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[Q] Paradox with underclock & battery savings, does it actually hurt? SetCPU, etc.
In theory, using SetCPU or other underclocking app to reduce CPU clock should reduce the power draw from the CPU, therefore reducing battery consumption.
However, underclocking does not reduce the amount of work that needs to be done. That is to say, whatever app or kernel processing that needs to be done will still be done. When UC'ed, they will be done at a slower pace, therefore taking longer time. In some cases, the UI becomes sluggish, requiring more user interaction time as well.
If, at 1Ghz, a process takes 10 seconds to complete and requires 10mA per second. This task should consume 100mA. By underclocking to 500mHz, perhaps the CPU takes only 6mA, but the task will require 20 seconds to complete. Now the task actually takes 120mA (plus the longer screen on time).
Is my theory sound?
Also, does the constant scaling itself consume power?
As far as I know, Froyo is supposed to scale the CPU anyway. So why underclock? Does it actually work or does it hurt the battery life?
Input please!
Thanks.
Edit: I know the function of CPU speed vs. efficiency vs. battery drain is never linear, and each situation has a different break-even point, but I'm curious the general application of underclocking within the Android environement and its effect on battery life, and more specifically, the Evo.
i'm a regular dude with a phone, but im educated...that being said im sure your aware of the diminishing marginal utitlity law. For example if me and you can mow a lawn in 2 hours, and we got one more guy, we can do it in in less than two...Bu you eventually reach a breakoff point where it is hurting you and those extra guy(s) are not needed and acutally slow down the process or are just a waste. Same thing here, although i am not sure of the numbers, im positive there is a sweet spot for underclock and if you go too low it actually is a waste or hurts battery life. It also could be in the middle meaning, im going to make up numbers. 1ghz uses 100 Mah in 10 seconds. 800 mhz used 50 mah. 900 uses 60 mah. Now, the difference ratio of battery usuage and spees would lean you towards using 900 because if you relate this to sales on products or even anything, for lack of better words this setting is the best abng for your buck...my 2 cents
http://www.google.com/m/url?client=...IQFjAA&usg=AFQjCNFlNlZCm-gnvD1PzEsDezCIPeA8jQ
Sent from my PC36100 using Tapatalk
Interesting stuff... Take a look at this thread:
[ROOT] Using SetCPU + Perflock Disabler to Save Battery, Underclock
The data seem to suggest that underclocking an Evo at idle yields real results. I would think that this can only work if there is not a lot of background/idle tasks going on?
snovvman said:
Interesting stuff... Take a look at this thread:
[ROOT] Using SetCPU + Perflock Disabler to Save Battery, Underclock
The data seem to suggest that underclocking an Evo at idle yields real results. I would think that this can only work if there is not a lot of background/idle tasks going on?
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both pics depicts very different device usages. not a fair comparison imo.
quocamole said:
both pics depicts very different device usages. not a fair comparison imo.
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Yea I went through and read the whole thread. I'm now even less convinced that SetCPU provides any tangible battery benefits at all.
snovvman said:
Yea I went through and read the whole thread. I'm now even less convinced that SetCPU provides any tangible battery benefits at all.
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Do you think i am right on any part of which i said or am i talking out of my arse lol
A microprocessor does not live by its clock alone. lol
It can cycle through a huge math operation, which is loaded into its registers lickity split with a fast clock. It will have to wait while the memory/code of the programs it runs are loaded either into its cache memory or into execution space. So in calculating theoretical energy use, you got to figure the bus speed, as well as the type of operations the processor is doing.
Golly, ( pronounced like a resident of Mayberry) the bus is key on loading programs to be run. What's the bus clock triggered off? That's the key. You don't want the bus to slow while slowing the cpu. If you can cycle the processor while it prefetches then you've got optimal use, providing it isn't thrashing.
Google cpu wait states for bus synchronization
This is basically the reason HAVS is supposed to be better than static scaling and underclocking. With HAVS, voltage is based on workload as well as clock speed, so you should get the benefits of running fast/idling more often combined with the benefits of using as low of a voltage as possible. As long as you don't have something pegging the CPU at 100% all the time in the background, it should, in theory, work better.
In practice, I haven't seen all that much of a difference.
iitreatedii said:
i'm a regular dude with a phone, but im educated...that being said im sure your aware of the diminishing marginal utitlity law. For example if me and you can mow a lawn in 2 hours, and we got one more guy, we can do it in in less than two...Bu you eventually reach a breakoff point where it is hurting you and those extra guy(s) are not needed and acutally slow down the process or are just a waste. Same thing here, although i am not sure of the numbers, im positive there is a sweet spot for underclock and if you go too low it actually is a waste or hurts battery life. It also could be in the middle meaning, im going to make up numbers. 1ghz uses 100 Mah in 10 seconds. 800 mhz used 50 mah. 900 uses 60 mah. Now, the difference ratio of battery usuage and spees would lean you towards using 900 because if you relate this to sales on products or even anything, for lack of better words this setting is the best abng for your buck...my 2 cents
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iitreatedii said:
Do you think i am right on any part of which i said or am i talking out of my arse lol
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What you wrote makes sense and the concept is sound. I just wish we knew what that sweet spot is, although I think it changes constantly based on load, code, and operational requirements.
With the two posts above, it would seem like phone manufactures would do everything they can to optimize efficiency. Having SetCPU loaded for 24 hours, I too, can say that I have not seen a huge difference...
Noxious Ninja said:
This is basically the reason HAVS is supposed to be better than static scaling and underclocking. With HAVS, voltage is based on workload as well as clock speed, so you should get the benefits of running fast/idling more often combined with the benefits of using as low of a voltage as possible. As long as you don't have something pegging the CPU at 100% all the time in the background, it should, in theory, work better.
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Does the stock HTC kernel, 2.6.32 "#11" have/use HAVS?
This is not a thread about best battery tips, etc. And I'm hoping it is not another standard thread about how to calibrate our batteries.
There is a lot of information flying around regarding battery calibration. A lot of it involves draining the battery, plugging it in at certain time, removing the battery, erasing batterystats.bin, etc. etc. etc.
Some feel the batterystats.bin file is key, and others believe it is completely unrelated to how the battery performs--just a log of stats.
How can this be reconciled?
UPDATE: Deleting batterystats.bin to "recalibrate" a battery is total and utter nonsense
http://forum.xda-developers.com/showthread.php?t=1442989
https://plus.google.com/u/0/105051985738280261832/posts/FV3LVtdVxPT
Over on the Nexus One forum, there was/is an extensive discussion, with REAL data gleaned from reading the technical datasheets of the battery itself, and the DS2784 chip within. The key to the Nexus calibration program was the ability to reprogram values on the battery chip.
http://forum.xda-developers.com/showthread.php?t=765609
I don't know if much of anything is going to be the same on the GNex battery, since the N1 was a HTC product. However, if the charging algorithms are all dictated by the Android OS, instead of hardware specific, then it could provide useful precedent. (I am not going to go through all the Samsung forums to look for valid battery calibration threads--if you know of some, for say, the Nexus S or Galaxy S2 (predecessor and comparable cousin, let's call them) please comment).
Here's a primer for all I learned that was used on the Nexus One battery calibration program. Full credit to those fine users who took the reins and made that happen, and to the fine users who continue to provide user support to the newcomers who don't know/refuse to acknowledge the existence of a search function.
My hopes are that this will lead to more rational battery life discussions and maximization for the Galaxy Nexus.
(I am not an engineer, so if any of you out there would like to tighten the language used here, please let me know).
What are the important values in battery/calibration?
1. mV = voltage
2. mAh = milliamp hours, a measure of capacity. This is how much 'juice' your battery has left/stored.
3. mA = milliamps, a measure of current. This is how much 'battery power' your phone is drawing/using at a set time. GPS/bright screen means large mA usage.
Apparently, Samsung (and Motorola phones) do NOT have mA readings in their battery drivers. This poses a problem. Apps that measure current (such as the excellent and free "current widget") cannot give a readout.
How is the battery life % calculated?
Present mAh / "full" capacity mAh (more on "full" later)
When does a phone shut down?
1. When mAh = 0
OR
2. When mV < 3416, which is coded on the battery as the "empty voltage"
Whichever occurs first.
If mAh = 0, then batt % = 0. However if condition 2 occurs, batt % could be anything.
I have found the empty voltage on the GNex to be the same, 3416 mV.
I have found the maximum voltage on the stock GSM battery to be 4197 mV.
Through experimentation, it was found that reprogramming the "empty voltage" down to 3201mv could provide extended battery life. The voltage was found to drop very quickly any lower than that, providing minimal gain afterwards.
What is the full capacity of a battery?
On the N1 battery, it is coded into a chip on the battery itself. This can be reprogrammed with the calibration utility. The stock value was ~1400mah. This is called the Full40 value (the mAh at 40oC). A value called "battery age %" is used to adjust how close the real capacity is to the full, which decreases with use and age. By multiplying (batt age * full40), you get the real assigned capacity.
Some non-OEM batteries, however, had miscoded capacities, usually LOWER than what was advertised. This led to very disappointed users who had purchased extended batteries that lasted no longer than stock, due to wrong mAh coding. (See below how this could be corrected).
Other low-end crappy non-OEM batteries had a crap chip which was coded with nonsensical values. This also led to unreliable battery life. These chips were not reprogrammable.
The very interesting thing is whenever the battery thinks it was completely charged, the mAh becomes SET to this number. mAh is NOT an independent value. Also, you could set it whatever you wanted, whenever you wanted, whether it was accurate or not. % battery left was basically calculated as present mAh / (full40 mAh*batt age). So you could get false values of either too little or too much battery left.
Why does this matter? If that was falsely low, the phone would cut out at 0% battery life, but you would still have usable battery left. If it was falsely high, it would cut out at 10% or whatever, since voltage would hit 3416 faster than mAh hit 0.
How does the battery know/think it is full?
When connected to a charger, the phone draws +mA. It can start around 1000mA (depending on the charger), and drops as the battery becomes more and more charged.
Another coded value, the "minimum charge current," tells the battery when to stop drawing current. This is set at default to +80mA.
Another coded value, the "minimum charge voltage," tells the battery that as long as the voltage is less than this #, it should continue to charge. At default, this is 4099mV.
An important concept is that once the charge amperage drops below minimum charge current (and the voltage is > the minimum charge voltage), the battery thinks it is done. Again, that state becomes 100%. Again, the capacity mAh is SET to the full capacity, no matter what is at that time. The actual mAh doesn't matter--it BECOMES whatever is coded as the (age % * full capacity).
As with other values in the battery chip, minimum charge current can be changed. It can be made to 40mA, or 20mA, or whatever you wish. By doing this, the battery will continue to draw current, and thus charge more and longer, until the minimum charge current is met.
Speaking of charging amperage, this can be an issue when using a non-OEM crap car charger when using your smartphone as a GPS. If the DC adapter is NOT truly giving 1A, the phone will use more current than it is receiving, and the battery will continue to LOSE current despite being hooked to a charger. Upgrade your car DC adapter! They are not all made the same.
How does 'bump' charging relate to all this?
Bump charging is essentially a way to trick the battery to continue charging despite the current draw being < the minimum charge current.
There is a problem with this "full" battery detection method:
If you draw enough current from the battery, while it is charging, after the minimum charge volt is reached, you can PREMATURELY fool the battery into thinking it is done.
Say the charging mA is at +200mA. If you turn on your smartphone, start GPS, turn the lights on, stream Pandora, etc., the mA will easily drop from +200 to a lesser value, negative even. The phone will think the charge is complete, since it is <80ma. THAT state becomes 100%, because the mAh get set to full capacity. Falsely.
However, this should only happen when the charge is ~90% or greater (when mv >4099). So, it may not play a huge significant role in battery time, basically missing out on 10% or so of battery life. Also, at the next recharge cycle, provided you don't fool it again, the mAh will be RESET to the more appropriate designated value.
If mAh can be set to whatever value whenever, how do we get it PROPERLY set/calibrated?
There are 2 times when mAh is automatically set. Upon draining the battery to empty (3416mv by default, 3201 preferably), when the phone shuts down, the mAh will be properly set = 0. This is good. We want mAh = 0 when mV = empty voltage.
The other time is when the battery thinks it's full, when minimum charge current is met--this is often not accurately set, not good.
If we start charging when the battery is empty, the mAh rises as the battery is charged. However, the MAXIMUM mAh needs to be watched. The mAh could be HIGHER than the programmed full mAh. Or far lower. Finding this maximum mAh, and reprogramming the battery accordingly, is the key.
Once again, when the battery hits the minimum charge current, the mAh will either jump up to the set battery capacity value (so the battery will die sooner than expected), or less commonly, drop down.
The goal is to get an accurate mAh capacity of the battery, for the voltage range between min + max, and have this set every time the battery is charged to capacity.
If we know the maximum mAh the battery reaches when charging, provided it started from 0, we want to reprogram the battery so that this value is set each time it completes charge.
There is a "learn mode" on the Nexus battery. Provided this was activated, through a series of very specific events, the battery would give itself a "battery age %". This is used to give the accurate (battery age % * full40) = true capacity. On the Nexus, the default battery age was 94%. So, mAh was set at every full charge to 94% of the full40 capacity. Obviously, this is not true for every battery forever.
Once again, why errors can and do occur:
mAh and mV are not directly linked. If mA falls to 0, or mV is less than the cutoff empty voltage, the phone will shutdown, even if the other value is still sufficient.
1. mAh is falsely high. The battery won't last as long as we think it will. Battery % is falsely high. Phone won't get to 0%.
2. mAh is falsely low. The voltage is adequate, but the mAh isn't correct. The battery % is falsely low. Phone gets to 0% too quickly. Perceived loss of battery life duration.
Why use mAh at all? Seems like mV is the only important thing?
I don't know. Why is mAh capacity important in telling the phone to shutdown? Someone enlighten me.
I think one reason is that voltage can and does fluctuate up. So using this to calculate battery % life would be extremely erratic and confusing.
What does this teach us, overall?
I'd have thought there would be much better technology built into battery calibration. Seriously. This is one big mess of poor design.
This is a bunch of technical mumbo jumbo. How does this help me?
On the N1, you can give yourself more battery life!
1. Set your 'empty voltage' lower
2. Set your minimum charge current lower
3. Calibrate the maximum mAh to a higher value to accomodate the new 'empty voltage' and 'minimum charge current' values
4. Don't play with the phone too much when it is >90% charging or it will prematurely end its charge cycle, give you a falsely higher charge %, resulting in the battery dying before you think it should.
5. Profit.
(On an extended 3200mAh battery from Seideo, after lowering the empty voltage and minimum charge current, I found >3900mAh (!) as my new maximum mAh. That's a heck of a lot of free juice).
On other phones? I'm hoping real programmers here can figure out how to do the same.
So, for the Nexus One, there is ABSOLUTELY NO correlation between battery calibration and the battery stats file. NONE. The values on the battery chip determine everything.
So, please comment on how battery calibration tech has changed over the past 2 Nexus generations. If it has.
ADDENDUM:
RogerPodacter, the xda guru/user who was instrumental in creating the N1 battery calibration app, has been looking into the GNex battery quite intently.
I just stumbled across some useful info about our battery fuel gauge from the sgs2 forum. Basically the result is there is not much we can do with our fuel gauge. But they do talk about how to truly calibrate it. And they discuss the improved version max17042 which is used on tbe sgs2 and has all the bells and whistles.
Heres the topic.
http://forum.xda-developers.com/show....php?t=1312273
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(If you found this info useful, please click the THANKS button!)
Somebody is looking at this already. That same somebody who made the nexus one battery app. This chip doesnt supply amperage either. After i told him my battery seems to only charge to about 4.15v and that on discharging/charging my voltage is everwhere so it is hard to ascertain how accurate my % is. He finally got a chance to look over some stuff and we both think the nexus only allows charging to 4.15v. And. I think the battery shutdowns at 3.6v this go around. From initial observation he led me to believe everyrhing seems to be fine and we might not be able to do much. He might be able to get 4.2v and 3.4v for the voltage cycle. This is partly my speculation but we did agree that samsung may have done this intentionally for longevity of the battery. We will have to wait and see because he is still tinkering with his phone and deciding how to initially proceed. Might be a few days though. I am getting the extended battery soon so i would like to see what changes there are from the 250mah difference.
Sent from my Galaxy Nexus using xda premium
To gleam is to shine or sparkle... to glean is to learn or become knowledgeable about.
FrayAdjacent said:
To gleam is to shine or sparkle... to glean is to learn or become knowledgeable about.
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..wow, just wow.
To the OP thank you for all this compiled information.
Sent from my Galaxy Nexus using XDA App
FrayAdjacent said:
To gleam is to shine or sparkle... to glean is to learn or become knowledgeable about.
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I thought the same thing but possible typo. N and m are next to each other. But if op ends up giving us something tangible positively foe the nexus he will have gleamed. Lol.
Sent from my Galaxy Nexus using xda premium
Agggh. I suppose gleam could be appropriate here. But yes, glean was the original intent.
Due to my grammar OCD-ness, it has been edited. =P
@rbiter said:
Somebody is looking at this already. That same somebody who made the nexus one battery app. This chip doesnt supply amperage either. After i told him my battery seems to only charge to about 4.15v and that on discharging/charging my voltage is everwhere so it is hard to ascertain how accurate my % is. He finally got a chance to look over some stuff and we both think the nexus only allows charging to 4.15v. And. I think the battery shutdowns at 3.6v this go around. From initial observation he led me to believe everyrhing seems to be fine and we might not be able to do much. He might be able to get 4.2v and 3.4v for the voltage cycle. This is partly my speculation but we did agree that samsung may have done this intentionally for longevity of the battery. We will have to wait and see because he is still tinkering with his phone and deciding how to initially proceed. Might be a few days though. I am getting the extended battery soon so i would like to see what changes there are from the 250mah difference.
Sent from my Galaxy Nexus using xda premium
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Great to hear! Is that on this forum or rootzwiki, or a private communication?
I have noticed that shut down is usually at 3.6 or so. I drained it completely one time with multiple reboot attempts, and I got battery monitor widget to log a 3.417 or so that ONE time, but yes, the battery prefers to quit more around 3.6.
Battery monitor widget outputs an 'estimated' mA, but that's the closest thing I could find.
Wow you brought up the nexus one battery project. I was actually the one who re-wrote that battery driver for the n1 linked in the thread in the first post. Then I wrote the apk with dvghl. I even got my altered battery driver officially merged into the cyan kernel repo for the n1.
Anyway my point is that I learned an ENORMOUS amount about how these fuel gauge chips work, specifically the ds2784 chip in the n1. The bad news is our galaxy nexus chip max17040 doesn't have all the cool features that I cracked open on the ds2784 chip. But still worth trying a few things. Specifically I'm curious what the rcomp register does in our battery driver.
Also the other bad news is our galaxy nexus max17040 cannot give current mA readings. It can only be estimated using battery monitor widget for example.
Unfortunately we don't have a learn mode or age register like we did in the n1, so we can't get too deep into the chip like we did in that project. Kinda unfortunate. Seems the max17040 only has about 7 memory registers, where the n1 ds2784 had about 30 or so registers we could hack into and tweak.
RogerP, so good to see you here! Hope my summary gave some hint as to the enormous amount of effort your project took, and the huge leap in battery charging knowledge it provided.
waylo said:
RogerP, so good to see you here! Hope my summary gave some hint as to the enormous amount of effort your project took, and the huge leap in battery charging knowledge it provided.
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Hey man, you did a near perfect job with the write up. That project was a one of a kind opportunity in the sense that the ds2784 chip, and the tech sheet and hacks we did, all lined up to be the perfect storm of what we can learn and do with these batteries. So much knowledge was extracted from that effort.
The bad news is that Samsung phones don't typically use the ds2XXX fuel gauge chips, instead they use max1704X chips. These chips use voltage to determine SOC along with their "secret" algorithm that they don't publish. In the end there isn't as much ability to do anything with our fuel gauge like we did with the n1. There are 7 registers or so, SOC, mode, volt, rcomp, but no current and no mAh. The rcomp is the one I was curious about tweaking.
This weekend I was thinking of setting up Ubuntu build environment and attempting to play arount with this new driver and see if we can learn anything more. I'm sure there are more capable devs who maybe already know about this fuel gauge cause the nexus s and other Samsung phones use similar chip. It'd be another fun project if so!
Thanks OP. Very helpful.
Glad to spread the word!
Don't forget to click the THANKS button if I helped!
thanks!! helps alot more knowledgeable now about batteries
I bought the spare battery kit that comes with an external charger. I run my battery to near empty or empty then swap it out. Do the external chargers behave the same way?
Sent from my Galaxy Nexus using Tapatalk
Very happy to see the same crew from the N1 battery calibration days on the GN. I was pretty disappointed when I got the NS and there was little discussion or attention given to the battery at such a detailed level. By the time I picked up the GN I had mostly accepted that the N1 situation and battery related dev/testing/discussion was unique in that it was both possible to tinker with and we had some dedicated fellas, especially you RP, that were willing/able to tackle the task.
As with the N1 battery testing, I'm all in to test and help whenever possible to break some ground with the GN.
This topic made me reminisce about my old N1, wish I hadn't sold it on eBay. I sold it to a Canadian, cost me a bloody fortune to ship to him bc of restrictions on amount of lithium cells/customs regulations. The guy was probably wondering if he bought it from some nut job when it arrived with like 7 batteries of many different manufacture/capacity and spare battery chargers. I half expect that US/CAN Customs put me on some kind of list when they inspected the shipment.
ellesshoo said:
As with the N1 battery testing, I'm all in to test and help whenever possible to break some ground with the GN.
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I'd also be willing to contribute to these efforts.
Sent from my Galaxy Nexus using Tapatalk
deekjx said:
I bought the spare battery kit that comes with an external charger. I run my battery to near empty or empty then swap it out. Do the external chargers behave the same way?
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That's an excellent question I don't know the answer to. I'm not sure what kind of charging algorithm the external chargers would use, except to stop charging once the current reaches a certain low level.
As RogerP described above, most of the GNex battery algorithms are a mystery at this point, with some proprietary methods that won't ever be voluntarily revealed =P.
There is probably not a whole lot that can be done with the nexus battery. Yall gotta remember there was a bugnor bad programming revealed and that is why so much time was devoted to that. Roger already found that the battery stops around 4.15 volts. Changing it 4.2 will not make a big difference here and im sure it is intentional to extend charging cycles.
My grandma beat me down and took my nexus. Sent from a jitterbug with beats by dre.
well i dont think this project is "dead". i still plan to compile a kernel with a few batt driver tweaks and see if we can extract what the "rcomp" register is, what values it contains, and if we can tweak it at all. same with the "mode" register. also if you guys browse the source, there is a different driver called max10742 and it has all the extra options including "age". if only samsung had given us that one.
the other thing i want to do, or someone here could do, is map the voltage readings to the batt percentages. we did this way back in the beginning on the n1, except we mapped percentage vs mAh. but here we dont have mAh readings, only volts. what we can learn from this is if the percentage is calculated precisely from the voltage, how linear the mapping is, or if it's loosely estimated based on their modelgauge algorithm or whatever they call it at maxim.
i think it would be easy to just use battery monitor widget and export a full day's worth of your logs. maybe i'll install it and give it a shot.
I already have weeks of mv vs. batt % if you need that, specifically from battery monitor widget.
Graph 1: All data from the start. 5000 data points.
Graph 2: ~600 data points, starting from after I ran the battery down to 0 completely, plugged in with phone off, and charged to 100%.
Not sure why all the data gives 2 distinctly different patterns. The lower data plots seems more favorable, with higher % at lower mV.
Hey, has anyone noticed their battery meter saying a low percentage and then seeing it increase after not touching the phone for a while? ive noticed my phone will say 2% for example and ill let it sit for a while and when i check it again its all the way up to 10%. I have calibrated the battery but it doesn't affect it and it still happens?
lol yea my battey is solar powered.. lol jkjk.. but naw its because when your screen is on it adjusts tye percentage based off how your using it.. if its asleep for a while tye battery percentage will increase because its not being used make sense?
Sent from my SPH-D710 using XDA
elliwigy said:
lol yea my battey is solar powered.. lol jkjk.. but naw its because when your screen is on it adjusts tye percentage based off how your using it.. if its asleep for a while tye battery percentage will increase because its not being used make sense?
Sent from my SPH-D710 using XDA
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Nope, it actually doesn't make sense.
You're gas gauge in your car doesn't go up when your car isn't being used. Percentages shouldn't increase without charging no matter what.
FWIW, I've experienced this a few times. My battery has increased as much as 5% without being charged and that's in one string. For example, my battery may go down to 50%, then over the next 20 minutes go to 55%, then an hour later 42% and rise up to 45% and so on. Not sharp spikes either, steady gradual increases.
elliwigy said:
lol yea my battey is solar powered.. lol jkjk.. but naw its because when your screen is on it adjusts tye percentage based off how your using it.. if its asleep for a while tye battery percentage will increase because its not being used make sense?
Sent from my SPH-D710 using XDA
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No, it does not work like that.
Battery app re-calculates the remaining battery based on the battery power currently being used (mV) and history. That's why we are doing the calibration to correctly measure the current battery status and range of it.
In most case, battery power (mV), it goes down from the top and it usually up & down within a small range but for overall, it goes down.
But sometimes, the current mV is goes up and it's caused by
1. Battery usage forecast was wrong or
2. Battery is recovering its power again - for example, after CPU intensive task, the voltage could goes up
3. the remaining percentage goes up if the battery usage is slower than the expectation (it's not going up because it's not being used. Even the screen is off, the battery is still being used). In this case battery app recalculate the percentage based on the current mV and trend that how fast battery mV is decreasing. If mV is increasing, then battery app will show like it's being charged...
There are couple of more things that we also consider in here but I think this is enough information to know.
Update: Let me add a couple of more.
From OP's screenshot, it shows that there's big drop in battery percentage. Usually, big drop happens (battery power is decreasing so fast), it's really hard to calculate the exact remaining percentage because battery shows some irregular pattern after that kind of fast drop. So, some point of time, battery app recalculate the percentage based on current voltage. That's why it's showing going up.
One more case is, the pattern change. After big drop and/or voltage is about the same (stay almost same), then battery app also adjust the remaining battery level indicator.
Simple example) Just like Human. I just finished eating and fully charged. After a meal, I worked so hard and almost exhausted. No power left. But after a little break, I could recover my power a little more.
This example is not exactly same but it would be more easier to understand.
I have noticed this. Could it be that after the battery runs out the phone puts itself in a low consumption mode, thus the battery cools down, increasing the efficiency of delivering power, thus increasing the apparent voltage available? This would be similar to putting the battery in the fridge to get a litte bit of extra juice...
Sent from my SGT10.1 using XDA Premium
Its just the phone reading the voltage wrong, the calibration is outta wack.
qwerty12601 said:
Nope, it actually doesn't make sense.
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Click to collapse
Makes complete sense. There is no accurate way to judge the potential energy stored within a battery. Changes in temperature are one of many things that effect the chemical availability of energy.
Little shifts in measured overall capacity and current charge change all the time on every device you own. Most of them do not update to reflect this, some dont update in the wrongest way. My ASUS gaming laptop doesnt report new full charge capacities to windows and now more than ever with the battery being half shot i can hit 150% but it always did this from new sometimes would show it had stopped charging at 98% when it reached full capacity or 101%.
I can explain the software aspects of the problem. But you will need an electrical engineer, chemical analyst to help you go over the batteries end of it. I of course am not familiar with Android in particular but Portable PC's Sony's PSP etc seen it everywhere.
Its due to a flaw in Samsung phones where it does not correctly read the battery. Sometimes a phone reboot will show as much as a 70% (from my experience) in battery but then my battery will start to "charge" itself as the phone reads the voltage better. I've seen this happen on our phones and the captivate
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qwerty12601 said:
Nope, it actually doesn't make sense.
You're gas gauge in your car doesn't go up when your car isn't being used. Percentages shouldn't increase without charging no matter what.
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Click to collapse
you have no idea how mechanical measuring works, do you? here is an example of how gas is measured; a floating ball attached to an arm changes the voltage of the signal depending on the amount of fuel in the tank. Higher the ball, higher the voltage, and thus higher the gas gauge.
Consequently, you will notice fuel gauges reading higher going uphill and lower when going down, because gas doesnt just sit in one place. The gauge is usually calibrated for when the car is standing still.
Now that you have an idea how mechanical measurement works, can you apply this to battery chemistry? NO, because they are completely different!
Battery life is measured using a formula, not a mechanical device. It is, in essence, a best guess. Some formulas are better than others, but they are all still estimates. And you will notice fluctuations.
Sent from my SPH-D710 using Tapatalk 2
rianbechtold said:
Hey, has anyone noticed their battery meter saying a low percentage and then seeing it increase after not touching the phone for a while? ive noticed my phone will say 2% for example and ill let it sit for a while and when i check it again its all the way up to 10%. I have calibrated the battery but it doesn't affect it and it still happens?
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Click to collapse
i had the same thing happened to me, and i have the pic somewhere.. where the battery just dropped from like 80% to 30% in less then 5 min.. i was using it, and had the screen off, and had it on again.. and it went down like crazy.. and afterwards.. it started to go up, as if i was charging the phone..
some one said that, its a bug by samsung, where if you charge your phone not quiet to 100% and use the phone, this can happen..
concerning what some other guy said about turning the phone off and on, can boost batery power.. that was hilarious sad..
likkkkkke thisssss?
first one is recent.. second one is from one of the initial ics leaks..
Or this freak
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Somairotevoli said:
Or this freak
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Click to collapse
Um or not lol. Considering you have charging in there
RainMotorsports said:
Um or not lol. Considering you have charging in there
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Click to collapse
Or yes as you can see it clearly (or in your case, not so clearly) going up at points it's not being changed
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Somairotevoli said:
Or yes as you can see it clearly (or in your case, not so clearly) going up at points it's not being changed
Sent from my SPH-D710 using Tapatalk
Click to expand...
Click to collapse
However very much expected. You have created a circumstance where accuracy was guaranteed to be off. Making sure that multiple corrections were a reality.
I would hope that in a 2 day period you had 3 to 4 hours to sleep where this phone could have reached 100% twice and only been on the charger about 4 times. Obviously a couple very busy days for you. I could guess any number of occupations that might have done this to you
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That looks almost as if to suggest the sampling did not occur at all while the phone was sleeping.
turbomeister said:
you have no idea how mechanical measuring works, do you? here is an example of how gas is measured; a floating ball attached to an arm changes the voltage of the signal depending on the amount of fuel in the tank. Higher the ball, higher the voltage, and thus higher the gas gauge.
Consequently, you will notice fuel gauges reading higher going uphill and lower when going down, because gas doesnt just sit in one place. The gauge is usually calibrated for when the car is standing still.
Now that you have an idea how mechanical measurement works, can you apply this to battery chemistry? NO, because they are completely different!
Battery life is measured using a formula, not a mechanical device. It is, in essence, a best guess. Some formulas are better than others, but they are all still estimates. And you will notice fluctuations.
Sent from my SPH-D710 using Tapatalk 2
Click to expand...
Click to collapse
Now that you've got that out of your system, let me explain it a little more simply so you understand.
It was an analogy. I never said that battery percentage was calculated the same way as fuel capacity. But it's an analogy to help you relate.
Batter percentage is a measure of volume of power left in the battery. It should never fluctuate UP without being charged, unless something is wrong with the battery/phone. 55% is 55%, no matter what temperature, usage time, current usage is. If the battery is 1800 mah, then 50% battery level means there's 900 mah left. It's not a calculation of anything else. Just like if your fuel tank hold 16gal, and the needle is at 1/2 (stationary of course, not parked/driving up or downhill as you needlessly pointed out), you have 8 gal left. There's no mathematical calculation needed there.
Just for reference, I own no other electronic device that magically increases in battery percentage. My laptop goes down unless it's being charged. It's a quirk/flaw with the system in the phone. Plain and simple.
BTW, no apology needed. I'm just happy to educate you!
Didn't you know? Our device's covering is actually made of solar panels
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qwerty12601 said:
Nope, it actually doesn't make sense.
You're gas gauge in your car doesn't go up when your car isn't being used. Percentages shouldn't increase without charging no matter what.
FWIW, I've experienced this a few times. My battery has increased as much as 5% without being charged and that's in one string. For example, my battery may go down to 50%, then over the next 20 minutes go to 55%, then an hour later 42% and rise up to 45% and so on. Not sharp spikes either, steady gradual increases.
Click to expand...
Click to collapse
My gas guage goes up when i park uphill.
Hey all, this is a thread I saw on different forum and think it is would be good for noobs like myself to benefit from. How to undervolt your CPU and also post your Galaxy Note 2 specific results. I have tried these next steps, and so far I'm doing okay (can't give an accurate results on battery life yet). Like I said (I'm not ashamed to say I'm a noob) but if others can throw their two cents in, we can all learn and this thread can be useful. The next part was cut and paste d from other forum. And I deleted the url for the kernel and root
Prerequisites:
1. Must be rooted and recommended kernel
2. Download and install System Tuner
3. Download and install Stability Test
Steps:
1. Open System Tuner and select CPU
{
"lightbox_close": "Close",
"lightbox_next": "Next",
"lightbox_previous": "Previous",
"lightbox_error": "The requested content cannot be loaded. Please try again later.",
"lightbox_start_slideshow": "Start slideshow",
"lightbox_stop_slideshow": "Stop slideshow",
"lightbox_full_screen": "Full screen",
"lightbox_thumbnails": "Thumbnails",
"lightbox_download": "Download",
"lightbox_share": "Share",
"lightbox_zoom": "Zoom",
"lightbox_new_window": "New window",
"lightbox_toggle_sidebar": "Toggle sidebar"
}
2. Drag the slider shown in the picture to overclock or underclock CPU. In this picture we are overclocking to 1.8ghz
3. Select Voltage at the top to get to CPU voltage settings.
4. Ok, here select the buttons as they are in the picture.
a. Select the Green circled button to save current stock default settings.
b. Select the Yellow circled button 4 times exactly to reduce the millivolts by 100.
Stability Testing:
Now we really should make sure that it can handle it under load right? :silly:
1. Open Stability Test and select CPU+GPU Stability Test.
2. Select Full Details - Proceed.
3. The app will now start stressing your cores. I waited until at least 10 cpu passes before quiting the app...
Cliffnotes:
-By default, your settings will revert back after you restart your phone. You can set them to load at boot, but don't do this unless your absolutely sure that they're stable!
Open System Tuner - CPU - Menu key - Settings - Active Tweaks - Reapply CPU Settings - On Boot Completed
-Whenever i tried to lower the mv more than 100 below stock at 1.8ghz, my phone rebooted
-I am in no way responsible for anything that might happen after performing the above, even if you start your sentence with the word "but"
-here's stock settings in case you need to revert
[/QUOTE]
This is an interesting project but I would think that the average user would not need this as battery life is pretty good. Speaking for myself, I am able to get through the whole day without any issues.
Of course there might be other reasons why someone would want to do this.
Doc
Thanks
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DocEsq said:
This is an interesting project but I would think that the average user would not need this as battery life is pretty good. Speaking for myself, I am able to get through the whole day without any issues.
Of course there might be other reasons why someone would want to do this.
Doc
Click to expand...
Click to collapse
from what i've read, undervolting save very little battery time as the processors are pretty efficient anyways. i don't have actual numbers, but i'd guess you'd get a few extra minutes - which some may really need.
it's that freaking gargantuan screen that sucks the most juice. there used to be a mod to undervolt displays. they had it working on an OG galaxy tab. i never really seen it used anywhere else.
I have an international version of galaxy note 2. I'm currently using AllianceROM and Perseus kernel. And my stock voltage is way way higher than yours. Like 1400mV mine, 913mV yours. Can I undervolt my note 2 to same specifications like yours? Thanks.
This is interesting but setcpu when I had it on my last phone worked awesome and was very easy to use.
Sent from my Amazing Galaxy Note 2!
rjisanandres said:
I have an international version of galaxy note 2. I'm currently using AllianceROM and Perseus kernel. And my stock voltage is way way higher than yours. Like 1400mV mine, 913mV yours. Can I undervolt my note 2 to same specifications like yours? Thanks.
Click to expand...
Click to collapse
You is 1400 mV on 200 MHz? It's probabky 1400 on 1.6 ghz.
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I also have Perseus kernel overclocked but still have great battery life. Thanks for the tip though might try it and compare the difference just in case.
I agree with DocEsq.. It is interesting indeed, but is it really necessary?
Can you overclock it?
My note 2 seems to be charging forever after undervolting. I'm talking for about 6-7hrs charging time here. What seems to be the problem? I'm using Perseus kernel. TIA!
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I once conducted a test with my evo3d. I basically ran an amp meter inline with the battery. Measuring the exact power consumption. I dont remember the exact specs, but undervolting and underclocking my phone compared to stock made a very minute difference in actual power consumption. A difference of about 8-15ma. This was during a CPU full load scenario for about 10 seconds. Even loading the CPU with the screen off to take as many variables out as possible it was very little difference. During normal operarion the power consumed was virtually identical.
So the 2 to 3% of the day (overall time) your phone is actually under HEAVY load, it won't make much difference. It did make a performance impact. So not much benefit, just reduced performance.
Now overclocking and/or overvolting did make a larger difference in consumption at high constant load.
Want to ACTUALLY make a large impact on your battery life? Make sure you don't have any apps preventing your phone from sleeping and run the absolute lowest screen brightness you can stand.
YMMV.
Sent from my Galaxy Note 2 using Tapatalk 2
The benefit I found from undervolting isn't better battery life, it's reduced heat which in heavy use provides better performance due to no cpu throttling. I'm running 1800mhz using less battery than 1600mhz and with same temps as stock. Very stable, been running this for a month now at least.
Action B said:
The benefit I found from undervolting isn't better battery life, it's reduced heat which in heavy use provides better performance due to no cpu throttling. I'm running 1800mhz using less battery than 1600mhz and with same temps as stock. Very stable, been running this for a month now at least.
Click to expand...
Click to collapse
What app did you use to undervolt?
Sent from my Amazing Galaxy Note 2!
yankees45us said:
What app did you use to undervolt?
Sent from my Amazing Galaxy Note 2!
Click to expand...
Click to collapse
I'm using the stweaks app that comes with perseus kernel.. I've undervolted quite a bit and I get better battery life.. Still not quite as good as I had stock, but definitely a lot better for being over clocked.. I just reduce each level to the level below it and run for a few to check stability and keep going from there.. So far I have had no trouble at all with undervolting.. Certainly nothing like I did with my elte.. Here's where I've been for almost a week as well as today's battery results so far with Pandora playing over 3 hours straight and moderate use..
Sent from my SPH-L900 using Tapatalk 2
Yeah, just to let you know that there certainly isn't a linear correlation between undervolting and underclocking and power usage. That might have been the case in simpler times, but with modern multi-core microprocessors, you might actually be decreasing battery life by screwing with your clock rate or voltage. Yes, the defaults err on the side of caution, but it's a whole lot of work for little to no gain.
For example, by reducing your phone's clock rate, you might actually be forcing your phone to be spending more time at load; thereby not allowing it to fallback to its sleep state. There is also something called the power wall, where an increase in operating frequency requires an exponential increase in power. However, the reverse is also true. It can be counter-intuitive to think of it this way, so a practical example is how on a 100 mile trip, a 25 mpg sedan saves 4 gallons of gasoline over a 12.5 mpg SUV. However, over the same distance a 50 mpg hybrid saves only 2 gallons over the 25 mpg car. By that same logic, a mythical 100 mpg vehicle would only save 1 gallon of fuel. It's the law of diminishing returns. Then of course, there are the stability issues that you should take into account.
There is a lot that happens behind the scenes regarding power management. Your phone is capable of intelligently scaling it's processors, voltages, and frequencies up or down all based on current and expected demand. There are people who spend a lot more time doing this for a living, and the idea that you can do it better is probably a falsehood. If you want MOAR POWER, by all means overclock/overvolt it (just don't fry it), but trying to get an extra couple minutes of run time is likely a waste of some hard work. It's the software that kills your battery, not the hardware.
Talking about computer architecture can be complicated and boring, but start with searches on "rise time" and "logic level transitions" if you want to want more background.
Action B said:
The benefit I found from undervolting isn't better battery life, it's reduced heat which in heavy use provides better performance due to no cpu throttling. I'm running 1800mhz using less battery than 1600mhz and with same temps as stock. Very stable, been running this for a month now at least.
Click to expand...
Click to collapse
Interesting... whenever I'm dling using a torrent client my phone gets a nasty fever and I've gotta set it down somewhere as it will literally make me sweat, lol. I do b there think I'll be undervolting just for that specific circumstance but that is a very interesting concept...
anishannayya said:
Yeah, just to let you know that there certainly isn't a linear correlation between undervolting and underclocking and power usage. That might have been the case in simpler times, but with modern multi-core microprocessors, you might actually be decreasing battery life by screwing with your clock rate or voltage. Yes, the defaults err on the side of caution, but it's a whole lot of work for little to no gain.
For example, by reducing your phone's clock rate, you might actually be forcing your phone to be spending more time at load; thereby not allowing it to fallback to its sleep state. There is also something called the power wall, where an increase in operating frequency requires an exponential increase in power. However, the reverse is also true. It can be counter-intuitive to think of it this way, so a practical example is how on a 100 mile trip, a 25 mpg sedan saves 4 gallons of gasoline over a 12.5 mpg SUV. However, over the same distance a 50 mpg hybrid saves only 2 gallons over the 25 mpg car. By that same logic, a mythical 100 mpg vehicle would only save 1 gallon of fuel. It's the law of diminishing returns. Then of course, there are the stability issues that you should take into account.
There is a lot that happens behind the scenes regarding power management. Your phone is capable of intelligently scaling it's processors, voltages, and frequencies up or down all based on current and expected demand. There are people who spend a lot more time doing this for a living, and the idea that you can do it better is probably a falsehood. If you want MOAR POWER, by all means overclock/overvolt it (just don't fry it), but trying to get an extra couple minutes of run time is likely a waste of some hard work. It's the software that kills your battery, not the hardware.
Talking about computer architecture can be complicated and boring, but start with searches on "rise time" and "logic level transitions" if you want to want more background.
Click to expand...
Click to collapse
Like the way you put that. Good analogies there it just seems like the other day that undervolting was the hip thing to do. Technology just moves at such a wonderful pace though. Just one little FYI though, since i do like you analogy i would like to point out that the law of diminishing returns actually refers to something else entirely. I know, I know, nitpicking, but it's just that everyone is always off the mark with that one and, well I guess I'm just an anal ahole (and an economics major, ,which I guess just overall makes me an a hole, ,lol)
If you have ever pulled apart a laptop and saw how much thermal paste the engineers at the factory "designed" for their to be on there, or seen the air/fuel ratio most cars roll off the lot with, or ever replaced an intake in a vehicle with a high performance unit I'm not sure you would feel the same way about you yourself not being to do a better job.
I get the point, and I believe often there is validity to that point, but sometime things just aren't that simple. This is where power gains come from in tuning a car (which i do). This is where efficiency is raised by removing restrictive components in a vehicle (intake, exhaust, etc) and where cooling performance is increased on a CPU with the proper application of a quality thermal paste.
Whenever time is money, and you are deciding between your bottom line and something that works and something that works as well as it can, shortcuts are made and corners are cut. Perhaps they could have spent another 200 hours for the team to absolutely optimize the processor for each device, but the cost would have been an additional $20,000 dollars. This is not always the case, but with processors I think it is. I will undervolt everytime and I do take objective measures for battery and I agree gains are relatively small. For cooling, I found the difference to be very significant at 1800, mhzI didn't check at 1600mhz, however. I can run a full Antutu benchmark as much as I want at room temperature and never exceed the throttling point (70 C if i remember correctly). Now, I am in no way saying these are facts, these are opinions, so I could be wrong of course.
Psychotic-Cerebellum said:
Interesting... whenever I'm dling using a torrent client my phone gets a nasty fever and I've gotta set it down somewhere as it will literally make me sweat, lol. I do b there think I'll be undervolting just for that specific circumstance but that is a very interesting concept...
Like the way you put that. Good analogies there it just seems like the other day that undervolting was the hip thing to do. Technology just moves at such a wonderful pace though. Just one little FYI though, since i do like you analogy i would like to point out that the law of diminishing returns actually refers to something else entirely. I know, I know, nitpicking, but it's just that everyone is always off the mark with that one and, well I guess I'm just an anal ahole (and an economics major, ,which I guess just overall makes me an a hole, ,lol)
Click to expand...
Click to collapse
The TIM wasn't put on there by the engineers who designed the chips; they are put there by workers being paid next to nothing.
Your phone doesn't have a CPU, it doesn't even use thermal paste; it's usually just a rubber contact patch and passive heat dissipation. This actually brings another point where overclocking can sometimes reduce performance due to throttling by thermal constraints (why our phone has such a low GPU rate than what it is capable of in other phones with better thermal envelopes).
You aren't replacing the SoC, you are changing the software that determines how to set the voltage/clock multiplier. The car analogy isn't valid.
And I stand corrected regarding the Law of Diminishing Returns; never paid attention in macro-econ. I think was because my prof. was more interested in forcing his political ideology upon us than actually teaching the subject. :silly:
EDIT: Keep in mind, the engineers rarely get what they want. The product the consumer ends up getting is usually dictated through a collaboration of what the business and marketing teams want. The engineer might request a large cooler clamp with a perfectly lapped surface and a carbon-based TIM. In reality, the consumer gets a dinky fan with melt-on TIM and retention springs. Money talks.
anishannayya said:
The TIM wasn't put on there by the engineers who designed the chips; they are put there by workers being paid next to nothing.
Your phone doesn't have a CPU, it doesn't even use thermal paste; it's usually just a rubber contact patch and passive heat dissipation. This actually brings another point where overclocking can sometimes reduce performance due to throttling by thermal constraints (why our phone has such a low GPU rate than what it is capable of in other phones with better thermal envelopes).
You aren't replacing the SoC, you are changing the software that determines how to set the voltage/clock multiplier. The car analogy isn't valid.
And I stand corrected regarding the Law of Diminishing Returns; never paid attention in macro-econ. I think was because my prof. was more interested in forcing his political ideology upon us than actually teaching the subject. :silly:
EDIT: Keep in mind, the engineers rarely get what they want. The product the consumer ends up getting is usually dictated through a collaboration of what the business and marketing teams want. The engineer might request a large cooler clamp with a perfectly lapped surface and a carbon-based TIM. In reality, the consumer gets a dinky fan with melt-on TIM and retention springs. Money talks.
Click to expand...
Click to collapse
1. The voltages are set by an engineer, that is what I was referring to.
2. The CPU thing was an analogy as was the car. Not a direct comparison. The analogy is referring to how there is set fuel and timing tables just like there is set voltage tables, both might not be the most efficient from the factory, tweaking them can improve things. How is this completely not valid?
Based upon this, very useful, article, I'm interested in knowing how to charge to a lower peak voltage. Apparently you can double the lifespan of your battery by lowering the maximum peak voltage by 0.1V, which is a thing I'm interested in! (as opposed to most people, who want more capacity, I'm prepared to sacrifice some capacity for longer lifespan!)
It feels like there should be 3 ways of solving the problem:
Pull the cord out at 80%?
Create some sort of hardware between the phone and charger that does something?
Tell the software to stop charging at a lower voltage?
#1 is clunky and not going to happen. #2 is hard because I'm not a hardware guy, but if anyone has any knowledge in this area I'd be interested in hearing! #3 is best for me, because at least I understand the internals of the phone, but I can't figure out what part of the phone might be in charge (heh...) of this.
So I guess my questions are:
What chip/etc is in charge of handling charging?
Is it possible to hack at this part?
Has anyone done it before?
Thanks!