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I think I figured out why the battery never seems to go below 100%

My original device always seems to take forever to go below 100%, and I just got a new device that has the opposite issue - it never goes above 94%. So I did some further tests, tonight.
My 94% device goes down fairly steadily once unplugged. But, the device at 100% does not. Also, when the 100% device is drained and I recharge it, it still says it's charging when its at 100% - so what does this mean?
I think that the battery calibration is off, as we already assumed. So, my 94% device is really 100% and I suspect that it would survive beyond 0% as it probably still has 6% juice left in reality. And, in the case of the 100% device, it's probably mis-calibrated to 105 or 110% (or more?). Since the UI can't show you 105%, it just shows the max of 100% until it goes below 100% which can take some time. I also suspect that the device would cut out at 5% or 10% since it's actually drained completely.
So that's the reason, I think. As to the fix, I don't know. What's weird is that these two devices are so different in terms of how the battery status is calibrated.

How can this be fixed? Or "Recalibrated?

I'm letting one of them completely drain, to see what happens.
At least the 94% one gives me an idea on what the battery life is, since I can just tack on +6%. But the one stuck at 100% is a complete mystery - it could be 5% off, 10% or even more.

Also, these run on 2 cell batteries making 7.4V nominal. All the devices before are using single cell batteries at 3.7V nominal. So Android may have issues with that voltage difference.

roebeet said:
I'm letting one of them completely drain, to see what happens.
At least the 94% one gives me an idea on what the battery life is, since I can just tack on +6%. But the one stuck at 100% is a complete mystery - it could be 5% off, 10% or even more.
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I had the 100% battery issue before and it took a long time for it to dip below 100% (so long that it seemed unreal). Later I decided to let it drain to zero before recharging it to full again. Since then the battery indicator seemed to behave normally and discharged at a normal rate when the tablet was in use.

Have you tried deleting /data/system/batterystats.bin to wipe battery status? Mine sits on 100% for ages so I'm trying this now.
roebeet said:
My original device always seems to take forever to go below 100%, and I just got a new device that has the opposite issue - it never goes above 94%. So I did some further tests, tonight.
My 94% device goes down fairly steadily once unplugged. But, the device at 100% does not. Also, when the 100% device is drained and I recharge it, it still says it's charging when its at 100% - so what does this mean?
I think that the battery calibration is off, as we already assumed. So, my 94% device is really 100% and I suspect that it would survive beyond 0% as it probably still has 6% juice left in reality. And, in the case of the 100% device, it's probably mis-calibrated to 105 or 110% (or more?). Since the UI can't show you 105%, it just shows the max of 100% until it goes below 100% which can take some time. I also suspect that the device would cut out at 5% or 10% since it's actually drained completely.
So that's the reason, I think. As to the fix, I don't know. What's weird is that these two devices are so different in terms of how the battery status is calibrated.
Click to expand...
Click to collapse

samepic said:
I had the 100% battery issue before and it took a long time for it to dip below 100% (so long that it seemed unreal). Later I decided to let it drain to zero before recharging it to full again. Since then the battery indicator seemed to behave normally and discharged at a normal rate when the tablet was in use.
Click to expand...
Click to collapse
I tried that once, by setting it to never shutoff and letting it go over night. The next morning I charged it to green plus 30m as someone suggested in the TnTL thread, but I still had the problem of the meter sticking at 100% for a long time.
Anyways, I installed 3.0.0(TnTL) on monday and decided to also use the CWM clear battery data option, and now it seems to be dropping more as expected, but I'm not entirely sure that I did it completely correctly as by the time that I did the clear battery data option it would've been below 100% charge since I did so AFTER running the update.zip... just have to wait and see now...

Battery Stays at 100% For Ages
My battery stayed at 100% for ages the first time I charged it. Then it dropped quickly and cut out around 50%. I recharged it and it seems to be behaving more normally now. It still seemed to hang at 100% for a while, but no where near as long as the first time. I'm waiting to see at what percentage it dies this time.

my zt 180 tablet never got above 94% also. And it dropped pretty quickly and at around 40% it seemed to get a second life and slow down, but eventually it went all the way down to about 10% and then I would charge it (about 3 hours max). It too is a 7.4v supply.
My Odroid T had a 3.4 supply and it was pretty linear, showed charged at 100% and went down accordingly, though the developers had some issues with a few software releases where it did behave erraticaly and they did a few patches that fixed it.

roebeet said:
My original device always seems to take forever to go below 100%, and I just got a new device that has the opposite issue - it never goes above 94%. So I did some further tests, tonight.
My 94% device goes down fairly steadily once unplugged. But, the device at 100% does not. Also, when the 100% device is drained and I recharge it, it still says it's charging when its at 100% - so what does this mean?
I think that the battery calibration is off, as we already assumed. So, my 94% device is really 100% and I suspect that it would survive beyond 0% as it probably still has 6% juice left in reality. And, in the case of the 100% device, it's probably mis-calibrated to 105 or 110% (or more?). Since the UI can't show you 105%, it just shows the max of 100% until it goes below 100% which can take some time. I also suspect that the device would cut out at 5% or 10% since it's actually drained completely.
So that's the reason, I think. As to the fix, I don't know. What's weird is that these two devices are so different in terms of how the battery status is calibrated.
Click to expand...
Click to collapse
Warning: Slightly off topic -
I'm glad Roebeet was able to get a 2nd Gtab. Hope you found a good discount. Happy Holidays!!!
Now back to the topic discussion...

Butch1326 said:
Warning: Slightly off topic -
I'm glad Roebeet was able to get a 2nd Gtab. Hope you found a good discount. Happy Holidays!!!
Now back to the topic discussion...
Click to expand...
Click to collapse
Off-Topic x2 : yep, got used one that another XDA user had returned!
On-Topic: Still waiting for the battery to discharge, it went to sleep last night. Getting close....

roebeet said:
Off-Topic x2 : yep, got used one that another XDA user had returned!
On-Topic: Still waiting for the battery to discharge, it went to sleep last night. Getting close....
Click to expand...
Click to collapse
I also had the issue of battery showing 100% for a long time and then cutting out around at 50%. One of the posts mentioned doing a battery stat wipe in CWM after charging to 100% + 30 minutes.
I did this with a little twist of my own.
I allowed the battery to drain completely and tab to shut off. Plugged in the charger and immediately did a battery wipe in CWM. Allowed the battery to charge fully upto 100% + let it be on charger for additional time till the battery symbol in the notification bar no more showed charging sign. Again did the battery stat wipe in CWM and then rebooted the tab.
Since then i observe that the battery has been draining as it should be expected to. down to 72% after about 4+ hours of use. I will still be monitoring the battery discharge further for two or three more charge cycles. But I feel doing battery stat wipe in cwm 2 times at full drain and then again at full charge might have helped caliberate it properly.
Let me know if anyone else tries this and gets same or different observations.

Try installing this to measure your current usage over the life of the battery... (dont have a GTab and still considering). Since most likely this widget and the battery monitor are using the same API we will see if its a hardware sensor issue or a software issue...
http://www.appbrain.com/app/currentwidget/com.manor.currentwidget
I suspect its in their battery monitor and not the sensor or API... if that is the case it should be easy to debug (if you have the source). Typically these issues are due to poor polling algorithms...
Im new to android so I am unfamiliar with profiling capabilities of the platform...(Still learning)

Perhaps this will be one of the 'little fixes' that will be present in the latest FW update when VS drops it tomorrow. I have the 100% unit BTW. A fix would be nice.

Reading this thread this morning it got me thinking about my gtab battery situation. When I first got the gtab, the battery stayed at 100% for hours, then the percentage dropped like a rock. Over time, the battery dropped in more regularly, although it drops in large numbers (like from 100% to 83%, then to 67%, and so on). I'm currently running TnT Lite 3.0.
This morning I charged the battery to 100%, and while plugged in (to the AC outlet), I reset the battery stats using cwm. The battery today has been steadily going down throughout the day as I would expect. In over 8 hours, I watched the battery go down steadily from 100% to 84%. So far, so good.

my exp
Tried draining once, just let it sit, didn't fix it.
Tried again but this time I kept the screen on and watched the voltage, shutdown was near 6.8 volts. Now the meter is accurate. YMMV...

@it'sDon - it wasn't fixed in the update.
I was in the same boat as most of you. Took a very long time to go down from 100% and then zonked out completely at ~10-15%. It's now been charging for a few hours and it's been sitting at 100% for quite a while but the light is still red (so it's still charging) which means it will probably happen again looks like it's charging to some value over 100% and when it discharges, knocks out while the meter is still reading as having juice. Roebeet is 100% on the money.
I am going to try the CWM battery value reset some of you mentioned to see if it does something once my light is green, then I won't charge it and watch it like a hawk once it hits 20% to see if it shuts down at 10-15% or a value less than 3% which is acceptable I think.

I never had a problem on my stock(ish) g-tablet. That is until I installed the latest update.
I had to do a data wipe before any of the cosmetic TnT changes would show. After that the battery now seems stuck at 100%. This wasn't that way before, so I will try draining the battery, and see what happens.
Since I found that this was tied to my latest update, I think that I should call CS and complain.

My battery drain didn't make a difference, either. Still haven't pinned down a fix that works.
At least those of you with 94% max have a general idea when your battery will die. With us "100% forever" ones, we have no clue.

Actually, I may not have a problem after all. I have had my tablet on for about two hours. It is now showing the battery at 86%.

[Q] Battery Drains with Phone Off?

I have long suspected something was wrong here. So last night, I charged my G2X to 100%, then turned the phone completely OFF!
Nine hours later I turned my phone back on, saw the nice Trinity animation, and saw that my battery was now at 89%!!!
WTF? Can anyone tell me what's going on here? My battery is only 7 months old! How does the battery drain so much with the phone off???

It could be that the battery is lying when it's at 100%... but I have read that the g2x drains while shut off.
Next time charge to 100, reboot phone, see what % it's at, then shut off the phone and test.

When I had charged the battery to 100%, I had left it connected to the charger for about five hours at 100%.

EEngineer said:
When I had charged the battery to 100%, I had left it connected to the charger for about five hours at 100%.
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Click to collapse
Still doesn't change the fact that it could be lying.
Sent from my LG-P999 using XDA

Mine does this along with a few others, there is a thread on the subject already.
Sent from my LG-P999 using xda premium

mt3g said:
Mine does this along with a few others, there is a thread on the subject already.
Click to expand...
Click to collapse
Some say it could be the kernel, but there doesn't seem to be any resolution.
As to battery gauge accuracy, I have Battery Monitor Widget Pro installed and it verifies the sensor accuracy.

Charged to 100%, pulled the battery & let it sit for 8 hours. Just put the battery back in and the fuel gauge and Battery Widget Pro both say 100%.

With the way virtually every rechargable battery works this is pretty normal. When you charge a phone battery or anything really overnight it doesn't actually take the whole time to reach 100%. Most phones only require a few hours and after it hits the 100% mark it actually starts draining a little (as you have it plugged in) to about 95% or a little lower (your phone however is programmed to still display 100% to reduce user anxiety and will slowly adjust to the actual battery percentage as time goes on) And as someone already said, leaving the battery in the phone (even while it is off) will drain the battery too. This can be fixed by simply removing the battery until you want to use it.

ehafling said:
With the way virtually every rechargable battery works this is pretty normal. When you charge a phone battery or anything really overnight it doesn't actually take the whole time to reach 100%. Most phones only require a few hours and after it hits the 100% mark it actually starts draining a little (as you have it plugged in) to about 95% or a little lower (your phone however is programmed to still display 100% to reduce user anxiety and will slowly adjust to the actual battery percentage as time goes on)
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Click to collapse
This is false and contradicts my measurements. BTW, the Android battery API shows the real percentage of the battery and doesn't "display 100% to reduce user anxiety". A battery meter that lied about its charge would INCREASE user anxiety.
it is well known that modern Android phones, including iPhones, have sneak circuits that still operate when the phone is switched off, including the GPS. It's a big privacy issue.

Then why doesn't it happen all the time on all phones and roms? I can confirm while using hfp 2.1 it drained with phone off and battery inside, but on cm7 nightly latest and stock kernel it hasn't done it to me yet.
Sent from my LG-P999 using xda premium

Because it's up to the kernel. Different kernels behave differently when the phone is off.

Kernel
Prob Has to do with Kernel. Maybe its the battery driver your using.
For example I'm using Hellfire phoenix Rom with this Kernel > http://forum.xda-developers.com/showthread.php?t=1073626
I can use the one with DebouchedSloth's Battery Driver "(funky readings, but great battery performance)" or with the Official CM7 Battery Driver "(smooth readings, but battery life is slightly less than DebouchedSloth's driver)"

I think it's because the phone isn't actually off when you "power it off." I say this because when it's "off" and you plug in a power source the screen shows a charging graphic almost immediately, so it must still be on in order to detect the charger and show something on screen that quickly.
I had mine charged to 100%, turned it "off", came back 3 weeks later and it was dead.
Not sure why they'd design it like that. I guess the phone needs to be "on" in some sense to be able to charge while "powered off." I assume other phones can charge the battery while the phone is actually completely off.

O.K., just lost 10% battery overnight when powered off.
I've read that a draining battery when off is caused by the Fast Boot setting. When powered off some things are still running so the phone boots up faster.
In OEM Android there is a "Setting > Power > Fast Boot" that I can uncheck, but on CM7 I can't find that setting. Any ideas?

[Q] Why do I lose 3% battery in 10 mins, then it's fine after that?

Not sure what's happening with my phone, but after removing the plug on my fully charged phone, I will let my phone sit idle for about 10 mins, when I go wake the screen, I see that I've already lost 3% of battery capacity.
The weird part is after this initial 3% is gone, my battery will drain normally. Does this mean I need to calibrate my battery? Is there anyway to do this without damaging it?

It means you need to get a new hobby... seriously, why do you care if it changes nothing what so ever. In order to fix this, you should try not checking your battery percentage every 2 minutes. On the upside, this will probably give you another half hour of battery life as well.(damn a change of attitude would fix like 90% of problems on this site)
On a more serious note, it's likely just because your phone doesn't keep charging when it hits full charge, it stops charging in order to not kill your battery, and lets it drain to like 90% at which point it will charge back up to 100%, so it may be at any point in between when you disconnect it. Even if it is truly at 100% when you disconnect the charger, the measurements may not be completely accurate when approaching 100%, so it is likely, that could make it drop faster at first. You need to do nothing in order to fix this, seriously don't mess with it.

CoronaDelux said:
Not sure what's happening with my phone, but after removing the plug on my fully charged phone, I will let my phone sit idle for about 10 mins, when I go wake the screen, I see that I've already lost 3% of battery capacity.
The weird part is after this initial 3% is gone, my battery will drain normally. Does this mean I need to calibrate my battery? Is there anyway to do this without damaging it?
Click to expand...
Click to collapse
Are you running stock or custom kernel and any custom ROM? Ive noticed this sometimes too but that's because the phone, when unplugged is running services to start phone on battery power versus the cord/wall charger. Check logcats to see what happens when phone unplugged to see what may be happening when phone starts on battery.

I think you are worrying about it a little too much. It could be searching for service (which drains a lot of battery), starting services as someone previously said, heat is horrible for a battery, anything. If the drain is normal after that who knows it could be the ROM you are on, battery percentage not being reported correctly.
Not worth an RMA by any means. Reset battery stats in recovery and see how that works out for you.

Bear in mind, these batteries are cell batteries, a user who plugs their phone in every time the battery hits 50%, is going to notice over a period of time the time it takes to go from 100% to 50% is shorter and shorter, and suddenly, 49%-0 holds a better charge. If you're constantly charging your phone, you'll wear those cells of your battery down. This is where the "hoax" of always letting your battery drain to 0% when you get it to "maximize" battery potential came from.

galaxy j7 battery problem

i think my phone has some serious problems and i'm wondering if it's the battery dying or a short circuit
when i plug it on a charger while of it shows a normal charging image but how it switches from one animation to the other so i can see the status of battery percent it's like a short on the screen happened
it chargers to 100 but when i switch it on it shows mybe 95 but never 100 and if i connect it to a charger to get to 100 it only decreases
it gets warm now days which did not happen and it like drains 50% overnight which is obviously not normal. these two days the battery life is like 4 hours with internet wich with j7's battery it should not happen. if i switch it off and then on again i loose like 20% of battery and if that is all i had i get 0% and the phone doesnt switch on. the phone never had contact with water . it's been 4 days since this started and it happened all of sudden like today my phone stays up to two days at most and i just woke up it barely finishes a day without data and with power saving mode
i'm sure it's not about background apps or any activities because i hard reset it already and i don't have any app. and it's not about wifi or sync or poor network i tried all that. i did everything it didnt help. i could buy a new battery but i'm scared it might be a short because i don't think a battery can just die in one night like this.
can anyone help me with this or it's nothing serious and i have to change the battery
galaxy j700H
running custom rom enigma v6
i had a habbit of charging my phone when i sleep and unplug it in the morning and i always switched it off while charging. never used it while charging

311y said:
i think my phone has some serious problems and i'm wondering if it's the battery dying or a short circuit
when i plug it on a charger while of it shows a normal charging image but how it switches from one animation to the other so i can see the status of battery percent it's like a short on the screen happened
it chargers to 100 but when i switch it on it shows mybe 95 but never 100 and if i connect it to a charger to get to 100 it only decreases
it gets warm now days which did not happen and it like drains 50% which is obviously not normal. these two days the battery life is like 4 hours with internet wich with j7's battery it should not happen. if i switch it off and then on again i loose like 20% of battery and if that is all i had i get 0% and the phone doesnt switch on. the phone never had contact with water . it's been 4 days since this started and it happened all of sudden like today my phone stays up to two days at most and i just woke up it barely finishes a day without data and with power saving mode
i'm sure it's not about background apps or any activities because i hard reset it already and i don't have any app. and it's not about wifi or sync or poor network i tried all that. i did everything it didnt help. i could buy a new battery but i'm scared it might be a short because i don't think a battery can just die in one night like this.
can anyone help me with this or it's nothing serious and i have to change the battery
galaxy j700H
running custom rom enigma v6
i had a habbit of charging my phone when i sleep and unplug it in the morning and i always switched it off while charging. never used it while charging
Click to expand...
Click to collapse
same thing happening with me from last one week since i left my phone charge at night while i was sleeping. ? after unplugging it goes from 100% to 95% suddenly and battery backup dropped don't know what's happening and yes after removing battery and reinsert it it goes down by around 20% may be someone can help.

Also got same issue..just replace the battery

Sahibjeet Singh said:
Also got same issue..just replace the battery
Click to expand...
Click to collapse
Did it work for you... I mean how is the battery life after you have replaced it

311y said:
Did it work for you... I mean how is the battery life after you have replaced it
Click to expand...
Click to collapse
I get around 4hours of screen on time

Phone charging at 100% for around 15-30 minutes

Hello. I just noticed something weird on my TCL 10L phone. When the phone reaches 100%, it displays fully charged on my lockscreen. Though, unlocking the phone I see the phone is still charging. I see the battery bar being green with a charging bolt. It takes around 15-30 minutes until it says charged (and the bolt removed). Is this normal? I do not remember the phone doing this when I bought it around 5 months ago.

Changes in charging and especially sudden loss of capacity can indicate a battery failure.
Check for cover swelling/bulging, battery swelling is a failure, replace asap if so.
A failure this early is rare but Li's can fail at any time in their life.
Inspect jack and port for contamination. Use a known good charger and cable. Try cycling the battery until the phone shutdown then charge to 100%, repeat... to calibrate battery indicator.
Minimum start charging temp is 72F
Best start temperature is 82-90F
Never attempt to charge a Li below 40F
Keep battery temperature below about 101F when charging.
Do not use phone while charging as it will skew the charging curve.

Thanks for the reply. There is no battery loss. I can play games on this device, browse, and check apps and drain the battery in the same period I did since I got it. I actually charged it to 100% since went to sleep. 9 hours later the device was still at 100%. 1.5 hour of playing a game after that and the battery was down to 84%. The issue is really weird. I am thinking a battery calibration may help. I do not know.
P.S. I am currently using Android 10 and I do not want to switch to Android 11.

I wouldn't worry about it.
It's best not to charge to 100%.or below 30%.
Lu's like frequent midrange power cycling (40-65%).
As for 11, no way that crapware is getting on my phones....

blackhawk said:
I wouldn't worry about it.
It's best not to charge to 100%.or below 30%.
Lu's like frequent midrange power cycling (40-65%).
As for 11, no way that crapware is getting on my phones....
Click to expand...
Click to collapse
Did you personally experience this on any device? This is the first time I saw something like this. According to some articles the phone may display wrong battery stats. So I was thinking calibration would be a solution to this issue.