Related
Firstly.... go here and read this -
http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries
The battery is fully charged when it is at 4.2 Volts and fully discharged at some predefined voltage (Lets say 3 volts).
The phone can measure these voltages directly from the battery. To see the voltage of your battery type *#*#4636#*#* into your phone and go to battery information.
If all that is so then what is the point or need of "recalibrating" and deleting battery stats and all that.
It seems logical to me that battery stats is just the place where your battery usage history is stored and nothing else.
Can someone confirm this or convince me otherwise?
(I rotate between 3 batteries and cannot grasp the idea that my phone can't consistently measure the charge level of the battery and operate accordingly.)
Measuring the Voltage to get the charge level is not very accurate, and has to be done with no load on the battery (that is, when its not in your phone).
So the phone has to count "energy used from"/"energy stored in" the battery for an accurate display. (called "Coloumb counter")
Did some test
I did a test on new a battery a while ago. Measure voltage when the battery completely empty and fully charged.
Empty battery
1% remaining, using SystemPanel
Take the battery out and measure it with Multimeter
Fully charged
100% charged
Again, measure it with Multimeter
The voltage showed on the phone using SystemPanel app is quite accurate with 0.04V margin of error. Most smart electronic measure lithium battery capacity according to the remaining voltage. In this case, fully charged SGS is 4.2V, empty is 3.5V.
Me too, don't know why we have to delete batterystats.bin to recalibrate battery indicator But I do know that SGS keep track on power consumption on each of its component/application. Its a little bit silly if SGS reads batterystats.bin and display it as battery indicator.
Yet again how is this android development.
Sent from my GT-I9000 using XDA App
xufos said:
I did a test on new a battery a while ago. Measure current when the battery completely empty and fully charged.
Empty battery
1% remaining, using SystemPanel
Take the battery out and measure it with Multimeter
Fully charged
100% charged
Again, measure it with Multimeter
The current showed on the phone using SystemPanel app is quite accurate with 0.04V error margin. Most smart electronic measure lithium battery capacity according to the remaining current. In this case, fully charged SGS is 4.2V, empty is 3.5V.
Me too, don't know why we have to delete batterystats.bin to recalibrate battery indicator But I do know that SGS keep track on power consumption on each of its component/application. Its a little bit silly if SGS reads batterystats.bin and display it as battery indicator.
Click to expand...
Click to collapse
Thanks for that, but you were actually measuring the Voltage, not current (Amperes).
In any case, for laptop Li-ion batteries there is normally a capacity counter (Coulomb counter) that reports the capacity in terms of mAh (milli-ampere hours). It can normally report the remaining capacity, maximum capacity, design capacity, and can be used to measure the *actual* power drain (in terms of Watts).
I wonder if Android has APIs that let apps access that kind of information?
Not really sure about this, but:
Phone seems to measure both voltage & discharge speed, "predicting" remaining charge.
It happens that after a flash battery indicator jumps to a higher value (not compatible with the couple of minutes of dc connection it had), and fall to a way too low value after any battery intensive task (a few minutes of audio call are enough), once more not compatible with the real usage.
I should inspect android code to be shure of this, but I suspect batterystats.bin is used to keep track of battery usage and to this sort of prediction, while a firmware flash seems to mess somehow the measurement.
Edit: this is based on my direct experience, even if on just "empirical" tests. I'll take a look to code asap
'mkay, battery talk... always interesting to see what people make of this.
Let's help out all the misunderstandings here and start with the basics
First of all: read the basics on Li-ion batteries:
http://electronics.howstuffworks.com/lithium-ion-battery.htm
second:
you DON'T measure your voltage when your battery is disconnected. Because it will rise to the normal values of the battery after a while. When you connect it, and use it, the voltage will lower. Compare it to a garden hose. if you let water run out, the presure drops and water starts flowing (presure is voltage, flowing is the current). If you measure the presure when there is no water running, the presure will always mount to the default value, even if there is "not much water left in the tank". But when it starts running again, it could very well run out very fast. So in comparison: voltage says something, but only when you "use" it.
Third:
When a battery ages, it's characteristics change, it will be full... and then all at once, empty. It's not linear. So calculating the capacity is always a bit "guessing". (compare it to stones in your water tank... they don't give you water, the tank doesn't change, but all of a sudden, you're out of water).
conclusion:
capacity of a battery is a very tricky thing to do, it's a combination of voltage, current, age... so the best way to determine capacity is by using the history of the battery as the "guide" to the future. Resetting the battery statistics will remove that history and your phone will have to "learn" it's behavior again. If you don't reset your stats, your values will become more reliable over time (depending of course on the time the stats are kept )
For those who speak dutch, i put a complete battery description/howto/misunderstandings post on www.modelbouwforum.nl (search for posts of "harrydg")
If there are more questions or so, just ask, i'll try to help out as much as possible...
wow harrydg that's great explanation, wish you were my physics teacher back in high school
someone add this post to the main FAQ!
I just wanna write it in a simpler way:
You've access to the battery stats from the kernel. And of course its current consumption which is measured not voltage. Voltage doesn't tell all that much. During high draws your voltage (at the battery level) can fluctuate quite a bit.
There's a regulator (or probably a bunch of them) get a stable voltage no matter what the input voltage is (well, still it has to be in the 3.3/5v range probably else the regulator burns)
Anyway, that's also why the battery stats have to be calibrated, while you can measure how much current is used (in maH aka milli amp per hour, or in mA aka "instant" milli amps), you don't know the battery capacity.
Not only the battery capacity changes from battery to battery but it also changes during the life time of the battery.
The *only* way to calibrate the battery, is to delete the stats, have a fully charged phone and let it drain out the battery until it turns off. That way the kernel will measure for example 1457mah used until it ran out of juice, and that's your battery capacity then. Having the full capacity allows the kernel to give you a rather precise estimate of your current battery status (eg "80%" that you see on the top of the screen) (of course the actual calculation is a bit more complicate but that's the basics)
If calibration stats storage is changed for any reason (probably kernel upgrade or just a whacky samsung implementation that gets corrupted for some reason) you need to delete it and make a new one to recalibrate.
If you want to make it simpler, make it at least correct...
"Anyway, that's also why the battery stats have to be calibrated, while you can measure how much current is used (in maH aka milli amp per hour, or in mA aka "instant" milli amps), you don't know the battery capacity."
First of al, it's mAh, which means milli ampere hour, NOT per hour, that would be mA/h, which it is not.
mA is milli ampere, which is a current
there is a significant difference between the 2.
the first is "capacity"
the second is "current"
it's like a bottle. The capacity is 2l and you pour at 1l per minut...
so... make it simple please...
My guess is, that android is measuring the known min and max by the battery reported values, stores them and calculates the percentages.
So it is device and battery independent.
harrydg said:
If you want to make it simpler, make it at least correct...
"Anyway, that's also why the battery stats have to be calibrated, while you can measure how much current is used (in maH aka milli amp per hour, or in mA aka "instant" milli amps), you don't know the battery capacity."
First of al, it's mAh, which means milli ampere hour, NOT per hour, that would be mA/h, which it is not.
mA is milli ampere, which is a current
there is a significant difference between the 2.
the first is "capacity"
the second is "current"
it's like a bottle. The capacity is 2l and you pour at 1l per minut...
so... make it simple please...
Click to expand...
Click to collapse
Sorry a typo and no caps deserve heavy flaming
bilboa1 said:
Sorry a typo and no caps deserve heavy flaming
Click to expand...
Click to collapse
hehe, sorry for the rant, but if you want to put it simple, make sure the terminology and abbreviations are correct. If not, people will take over the mistakes and conversations will go totally wrong because of misunderstandings...
Thanks very much for the feedback guys. It makes more sense now.
It's using batterystats to get familiar with discharge rates in order to give an accurate estimation of remaining charge and a prediction of when it will run dry.
Can it misreprasent these values and forcibly power down the phone when there is still charge remaining?
And likewise can it stop the charging process prematurely, estimating the battery to be at 100% charge when it is lower?
Is this the reason to recalibrate?
Heres one thing what I noticed about the battery stats, some say deleting it fixes the guage and does not really recalibrate the battery, I really doubt there is a way for end users to do that, even if you never delete the battery stats bin and your drain is pretty fast, it significantly slows down when your battery hits around 25~35, the lower the power on the battery the more accurate it can be represented regardless of the calibration. This is applicaple for the SGS only.
Now it comes to the question..
If the phone create battery stats every time the phone reboot, then when is the best time to delete and the best way to calibrate?
This is what I normally do..
..delete stats at 5%, let it run dry til it turn itself off, dont turn on but connect the charger til it fully charged. Turn phone on and ill have fully charged battery along with fresh stats.
Is this correct?
vosszaa said:
Now it comes to the question..
If the phone create battery stats every time the phone reboot, then when is the best time to delete and the best way to calibrate?
This is what I normally do..
..delete stats at 5%, let it run dry til it turn itself off, dont turn on but connect the charger til it fully charged. Turn phone on and ill have fully charged battery along with fresh stats.
Is this correct?
Click to expand...
Click to collapse
On the SGS theres no real point in deleting it, unless you dont really wanna see the battery go down to 35% and stay there for a while, how ever busted your battery indicator is it gets very accurate as the lower it goes.
I never found batterystats made any difference. What did make a difference is the rom or kernel, what widgets, lagfix e.t.c
If you get more than 1% battery drain per 5hr standby then something is wrong
Sent from my GT-I9000 using XDA App
android53 said:
I never found batterystats made any difference. What did make a difference is the rom or kernel, what widgets, lagfix e.t.c
If you get more than 1% battery drain per 5hr standby then something is wrong
Sent from my GT-I9000 using XDA App
Click to expand...
Click to collapse
I find that conclusion quite flawed.
First of all, what's your definition of standby?
3g on? Wireless on? Autosync on? There are also noticeable differences between different firmwares and between 2.1 and 2.2.
In addition, most people are reporting somewhere around 1% per 1 hour standby or 1% per 2 hour standby, which it what I have been experiencing as well. Sometimes, apparently for no reason, it can drain faster than that, maybe 1% per 0,5 hour or more. I think this might be some widgets fault.
1%/5h standby 3g no sync
i get 1%/2h with data and sync
Depends on your reception, im just basically saying if your losing say 8% battery overnight or more then something is wrong unless your polling several push email accounts
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
Click to expand...
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.
Click to expand...
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?
Click to expand...
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.
Click to expand...
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.
As a Captivate owner, I know that we aren't the luckiest smartphone owners when it comes to battery capacity. Since I first got my phone, I've struggled to keep it above 10% by the end of the day even on the stock ROM. My battery currently drains at about 1% every 10-20 minutes when idle, or every 2 minutes under load, but enough about me.
Using "Spare Parts" or a similar app, could some other users please post what their battery voltage reads at 100% (off charger) and at 1% (off charger). For me, those values are
4243mV at 100%
3510mV at 1% (read with multimeter)
Hopefully this will give us a reference for more accurate battery health/calibration.
The ADC might be a little off. 4235mV is the maximum safe voltage for Li-Ion and the phone shuts off when it reaches 3500mV.
Voltage is not as important as current though. The voltage can reach 4.2 with as little as 20% charge and continue charging until cell resistance reaches cutoff. The battery meter is calculated based on current draw accumulated over time (or accumulated * 100 / capacity = percent), which is why you need calibrate or to go from full to empty back to full when the accumulated value is lost. There's better info on this subject in other threads.
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.
This post is to make an attempt at giving the best new battery start up advice based on research. The battery calibration is well know and should be followed either here, here, or of course here. After days of reading about how lithium ion batteries are stored and charged and also reading actual confidential battery datasheets (not available on sites like Battery University), and installing 5 different 3500mAh batteries in the same phone, have drawn up this checklist:
1. Obtain a charger and length of charging-cord combination that allows 0.2 C to 0.5 C charging currents based on your testing. (You may want to do this on the old battery to avoid multiple new battery mini charge sessions.)
To be strictly by the book to the manufacturer, limit charge to the 0.2C to obtain 100% capacity. Other sources state charging doesn't matter up to 1C but I don't think this is true for most smartphone batteries and not affecting capacity at least by 5% if not more.
2. Verify new battery is adhered to phone and plug connector is seated firmly. Let phone sit at 23 degreee C to 25 degree C for an hour.. Turn phone on 1st time.
3. Install AccuBattery if not done previously
4. Increase charge or decrease charge to get to 70%. Attempt to keep battery temp around 23 C during this initial run.
5. Use the phone or don't (screen off, powered up) until battery hits 55%.
6. Repeat steps 4 and 5 for a week. The goal is to have less than 0.3 cycles of daily wear on the battery initially. Use battery wear graph in AccuBattery to keep track. We are slowly waking up the battery and not hitting it with 100% capacity or long charges yet. It had sat dormant for at least 3 months if not much longer. Why charge it fully just yet?
Note 1 for step 6: Try to keep battery at 23 degrees C if possible during charge. After a couple days I think a higher temperature is ok as long as the charge % is consistent with previous days.
Note 2 for step 6: A few days in the initial week which drops lower or charges higher isn't a problem....just try to keep the battery wear low. You will notice, even without calibration yet, the AccuBattery capacity estimate is getting better and better each day using the same charge sessions and % start and stops....so this is a good sign. I've tanked new batteries with 1 full maybe even 1.8 cycles per day and the capacity estimates go down, not up doing that.
7. Take battery to 80% the following week. Discharge to 20% is ok but shorter charges are always better. Anything 20% to 80% is fine. Keep battery wear 0.6 cycles or less.
8. Now it's time for a baseline capacity charge test. Let battery down to 15% and charge it to the full 100% +1 hour at 100%. Note the capacity estimate and also the full mAh for that session.
9. Wait one day.
10. Perform calibration (try to spread it over two days to make it easier on the battery)
11. Repeat step 8 and see if capacity goes up or down. If down, go back to step 4 and 5 for a week then retest. If it's better, it proves that high cycle count on battery is a short term capacity killer.
Note 3 for steps 1 to 11: always charging at 0.3 to 0.5 C rate.
12. Using a fast charger (2.4 A to 1C) charge the battery as done in step 8. See if capacity goes up or down. If down, it proves fast charging is a killer of short term capacity. If up, it may prove the voltage during charge is higher and CV is a bit higher during end of charge. Remember most packs can take CV 4.35 volts but most android phones won't allow more than 4.300 volts. Mine quits at 4.296 V.