Database Info

Useful Battery Information and Calibration

Here is some information that should be useful to everyone in one way or another if not then you should have told us your secret months ago. lol
A Li-ion batteries life is on a time clock from the day it's produced and how it is used, maintained and the number of cycles it goes through reduces it's life. Even when not being used at all the clock is ticking and life is shortening.
So if any of you are like me I know many of you are far worse than me when it comes to the amount of stress put through it with flashing and extreme general use. Hopefully this will shed some light for us as to what we can do to try and prolong the life of our batteries.
The majority of the following information is from the book “Batteries in a Portable World – A Handbook on Rechargeable Batteries for Non-Engineers” (2nd edition) and Battery University™
Special thanks to the books author and sponsor of Battery University™,
Isidor Buchmann
CEO and Founder, Cadex Electronics Inc.
How to Prolong the Life of Li-ion Batteries
Battery wear-down on lithium-based batteries is caused by two activities: actual usage or cycling, and aging. The wear-down effects by usage and aging apply to all batteries but this is more pronounced on lithium-based systems.
The Li-ion batteries prefer a shallow discharge. Partial discharges produce less wear than a full discharge and the capacity loss per cycle is reduced. A periodic full discharge is not required because the lithium-based battery has no memory. A full cycle constitutes a discharge to 3V/cell. When specifying the number of cycles a lithium-based battery can endure, manufacturers commonly use an 80 percent depth of discharge. This method resembles a reasonably accurate field simulation. It also achieves a higher cycle count than doing full discharges.
Simple Guidelines
Charge the Li-ion often, except before a long storage. Avoid repeated deep discharges.
Keep the Li-ion battery cool. Prevent storage in a hot car. Never freeze a battery.
Avoid purchasing spare Li-ion batteries for later use. Observe manufacturing date when purchasing. Do not buy old stock, even if sold at clearance prices.
Hints to long battery life
3.92V/cell is the best upper voltage threshold for cobalt-based lithium-ion. Charging batteries to this voltage level has been shown to double cycle life. Lithium-ion systems for defense applications make use of the lower voltage threshold. The negative is reduced capacity.
The charge current of Li-ion should be moderate (0.5C for cobalt-based lithium-ion).The lower charge current reduces the time in which the cell resides at 4.20V. It should be noted that a 0.5C charge only adds marginally to the charge time over 1C because the topping charge will be shorter. A high current charge tends to push the voltage up and forces it into the voltage limit prematurely.
Memory Myth or Fact?
Lithium batteries are not affected by memory, but the chemistry has its own peculiarities. Current inhibiting pacifier layers affect them through plate oxidation. This degenerative effect is non-correctable on a lithium-based system
Calibration
A more serious issue is maintenance requirements, better known as capacity re-learning. This procedure is needed on a regular basis to calibrate the battery.
Why is calibration needed?
The answer is in correcting the tracking errors that occur between the battery and the digital sensing circuit during use. The most ideal battery use, as far as fuel-gauge accuracy is concerned, is a full charge followed by a full discharge at a constant 1C rate. This ensures that the tracking error is less than one percent per cycle. However, a battery may be discharged for only a few minutes at a time and commonly at a lower C-rate than 1C. Worst of all, the load may be uneven and vary drastically. Eventually, the true capacity of the battery no longer synchronizes with the fuel gauge and "a full charge and discharge are needed to ‘re-learn’ or calibrate the battery."
How often is calibration needed?
The answer lies in the type of battery application. For practical purposes, a calibration is recommended once every three months or after every 40 short cycles.
What happens if the battery is not calibrated regularly? Can such a battery be used in confidence?
Such a battery is able to function normally, but the digital readout will be inaccurate. If not corrected, the fuel gauge information simply becomes a nuisance.
Just Tell Me WTF I Should Do!
Charge your battery as often as possible, partial discharges are actually better for your battery
Once your battery is charged to 100% avoid leaving it plugged in any longer if you are not using a OEM charger.
Your battery should never get hot from charging if it does this is a sign it may be damaged.
If fuel gauge starts acting up calibrate your battery.
Yeah but how the f^$% do I calibrate my battery?
Charge phone up and then delete your battery stats.
Unplug your phone from your wall charger and let your battery drain all the way down until phone shuts off.
While still off charge phone to 100% and then boot up as normal.
There is so much more that it's mind boggling but I think this covers the main parts and beyond for everyone. So far it appears that the bump method is not necessary nor are the numerous other steps.
I can only laugh when I think that the reason the method of calibration I was using was actually working is due to the fact that the "wipe batt stats, drain battery completely and charge to 100%" is basically the last step and all that is essentially needed.

3 hours? That's it? I thought whenever I charged from empty to full when it's off it's longer.. I should time it.. hmm

darkamikaze said:
3 hours? That's it? I thought whenever I charged from empty to full when it's off it's longer.. I should time it.. hmm
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Click to collapse
I removed the time completely since some may vary. But the 3 hours is how long it should take to charge on a standalone battery charger. So rather than confuse or have questions it's better without it.

Nice work!
Charging a 1500mAh battery at 500mAh for example will take 3 hours. The Captivate charges at 2 levels though depending on if it's USB (500mAh max for charge + phone use) or a charger (whatever it says on the charger up to ~1200mAh) so it can probably get done in under 2 hours.
The phone charges to 4.23V and stops charging when full but continues to run on external power, and shuts down at 3.500V where it only consumes current to monitor the power button.
Just for reference.

Battery Stats
Since this is the first time i had a really good battery life. I would like to share it with everyone. Please see the attached screen shots.
I am using Darky's 9.1 with SuckerPunch's 1280/500 Kernel and TLJL3 modem.
I hope this will help anyone trying to get more battery life out of their Captivate.
Thanks,

CuriousTech said:
Nice work!
Charging a 1500mAh battery at 500mAh for example will take 3 hours. The Captivate charges at 2 levels though depending on if it's USB (500mAh max for charge + phone use) or a charger (whatever it says on the charger up to ~1200mAh) so it can probably get done in under 2 hours.
The phone charges to 4.23V and stops charging when full but continues to run on external power, and shuts down at 3.500V where it only consumes current to monitor the power button.
Just for reference.
Click to expand...
Click to collapse
Thanks Curious appreciate it and thanks for the additional info.

I had some other random thoughts about the calibration because I keep seeing so many posts daily.
For example "I installed a new kernel 15 minutes ago, recalibrated and the battery drain is horrible." or "After a few charges it lasted longer."
I don't think people get the idea of calibration. Recalibrating determines the capacity of the battery to convert to a % full gauge. To do that you need to fully charge until the "Battery full. Unplug charger." notification, and not rely on the display and unplugging as soon as it hits 100%. That's the inaccurate display that you're trying to calibrate.
Think of it like having an opaque container and a teaspoon. You think the container can hold 100 teaspoons, so you stop filling at 100. All you can get out of it is 100 until you try to fill until it tops off and then count how many come back out.
The phone works the same way. It has an ammeter that monitors the charge current and drain current from the battery from the time you unplug it until it shuts off and remembers that total as the capacity. Unless it's recharged in the middle which voids the data.
After that full discharge, it should stay pretty accurate even with partial discharges. At least until the next rom/kernel flash which wipes it out. At that point (I assume) it uses a simple voltage level and some relative amps drawn to display the gauge, instead of the smarter method of keeping a constant value of mAh by adding when charging and subtracting when draining to know exaclty how full the battery is.

CuriousTech said:
Nice work!
Charging a 1500mAh battery at 500mAh for example will take 3 hours. The Captivate charges at 2 levels though depending on if it's USB (500mAh max for charge + phone use) or a charger (whatever it says on the charger up to ~1200mAh) so it can probably get done in under 2 hours.
The phone charges to 4.23V and stops charging when full but continues to run on external power, and shuts down at 3.500V where it only consumes current to monitor the power button.
Just for reference.
Click to expand...
Click to collapse
hm. so if the phone switches to external power when the charge is full, is it okay to leave my phone plugged in once it's done charging? or is it just the fact that the battery is holding a full (4.2V) charge for a long time that's bad for its health?
in any case, useful post! i knew there were ways to preserve the life of li-ion batteries, but was never well-versed on the details.

Yes to both. Once the battery is fully charged, the charge circuit stops completely. It doesn't even need to trickle charge, so leaving it plugged in doesn't hurt anything.
Once the charge is complete the voltage isn't being held at 4.20V so it can come back down a little. I think BatteryUniversity generalizes becuase there have been many different designs over the years that weren't as good as what we have now, and some may have trickle charged their Li-Ions which shortens the life.

Which is it that wipes the battery stats, ROM or kernel? or is it both?

CuriousTech said:
Yes to both. Once the battery is fully charged, the charge circuit stops completely. It doesn't even need to trickle charge, so leaving it plugged in doesn't hurt anything.
Once the charge is complete the voltage isn't being held at 4.20V so it can come back down a little. I think BatteryUniversity generalizes becuase there have been many different designs over the years that weren't as good as what we have now, and some may have trickle charged their Li-Ions which shortens the life.
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Click to collapse
One word of caution though is to ensure that you are using an OEM charger. Battery University recommends that you unplug once capacity is reached but perhaps this is a general statement for Li-ion batteries as you state.

zerkai said:
Which is it that wipes the battery stats, ROM or kernel? or is it both?
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Click to collapse
Both. The first thing in a ROM flash script is to format all the partitions, so that means the batterstats.bin file is erased. When flashing a new kernel the file gets reset by some other means. No idea what. It could be CWM.

Yeah but how the f^$% do I calibrate my battery?
Charge phone up and then delete your battery stats.
Unplug your phone from your wall charger and let your battery drain all the way down until phone shuts off.
While still off charge phone to 100% and then boot up as normal.
My noob question is, how do you delete the battery stats?

iNFRiNGE said:
One word of caution though is to ensure that you are using an OEM charger. Battery University recommends that you unplug once capacity is reached but perhaps this is a general statement for Li-ion batteries as you state.
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Click to collapse
What happens when you introduce the variable of occasional car charger use?

Sanctus Peregrinus said:
Yeah but how the f^$% do I calibrate my battery?
Charge phone up and then delete your battery stats.
Unplug your phone from your wall charger and let your battery drain all the way down until phone shuts off.
While still off charge phone to 100% and then boot up as normal.
My noob question is, how do you delete the battery stats?
Click to expand...
Click to collapse
the file is located at /data/system/batterystats.bin . you'll need a file browser with root access (i use root explorer, a paid app). make sure you mount the storage as read/write or you won't be able to delete the file.
after that, reboot your phone and it will rebuild the batterystats file.
***disclaimer: be careful doing this. if you delete a crucial file, you risk messing up or bricking your phone. such is life.

Nice write up with alot of interesting information. I have never calibrated my battery but will have to try it out. Thanks for posting.
Sent from my SAMSUNG-SGH-I897 using XDA App

I'm not positive of this, but I don't think batterystats.bin holds any battery capacity or health info. I was looking at BatteryManager and it looks like a database of processes and what they use only. But there is info somewhere that gets lost easily, which is the capacity and current amount consumed.
I've been skipping the delete of that file (using CWM) and have noticed that it recalibrates fine anyway. This coming from the point of dropping just after unplugging, which is a good indication that the info is gone.
It doesn't matter if you use a car charger, USB, or AC. The phone has the actual smart charger in it, the external connection is just the power supply. The chip inside regulates and monitors the charge.
So think of it this way. The charger knows when the battery is empty or full, and measures what goes in and comes out. So to know the capacity, it has to go from full to empty. That's really all there is to it. Just wait for the real "Battery full" before unplugging.

[Q] Battery charging issue

My phone charges steadily till around 75% to 80%. After that charging speed becomes very slow. It takes almost 2 hours to reach 100% from 80%. Also the charge value remains steady at any random level for a long time and then suddenly jumps 3-4% in one second. If I reboot the phone anytime when the charge is more than 80%, then on rebooting the phone suddenly shows 100% charge!
I tried various battery monitoring apps from the market and all report battery condition to be 'good'. I have done the 'full charge - full discharge' cycle many times. Is this how all HTC Sensation's charge?

MY XE only goes to 99%. Tried to wipe battery stats but still only up to 99%.

Do you charge while connected to a computer or directly from the socket? Both methods behave very different in my experience. You should try the other one, to see what it does.
Edit: Also, what voltage do you end up with after charging to 100%?

Gödel said:
Do you charge while connected to a computer or directly from the socket? Both methods behave very different in my experience. You should try the other one, to see what it does.
Edit: Also, what voltage do you end up with after charging to 100%?
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Click to collapse
I charge from the ac mains socket. Voltage I will have to see. I havent given it particular attention but I will check and report back.

Purposely drained battery, charged for 2 minutes, restarted, now at 50%

I'm on CM10 8/31 and I've been noticing that my battery life has been really poor lately, so I wanted to find out what the problem was. I thought about draining my battery fully and then charging it again. Once I drained the battery, I charged it, and restarted the phone after the charging began. Once the phone booted, it reported a 50% or so charge. I'm wondering if my phone is stuck at reporting battery at half capacity, and that when it charges to 100%, it's actually 50%. Anything I can do?
EDIT: Also, I should note that the battery has sometimes spiked up/down by about 20% after a reboot (including today before the drain).

This phone has a fuel gauge chip, fully discharging and recharging will not calibrate it. False readings after reboot are common, you may even notice it will climb back up as it begins to accurately reflect level.
There are apps to let you know what is causing drain. BetterBatteryStats and CPUSpy are recommended a lot.

ALBGunner04 said:
I'm on CM10 8/31 and I've been noticing that my battery life has been really poor lately, so I wanted to find out what the problem was. I thought about draining my battery fully and then charging it again. Once I drained the battery, I charged it, and restarted the phone after the charging began. Once the phone booted, it reported a 50% or so charge. I'm wondering if my phone is stuck at reporting battery at half capacity, and that when it charges to 100%, it's actually 50%. Anything I can do?
EDIT: Also, I should note that the battery has sometimes spiked up/down by about 20% after a reboot (including today before the drain).
Click to expand...
Click to collapse
Entropy doesn't frequent our forum much anymore, but he left some nuggets of wisdom behind.
As you have probably seen, he mentioned several times that generally our fuel gage doesn't need much attention. It may get a little out of whack if you have heavy usage followed by reboot, but generally the error is short-lived and goes away quickly (within an hour or so).
But apparently sometimes the fuel gage gets really confused, and in that case you can reset it (to un-confuse it) by powering down and pulling battery for 20-30 seconds. It certainly can't hurt to try.. that's what you try for any computer that was acting weird. That was discussed by Entropy here:
http://forum.xda-developers.com/showthread.php?t=1209087&highlight=+gingerbread+fuel+gauge+
By the way, here is a link to the fuel gage chip (MAX17040) used in Infuse
http://datasheets.maximintegrated.com/en/ds/MAX17040-MAX17041.pdf
It has a heuristic model of the battery. The only input is the battery voltage. So it looks at time history of voltage and provides an output signal. Exactly what the output is I’m not sure. You’d think it would be an estimate of %. But according to the circuit diagram there is no inputs to the MAX17040 other than battery voltage.
And yet our phone also knows when it’s charging. And our Infuse phone also has a sensor that enables it to measure current while charging (but not to measure current while discharging). This according to the developer of Battery Monitor Widget:
http://forum.xda-developers.com/showthread.php?p=31295223&highlight=infuse#post31295223
Why the heck would we not use sensed charging current and charging status as an input to calculating our % battery (since the signal does not go to the Max17040)? Beats me, doesn't make sense. Maybe the output of he fuel gage chip goes to the integrated power chip MAX8998 which looks at these other inputs (charging status and charging current) and develops the % estimate... I’m not sure.

[Q] CM10 not charging past 90%

I'm running the 12/28 CM10 nightly, and I'm having an issue with charging my battery. When the phone is on, the battery charges normally to 90%, at which point the LED changes from red to green, indicating full charge. If I leave it plugged in, the phone continues to charge to 100. However, the battery doesn't really charge past 90 because once I begin to use it the charge drops really quickly down to 90. Similarly, if I restart the phone, even if it said 100 before, when it is on again it says 90. I have had this issue with previous CM10 nightlies as well. It is a software issue, because if I turn the phone off and charge it, it charges to 100.
Any ideas on how to fix this? Thanks!

This is a suggestion out of the blue but maybe try recalrubratung your battery

omario8484 said:
This is a suggestion out of the blue but maybe try recalrubratung your battery
Click to expand...
Click to collapse
I did to no avail
Sent from my One X using xda app-developers app

A0A said:
I'm running the 12/28 CM10 nightly, and I'm having an issue with charging my battery. When the phone is on, the battery charges normally to 90%, at which point the LED changes from red to green, indicating full charge. If I leave it plugged in, the phone continues to charge to 100. However, the battery doesn't really charge past 90 because once I begin to use it the charge drops really quickly down to 90. Similarly, if I restart the phone, even if it said 100 before, when it is on again it says 90. I have had this issue with previous CM10 nightlies as well. It is a software issue, because if I turn the phone off and charge it, it charges to 100.
Any ideas on how to fix this? Thanks!
Click to expand...
Click to collapse
This is the intended bahavior. The type of battery used in phones last longest when they say between 80% and 20% of charged. So your phone will pull the maximum amount of power it can until it hits 90% then reduce power draw to a trickle charge.
The rapid drop is power is often the chip in the battery lying that it is fully charged when it is not. That is why you may see a rapid decline to 90% where your battery drain will go back to normal.
You might also see the phone telling you that it has 15% power then turning off. Upon reboot it will say it's at 0% or 1% that also is the battery trying to protect it self from damage.
This is a simplified explanation of how all phones work these days. The only difference you'll notice is how good the software is designed to lie to you about the power level. If it's good you won't notice these types of anomalies but they are still there.

Have you wiped battery stats?

dc211 said:
This is the intended bahavior. The type of battery used in phones last longest when they say between 80% and 20% of charged. So your phone will pull the maximum amount of power it can until it hits 90% then reduce power draw to a trickle charge.
The rapid drop is power is often the chip in the battery lying that it is fully charged when it is not. That is why you may see a rapid decline to 90% where your battery drain will go back to normal.
You might also see the phone telling you that it has 15% power then turning off. Upon reboot it will say it's at 0% or 1% that also is the battery trying to protect it self from damage.
This is a simplified explanation of how all phones work these days. The only difference you'll notice is how good the software is designed to lie to you about the power level. If it's good you won't notice these types of anomalies but they are still there.
Click to expand...
Click to collapse
Thanks for that informative answer. So I take it that means there would be no performance difference between turning my phone off, charging it, and then using it (with it saying 100%) vs leaving it on, charging it to 90% (green LED turns on) and then using it?

Need help, weird battery problem

Hi everyone, im having a problem with this phone:
1- Charging the phone never reach 100% in one charge, it always stops charing at a random number, for example 70%, no matter how much time i let the phone charging it never goes past that. The solution is unplug and plug again, then it reaches 100%.
2- The number 1 is not a big deal but this is. The phone automatically turn off at a random number again, let say 66%, and i cant turn it on. If i connect the phone to the charger it says 0% battery. Is not like the % freezes at 66% and i use it all day and then turn off. For example, i have the phone at 100%, i start using it and i see the % going down like normal and after an hour or two of using it suddenly turn off and im not able to turn it on again because the battery is at 0%.
I tried:
Hard reset, wiping cache, data.
Hard reset, wiping cache, data and installing the latest stock rom.
New battery.
Different charger.
I have no idea what else to try, anyone have a clue?
Thanks!

I think the battery is broken, also had the problem. Then I bought me one on Ebay for 9,99€ and now everything is good again.

Try using a -known- good cable and charger.
Make sure the port contacts are clean and debris free. Always charge with screen off.
You can also try powering the phone off and see if this alters its charging pattern.
My best guess...
When it auto shuts down again pull the battery and measure its actual voltage to determine if it's at about 6%.
If actual voltage indicates it's at 6%* may be a bad battery (limited capacity) or a hardware failure (shutting the charge cycle down prematurely).
If battery actually has 20% or higher when the phone shuts down) it indicates a hardware failure in the phone.
If battery temp exceeds about 102°F during charging the phone will abort the charge; make sure this isn't the cause. A hot charging battery in a cool room could indicate a battery or hardware failure. If battery temp exceeds 107°F or so in operation the phone may also auto shutdown.
Excessive cold (>32°F) will effect battery capacity severely.
Don't charge a cold Li battery (under 70°F).
Never charge if at or below freezing**.
Li's like a charge temp range of 80-95°F
They prefer frequent, short mid range charge cycles (40-65%) vs topping them off beyond 80%
*hunt down the voltage/% charge for this battery
**can cause Li plating which will permanently degrade the cell