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All you ever wanted to know about NFC and battery drain.
Here's a starter:
A typical NFC transceiver draws ~50mA of current when powered up. For reference, this equates to around 25% of the total consumption of a typical smartphone with the screen powered on.
Left unchecked, this could have noticeable, adverse effect on battery life.
However, there are optimization techniques that can significantly reduce the effects of NFC on battery life. For instance, the Android NFC subsystem carries out the following:
Intelligent polling - Android doesn't leave the NFC transceiver running at all times, instead it polls for tags at a rate around ~10Hz to conserve battery life. Maybe a feature in future ROMs would be the ability to change the polling frequency down to 1Hz.
Polling disabled on screen lock - when the screen is locked Android ceases to poll for tags, however card emulation continues (this is how
Google Wallet functions even when the screen is locked) .
Screen off = NFC off - the NFC radio is powered down when the screen is locked.
Click to expand...
Click to collapse
Preface:
Although I have been "reading the mail" for a while, I am a new member so I cannot put this in the same thread as the existing wireless mod this is meant to update. Likewise, I cannot link to my pictures directly until I get at least 10 posts submitted so the smaller attached versions will have to do for now. With that said, I see many people are not happy about the lack of native wireless charging support in regards to the T-Mobile Note II (T889). With over 18 years of engineering experience and a T889 myself, I decided to investigate this issue. After 10+ hours of tearing down my own Note II and trying many of the options others have already attempted, I have a few findings.
A. The core design of the T889 is the same as the i317 and N7100. Samsung even uses a mixture of the various device parts to make the T889; including the main system board.
B. The only obvious difference looks to be the actual core processor, which has the hard coded framework (similar to a BIOS) that controls the fundamental parameters of the radio and device capabilities. This framework also takes presentence over any middleware ROM loaded on to the device so there is only so much that can be modified (liberated) without causing too many underlying issues. This method of development is common when creating customized versions of a device for multiple clients while also making sure the FCC part 15 type acceptance regulations here in the USA are adhered to without resubmitting each device multiple times for each client version.
C. In the case of the T889, I believe the ability to facilitate the 802.11 calling feature (either ON or OFF) cost the device its ability to also allow for wireless inductive charging. It may be the stray RFI created by both functions operating at the same time would either not pass FCC type acceptance or the device was never originally type accepted with both features enabled at the same time. Regardless, my overall conclusion is the wireless charging feature in the T889 is disabled on the hardware level and there is no cost effective nor reasonable way to change this.
Other notes:
The above may also explain why the N7100 USB charging board swap doesn't work and why the T889 crashes when loading the home screen; even if a N7100/i317 ROM is loaded on the device. It looks like the processor and/or power management chip is hard-coded to poll the little logic chip on the T889 and i317 charging boards regardless of the ROM. If it does not see that chip (the case with the N7100 USB charging board), it cries foul and triggers a reset (shut down) command. So, it is what it is and we must "skin the cat" a different way.[see image usb_cb_lg.png]
Updated Mod:
The current wireless mod to enable inductance charging on the T889 is a great option, but while ripping my T889 apart, one action item I wanted to do was see if I could make the modification easier and cleaner at the same time. I believe I have achieved this. With my version of the modification, the distance from point A to point B has been reduced to less than 45mm and there is no need to remove or navigate a conductive trace from the charging board/speaker housing assembly. With that said, let's begin. -
* Please proceed at your own risk knowing that you will most likely void your warranty performing this mod. I nor anyone else will be held responsible if you fail to perform this modification correctly and physically damage your device. You have been warned.
- This procedure requires the use of the following tools:
1. A non-conductive and clean work space such as a wood table or natural stone counter top.
2. A soft micro-fiber cloth or pad to lay the device on while working on it.
3. A multi-meter capable of reading resistance in Ohms and DC voltage.
4. A small razor blade.
5. A #0 Phillips head precision screw driver.
6. A small plate to keep the fasteners secure while working.
7. Common case separating pick
8. A professional temperature controlled soldering iron with a pencil tip no larger than 2mm in width – set to no more than 725̊ F.
9. A small roll of rosin core 60/40 solder.
10. 45mm of AWG-30 [0.01" / 0.255mm] or similar sold core vinyl sleeved wire.
11. Fine tip tweezers.
12. Experience and patience.
Now, the good stuff!
- The new location to tap into the +5VDC is on the (+) side of the zener diode located just north of where the charging board header connector feeds the main system board. Form there, it is only 40mm to the positive voltage side of the wireless charging contacts. [see images t889wcmsp.png and t889_wmod_a.jpg]
- This is how is should look like once done... [see image t889_wmod_b.jpg]
- Note the small compression mark caused on the wire when I first tested the casing reassembly. This can be rectified by carefully cutting a small "V" shaped groove in the casing fastener hole cross member. This will also facilitate a 1-2mm gap guide on the inside of the casing wall once reassembly is complete. [see image t889_wmod_c.jpg]
Once done, install your compliant (5vDC @ 1000mAh) inductance receiver plate and you are good to go with a clean voltage line that will be reliable and allow you to charge the T889 via any QI compliant charging pad such as the one made for the Samsung S4.
Have fun and be safe,
Scott
Bye the way, I have also attached a pic (see image t889pcb_sm.png) showing both sides of the T889 main system board with a message on where to get the higher definition version. It is very enlightening regarding what makes up the T889 and what I have been talking about.
Here are some additional pics of the mod working with the new Samsung S4 wireless charger that was on sale last week.
Scott-
What type of wireless charging pad did you use to put in the back of the phone? Links/pics would be great to show a 100% guide.
When placed on the wireless charger, do you get a confirmation popup every time it's placed on it?
How fast is the wireless charging rate? Same as plugging it in?
imaleecher said:
What type of wireless charging pad did you use to put in the back of the phone? Links/pics would be great to show a 100% guide.
When placed on the wireless charger, do you get a confirmation popup every time it's placed on it?
How fast is the wireless charging rate? Same as plugging it in?
Click to expand...
Click to collapse
The receiver pad is a common 5vDC up to 1.0amp "Note2 N7100" QI compliant pad you can find easily on eBay. Since I do not have enough posts yet, I cannot link to the source I used, but again, they are easy to find.
Re: Notification
Since the T889 does not natively support the wireless charging feature, there is no "wireless charging" notification popup present. However, functionally, everything works perfectly fine and the same notifications apply whether you place the T889 on the Samsung charging pad or plug in the traditional USB charging/sync cable.
Wireless charging pad with the T889 OFF:
- The charging pad light first turns ON/Green within 1 second of placing the unit on the pad properly.
- Then, within another 2-3 seconds, the T889 launches the battery icon and begins the charging process.
- After about 30 seconds or so, the battery icon and screen go to sleep and the red charging indicator LED takes over.
Wireless charging with the T889 ON:
- The charging pad light first turns ON/Green within 1 second of placing the unit on the pad properly.
- Then, within another 1-2 seconds, the T889 produces the two-tone (default) audible charging notification with the lightening bolt showing up on the display inside the battery icon.
- The charging process is now active and doing its thing.
Although it acts the same way as charging via the USB port, the efficiency of wireless charging is still in the 75-80% range so in reality and accounting for the circuit overhead that peaks out at 1000mA, my initial finding is the charge rate is about 15% per hour when paired with the stock 3100mA battery (or approximately 6.75 hours for a complete charge). Regardless, it is still pretty snappy and I will test it some more over the coming days.
One thing that should be noted is the 1000mA receiver pad takes up 100% of the marginal space in the T-Mobile rear cover plate so do not try this with anything larger than the standard 3100mA battery unless a deeper rear cover plate can be sourced.
Scott-
One little note, the 1000 Ma can not be achieved with stock kernel, I use Perseus kernel that can tweak the USB charging from 450 ma, to 1000.
For an accurate (more or less) measurement, use Galaxy Charging app from Play Store.
Sent from my SGH-T889 using xda premium
premiatul said:
One little note, the 1000 Ma can not be achieved with stock kernel, I use Perseus kernel that can tweak the USB charging from 450 ma, to 1000.
For an accurate (more or less) measurement, use Galaxy Charging app from Play Store.
Sent from my SGH-T889 using xda premium
Click to expand...
Click to collapse
Thanks for the heads up. I will look into this.
Scott-
Alright, here are the enlightening results of the wireless and USB direct charging current utilizing Galaxy Charging Current Pro v1.6.
As stated, I am going to continue to test the actual charge times more in the coming days. :good:
Scott-
Amazing work. It's always great to see people still tinkering with their devices.
Today, I changed the stock kernel to the Saber variant and I am liking the results. With no others changes or mods, I am now seeing 900mA of the 1000mA the QI receiver pad is spec'd at.
I was also able to charge from 81% to 91% in exactly 25 minutes with the T889 ON, the screen awake, Wi-Fi active, and the phone idling. This would equate to approximately 4 hours and 10 minutes per complete charge, which is very respectable.
Scott-
Just wanted to give thanks to the very in depth" and professional manor of which you take time explaining all of this along with very :thumbup:detailed illustrations.
If you know so much about modifying the hardware in such a way to achieve this, you could very well be the guy every android owner has been waiting for
to maybe one day software mod these phones to one day get 3-4 day batt life regardless of any battery mah size
Once again thanks for the info
Sent from my SGH-T889 using xda premium
lojak29 said:
Just wanted to give thanks to the very in depth" and professional manor of which you take time explaining all of this along with very :thumbup:detailed illustrations.
If you know so much about modifying the hardware in such a way to achieve this, you could very well be the guy every android owner has been waiting for
to maybe one day software mod these phones to one day get 3-4 day batt life regardless of any battery mah size
Once again thanks for the info
Sent from my SGH-T889 using xda premium
Click to expand...
Click to collapse
Thanks, but I am more on the hardware side and not the software arena. Plus, this mod concept was originally not my idea so I cannot take complete credit for it. I simply investigated the situation and found yet another way to achieve the end result. Regardless, the battery chemistry is just not there yet so if you want 3-4 day operation between traditional charges, I suggest looking into one of these new solar and other alternative charging options.
http://www.hongkiat.com/blog/extraordinary-smartphone-chargers/
For now, I am back to enjoying this current QI solution and have established a repeatable charging cycle time that is within 5 minutes on each benchmark. With the Saber kernel allowing for 900mA of wireless charging current to make it through the circuit, the 0-2% to 100% charge time looks to be 4 hours, 25 minutes (+/-5 min). My latest charge cycle that just completed is shown below.
I'm happy -
Scott
Thanks for this info.
I have an AT&T SGH-I317 with a wireless charging pad. It works but is fairly slow charging at about 460 mA. I've read that the original mod with the Perseus kernal would allow the device to charge faster.
Before I jump into it I'd like some confirmation that this mod would give my wireless charging a boot on my AT&T Note II. I haven't found a lot if complete info and am concerned.
Thanks...
RojasTKD said:
Thanks for this info.
I have an AT&T SGH-I317 with a wireless charging pad. It works but is fairly slow charging at about 460 mA. I've read that the original mod with the Perseus kernal would allow the device to charge faster.
Before I jump into it I'd like some confirmation that this mod would give my wireless charging a boot on my AT&T Note II. I haven't found a lot if complete info and am concerned.
Thanks...
Click to expand...
Click to collapse
As your i317 is already QI capable, then there is no need to perform this mod. Your specific focus should be confirming the following before flashing the kernel:
1. Is your QI charging (transmitting) platform rated at 2A (input) with an effective output of approx. 1A? Likewise, is the wall adapter feeding the pad rated at up to 2A?
2. Is the QI receiving pad mounted on your i317's rear case panel or the battery rated at 1000mA @ 5V? [Anything lower like 700mA will obviously limit your charging rate, which results in longer charging times].
I have not tested the Perseus kernel, but the Saber kernel on my T889 does liberate the higher charging rate as long as the hardware TX/RX pads support it (as covered above). I average about 980mA, which is within 5% of the rated peak for my Samsung charging platform.:good:
Scott-
SGBE said:
As your i317 is already QI capable, then there is no need to perform this mod. Your specific focus should be confirming the following before flashing the kernel:
1. Is your QI charging (transmitting) platform rated at 2A (input) with an effective output of approx. 1A? Likewise, is the wall adapter feeding the pad rated at up to 2A?
2. Is the QI receiving pad mounted on your i317's rear case panel or the battery rated at 1000mA @ 5V? [Anything lower like 700mA will obviously limit your charging rate, which results in longer charging times].
I have not tested the Perseus kernel, but the Saber kernel on my T889 does liberate the higher charging rate as long as the hardware TX/RX pads support it (as covered above). I average about 980mA, which is within 5% of the rated peak for my Samsung charging platform.:good:
Scott-
Click to expand...
Click to collapse
Thanks for the reply.
I have read that the charge rate is limited by the device to something like 466mA. Mine charges at 460. Some say the kernel will raise it the others say the kernel alone won't do it, a hardest mod (like this) is required.
To answer your questions:
1. Transmitter Nokia DT-900 output 750mA.
2. Receiver rated at 650mA
I'd be happy to get the charge rate around 600mA. I know my setup I'd not capable of charging at 900mA, but would like to do better than the 460mA I'm now... getting off possible.
If I can get it charging rate higher, I'd look into getting a 1000mA receiver, but won't be getting a new transmitter until the prices drop. I was able to get several Nokia charges for just under $20a piece.
When I get home I will try Saber kernel.
Sent from my Nexus 7 using Tapatalk 4
Try the custom kernel since that does control the charging manager functions. If the change is marginal, your RX pad may be actually functioning like a 500mA rated pad. Hopefully, you will see something closer to 600-640mA with your setup (even if the charge time will not be significantly reduced). If anything, invest in a good RX pad that is rated up to the 1000mA so you know you are able to accept any level energy up to the 1A regardless of the charger you use now or buy later.
SGBE said:
Try the custom kernel since that does control the charging manager functions. If the change is marginal, your RX pad may be actually functioning like a 500mA rated pad. Hopefully, you will see something closer to 600-640mA with your setup (even if the charge time will not be significantly reduced). If anything, invest in a good RX pad that is rated up to the 1000mA so you know you are able to accept any level energy up to the 1A regardless of the charger you use now or buy later.
Click to expand...
Click to collapse
With Saber Kernel 39.3 I am somehow getting a reading of 899mA, not sure how, as neither my receiver or transmitter should allow this. Though the pic on the FastTech site showed a green receiver pad that had 5v650mA printed on it, the one I got doesn't say anything, so it may be capable of up to 1000mA. Even so my Nokia should not be ab;e to supply enough to charge at the reading I'm getting.
Well, I've always used Perseus Kernel because Saber did not support my 64GB MicroSD card. Flashed Saber Kernel 39.3 and it does support my 64GB MIcroSD, Even the stock saber kernel that comes with Jedi X17 dose not support my exfat 64GB card. So I guess I'm happy.
We'll see what happens. Thanks for the help, it is greatly appreciated!
Very cool! Your charging time should be greatly reduced if eveything is being reported correctly by the app. Please confirm once you test a few cycles.
Sent from my SGH-T889 using Tapatalk 4
SGBE said:
Very cool! Your charging time should be greatly reduced if eveything is being reported correctly by the app. Please confirm once you test a few cycles.
Sent from my SGH-T889 using Tapatalk 4
Click to expand...
Click to collapse
My battery drain seemed to be much greater with the Saber Kernel vs the Perseus kernel I was using. So I went back to the Perseus kernel and even the though it reads 466mA vs Sabers 899mA they both seem to charge at about the same rate (10-12% per hour). I didn't do a real detailed comparison so the Saber my get an extra percent or two per hour, but that means little if it drains the batter much faster.
Maybe I'll try saber 39.3 again to double check the drain and charge times.
on a sad note I cracked my screen again. Luckily the replacement screen price has dropped considerably. I paid less than half of what I did the first time I had to replace it.
SGBE said:
Today, I changed the stock kernel to the Saber variant and I am liking the results. With no others changes or mods, I am now seeing 900mA of the 1000mA the QI receiver pad is spec'd at.
I was also able to charge from 81% to 91% in exactly 25 minutes with the T889 ON, the screen awake, Wi-Fi active, and the phone idling. This would equate to approximately 4 hours and 10 minutes per complete charge, which is very respectable.
Scott-
Click to expand...
Click to collapse
SGBE, thanks for all the info you've provided on this thread. I have a few request, what settings are you using in the saberkernel and where did you go to change these settings? Thanks again!
Sent from my SGH-T889 using xda premium
I'm having problems getting the solder to stick to the resistor up by the charging contacts. I'm afraid if I try much more the resistor will be toast. Can I solder directly to the top contact and it would still work?
Hi,
I'm using some Nexus 7 (2013) with Android 4.4.4 as control panels, being 24/7 powered with an AC charger. After ~2 years operation, the batteries in my Nexus 7s expanded dramatically to the point I have to replace them. I guess it's due to them being constantly held at maximum level (4.25V) at a moderate temperature ~5°C above ambient. Since I don't really use the battery - and the Nexus 7 won't boot with the battery detached (tried it), I'm looking for a way to disable the battery charging via ac (and usb/wireless) completely via software, so I can make my own charging logic that tops the battery at ~3.80V which should make it way more happy.
I already did some research and found https://android.stackexchange.com/questions/54902/disable-usb-charging or https://android.gadgethacks.com/how...oid-device-avoid-excess-battery-wear-0176280/
Command "dumpsys battery set ac 0" or "dumpsys battery set status 4" didn't have an effect.
The file "/sys/class/power_supply/battery/charging_enabled" doesn't exist on the Nexus 7 (2013).
I do have root...
Can someone help me out?
Thx
Edit: Problem solved with custom kernel, see post #10
That funcionality must be enabled in the kernel. However, I guess is not possible because it must be supported by the hardware, which is not the case
Maybe you can detach the battery and supply about 4 volts by using and external power supply and voltage regulator connected to the board pins
I am interested on this too...
bamsbamx said:
it must be supported by the hardware, which is not the case
Click to expand...
Click to collapse
Do you know for sure? Do you have any information about the power management chips used and/or schematics?
bamsbamx said:
Maybe you can detach the battery and supply about 4 volts by using and external power supply and voltage regulator connected to the board pins
Click to expand...
Click to collapse
Using an actual regulated voltage source is not a good idea, since the device will try to charge it.
Best fake battery might be a capacitor. I've tried a 100µF cap and it tricked the Nexus 7 into thinking a proper battery is connected and it bootet. But after a second it did shut off. I guess it actually tried to drain the battery despite the fact that a AC supply was connected and thus the cap drained immediately.
A supercap might work, but I don't have one. I also don't know if slim ones actually exist that would fit into the case.
Another mod would be to place two antiparallel schottky diodes between the plus terminal and the battery. This way it would only charge to ~4.0V, but as soon the charging stops, the battery would read ~3.7V and I guess that would drive the charging circuit crazy.
Also, I'd prefer to not do any hardware mods... I have lots of these devices
Edit: Actually, with a 1500µF cap the boot screen appears and I can also enter recovery. But as soon as android starts to boot, the voltage collapses and the device reboots.
bamsbamx said:
Maybe you can detach the battery and supply about 4 volts by using and external power supply and voltage regulator connected to the board pins.
Click to expand...
Click to collapse
Connecting power directly to the motherboard, presumably without a battery and the data lines, has not been tested, but removing battery from its control PCB and connecting a 5V power supply instead works fine.
RFZ said:
Do you have any information about the power management chips used and/or schematics?
.....
Using an actual regulated voltage source is not a good idea, since the device will try to charge it.
......
A supercap might work, but I don't have one.
Click to expand...
Click to collapse
Here is some info on battery control IC.
If the regulated voltage source is 5V (vs 3.7-4.2V), the device will have no reason to charge it, but "charging" a power supply is harmless anyway.
A supercap is still not good enough as the initial boot up current peaks at 1A and takes several seconds, while an external power supply on the USB port can contribute only a small portion of it. Another option is a different battery - the Nokia battery never expanded after years of being constantly powered with an AC charger.
Applying 5V to the battery protection pcb that expects a Li-Po isn't the first idea I'd have... According to ifixit, the N7 uses a PM8921 Battery Management Chip. It's rated maximum for V_bat is 4.5V (section "3.2 Recommended operating conditions" https://developer.qualcomm.com/down...er-management-module-device-specification.pdf )
Also, I'd prefer to keep the battery. It is still useful in power outage scenarios.
An interesting idea however is to modify the chip on the battery itself. Maybe I can program it to a lower maximum voltage and the PM8921 will then respect that?
I also found the kernel driver for the PM8921
https://android.googlesource.com/ke...3.4-kitkat-mr0/drivers/power/pm8921-charger.c
It looks like it supports stopping the charge... But I don't know how if it's possible to use that...
After receiving a logic analyzer, I had a look at the I2C communication with the bq27541-G1 chip on the battery.
The Nexus 7 only reads Voltage( ), StateOfCharge( ), Temperature( ), AverageCurrent( ) and Flags( ) during boot and when the usb plug is (un)plugged. I was hoping it would read parts of the configuration of the bq27541-G1, e.g. the Charging Voltage, to get parameters for the power management IC.
I also read other devices on the bus besides the bq27541-G1 (0xAA/0xAB): These are i2c addresses 0x72/0x73, 0xD4/0xD5 and 0xEE/0xEF
I guess I will have to take a different approach... Modifying the kernel.
Actually, the problem is, I really don't know what a kernel is or does in the context of a complete android system. I never looked at different kernels and what they might offer. However, since the stock kernel (right?) doesn't expose any access to the Nexus power management IC, I will have to expose it myself... As far as I can tell, the ability is there ( https://android.googlesource.com/ke...3.4-kitkat-mr0/drivers/power/pm8921-charger.c ) and others, like "Timur's Kernel", seem to have been able to change parts of the power management within the kernel.
Is there someone of you out there who has some experience in compiling his own kernel and can tell me if that's the proper way to go?
RFZ said:
I guess I will have to take a different approach... Modifying the kernel.
Actually, the problem is, I really don't know what a kernel is or does in the context of a complete android system. I never looked at different kernels and what they might offer. However, since the stock kernel (right?) doesn't expose any access to the Nexus power management IC, I will have to expose it myself... As far as I can tell, the ability is there ( https://android.googlesource.com/ke...3.4-kitkat-mr0/drivers/power/pm8921-charger.c ) and others, like "Timur's Kernel", seem to have been able to change parts of the power management within the kernel.
Is there someone of you out there who has some experience in compiling his own kernel and can tell me if that's the proper way to go?
Click to expand...
Click to collapse
This one is for building AOSP kernel for Sony devices. However, the script might help you in the build: https://github.com/bamsbamx/aosp-sony-kernel/blob/aosp/LA.UM.5.7.r1/utils/build.sh
Keep in mind you will also need a toolchain.
Here is what the kernel looks like: https://github.com/bamsbamx/aosp-sony-kernel
Although it wont be easy at all if you never built one
Thx. I don't think building a kernel is that hard. For the Nexus 7, this should be well documented. ( e.g. http://pete.akeo.ie/2013/10/compiling-and-running-your-own-android.html and https://source.android.com/setup/building-kernels )
The other problem is to find out where to start modifying the stock kernel. I still think https://android.googlesource.com/ke...3.4-kitkat-mr0/drivers/power/pm8921-charger.c is the right place. Probably just overwriting pdata->max_voltage in https://android.googlesource.com/ke...itkat-mr0/drivers/power/pm8921-charger.c#4539 to 4000 does the trick. Or I have to find out where this platform data initially comes from.
Biggest problem is, without having any experience in compiling a kernel, I have no Idea how to debug the changes - e.g. how to look at the data pdata gets initialized with.
Okay, long story short: It works! :victory:
Actually, the Nexus 7 (2013) doesn't use "pm8921-charger" at all... It's using "smb345-charger" (SMB345ET-1850Y IC, haven't found a datasheet though ).
In smb345-charger.c the #define FLOAT_VOLT_43V 0x28 actually defines the max charging voltage. Despite the fact that I don't have a datasheet, I'm pretty sure the value represents the charging voltage in 20mV increments, starting at 3.50V (0x00) up to 4.76V (0x3F). 0x19 results in a charging voltage of 4.0V etc...
Since I'm obviously not able to compile my own kernel in just one day, I have to thank @pfent who did this for me :highfive:
The patched code can be found here on github.
What's the result? Well, the Nexus 7 (2013) now will top out charging at 4.0V and stay there. I hope this will noticeably increase the lifetime of the battery and especially prevent it from swelling. I don't know how or if this might effect / confuse the gas gauge meter on the battery or the devices capacity calculations, but I think it will be fine. We'll see in 1-2 years
Edit: Attached a charging curve screenshot. The battery is charged to 4.0V, then no current is flowing in or out the battery.
Edit 2: Looks like other kernels implemented similar features: https://github.com/flar2/flo-Elemen...7067e030e/drivers/power/smb345-charger.c#L958
After installing Magic Charging Switch disable charging.
RFZ said:
Hi,
I'm using some Nexus 7 (2013) with Android 4.4.4 as control panels, being 24/7 powered with an AC charger. After ~2 years operation, the batteries in my Nexus 7s expanded dramatically to the point I have to replace them. I guess it's due to them being constantly held at maximum level (4.25V) at a moderate temperature ~5°C above ambient. Since I don't really use the battery - and the Nexus 7 won't boot with the battery detached (tried it), I'm looking for a way to disable the battery charging via ac (and usb/wireless) completely via software, so I can make my own charging logic that tops the battery at ~3.80V which should make it way more happy.
I already did some research and found https://android.stackexchange.com/questions/54902/disable-usb-charging or https://android.gadgethacks.com/how...oid-device-avoid-excess-battery-wear-0176280/
Command "dumpsys battery set ac 0" or "dumpsys battery set status 4" didn't have an effect.
The file "/sys/class/power_supply/battery/charging_enabled" doesn't exist on the Nexus 7 (2013).
I do have root...
Can someone help me out?
Thx
@VR25
After installing Magic Charging Switch its disable charging. I am tried to disable/uninstall Module from magisk but still my mobile not charging. Disconnecting again and again.
Click to expand...
Click to collapse
Dinesh 1C0N said:
@VR25
After installing Magic Charging Switch its disable charging. I am tried to disable/uninstall Module from magisk but still my mobile not charging. Disconnecting again and again.
Click to expand...
Click to collapse
What device is it?
If it's a Nexus 7, try echo 1 >/sys/devices/i2c-0/0-0055/battery_smbus.
BTW, aren't you in the wrong thread?
So I have the wireless charging mod and I have several wireless chargers “All the same brand and model” I mostly only use two. The one beside my bed and the one at work. I know this is going to sound crazy but when I use the charger beside my bed and charge to %100 the battery life is not nearly as long. It is enough to be VERY noticeable I have tested and compared like 6 times. Charging on both to 100% and just let the phone sit for an hour and when it is charged by the one beside my bed it drains about 20% faster. Can a charger effect battery life in this way????
Based on my experiences... yes!
enetec said:
Based on my experiences... yes!
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Click to collapse
I've never had that happen till now. I wonder if that particular charger is going bad or something
X_man. said:
I've never had that happen till now. I wonder if that particular charger is going bad or something
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Experiment... swap the chargers? bring the work one home and vice versa? maybe different mains or "dirty mains" could be the culprit? see if the issue follows the charger or area?
Uzephi said:
Experiment... swap the chargers? bring the work one home and vice versa? maybe different mains or "dirty mains" could be the culprit? see if the issue follows the charger or area?
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Great idea! I'll do that next week and post what happens.
X_man. said:
Great idea! I'll do that next week and post what happens.
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Any time. I personally ran into that. It wasn't 20% more like 5% (average 3hr drain on my old Rezound was 2hrs and 45mins when charged from work. It was due to ingress on my work's lines that wasn't there at home. We had little oddities with some PC's until we found the UPS for our server was causing noise on our circuits).
This is absolutely normal. I build custom vape systems, some on li-poly Batts, some on li-ion. In both cases, charge rate -can- drastically affect charge effectiveness.
Most of this in your case likely has to do with thermal reads. Remember, not only is your phone and charger loaded with chips to be smart and safe about the charge, the battery (and sometimes individual cells within it) are also microchipped. Wireless charging creates a lot of heat. Should any one of the three components recognize this heat as excessive, the voltage will drop. I _believe_ this is most relevant during the end of "saturation" phase during charging, because if the battery says "no" during this phase, or anytime after (during completion/final) , the charger's subsequent "topping-charge" will also be denied. This kind of results in cycle of the charger saying "take it!" , The battery saying "no", dropping the voltage, the charger seeing the drop and expecting it to need a top-off and immediately trying to push again, repeat. The reason you're seeing the difference is because the charger is getting it's numbers from current output from the battery. The battery can drop down to zero current when overheated to prevent thermal rail? From occurring, which the charger then translates " 0 current must mean full".
That's one part of the difference, and not necessarily what is occurring... The other part has to do with manufacturing intent. Most USB 3.1/c power supplies are actually pushing out the maximum amperage and thus has a huge stage-1 charging state, with a minimum stage-2 (saturation) charging state. This basically translates into , your charger and phone are both lying when you rapid charge.
I'm sure I'm missing some facets or misrepresenting them here as I can't remember all the damn physics, but short story is: for absolute saturation, battery life, battery runtime, and safety... Charge at the same rate as battery discharge.
Edit: also what Uzephi mentioned about dirty power is also relevant. When power factors are not near 1.0 (1:1, meaning everything drawn is used, and everything requested is given), bad sh*t happens. This actually relates to the physical wave (sinusoidal) of electricity. All the anomalies are probably listed somewhere by some physicist, but suffice to say, there's a lot of possibilities, none of them "good" when out-of-phase power factors occur. This is why sensitive equipment almost always gets run through a power conditioner. The more sensitive and volatile the system, the more aggressive the conditioner needs to be (hence massive amplifiers for sound systems like the ones I use in my work need $200 glorified power strips).
Some_Donkus said:
This is absolutely normal. I build custom vape systems, some on li-poly Batts, some on li-ion. In both cases, charge rate -can- drastically affect charge effectiveness.
Most of this in your case likely has to do with thermal reads. Remember, not only is your phone and charger loaded with chips to be smart and safe about the charge, the battery (and sometimes individual cells within it) are also microchipped. Wireless charging creates a lot of heat. Should any one of the three components recognize this heat as excessive, the voltage will drop. I _believe_ this is most relevant during the end of "saturation" phase during charging, because if the battery says "no" during this phase, or anytime after (during completion/final) , the charger's subsequent "topping-charge" will also be denied. This kind of results in cycle of the charger saying "take it!" , The battery saying "no", dropping the voltage, the charger seeing the drop and expecting it to need a top-off and immediately trying to push again, repeat. The reason you're seeing the difference is because the charger is getting it's numbers from current output from the battery. The battery can drop down to zero current when overheated to prevent thermal rail? From occurring, which the charger then translates " 0 current must mean full".
That's one part of the difference, and not necessarily what is occurring... The other part has to do with manufacturing intent. Most USB 3.1/c power supplies are actually pushing out the maximum amperage and thus has a huge stage-1 charging state, with a minimum stage-2 (saturation) charging state. This basically translates into , your charger and phone are both lying when you rapid charge.
I'm sure I'm missing some facets or misrepresenting them here as I can't remember all the damn physics, but short story is: for absolute saturation, battery life, battery runtime, and safety... Charge at the same rate as battery discharge.
Edit: also what Uzephi mentioned about dirty power is also relevant. When power factors are not near 1.0 (1:1, meaning everything drawn is used, and everything requested is given), bad sh*t happens. This actually relates to the physical wave (sinusoidal) of electricity. All the anomalies are probably listed somewhere by some physicist, but suffice to say, there's a lot of possibilities, none of them "good" when out-of-phase power factors occur. This is why sensitive equipment almost always gets run through a power conditioner. The more sensitive and volatile the system, the more aggressive the conditioner needs to be (hence massive amplifiers for sound systems like the ones I use in my work need $200 glorified power strips).
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Some very good points! Doesn't seem quite as strange now LOL Thanks!
@Some_Donkus than for your complete explanation...
I've found even "about same rate" chargers (measured on phones...) often differs in heating battery: on my old Moto Z, the OnePlus X charger and the Samsung Galaxy Tab one both charged my phone (quite fast...), BUT the first heated it A LOT more, while the second hot A LOT itself!!
I think it's related to components quality too...
What I don't undestand well is why the Incipio MotoMod battery, which charge the phone at quite low rate, is able to heat it more than fast chargers....!?!?
enetec said:
@Some_Donkus than for your complete explanation...
I've found even "about same rate" chargers (measured on phones...) often differs in heating battery: on my old Moto Z, the OnePlus X charger and the Samsung Galaxy Tab one both charged my phone (quite fast...), BUT the first heated it A LOT more, while the second hot A LOT itself!!
I think it's related to components quality too...
What I don't undestand well is why the Incipio MotoMod battery, which charge the phone at quite low rate, is able to heat it more than fast chargers....!?!?
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Without knowing the specific charge voltage and stage setup of the individual batteries it's tough to speculate. One thing that comes in mind relates back to the power factors I was speaking of. It might actually be a high quality device that just has a lot of extra MOSFET + capacitors built in. These are used in order to "clean and manage" power on the fly. Capacitors are used to provide extra little bumps of discharge / supply when the battery cells themselves can't necessarily output enough mA/amp in a peak. MOSFETs do the opposite, providing a safe gateway for extra unused power either coming into the device from the battery, or from outside power to charging battery...
Both of these little guys basically are giant heat retainers (MOSFETs actually usually have heatsinks pasted to them, even the micro sized ones used in small devices)....
Just a thought.
Some_Donkus said:
...
Just a thought.
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Well, it surely could be but two weird things still happen with Incipio battery MOD (and, they say, NOT with the new Turbo Power which do fast charging instead! ):
- the overheat seems to be coming from the phone and not from the battery MOD...
- the Incipio battery MOD I have adds wireless charging too to the phone. What it's weird is that wireless charging phone (by the same rear connector on the phone) seems to overheat it less than using battery to charge it... (and battery charge rate is a bit lower...).
I think it could be related from the fact that battery MOD has probably to raise his voltage to charge phone... but strangely this overheats more phone than battery...!
enetec said:
Well, it surely could be but two weird things still happen with Incipio battery MOD (and, they say, NOT with the new Turbo Power which do fast charging instead! ):
- the overheat seems to be coming from the phone and not from the battery MOD...
- the Incipio battery MOD I have adds wireless charging too to the phone. What it's weird is that wireless charging phone (by the same rear connector on the phone) seems to overheat it less than using battery to charge it... (and battery charge rate is a bit lower...).
I think it could be related from the fact that battery MOD has probably to raise his voltage to charge phone... but strangely this overheats more phone than battery...!
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Ohhh, I see what you're saying...
Okay well, from what I understand, the Incipio Wireless mod actually charges the phone's battery first, THEN the pack within the mod. By default, magnetic induction (wireless charging method) actually will charge everything and anything within the field simultaneously.. but.. what I assume the incipio mod does is this....
Wireless charger sends out induction wave > (Induction wave charges both internal battery and mod for a moment) > Incipio mod get's a mV current reading from phone's internal battery > If internal phone battery mV current is ≠ 0, Incipio mod uses MOSFET's to gate-drain incoming charge from wireless for X amount of time (and possibly send charge to internal battery via connectors) + > induction wave continues to charge internal phone battery > Incipio takes another mV current reading from phone battery to see if it's full >>>
Cycle continues until Incipio gets mV current reading = 0, at which point it stops using gate-drains and accepts induction wave charge.
^^^ -IF- that's accurate, then it would mean that the Incipio mod is passing it's charge into the phone battery (received from induction wave) at the same time that the internal phone battery is receiving the induction wave from pad... So that internal battery is receiving a shiz-load of joose quickly...
again, pure speculation.... but it would make sense...
I'm posting in the original Android development since I hope to get more involved people to help.
Hi all,
I want to wall mount my P600, I've already did this with Lenovo and Huawei tablets without any problem.
I'm powering my P600 by an external PSU set to 4.12V and connected directly to the battery terminals. The battery is removed. No battery is present, the power is stable up to 1-2mV ripple.
However the battery as percentage is lowering every minute until it reaches 1% and shuts down.
Changing the voltage just sets the battery percentage that shows up at startup, not the "battery" fake drainage. (eg 4.12V~87% 4.02V ~76% etc)
It doesn't matter what ROM I'm using.
This behaviour is also present if tablet is left standing at TWRP screen. So is not even kernel dependent.
Do you know of any kind of "timer" set in the bootloader or wherever that keeps showing battery as draining even though there is no battery present and the voltage is constant?
Thank you kindly.
I never heard of something like that. But it could be present in many devices.
The purpose is to turn device into a doorstop once the battery is dead, sort of.
The timer will allow to reset and precharge batteries where the safety circuit had been triggered, so they can be recognized again by the system. How long does it take to count to zero? Because it wouldn't make sense to wait longer to proceed to step 2 then. In the situation where the battery is just deep-discharged, which i encountered more than once on various devices.
Whether i'm correct or not, it seems the Note(and many or most other devices) becomes crap once there are no more replacement batteries,instead of serving many more years for specific purooses, like a digital picture frame or wall mounted terminal for smart home management.
Same idea
Hi! Did you or someone else ever figure out if the P600 could be well mounted without a battery? Which wires should be connected to the external power source if I'd try?
Big thanks in advance
In the meantime i heard from various people who just attached a stabilized DC source directly to the internal battery jack instead of usb. This should work with any device. The voltage should stay in the range of higher than 3,5 volts to a max of 4,2 volts, idle and load(for 3.7v battery replacement). So you can't use any cheap 5v source,that requires the voltage regulator behind the usb jack and before the battery.
Edit: After also re-reading the first post i see the isdue, which will strike all Note users. I think you have to provide the system with info about the battery capacity. This is normally either retrieved from the internal safety chip or measured during the first charge cycles. I don't have a clue how to hack this into the system before or after flashing.