[Q] Run Nexus One on AC power alone - Nexus One Q&A, Help & Troubleshooting

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.

Related

[UTIL] current widget - shows actual current output of a charger

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

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.
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.

Technical details about nook HD+ charging

As an engineer I pulled some info from the datasheet for the chip the nook uses, it may help better understand charging issues.
full datasheet is on the TI site at:http://www.ti.com/lit/ds/symlink/bq24196.pdf
USB Timer when Charging from USB100mA Source
The total charging time in default mode from USB100mA source is limited by a 45-min max timer.
Click to expand...
Click to collapse
If you connect the nook to a low power pc port you will only be able to run the charging for 45 minutes before the charger IC stops. To start it again you have to unplug and re-plug the USB cable. The charge current for a 500ma usb port is about 440ma.
The device initiates and completes a charging cycle without software control. It automatically detects the battery
voltage and charges the battery in three phases: pre-conditioning, constant current and constant voltage. At the
end of the charging cycle, the charger automatically terminates when the charge current is below a preset limit in
the constant voltage phase. When the full battery falls below the recharge threshold, the charger will
automatically start another charging cycle.
Click to expand...
Click to collapse
The device fast charges at 1.5A using the charger and charges at 4.208V to the battery. The bad battery setting is for 1.8V, so if your device battery falls to that level it will not charge because the chip assumes a failed battery. I see this a lot in tablets. Someone stops using the tablet when the charge is 10% or less and then 2 weeks later picks up the tablet and it appears dead. The battery cells have discharged below the limit and now will not charge. The device will consume power even if you power off the device because the charging controller is on 24/7 regardless of any mode except shipping mode which we do not have access to . Fix for dead battery is remove the battery from the tablet, charge on external charger , replace.
The USB ports on personal computers are convenient charging source for portable devices (PDs). If the portable
device is attached to a USB host, the USB specification requires the portable device to draw limited current
(100mA/500mA in USB 2.0, and 150mA/900mA in USB 3.0). If the portable device is attached to a charging port,
it is allowed to draw up to 1.5A
Click to expand...
Click to collapse
if you want the info on your own charge stats just type dmesg in a shell prompt.
data to look for is like this:
Code:
<7>[224884.880706] bq2419x_is_vbat_in_range: vbat = 4135000
<7>[224884.881378] bq24196 1-006b: bqSetSYSMIN: 3200
<7>[224884.882019] bq24196 1-006b: adj_fast_ichg_lim: 2036, 240, 2036
<6>[224904.594329] android_usb gadget: high speed config #1: android
<7>[224904.594818] bq24196 1-006b: USB_EVENT_ENUMERATED
<6>[224904.595306] android_work: sent uevent USB_STATE=CONFIGURED
<7>[224904.600708] bq24196 1-006b: INTERRUPT 08=6c, 09=0
<7>[224904.600952] bq24196 1-006b: S: Power Good
<7>[224904.601165] bq24196 1-006b: S: CHARGE STATE = 2 (FAST CHARGING)
<7>[224904.601531] bq24196 1-006b: S: VBUS STATE = 1 (USB host)
<7>[224904.601745] bq24196 1-006b: S: Dynamic Power Management enabled
I have had a few close calls with my battery. It does not charge if verygreen's or other app that permits the Nook to host other USB devices is active, and in most cases I had accidentally activated it. Since it then refuses to charge when connected to power, its in greater danger of completely depleting. Easily fixed as long as the unit is still operating, but no obvious clue when that's the problem.
Also, when you put the power plug in real slow at the nook port, even when the battery is not 100%, it will turn green as if full charged and will no longer show that its charging. Possibly, could be initiated in another way I would think.
modelworks said:
If you connect the nook to a low power pc port you will only be able to run the charging for 45 minutes before the charger IC stops. To start it again you have to unplug and re-plug the USB cable. The charge current for a 500ma usb port is about 440ma.
Click to expand...
Click to collapse
Interesting about the "low power" port. But I haven't seen one yet. Nowadays, many USB2 ports provide up to 1000 mA without negotiation. Originally, the USB specification required that devices connect in a low-power mode (100 mA maximum) and communicate their current requirements to the host, which then permits the device to switch into high-power mode. But the USB Battery Charging Specification changed that. In recent years I've tested several PC mainboards, and an Xbox 360, all of them provide around 1000 mA on USB2 ports without negotiation.
But the Nook HD+ won't make use of that and limit itself to the 440 mA you mentioned. Why? Because it uses the two data lines (D+ and D-) of the USB connection to detect dedicated USB chargers. If the data lines are shorted, the Nook assumes it's connected to a dedicated USB charger and it will draw up to 2000 mA (about 1880 mA in my measurements). If the data lines aren't shorted, it'll limit to 440 mA no matter if the USB power source could provide more.
modelworks said:
The device fast charges at 1.5A using the charger and charges at 4.208V to the battery.
Click to expand...
Click to collapse
From where do you get the 1.5 A? Your own dmesg output says "adj_fast_ichg_lim: 2036, 240, 2036", and as I said, mine charges with around 1.8 A.
Also, the line in the dmesg output that gives away the charging speed isn't "CHARGE STATE". It always reads "= 2 (FAST CHARGING)" when an external power source is connected.
The line "DCP detected" is the real confirmation (DCP = dedicated charging port), and apparently also "VBUS STATE".
"VBUS STATE = 1 (USB host)" means the data lines are NOT shorted => max. current intake is 440 mA
"VBUS STATE = 2 (Adapter port)" means the data lines ARE shorted => max current intake is ~2 A.
Furthermore, keep in mind that power from the external source is prioritized to first supply the system, and then the battery. That is, the battery is charged with the "leftovers". Therefore, if you connect the Nook to a source from which it'll only draw the mentioned 440 mA, and you're continuing to use the tablet, then it can happen that the battery won't be charged, or even will be discharged! If you perform some CPU/GPU intensive tasks on the tablet, its power consumption can easily exceed 440 mA, meaning the tablet will use the external source in combination with the battery to satisfy its hunger.
TL;DR:
Nooks will only fast charge on dedicated charging ports, which are recognized by having their data pins shorted. That's more or less standard nowadays for generic USB chargers (USB Battery Charging Specification). However, some chargers still don't meet this requirement, and Apple has their own incompatible standard, naturally.
Don't use your tablet if you want to charge it from a low-power source (i.e. USB data connection on the Nook), because depending on the workload, the battery will be charged very slowly or will actually be discharged.
Tzul said:
Interesting about the "low power" port. But I haven't seen one yet.
Nowadays, many USB2 ports provide up to 1000 mA without negotiation. Originally, the USB specification required that devices connect in a low-power mode (100 mA maximum) and communicate their current requirements to the host, which then permits the device to switch into high-power mode. But the USB Battery Charging Specification changed that. In recent years I've tested several PC mainboards, and an Xbox 360, all of them provide around 1000 mA on USB2 ports without negotiation.
Click to expand...
Click to collapse
Read page 19 of the document.
From where do you get the 1.5 A? Your own dmesg output says "adj_fast_ichg_lim: 2036, 240, 2036", and as I said, mine charges with around 1.8 A.
Click to expand...
Click to collapse
I just posted that for people to know the general section not as a specific example.
Page 28 of the document explains why the log may read 2036 but actually be 1.5A
modelworks said:
Read page 19 of the document.
Click to expand...
Click to collapse
Have you read it? It's talking about the USB standard there rather than the bq24196. "If the portable device is attached to a charging port, it is allowed to draw up to 1.5A". That's straight from the USB standard, as the common USB2 connectors are rated for up to 1.5 A. However, B&N have engineered their own proprietary cable and connector and provide a 2 A capable power supply, so that limit doesn't apply.
Also, see Table 2 on the same page. The automatic input current limits are 100 mA, 500 mA, and 3 A. Not 1.5 A.
modelworks said:
I just posted that for people to know the general section not as a specific example.
Page 28 of the document explains why the log may read 2036 but actually be 1.5A
Click to expand...
Click to collapse
It would be interesting to open a Nook and take a look what resistor value they used for that safety setting, if they used one at all. As I said before, I've measured currents up to 1.88 A on my Nook HD+ from the official charger, so I seriously doubt they hardwired it to 1.5 A max (and wasted money by providing a 2 A power supply when a 1.5 A one would suffice).
PS: Do you know the power supply dir in the Linux SysFS? Check out /sys/class/power_supply/ and its subfolders (one for each power source). There you can find various virtual files, part of which contain monitoring values straight from the hardware, as read by the driver.
In /sys/class/power_supply/bq27500-0/current_now (or in the file "uevent" which contains a summary of the individual values) you can read the battery charge/discharge current, as measured by the PMU chip. I saw values above 1.7 A there last time I charged and checked. And in order to check, I had to wake up the tablet from standby, of course, meaning that some of the power was spent on running the system rather than charging the battery... All of this paints a pretty clear picture: the device really does fast charge at about 2 A (if you use a suitable power supply and if you let the tablet sleep while charging). Not 1.5 A.
modelworks said:
The device fast charges at 1.5A using the charger and charges at 4.208V to the battery. The bad battery setting is for 1.8V, so if your device battery falls to that level it will not charge because the chip assumes a failed battery. I see this a lot in tablets. Someone stops using the tablet when the charge is 10% or less and then 2 weeks later picks up the tablet and it appears dead. The battery cells have discharged below the limit and now will not charge. The device will consume power even if you power off the device because the charging controller is on 24/7 regardless of any mode except shipping mode which we do not have access to . Fix for dead battery is remove the battery from the tablet, charge on external charger , replace.
Click to expand...
Click to collapse
Just wondering how do you charge the battery externally?
invinciblemo said:
Just wondering how do you charge the battery externally?
Click to expand...
Click to collapse
By opening the tablet, removing the battery, and connecting it to a dedicated Li-ion charger, of course. Something like this - but that's just an example, that model would not work. You'd probably have to do some soldering for the connector, too.
Tzul said:
By opening the tablet, removing the battery, and connecting it to a dedicated Li-ion charger, of course. Something like this - but that's just an example, that model would not work. You'd probably have to do some soldering for the connector, too.
Click to expand...
Click to collapse
I tried finding online to see if anyone had tried charging the battery externally.
It seems that dormouse1, from the second post in this thread http://4pda.to/forum/index.php?showtopic=431820&st=1900, had tried charging it using Imax B6.
I'm going to try charging my battery using his setup and see if it works.
To anyone that is interested in charging their battery externally, i think a TP4056 a Lipo Battery Charging Board works.
I had managed to charge my battery, and it shows that it has a discharge voltage of 4V, but I am not sure if it is correct.
When my charged battery is connected to my tablet, the battery discharged and my tablet became hotter.
However, my tablet failed to boot.
So its either that my tablet is bricked, or the charger did not charge my battery properly.
I would like to ask does anyone knows, what is the voltage of a fully charged battery?
invinciblemo said:
I would like to ask does anyone knows, what is the voltage of a fully charged battery?
Click to expand...
Click to collapse
Lithium-ion cells are typically charged to 4.20V. The Nook HD+ uses that value, too. Nominal voltage is 3.7V. I forgot the cut-off voltage that the HD+ uses to decide that the battery is empty, but I think it was 3.4V or 3.5V.
Tzul said:
Lithium-ion cells are typically charged to 4.20V. The Nook HD+ uses that value, too. Nominal voltage is 3.7V. I forgot the cut-off voltage that the HD+ uses to decide that the battery is empty, but I think it was 3.4V or 3.5V.
Click to expand...
Click to collapse
To add to that, make sure you put a load on the battery if you are measuring the voltage of the battery disconnected.
Something like a single 330 ohm resistor would be good.
Bad lithium batteries sometimes will appear charged until you place the load on it then it falls to 2 or lower volts.
Another quick check is to make sure the battery casing is completely flat, if the battery has bulges of more than a few millimeters the battery is about to fail and should be discarded immediately. Another trick you can use is smell the battery, I know sounds weird , but failing lithium batteries have a very unique odor , almost sweet, reminds me of the smell of bananas.
HTML:
Tzul said:
[*]Nooks will only fast charge on dedicated charging ports, which are recognized by having their data pins shorted. That's more or less standard nowadays for generic USB chargers (USB Battery Charging Specification). However, some chargers still don't meet this requirement, and Apple has their own incompatible standard, naturally.
[*]Don't use your tablet if you want to charge it from a low-power source (i.e. USB data connection on the Nook), because depending on the workload, the battery will be charged very slowly or will actually be discharged.
Click to expand...
Click to collapse
I have an HD+, which I have not been able to get to charge on a 3amp, 2amp or even a 1amp wallwart, but it does charge via its Nook wallwart. Does the above mean that were I to 'repurpose' a short USB extension and simply short the D- and D+ (clear of the +ve and ground) together in the USB lead, that I should then find it will charge via that lead? Please?
harrym1byt said:
Does the above mean that were I to 'repurpose' a short USB extension and simply short the D- and D+ (clear of the +ve and ground) together in the USB lead, that I should then find it will charge via that lead? Please?
Click to expand...
Click to collapse
Sorry for the late response.
Yes, that is correct, I have built such a cable myself and it does work.
Battery Issues
I have a Nook HD and it immediately dies as soon as it is unplugged, however there is no apparent damage to the battery, no bulges, leaks, or smells. After I plug it in and it reboots it goes from 10-20% charge to 100% charge within minutes. Is there a way other than removing the battery and charging it externally (outiside of my mechanical ability) to reset the battery to determine if it is a software issue or an issue with the battery itself. Currently running CM 10.2.1 stable.
Charging problem - solved
I had similar symptoms with my Nook HD+ : when plugged into charger the indicator light turned green, then orange, but only for a second, then went dark. When left on charger for many hours, the indicator would start blinking red. Nothing worked, until I read technical details in this thread.
The bottom line: if the battery voltage drops below 1.8 V, the stupid control chip assumes the battery is "bad" and refuses to pass the charging current; consistent with the observed symptoms. This gave me an idea on how to fix this:
Step 1: Open the Nook by prying the front panel to get access to mounting screws, then unscrew the back panel.
Step 2: Locate the battery cable composed of three red, three black, one blue, and one yellow wires.
Step 3: Locate the gold test points on circuit board _under_ the wires: "VBAT" under the red wires, "BAT-" under the black wires.
Step 4: You have to trick the control chip into "thinking" that the battery is still "good". For this, you'll need an external voltage source. I used my homemade adjustable DC power supply setting it to 2.5 V. I guess, any voltage between 1.8 - 3.7 should work.
Step 5: Connect the _positive_ lead from the external power source to the "VBAT" test point, connect _negative_ (or ground) lead to the "BAT-" test point.
Step 6: Plug your Nook into charger and wait a few seconds: the indicator light will now stay solid orange meaning the charging current is passing through. Yay! You should disconnect the external DC source; it's no longer needed.
I can confirm that applying voltage to the test points does absolutely nothing. In examining the PCB the test points mirror the positive and negative connections of payload from the battery.
That is NOT how the charging chip works. There are 2 control lines tied internally to the LiPo battery which are NOT payload lines. That is what we need to play with but there's no information on how those control lines are tied into the cell's internal chemistry or what the expected levels might be for the chip to "think" that the battery is good. It could even be an interface, i2c or who knows
I guess I am in trouble then...
I found my Nook HD+ back after not having used it in 3 years. Battery is dead as a door nail. When I plugged it in though, it showed the battery symbol for a dead battery and then the amber light next to the cable connector lit up and is still lit 30 minutes later. I am going to let it charge overnight and hope that it works again. If not, I don't think I will bother with pulling the battery, etc.

Force slow (500mA) charging

Hey folks,
you are reading right: For a certain reason* (if you care, pls scroll down) I need to "limit" the charging current to something like 500mA.
I am running stock rom (20c, rooted) but if there are solutions for custom roms / kernels I'd give it a try.
1st thought: The phone has an inbuilt "Thermal Protect" which can be disabled via hidden menu. It seems that the file (/sys/devices/platform/lge-battery/power_supply/battery/temp_control) only accepts the values "164" and "0". I'm looking for a way to actualy lower the temperature to trick the phone into thinking "wow, battery is too hot, I'll better charge slowly"
There are also a bunch of temp throttling files in /d/tegra_thermal, but as I unterstood they do only throttle the tegra chip which I don't want.
2nd thought: I've read articles about building special cables where the usb data ports are short wired, which then is interpreted by the phone as "charge only" and draws as much current as possible. I'd need it other way round and tried to just physically block the data ports but no success.
Why am I trying this? I bought a lamp for my bicycle which has a small (150mA) battery and a usb-out. The dynamo (generator) will charge the (inbuilt) battery like up to 40%, then the lamp will activate the usb port. The phone will then charge quickly (~1A) until the battery inside the lamp will go below the threshold, and the usb port will be deactivated.. and it starts all over. I'm ending up with a few hundred charging connections/disconnections a day of cycling with actually pretty few breaks. Thanks to snoozy it's not that bad.. but it still sucks.
Any ideas appreciated, hardware and software vise.
Regards, kugelz
I guess you mean 150mAh battery.
It's interesting how you say the phone gets about 1A during charging. How do you know that? One would think this kind of USB port (driven by a small battery and a dynamo) would provide max the standard 500mA (which is the slow charging you want).
Anyway, you could try the cheapest sh*tiest USB cable you can find, since the reason for being cheap is having a thin cable, and a thin cable means less current can flow.
Iodak
You are right, 150mAh is what I meant.
Someone created a diagramm for serveral similar devices (speed / power) and for speeds > 15km/h the current is about 800mA.
I flashed iodak kernel as it has the fast charge mod, but unfortunately in the latest ready-to-flash iodak kernel (v10) there is not the latest fast_charge mod included (where you can actually specify the current) but an older version where you can only switch it on or off

How to enable Fast Charge with Screen on?

do rooted/custom roms enable this or is this a hardware limitation? I understand its a temperature related issue. I am not saying fast charge while using overlclocked cpu and playing games. It just seems a tad annyoing that i cant charge my phone while driving in my car and navigating at the same time. (it will charge but only so very slowly....)
i am talking about the "adaptive fast charge" which really only fats charges when the screen is off or in AOD (always on display)
When you, lets say, have google maps open while driving the "fast charging indication is actually lying to you. It will only draw about 5 Watts there.
sgtpepperaut said:
I understand its a temperature related issue
Click to expand...
Click to collapse
I see someone wants to recreate a newer Note 7. I don't think is is a hardware limitation, of the physical phone or the stock charger, but the (stability of the) battery itself. Playing a game at full brightness would require adaptive fast charging to generate too much heat in the battery itself to compensate for the rapid battery drain, and maxing out the factory charging cable to replenish what was lost during current use and charge the phone in the same quick time you are accustomed to (with the screen off).
You are really asking another Note 7 disaster
Anonymously_Unknown said:
someone wants to recreate a newer Note 7.
Click to expand...
Click to collapse
haha not quite. i think you are confusing some concepts here. The net energy / charge arriving at the battery is actually less when the device would be under full load because the device itself uses a portion of the energy supplied by the charger... or am i missing something?
I think the gpu/cpu/screen heat in combination with charging is what the issue was on the Note 7. The battery itself can, as it might be obvious, easily be charged with ~15w. I believe the smart solution here would be to simply reduce/throttle charging with relation to CPU/battery temp.
I can tell you that when in a holder in an air conditioned car using google maps the battery will be fine with quick charge unless there is some weird coupling between two ICs.
Any decent quality USB cable will not be a limiting factor. 2 Amps @ 5V or 9V is really not a problem/
My measurements with the factory cable and charger at about 85% battery were around 1 Amp @ 5 Volt with screen ON and about 1.67 Amps @ 9Volts with screen Off or AOD on.
anyways. really only wondering if custom ROMS support this is or not. having my phone quick charge in my car while navigating is very important to me.
I think Samsung just played it very very very Safe after the Disaster. Limiting current and battery size that a guy who quick charges his phone in a Sauna can play candycrush on max brightness in performance mode....
sgtpepperaut said:
The net energy / charge arriving at the battery is actually less when the device would be under full load because the device itself uses a portion of the energy supplied by the charger.
Click to expand...
Click to collapse
I agree, I should have made that point clear in the first post.
sgtpepperaut said:
I believe the smart solution here would be to simply reduce/throttle charging with relation to CPU/battery temp
Click to expand...
Click to collapse
Samsung smartly chose to avoid the issue altogether.
Heat dissipation will be that issue to contend with in my opinion. My phone's charger only does 18Watts on a good day (screen-off) in an airconditioned room (measured by a USB multimeter). There needs to be adequate overhead left in the thin stock cable that is shipped with these phones (which isn't even USB 3.0).
I believe that this maybe an safety feature built in by Samsung in the wake of the Note 7 battery issue. There may not be a work around for it.
iceepyon said:
safety feature built in by Samsung in the wake of the Note 7 battery issue
Click to expand...
Click to collapse
You aren't helping the OP's case in trying to re-create another (explosive) Note7. Suggest something nerdy, like creating a custom kernel that tricks the charging circuit into thinking that the screen is off when the the charger is connected.

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