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[Q] Paradox with underclock & battery savings, does it actually hurt? SetCPU, etc.

[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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Click to collapse
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?

Downclock CPU to save battery?

I`m not playing games or running CPU demanding apps, just phone calls/sms/bit of non flash web.
Is it possible to downclock CPU to increase usage(save battery)?
Or CPU doesn`t eat that much battery and downclocking would have very little effect on battery?

With a rooted device, you might want to try CPU Master Free. You will be able to decrease the clock speed.
Also, you could try to UnderVolt your CPU. Search for your phone model UV in te forums.

Min frequency is 350MHz so if your not doing anything it will be idling at 350mhz

rbs_uk said:
I`m not playing games or running CPU demanding apps, just phone calls/sms/bit of non flash web.
Is it possible to downclock CPU to increase usage(save battery)?
Or CPU doesn`t eat that much battery and downclocking would have very little effect on battery?
Click to expand...
Click to collapse
It does help you save precious battery life.
You can download the best app for overclock, SetCpu, from the XDA site, it's free for XDA members:
http://forum.xda-developers.com/showthread.php?t=505419

How much more battery life I could get by downclocking CPU? Any feedback from people who have tried such thing?

On my gn i find the screen to be the biggest user of thr battery power so underclocking prob would have little use, ohh and iirc the phone uses race to idle which procesess overything as fast as possible to get the cpu back it low power idle state.

rbs_uk said:
How much more battery life I could get by downclocking CPU? Any feedback from people who have tried such thing?
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I normally charge my phone before go to sleep, I don't overcharging it during the night.
My SetCpu frequencies are Min 19/ 692 Max.
I am connected through 3G data ALL day and I am always online on Skype, I use my phone a lot, browsing, games, and phone call, and I can tell you, thanks to the undervolting, I got home at night with 50% juice remaining.
Without SetCpu, I would have 10/15% left at night...

yukinok25, that`s huge improvement, I`ll try it definitely.

rbs_uk said:
yukinok25, that`s huge improvement, I`ll try it definitely.
Click to expand...
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And...this is why we all love XDA...
Remember that battery life also depends on Radio version and kernel installed.

I remember there was a topic about "How to charge your phone first time" - cannot find it any more.

rbs_uk said:
I remember there was a topic about "How to charge your phone first time" - cannot find it any more.
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If you mean after you just bought it, Its enough to let it fully discharge twice, without charging it, in between this two circles.
Anyway with nowdays Li-ion battery, you won't really need to this so anymore, since the lifespan of battery start to decrease from the moment that they left the production factory.

yukinok25 said:
If you mean after you just bought it, Its enough to let it fully discharge twice, without charging it, in between this two circles.
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Yes.
Discharge twice without charging - hmm... once its dead its dead. I didn`t get it

rbs_uk said:
Yes.
Discharge twice without charging - hmm... once its dead its dead. I didn`t get it
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Sorry for my english.
I meant during your usage time (during the day) don't charge your phone at all. let it discharge fully twice.

yukinok25 said:
Sorry for my english.
I meant during your usage time (during the day) don't charge your phone at all. let it discharge fully twice.
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Ok, thanks.

Anytime mate!

Ive read good results on using juice defender app to prolong battery life:
http://android.modaco.com/topic/349071-galaxy-nexus-battery-drain-issues/

L60N said:
Ive read good results on using juice defender app to prolong battery life:
http://android.modaco.com/topic/349071-galaxy-nexus-battery-drain-issues/
Click to expand...
Click to collapse
I would not recommend juicedefender. Doesn't do anything at all. The only thing I notice is that nu wi-fi turned itself off when it shouldn't.
You could try AutomateIt. You can set up your own actions.
Ex: Within 100 meters of school > Sound off

Safe battery temps

So im using tbaldens cm9 and set the CPU to performance, which sets CPU at 1400 constant. So I was playing temple run for about 10 minutes and my battery temp got up to 50 degrees. I have a program called Droid system suite and it said my battery was overheating at that temp. My question is, what is a safe temp for the battery? And how long should that temp be maintained? Thanks advance.
Sent from my CM9 Powered HOX

shinigamikris said:
So im using tbaldens cm9 and set the CPU to performance, which sets CPU at 1400 constant. So I was playing temple run for about 10 minutes and my battery temp got up to 50 degrees. I have a program called Droid system suite and it said my battery was overheating at that temp. My question is, what is a safe temp for the battery? And how long should that temp be maintained? Thanks advance.
Sent from my CM9 Powered HOX
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to be safe don't let your battery temperature exceed above 50 c
below that temp its safe

vivek_bhoj said:
to be safe don't let your battery temperature exceed above 50 c
below that temp its safe
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Click to collapse
So would it be OK to sit at 50 c for periods of say 30 minutes? It gets bloody hot to touch
Sent from my CM9 Powered HOX

As lithium battery exceeds their operating temperature regulary, it will impact on it's life. While working on overheating state, it may not able to provide stable/enough currents to the phone. Wrost case scenario == blow (ignore, this need really hot).

shinigamikris said:
So would it be OK to sit at 50 c for periods of say 30 minutes? It gets bloody hot to touch
Sent from my CM9 Powered HOX
Click to expand...
Click to collapse
well i would say if temp reaches 50 c then leave ur phone for some time as it will affect battery life and also don't use ur phone while charging until the battery is charged more than 50% as many times while playing games at charging less than 50% our phone consumes more power than the power it is receiving

HebeGuess said:
As lithium battery exceeds their operating temperature regulary, it will impact on it's life. While working on overheating state, it may not able to provide stable/enough currents to the phone. Wrost case scenario == blow (ignore, this need really hot).
Click to expand...
Click to collapse
What temp would be "really hot"?
vivek_bhoj said:
well i would say if temp reaches 50 c then leave ur phone for some time as it will affect battery life and also don't use ur phone while charging until the battery is charged more than 50% as many times while playing games at charging less than 50% our phone consumes more power than the power it is receiving
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It gets to 50 c after only 10 minutes of game time. So you think 50 c for battery is too high? Should I stop gaming if it gets to 50? Don't really care if it uses heaps of battery, just don't want to damage it. Lol.
Sent from my CM9 Powered HOX

shinigamikris said:
What temp would be "really hot"?
It gets to 50 c after only 10 minutes of game time. So you think 50 c for battery is too high? Should I stop gaming if it gets to 50? Don't really care if it uses heaps of battery, just don't want to damage it. Lol.
Sent from my CM9 Powered HOX
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Click to collapse
which game are you playing? i have played many games and none take me to 50 c in 10 minutes
may be u can try faux kernel to reduce battery temperature and which rom are u ysing?
---------- Post added at 07:48 AM ---------- Previous post was at 07:36 AM ----------
vivek_bhoj said:
which game are you playing? i have played many games and none take me to 50 c in 10 minutes
may be u can try faux kernel to reduce battery temperature and which rom are u ysing?
Click to expand...
Click to collapse
As most of the smartphones now use LiPo battery, so here is a safety guide:
http://www.icharger.co.nz/articles/ArticleId/3/Lipo-Lithium-Battery-Safety-Guide.aspx

Wowza!!! That's hot!

All good, took it off performance mode and set the minimum speed to 475, seems to be not getting as hot now, where as I had it set to 1400 all the time and it would get really hot...
Sent from my CM9 (Beta 5 / Tbalden) Powered HOX

htc released a statement near to when the hox was released. it said that 55 celcius was normal and safe.

Yea mine is running under that most of the time on CM10 ROM. Playing 3D intensive games like Dead Trigger. Does get hot after quite sometime but not 10min. Good thinking with the CPU Speed adjustment, i used an overclocked kernel for a short bit @1.7GHz but that got pretty hot pretty fast so I have left that for now. Don't really need it on a quad core. Yet.

[Q] CPU & Battery Temperature

what is the normal temperature for CPU & Battery while charging (AC) and not charging (while in usage, not idle)
while i charge (AC) my GNex my CPU temperature is 51°C ~ 54°C and my Battery temperature is 44°C ~ 46°C. is that normal?
and sometimes when i used my phone for listening music and chatting with whatsapp my CPU and battery temperature just like above 51°C and 44°C. and once i got my CPU temperature 60°C while charging
so my phone is a little beat warm in the back and front, is that normal guys? or that problem maybe comes from custom kernel or custom ROM?
btw thanks

youre normal.

If you know anything about computer's take a second and think about what would happen if you ran your computer without a fan or heatsink. Then be amazed your phone only gets "warm".

okay thanks for the answer guys
and just to make sure we can call the battery and CPU "hot" in what degree? thanks again

Syfer_Fever said:
okay thanks for the answer guys
and just to make sure we can call the battery and CPU "hot" in what degree? thanks again
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Click to collapse
the cpu will shut itself down automagically at 110C. but way before that, your thermal throttle will kick in. the thermal throttle will lower your cpu speed to cool itself down.
the battery should usually be below 45C. it can get hotter especially when plugged in and doing something cpu or gpu intensive. the hottest ive gotten my battery is 120F(49-50C), and i dont recommend letting it get that hot.

120C?! That's 248F. And we'll above the boiling point of water. You absolutely sure about that?

063_XOBX said:
120C?! That's 248F. And we'll above the boiling point of water. You absolutely sure about that?
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Click to collapse
no no no, 120F, sorry :angel:

thanks sir simms22 your post is very usefull for me and 063_XOBX thanks for your answer too
so when i using my phone intesively and my phone get warm i should put my phone and wait untill cold/normal again right?

Syfer_Fever said:
thanks sir simms22 your post is very usefull for me and 063_XOBX thanks for your answer too
so when i using my phone intesively and my phone get warm i should put my phone and wait untill cold/normal again right?
Click to expand...
Click to collapse
just use it normally. if the cpu is too hot, your device will let you know. if you feel that the battery is too hot, unplug it from the usb, let it cool down.

thanks for your advice sir

[Q] Normal/Excessive CPU temperature for S4 ?

Hi,
I'm using a Canadian Galaxy S4, SGH-I337M.
Rooted, running on Liquidsmooth 4.4.4 ROM. Also has Ktoonsez kernel. It is currently undervolted+underclock a bit, and is stable (I could overclock it, but I don't. No need).
Been wondering for a long time about the operating CPU temperatures of the Galaxy S4... Never had the possibility to do testing with CPU temperatures before. I do have a LG P500 that I have overclocked a ton in the past, still work just fine, but the LG P500 is old and do not support viewing CPU temperature, so it's my first time experimenting with that.
How hot would be too hot for this phone? There are several opinions, but never figured out if I... "minimize" the risks of my actual temperatures, for some reason. My laptop CPU throttle at 85 celcius for instance. While it's a phone, it's completely different.
At night, while connected to charger, it would be pretty cool, at 25-30 degrees when I wake up;
I would say that most of the time, my CPU is running at 50 celsius, and rarely ever exceed 65-70 under normal use, or even gaming. Plus, the CPU is undervolted and a bit underclock, so I do feel like it run cooler than usual.
Quoting Meowmix from Rogers forums:
It varies on the usage of everyone else & how you handle the phone ( cases & such). Also if you are in extreme heat or having the device in direct sunlight.
Click to expand...
Click to collapse
So, the case does matter? I do have that Otterbox case which is pretty tight and enclose the phone pretty well, I would believe that the phone would get less.. air.. but I mean, it's just a case, didn't thought it would affect much..?
Quoting Ahmed from AndroidCentral Forums, I would say that I have a quite similar situation.
No, just when i ran AnTutu when it runs the 4 cores at the maximum frequency the temperature is between 80-91c, and at normal use while surfing the internet the temp. 45-55c and the battery reaches 38c after an hour of continuous using.
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I CAN reach 80-90 celsius, but only if I really want it to happen. 38 celsius for the battery is also correct, I never exceeded 41 degrees yet, on any Android phone (I don't know the dangerous battery temps.. But when I reach 40 degrees I try to put it down as fast as possible). With benchmarks, usually at the max frequency, or testing my undervolt with Stability Test, I CAN reach 80-90 celsius, which look really high. Additionally, I would remind that I don't overclock, and the CPU is undervolted so seems a bit cooler.
So on AndroidCentral, this is the reply Ahmed got, from "CR6" user:
I had to use my temp converter to look up & convert them to Fahrenheit. 80-91c equates to 176-195 Fahrenheit and that's extremely dangerous. These temps will not only physically burn you, but will fry your phone if you continue using it at these temperatures. 45-55c equates to 113-131 degrees Fahrenheit, and that is normal under really heavy usage. Optimally, you'd like to keep it at 38-45c. You may have a defective device if you regularly see temps over 80c and I would advise checking on a replacement.
Click to expand...
Click to collapse
THAT dangerous? Well, I don't phisically feel the heat - I do feel it, but since I have that phone case, that doesn't hurt at all. But like I mentionned, I never reach 80 celcius or more unless doing benchmarks. Usually I never exceed 65-70. But still it left me wondering - Why does Android allow such high temperatures in first place? Isn't the system suppose to shut down at some point in case of danger, and when?
I've also experimented with thermal throttling in the Ktoonsez kernel, and the throttling values of the ROMs. Touchwiz Stock ROM with DVFS disabled, seems to throttle at 80 celsius, look decent. Liquidsmooth AOSP ROM, stock kernel, does not seem to throttle at all (Huh)! Once, and that was exceptionnal, I've reached 100 CELSIUS using Wifi, connect to a charger after like 2 hours, room temperature was very warm, was not surprised, but when I noticed I reached 100 CELSISUS, I was WOAW, I should shut down. I did reached 100 degrees again, using Stability Test at max frequency after a few minutes. Needless to say I manually stopped the test, because I had no idea how much heat the phone could handle...
So been aware of this, "Ktweaker" app, for the Ktoonsez kernel I use now, does have a thermal throttling option, but I wondering which thermal value should I enter for best "performance"? Default was 70 degrees, I set mine at 80, I've heard of people even putting 90 for the same kernel. Besides, maybe I worry about it too much, because in no way the phone should exceed 70 degrees celcius under normal use anyway, or even gaming. Only way to reach insane temperatures would be benchmarking/stress testing...
Still, first time seeing these CPU temperatures also. I've overclocked my LG P500 several times in the past, dealing sometimes with random reboot, so make stability/overheating questionnable, but the device did not supported seeing the actual CPU temp. So I don't know which temperatures would be considered normal - probably, nothing above 75-80, correct (For the Galaxy S4, actually)?
(Jason) said:
(From another thread)
I do know it can run up to about 180 before hitting critical and shutting down
Edit: its about a 75 degree ambient temp where im at.
Tapped² from my I5³5
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Click to collapse
At which point is the device supposed to shut down? Is that in the kernel or a hardware CPU trigger? Because heck, I've reached 100 degrees 2 times, I mean, how far/close was I from a shut down? I'm quite surprised.
I've also read of people complaining of S4 overheating, especially maybe after it was released - It's possible that it heats up more than other phones, but honnestly I have no idea.
Thanks for your answer =)

Going thru this exact same thing. Same temps. This is not normal. Mines just started happening one day. Idk how or exactly when

Kennii said:
Going thru this exact same thing. Same temps. This is not normal. Mines just started happening one day. Idk how or exactly when
Click to expand...
Click to collapse
Thank you for your answer;
Used to think some temps look normal to me - Besides, since I've undervolted last week, it's stable and run cooler, maybe better battery as well. I never can exceed 70 degrees even when gaming I supose..
I can reach 80 degrees, but only when benchmarking or stability testing, so I'm not worried, but I do wonder;
I've reached 100 degrees 2 times, once while doing a stability test at 1,89 GHz for like 5 minutes (or more), I had to manually stop. And last time was long ago, watched YouTube videos in bed, like under covers ha, maybe as well connected to charger. Not even surprised I've reach such temps after a while in such conditions, under covers, just no air (Used to do it with my LG P500 too. While I never was able to see the CPU temps on this device. Even then, LG P500 still works, but guessing build quality was much better). Needless to say I was like WOAW when I've noticed 100 degrees, and just put the phone down. Probably went from 80 to 100 quickly, didn't noticed that fast. But yeah, that 100 degrees was.. almost expected under such conditions.
I just really wonder about thermal throttling. Like I've mentionned, stock Touchwiz with DVSF disabled seems to throttle at 80, while KTweaker app for a different AOSP kernel have the default temp limit set to 70. Liquidsmooth ROM, AOSP, does not seem to have a throttling point, since I've reached 100 degrees 2 times with it (Don't intend to test 100 degrees again, huh). What would be the maximum ideal temp for throttling? Maybe I think about it too much, since under normal circumstances, I never exceed 70 degrees, besides benchmarks.
Also wondered at which temp is the phone supposed to shut down... 120 degrees?! XD Because 100 seems ridiculous to me, probably is, but yeah, my laptop throttle at 85, and it's a laptop (Intel Core i3) - Can't imagine a phone going any higher without any risk.
Thanks for the feedback