA from the wall & 1050mA from my truck (generic BB charger).
So, 427mA, 511mA & 525mA respectively?
-bZj
down8 said:
Showing 854mA from my PC. 1022mA from the wall & 1050mA from my truck (generic BB charger).
So, 427mA, 511mA & 525mA respectively?
-bZj
Click to expand...
Click to collapse
Here are some real numbers (the 2X is close, but not quite)
Batt_chg_current: 1102
Measured: 600ma
Batt_chg_current: 814
Measured: 450ma
1.8X actual current equals Batt_chg_current is more like it.
http://forum.xda-developers.com/showpost.php?p=8006129&postcount=6
so it is half of what the widget actually shows just to clarify.
Yes, but it is not the widget's fault.that is the actual value stored by samsung. Other phones may use this value too and display it correctly or samsung may fix it later.
Sent from my SGH-T959 using XDA App
DaSmittyman said:
so it is half of what the widget actually shows just to clarify.
Click to expand...
Click to collapse
It depends how accurate you want to be. Actual measurements show more then half by a decent amount.
So let me get this straight. My 1a charger which the widget reports as 1100 is putting out 1/2 of it's rated ability. The 1a charger in my car that is being reported by the widget at 860 is wrong as well? I have tested two other chargers and the widget is reporting the charger's rated output +/- 100mAh. So are all my chargers rated output all wrong?
KerryG said:
So let me get this straight. My 1a charger which the widget reports as 1100 is putting out 1/2 of it's rated ability. The 1a charger in my car that is being reported by the widget at 860 is wrong as well? I have tested two other chargers and the widget is reporting the charger's rated output +/- 100mAh. So are all my chargers rated output all wrong?
Click to expand...
Click to collapse
Nope. 2 things determine how much current a phone uses.
1) The maximum rated output current of the charger. If the phone pulls more, then the charger will only output to the max rated current.
2) The phone will only pull what it is programmed to. There is typically a built in regulator circuit (could be in SW, HW, or a mix). In the case of the Vibrant it looks like it is around ~600mA which is based on the measurements folks have taken with 1A chargers. There is a reason why Samsung provides a 700mA charger for the Vibrant.
This all assumes that Samsung hasn't messed up with the batt_chg_current file value. The only sure way to measure what the phone is pulling is to get a proven >1.2A charger and hang a digital multi-meter in series and measure the current.
sfsilicon said:
Nope. 2 things determine how much current a phone uses.
1) The maximum rated output current of the charger. If the phone pulls more, then the charger will only output to the max rated current.
2) The phone will only pull what it is programmed to. There is typically a built in regulator circuit (could be in SW, HW, or a mix). In the case of the Vibrant it looks like it is around ~600mA which is based on the measurements folks have taken with 1A chargers. There is a reason why Samsung provides a 700mA charger for the Vibrant.
This all assumes that Samsung hasn't messed up with the batt_chg_current file value. The only sure way to measure what the phone is pulling is to get a proven >1.2A charger and hang a digital multi-meter in series and measure the current.
Click to expand...
Click to collapse
Additionally, charging a battery without destroying it, or causing degradation is a science too. You can't just dump as much current as you want into a battery - you have to take into account heat and internal resistance of the battery. Samsung is using the phone's circuitry as the smart part of the battery charger, and they have imposed some sort of upper limit on current. Hot batteries charge slower (if using a smart charger), so it doesn't matter about the amperage of a charger if the battery is hot. If you are doing GPS, Maps, BT and other things in your car, your battery will get hot and charging (even a wall charger) may not keep up with discharge.
The widget is reporting a number in a file - it is not reporting mA - we know this for 2 reasons:
1. someone has measured actual current with Ammeter and posted it along with file values
2. a charger can't put out more current then it is rated for (well maybe one could but not all)
There is still value in buying a 1A charger as most other car chargers just put out the USB amount of 0.5A
I've been doing some reading on this and can't seem to find the proc in sys for current_now...which shows battery drain in mah or micro amps (which ever it reads). That's how the Nexus version of Current Widget shows charge, draw, or a net gain. I'm assuming this is because of the Vibrant Kernel?
I'm trying to take the charge and deduct the current draw to see what my net gain or loss is charging (or discharging). I have gps, bluetooth, display and media going all the time while driving.
If I can't figure it out I'm going to take an AC/DC converter, plug that into the cigarette lighter and just directly wire it to the battery *poof*.
weird
Hello
First of all, im sorry if this is not the right thread - please correct me if im in the wrong place?
This is my first post on XDA.
I must say I love this forum, since I just got my first android, HTC legend.
I have no problems with the batterylife on this phone, but it seems like "somthing" is wrong!!??
I have tried the currentwidget and have logged usage (1 minut interval) for a couple og hours. I have logged both mah and apps running. Most of the times it says that im using 90-100 mah when the phone is on standby. It has been down to 12 mah only a few times.
Due to this, im now charging via usb at work, and this is where my problem is. The phone is NOT charge... well i guess its charging, because the orange led is on, the icon is flashing green etc. BUT it keeps saying 64% and it is not going up, it is sometimes going down to 63% even in standby.
To find out if its maybe a faulty usb cable i need to see how much current is going in to my phone when charging, but i cant seem to figure it out, even though all of you say that the currentwidget shows use of current or input from charger - do you know how to do this?
If anybody knows, please help me.
Thanks in advance
Glenn
glennfilbert said:
Due to this, im now charging via usb at work, and this is where my problem is. The phone is NOT charge... well i guess its charging, because the orange led is on, the icon is flashing green etc. BUT it keeps saying 64% and it is not going up, it is sometimes going down to 63% even in standby.
To find out if its maybe a faulty usb cable i need to see how much current is going in to my phone when charging, but i cant seem to figure it out, even though all of you say that the currentwidget shows use of current or input from charger - do you know how to do this?
Click to expand...
Click to collapse
Kinda the wrong thread and the right thread at the same time. The problem is likely due to the USB port on the computer you're charging from. Have you tried charging on a different USB port? Also, if you load the widget while charging, what value is it reporting?
Some USB ports are unpowered, which means they really won't charge anything and some devices won't work on them. Others, for whatever reason, provide only a small amount of power, which may be just enough to keep up with your phone's battery usage but not to actually charge it.
lotherius said:
Kinda the wrong thread and the right thread at the same time. The problem is likely due to the USB port on the computer you're charging from. Have you tried charging on a different USB port? Also, if you load the widget while charging, what value is it reporting?
Some USB ports are unpowered, which means they really won't charge anything and some devices won't work on them. Others, for whatever reason, provide only a small amount of power, which may be just enough to keep up with your phone's battery usage but not to actually charge it.
Click to expand...
Click to collapse
Also possible that it is the cable. Are you using the stock Samsung cable and charger? That combo should get you ~1100 in the widget. If your using adapters or extension cords take them off.
Best way to check for a faulty cable is set the widget to update every second and wiggle around. If you see the current value jumping around a lot (e.g. from 100 to 800/1100) then it is the cable. The cable can have trouble near the micro USB plug or the actual cable itself.
On the USB port make sure that you have the Samsung drivers installed. They are available in the DEV area.
Finally it could be your chargers. I had some really bad/cheap ones that did around 400. I've also had a car charger that started at 1100 and then drop within seconds to <200.
Has anyone passed the information back to the original app developer? I've gotten 3 app updates for the original app since the OP first posted this modified widget. The original app developer is open on supporting other phones.
sfsilicon said:
Has anyone passed the information back to the original app developer? I've gotten 3 app updates for the original app since the OP first posted this modified widget. The original app developer is open on supporting other phones.
Click to expand...
Click to collapse
Originally Posted by rm9 View Post
good enough for me.
Just wanted to know it's useful.
I'll add it to the next version.
SF>Thank you. Looking forward to it. I'll let the Vibrant folks know.
http://forum.xda-developers.com/showpost.php?p=8379294&postcount=205
Working to add Vibrant support to the official current widget from rm9 so we can download it from the market. Could you please provide feedback on what to display (raw value vs divided by ~2) in this post:
http://ip208-100-42-21.static.xda-developers.com/showthread.php?t=796789
When booting the Nexus One, for as long as the X logo is displayed the battery can be removed and the phone will stay on and remain booting on USB power alone - try it!
Once the boot process continues past the X disappearing however, this no longer works. Regardless of USB power being present the phone will switch off as soon as the battery is removed.
I wonder: Is this behaviour configurable? Is there any kernel code that could be altered to allow the Nexus One to continue running on USB power alone?
I have a few spare batteries, when charging them up it would be useful to be able to switch batteries out while the phone continues to run.
Wrong section, but yeah great idea. I could do this on my PSP, and was quite disappointd when I couldn't do it my N1.
Very good job to find that. It will be awesome to find a way to make this.
It will be good to tether usb and dont charge/discharge the batteri to
make life shorter.
My Dell Axim x51 does that and rules without battery, its good to put the tom tom in car and not to worry about battery.
Will be good to all that have access to a computer in work.
The battery has 4 contacts and the phone connects to them using 6 pins.
*Wild Guess* These are probably for +/- charging +/- discharging
It may be possible to connect the charging pins to the discarging ones to trick it into thinking there is a battery. (Dont experiment and blow yourself up if you dont know ) The charging voltage/current may need to be stepped up/down.
Note: I have a battery charger from ebay and it only uses the outer pins to charge the battery.
britoso said:
The battery has 4 contacts and the phone connects to them using 6 pins.
*Wild Guess* These are probably for +/- charging +/- discharging
It may be possible to connect the charging pins to the discarging ones to trick it into thinking there is a battery. (Dont experiment and blow yourself up if you dont know ) The charging voltage/current may need to be stepped up/down.
Note: I have a battery charger from ebay and it only uses the outer pins to charge the battery.
Click to expand...
Click to collapse
I have a battery which is marked with the following. (from outside to inside)
| + | DQ | T | - |
The charger that I have uses + and - only.
Not sure what they mean though T= Temp? DQ = Data?
The other pins are to "split the voltage". That's how you can have a 3.7V battery putting out multiple levels of voltage (1.2, 1.8, 3.7 for example). I would imagine a common negative, then the "master" 3.7V positive, then a couple of other voltage levels. I'll get my multimeter later on and play with it, just for kicks and giggles, but that's the same reason why laptop batteries have multiple contacts (though the motherboard still needs to be able to step voltage coming in from the PSU, in case the battery is missing...it's just more efficient to be able to bring it in directly from the battery at the correct voltage level.
MaximReapage said:
The other pins are to "split the voltage". That's how you can have a 3.7V battery putting out multiple levels of voltage (1.2, 1.8, 3.7 for example). I would imagine a common negative, then the "master" 3.7V positive, then a couple of other voltage levels. I'll get my multimeter later on and play with it, just for kicks and giggles, but that's the same reason why laptop batteries have multiple contacts (though the motherboard still needs to be able to step voltage coming in from the PSU, in case the battery is missing...it's just more efficient to be able to bring it in directly from the battery at the correct voltage level.
Click to expand...
Click to collapse
If it were to just step down voltages, how does the phone get the data of battery condition? I think there's more to it than just that.
I can't do this on my Nexus. I just tried it, because I have 2 spare uncharged batteries I would like to charge while the phone is on. I turned off the phone, turned it on while plugged in to its AC charger, removed the battery while it was on the Google X (static, not animated) logo, and the phone turns off. The little LED indicator blinks interchangeably between orange and green and the phone remains off.
I'm on AT&T Nexus One, with a custom bootloader, and a rooted, deodexed, lightly modified stock ROM.
Thread moved to Q&A, and [Q] tag added. This seems very interesting.
momentarylapseofreason said:
If it were to just step down voltages, how does the phone get the data of battery condition? I think there's more to it than just that.
Click to expand...
Click to collapse
I would imagine by measuring actual vs. desired voltage, as well as voltage "jitter"
wornbat said:
I have a battery which is marked with the following. (from outside to inside)
| + | DQ | T | - |
Not sure what they mean though T= Temp? DQ = Data?
Click to expand...
Click to collapse
Correct indeed. This battery only supplies one voltage.
You should check the battery calibration thread in the development section for more info.
The battery has nothing to do with this however. The kill switch is somewhere in the software.
When the phone locks up and the battery is removed while on USB, it won't turn off.
There's a good reason for this to exist though. The battery acts as a regulator and current supplier when the USB line can't provide enough.
Disabling this protection will make the system unstable when overloaded.
MaximReapage said:
The other pins are to "split the voltage". That's how you can have a 3.7V battery putting out multiple levels of voltage (1.2, 1.8, 3.7 for example). I would imagine a common negative, then the "master" 3.7V positive, then a couple of other voltage levels. I'll get my multimeter later on and play with it, just for kicks and giggles, but that's the same reason why laptop batteries have multiple contacts (though the motherboard still needs to be able to step voltage coming in from the PSU, in case the battery is missing...it's just more efficient to be able to bring it in directly from the battery at the correct voltage level.
Click to expand...
Click to collapse
The other pins are definitely not to split the voltage. I have opened one of my dead batteries and behind the connector pads there is a circuit board with several SMD devices on it. there are only two straps going off to the battery on either side.
Background
Hi all, I, for a very short period of time was suffering from the problem of my phone DISCHARGING while it was charging. This made no logical sense to me until I did some research, which I will detail below.
How USB Power works (Roughly)
Firstly let's discuss USB power provisioning. Strictly speaking, the specifications say that any given USB port should provide a maximum of 500mA (or 0.5A) at 5 volts. *Don't shoot me electronics guys, I'm simplifying for ease of explanations sake*. Imagine that ampage as the actual force of the charger, how quickly it can ram power into your phone. Like the rate of flow on a pipe.
The beginning of the problem
This was all fine and dandy when all USB was really used for was Keyboards, Mice, Memory, etc, low current draw devices. Something else I should mention here is that the Ampage that a port CAN provide is not the Ampage it DOES provide - the device draws a certain Ampage and if the USB controller agrees it outputs said Ampage. Later, when USB was beginning to be used for more power hungry applications, ie External hard drives, these required more power than the port could (In theory) provide. However, most more modern motherboards/USB controllers were more than capable of supplying plenty more Ampage if it was requested. This was breaking the specification but not in any massively dangerous way so as such nothing bad happens.
This is where we get to the actual issue people are experiencing here. The Nexus 4 is a standards compliant device in the respect that it seems to only draw 500mA from any USB port no matter what it's potential, unless it's an AC Wall wart. If you're experiencing problems with wakelocks (see XDA) and other things, this causes your phone to draw more than 500mA which means your phone actually discharges while it's charging! Terrible!
This is quite easy to get around, but again I'm going into detail so let's explain how the phone tells the difference between a dumb wall wart and a USB controller. Easily! The USB controller obviously makes use of the data pins found within the USB cable, whereas a wallwart just (almost always) shorts them out. The Nexus 4 can detect this short, and as such draw more power *While still in quotation marks staying in spec*.
The root problem is not with how the N4 is charging, it's with the wakelock you're experiencing which is causing the phone to draw so much power while the screen is off. While the screen is off and the phone is in Deepsleep (A CPU state where it uses very little power) - it should draw no more than 50mA leaving 450mA for charging the battery, but you guys are probably experiencing a wakelock of some sort.
Solutions to the problem or How to break a specification for the good of mankind
The simple solution is to install this app: https://play.google.com/store/apps/details?id=com.rootuninstaller.batrsaver
This forces the device into a Deep sleep when the screen goes off by killing applications and turning off all internal chipsets that have wakelock capability, most commonly networking on the Nexus 4. This will allow your phone to charge (slowly) off USB without an issue. Another common wakelock is when the device is picked up by your desktop as a media device. The USB controller inside the Nexus 4 forces a wakelock which keeps it from charging. Stupid design, I know.
* A more hackish solution is to install Francos kernel, buy his app, and tick the Fast charging option in the kernel settings dialog. This will force the phone to think that everything is an AC adaptor and will force the phone to draw as much current as it can from the USB port (which on most modern motherboards is fine, and results in extremely quick charging).
* An even simpler solution than all this is to just use a 'USB Charging cable' - this is simply a cable that does not have the Data pins, and as such does exactly the same as what enabling USB fast charge above does. http://www.ebay.co.uk/itm/Micro-USB...487076?pt=PDA_Accessories&hash=item51a465d124
If you live near a Poundland store here in the UK they sell a 4 in one USB cable type thing which turns 1 USB port into Ipod sync connector, Nokia connector, MicroUSB and MiniUSB, and this doesn't have the data pins and as such is excellent.
One final point, an excellent app for monitoring whether your device is actually charging or not and how quickly is Current widget: https://play.google.com/store/apps/details?id=com.manor.currentwidget&hl=en
This widget will tell you how much Ampage is going into or leaving your battery. If the battery icon is green, then it's discharging, if it's black/white then it's charging. The bigger the number, the faster the discharge/charge. This is an extremely easy way to test speed of chargers too.
Recommendations
Another solution, just use an AC Wall wart - they're cheap as hell and the one supplied with the Nexus 4 is an extremely fast charging one. Shame I've gone and lost mine.
A way to roughly monitor charging current draw
I'd also recommend you install https://play.google.com/store/apps/details?id=com.manor.currentwidget&hl=en and monitor, if the battery is green while charging it's discharging and you need a more powerful charger/to figure out what's causing your phone to use so much power.
General good values in Current Widget
I generally saw a max draw of about 750mA for charging (not including draw for powering the device, the Nexus 4 can draw more power to charge and power the device) on my old Rev10 first generation Nexus 4. On my new Rev12 board I'm noticing this increase to about 850mA.
Are higher amperage chargers any benefit to anyone?
Yes and no. You will not notice faster charging unless you use your device while charging. Your nexus will draw as much power as it needs to power the phone while charging at the fastest rate. For example on the stock 1.2a charger
1200mA | 800mA goes to charging 400mA goes to powering the phone idling
Let's say you start a stability test. Your phone will obviously be using a lot more power so this will happen
1200mA | -600mA goes to charging and 1800mA goes to powering the phone stability testing
That minus value above may look strange! Let me explain. If the phone needs more power than the charger can supply, it will draw from the battery. That's the minus number.
If you have a higher ampage charger like for example a 2.5a charger
2500mA | 800mA goes to charging 400mA goes to powering the device
Stability testing
2500mA | 700mA goes to charging 1800mA goes to powering the device
Can you see the difference?
DISCLAIMER: I am not an electronics engineer nor do I claim to be, I am simply a hobbyist and this is what I've found to be the case. Please correct me if I've made any mistakes, I want to learn.
Thanks!
Thanks so much for this post. It's very helpful.
kn100 said:
Another common wakelock is when the device is picked up by your desktop as a media device. The USB controller inside the Nexus 4 forces a wakelock which keeps it from charging. Stupid design, I know.
Click to expand...
Click to collapse
This isn't true for everyone then as mine connects and charges just fine off of my laptop and desktop when connected as a media device. In fact its on my laptop right now charging, gone from 68% to 81% in about 30 minutes and it shows connected as a portable media player.
Great info! Thanks for writing this!
In certain use cases the Nexus4 discharges faster than it charges and this is a very useful guide.
I use my phone for navigation in my car and having the GPS on and the screen at high brightness
drains the battery faster than the 0.5A car chargers can supply. Car chargers rated for 2.0A work well.
I haven't tried a 'USB charging cable' with the data pins shorted, it may work as well.
-Mindroid- said:
Great info! Thanks for writing this!
In certain use cases the Nexus4 discharges faster than it charges and this is a very useful guide.
I use my phone for navigation in my car and having the GPS on and the screen at high brightness
drains the battery faster than the 0.5A car chargers can supply. Car chargers rated for 2.0A work well.
I haven't tried a 'USB charging cable' with the data pins shorted, it may work as well.
Click to expand...
Click to collapse
was over in Nexus 7 forums and the 4.2.x kernel should have solved the problem at least for having to use shorted cables. have to wait and see if 4.2.2 brings any more changes.
http://forum.xda-developers.com/showthread.php?t=1984838
Section 6 in this link is about power supplied through USB
http://en.wikipedia.org/wiki/Universal_Serial_Bus
I can't tell if we have an updated kernel allowing faster usb charging as I'm limited by the power output of the usb port in my laptop. The output (5V at 500mA max) is controlled by the laptop (USB Standards) and it doesn't matter what the phone or cable is capable of as that's the max it will give out and that's about what I'm charging at. If I had a dedicated charging port in my laptop then it would be different and I could see if its able to draw more power. I have a 1.0 amp port in my car and it does charge at the higher amperage, I would assume it would do the same thing if I had a 2 amp usb port in the car. So I think the stock kernel has the fast usb charge built in it just depends upon if you have a usb port capable of providing a faster charger, it has nothing to do with the cable as I'm using a standard unmodified micro usb cable and its able to draw the max a usb device is able to put out.
thanks
thanks for a great detailed post!!!
I have the same trouble with my N4 when I was charging while using my phone...
I find it very slow... I guess I've been spoiled by my previous iPhone (which charges fairly fast)....
i might be stating the obvious but I find the phone charged "a lot" faster when it's OFF
if you are running low with your battery and need a quick 10 min charge, just do yourself a favour by turning off your phone...
the difference is quite significant!
kzoodroid said:
This isn't true for everyone then as mine connects and charges just fine off of my laptop and desktop when connected as a media device. In fact its on my laptop right now charging, gone from 68% to 81% in about 30 minutes and it shows connected as a portable media player.
Click to expand...
Click to collapse
Yup, me too. It only discharges while charging when I am playing like NFS most wanted.
Sent from my Nexus 4 using xda app-developers app
The issue with cables is with the LG usb wall charger as the one supplied isn't capable of getting the 5 volts at 1.2 amps that the charger is rated at, mine is getting around 300 - 400 mA. The micro usb cable I have in my car and use with my laptop (for charging and data transfer) is able to handle the higher amperage, it gets around 1 amp with the LG plug. There are no specs on these cables so I can't list a definitive difference and I would assume that the cable mod in the OP might help with the LG cable. It also might just be simpler to only buy those cables capable of handling higher amperage as obviously they are out there from my experience.
The cable I'm using is an RCA coiled charging/syncing cable model AH732CBR (has data pins). The maximum I'm getting from this is about 870 mA regardless of the amperage of the usb port, I've tried a 1.0, 1.2 and 2.1 and they are all around 870 mA on current widget. I would suppose if I could find a strictly charging cable I could get higher (link to ebay in OP is outdated) but this is still 2x that which I'm getting from the LG cable supplied with the phone which only puts out 300-400 mA. Our phone also has Qualcomm's quick charge which is supposed to improve battery charging times by 40%.
http://www.droid-life.com/2013/02/1...allows-your-device-to-charge-up-to-40-faster/
How do you measure how much mA the device draw from the charger?
Sent from my Nexus 4 using Tapatalk 2
omrij said:
How do you measure how much mA the device draw from the charger?
Sent from my Nexus 4 using Tapatalk 2
Click to expand...
Click to collapse
current widget, link is in the OP
kzoodroid said:
The cable I'm using is an RCA coiled charging/syncing cable model AH732CBR (has data pins). The maximum I'm getting from this is about 870 mA regardless of the amperage of the usb port, I've tried a 1.0, 1.2 and 2.1 and they are all around 870 mA on current widget. I would suppose if I could find a strictly charging cable I could get higher (link to ebay in OP is outdated) but this is still 2x that which I'm getting from the LG cable supplied with the phone which only puts out 300-400 mA. Our phone also has Qualcomm's quick charge which is supposed to improve battery charging times by 40%.
http://www.droid-life.com/2013/02/1...allows-your-device-to-charge-up-to-40-faster/
Click to expand...
Click to collapse
Bit of a late reply but please bear in mind the Nexus will NOT draw anything more than about 800mAh from the wall for charging alone. That is the absolute max and is a hardware limit - If the cable is transmitting that and it's showing in current widget you've got a good setup. See the added section in OP for more info on higher amperage chargers.
The following is some testing I did out of curiosity. My methodology is decidedly short of scientific, don't take any of it as the gospel truth/hard fact. Proving me wrong is encouraged.
It's also well into reasonably-TL;DR territory. There's a summary at the bottom.
A while back, I bought a Xiaomi power bank, and with it a reasonably powerful charger to fuel it.
During one particularly sleepness night, I'd settled down in bed with my phone - which was nearly dead after laying neglected on my desk for a couple of days - and set it charging whilst reading news and whatnot. A half hour later, I noticed that it had accumulated a surprising amount of charge, despite me using it.
Curiosity piqued, I bought a Charger Doctor sort of thing - which from here on out I'll refer to as a "monitor". It's one of these specifically (chosen based on review found here), to see how much amperage the phone actually pulls if given as much juice as it wants.
Unfortunately, these tests are a bit flawed - I have a pair of 24/28AWG micro-USB cables on order, but for the moment all I have is the input pigtail that's on the monitor (it also has a micro-USB port for input) and a short cable that came with my power bank to go between monitor and phone. I think that the input pigtail is limiting the maximum delivered amperage, because the amperage doesn't rise above the maximum observed even while in use on the charger (more on this later). I'll get another batch of samples when the new cables arrive.
Does not seem to be the case, or at least, the pigtail is reasonably capable. Switching to the micro-USB port actually lowered the current delivered.
It looks like short of soldering a new pigtail in (using thicker wires), there's nothing I can really do to eliminate this potential bottleneck. The pigtail is short enough anyway that it might not be adding enough resistance to make an appreciable difference.
The charger used was a Xiaomi MDY-30-EC (2A output max, Quick Charge 2.0-able apparently). In hindsight, I should have gotten an MDY-30-EH for future-proofing (2.5A/QC 3.0), but you know what they say about hindsight.
I drained the phone to 10% and set it charging, checking on it every now and then to see what it was doing. Then I proceeded to forget about it for a bit, so it kind of got away from me, but the power curve for 10%-33% proved to be fairly flat.
10% ~ 33% - ~1.58a
33% - 1.5a update: observed to still be holding 1.58a up to at least 43% in the second run
50% - 1.14a
57% - 1.05a
60% - 0.965a
79% - 0.865a
80% - 0.775a
83% - 0.645a
85% - 0.565a (0.50a)
87% - 0.505a (0.465a)
87% - 0.475a
95% - 0.165a (~0.115a)
100% - ~0.07a (intermittent)
Note that for much of the time above 60%, I had the screen on at the lock screen and auto-dimmed ("keep awake while charging" on via Development Options). It wasn't until 85% or so that I thought to check if the phone will pull additional needed power directly, instead of draining the battery. It does seem to, so at 85% and 87% I shut the screen off and recorded the draw.
As you can see, the phone will use up to 1.58 amps if given as much, and stays above 1A until 60% (where it suddenly drops to 0.96A). It's only when it reaches about 80% that the stock "fast"/travel charger becomes adequate, and 85% when a standard charger or USB connection can charge it with the screen off, and neither of those leave much if any excess capacity for the phone to consume if it's awake/being used.
Overall, it seems like quite a sane charging curve, edging into overly cautious. I'd guess this is because the battery is technically non-removable, and they didn't want people sending their phones in under warranty for the battery replacements that a more aggressive charging curve might have caused. Not that any of it mattered, what with them only ever offering a 750mA charger anyway.
Again, this test is flawed from the outset due to lack of a decent input cable. I seriously doubt it pulls much more for charging, but a proper cable might allow the phone to pull more for active use; at 10%, the current didn't go above 1.58A even while messing with it.
Fast-charging the battery might also cause longevity issues, because of potential heat build-up. Don't be an idiot like me and set it next to your pillow, only to find it under said pillow or blankets in the morning all toasty and only half charged because the safeties - yes, surprisingly we do have over-temperature safeties - kicked the charging circuit off. Also probably not the best idea to do gaming or anything else intensive on it while charging at full tilt, what with the processor's EMI shield being in direct contact with the battery and all.
Further on this: The heat build-up doesn't seem to be bad, with the phone sitting back-down on a wooden desk. In fact, the casing on the charger itself got much warmer than the back cover of the phone after half an hour of running at maximum input, to the point I started worrying about it instead.
I would tentatively say that "fast-charging" won't hurt the battery, at least, not by way of overheating it.
Some further power draw tests. Anything under .5a might be (probably is) inaccurate to some degree, and the monitor's minimum seems to be 0.07a.
Booting the phone - 0.44a (note that this isn't even enough to power the boot process what with the CPU saturation, so rebooting at <10% is probably a bad idea)
100%, screen on at launcher, brightness maximum - ~0.195a
100%, screen on at launcher, brightness minimum - below cutoff
Following is at 100%, brightness maximum:
GPS on (no satellites in view) - 0.30a
Bluetooth on (active scan) - ~0.42a
Bluetooth on (passive, unlinked) - 0.215a
Bluetooth on (actively broadcasting) - intermittent bumps to ~0.24a
CPU loaded (1.3ghz) (Passmark integer math) - ~0.78a
GPU loaded (Passmark 3d test - complex) - ~0.59a
GPU loaded (3dMark Ice Storm) - ~0.42a
3dMark physics test - ~0.68a
In summary:
We can use up to 2A chargers (possibly more if excess capacity is needed by the phone being under load while charging), despite only ever having been officially offered a 750mA charger at most. Thanks for that, Motorola.
The charging circuit supports bypassing the battery for direct power, if charger capacity beyond what's needed for topping the battery up is available
The screen uses a fairly tiny amount of power at minimum brightness
The screen uses a lot of power at max brightness
The GPS also uses a lot of power, roughly half that of the screen at full brightness if measurements are accurate
The GPU uses a large amount of power (note: real-world usage for the GPU outside of games is normally very bursty, but tends to get saturated a lot for UI acceleration in LP/MM)
The CPU uses a ton of power (note: real-world usage generally has the CPU napping at 300mhz where it barely consumes anything, and/or bouncing between 600mhz-1ghz)
More:
The charging circuitry seems to be able to utilize capacity above 1.585a, based on momentary spikes to 1.6a/1.64a. I'd guess my charger is a limiting factor here.
Our phone meets and exceeds Quick Charge 1.0's nebulous "30% in 30 minutes" marketing blurb/guideline.
New USB cables arrived today. Some additional things:
- Monoprice USB cables kind of suck. One can only pull slightly less than the short ribbon cable that came with my power bank, the other one pulls a good .15a less. I'll have to fiddle with them a bit to see if it's a connector pressure issue or what. Not really what I was hoping for from 24AWG cables.
- Charging starting at 5%, the phone tops out at about 1.585a, with occasional spikes (probably combined hits to CPU+GPU+disk) to 1.6-1.64a.
- The 1.585a number is only for screen on and working, actual charging seems to be capped at roundabouts 1.5a.
- The charger monitor actually has higher resistance through its micro-USB port than it does the crappy little pigtail...hooray for Made in China I guess. Maybe I'll make a new pigtail of this thick old cable end I have laying here...
- At maximum speed and the screen dimmed, with the phone sitting at ~26%, the lock screen reports 1 hour, 22 minutes until full. Not too shabby at all, if it's accurate.
For my next trick, I'll measure the time it takes to go from ~5% to 60%, since emergency charging is probably more relevant to people, and I'm a bit curious about how it compares to Qualcomm's super-special Quick Charge.
Last post, since I feel like I've gotten about as much as I can out of experimenting with my current equipment. I'll edit the first post to reflect all the information so far.
In 33 minutes, the phone recharged 38% of its capacity (coming to 43% total). This is actually into Quick Charge 1.0 territory (which seems to aim for 30% in 30 minutes using "up to" 2A), so that's pretty neat.
At this stage, unlike the earlier test, it was still pulling a steady 1.58a...with the screen off. *shrugs* I'm not sure what to make of it, maybe there's something I'm missing. It was markedly warmer in here this time, so if anything the charging circuit should have began ramping the current down sooner.
And yes, 1.58a again. I'm not sure what's going on, it just randomly decides it doesn't want to charge at full speed.
I'm wondering at this point if it's not my charger that's a limiting factor. It got fairly toasty earlier when the phone was charging balls-to-the-wall, and it's only a (supposedly) 2A adapter. I do need to buy another charger, as a household member needs a new one, maybe I'll look into getting a 3A unit...
Anyway,
In 60 minutes, it had recovered 66% (coming to 71%). I was going to go for timing 60% (which appears to be the Quick Charge 2.0 target), but instead set an actual hour timer because 1: we'd missed it anyway (60% in 30 minutes) and 2: I didn't want to wake the phone up every now and then to see what % it was at, nor did I want to leave the screen on and affect the result.
'course, the QC 1.0/2.0 targets don't mean much, because they don't specify the capacity of which you're trying to fill 30%/60%. Still, now you can brag to your friends that yea, you totally have a Quick Charge-capable phone...and it's almost true.
people do this, right? compare phone-charging e-peens? no? : \
So yea, hey. Small battery even in its day, but if you plug a big enough charger (or a capable power bank) into it, it juices up pretty fast.
This post didn't seem to get enough attention.
Very thorough and enlightening.
I think I have a 2amp charger laying around somewhere and I can plug in a fast-charge USB cable from my brother's Samsung G6 Edge.
I'll see if it speeds up charging at all.
Hi I'm using stock XZ1 Compact as 3d print server through Octo4a, but having it connected and running 24/7 is probably not exactly battery friendly. Would it possible to disconnect the battery and use it on USB power only?
I tried it with my older stock Z3c, but it wouldn't even boot.
I'm not an electrician and i'm quite out of the loop with custom ROMs and firmwares, the last time I used one was on X10 mini pro.
I would be glad for any advice.
It's not designed to function that way. Not even sure you can sink enough current to run the phone on just port power only. These devices can have high current spikes when running and especially booting up. If the required current isn't available on demand they will crash.
Hooking in a well regulated 4(?) VDC power supply directly to the battery input (less battery) may be an option. It must be able to support peak current loads.
A ultra capacitor in place of the battery may work if the primary power source provides enough power most of the time and it's compatible with the phone's power controller.
Rather then doing all that I probably hook it up to a brick that has enough watts for it to run continuously with the battery in place. Replace battery as needed which will be more frequent because of the constant high cell voltage. This may or may not work.
Right now I have it connected to 20W wall charger, through PD OTG dongle, that does keep it running and allows USB connection to the printer.
But I was more worried about possible fire hazard of charging it 24/7, rather than battery going bad.