# Opinions on Undervolting



## GSUS969 (Jul 19, 2011)

I'm looking for opinions on undervolting. What are some advantages and disadvantages? It is supposed to help battery life, but by how much? How much should one undervolt? Etc. Basically looking for a reference for how to undervolt my phone and if there are things I should be aware of. Thanks in advance.


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## Kancerstick (Dec 25, 2011)

ive been undervolted quite a bit from stock voltages for a good 2 weeks and i havnt had anything abnormal happen to my gnex. If you go too low though, your phone will hard reset or become unresponsive. Its nothing that a battery pull wont fix as long as you have "set on boot" options unchecked. As far as battery goes, im sure it helps.. A little or alot im not sure. The one thing that eats battery for me is the screen since im in the car most of the day so my screen is always on while its in the dock.

if you want to undervolt, you need to root and install a custom kernel / rom. Then use setcpu or if your rom supports the built in function, do it from there.


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## GSUS969 (Jul 19, 2011)

What volts are you using for the different clock speeds?

And I'm rooted (using AOKP m2 and Franco's kernel 13.1)


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## nklenchik (Dec 1, 2011)

It's probably best to just play around with the voltage until you find what's right for you. I'm on the latest stable leankernel and I can undervolt 350mhz and 750 to -250 in voltage control and my phone runs great. You'll know if you undervolted too much if the screen just freezes and restarts, but like kancerstick said, don't set at boot unless you know it's running fine.


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## sonicxml (Oct 1, 2011)

so my question is: does undervolting have long term effects on your cpu - like overclocking does? in other words, will your cpu not last as long if you consistently undervolt?


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## 2defmouze (Oct 12, 2011)

The advantage is squeezing a bit more battery life out of your phone.. I don't even bother personally, as most of the kernels you have here.. Franco's, imoseys, and jd's...are already undervolted a good amount out of the box. (correct me if I'm wrong, of course)

The best advice I read if your dying to push it, is start at one frequency such as the 350, lower the voltage in one increment at a time (increments are 25), see if you get and freezing or rebooting during use and running stress tests (easy thing to do in SetCPU).. Once you do find that bottom limit where stuff goes bad, set the undervolted value to 50 above it and move to the next slot with the same procedure...

Obviously this can take some time, and the end result when you find your phone's sweet spot for each value is probably just a relatively small amount of batt life.... So I say don't even bother? Like i said, all the kernels come undervolted anyway within reasonable limits, some people's phones can take more, but some can't, all silicone is not created equal, same reason one kernel might do great for you but another's phone doesn't like it.

So... Moral of the story: don't stress it. Even when you go through the effort, these devs are cranking out updated kernels so fast that you'd have to do it again in a few days when you update the kernel.. It's not worth the effort for the, literally, minor increase in batt life.

Hope that helps









Sent from my GalaxyNexus


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## abqnm (Jul 3, 2011)

2defmouze said:


> The advantage is squeezing a bit more battery life out of your phone.. I don't even bother personally, as most of the kernels you have here.. Franco's, imoseys, and jd's...are already undervolted a good amount out of the box. (correct me if I'm wrong, of course)
> 
> The best advice I read if your dying to push it, is start at one frequency such as the 350, lower the voltage in one increment at a time (increments are 25), see if you get and freezing or rebooting during use and running stress tests (easy thing to do in SetCPU).. Once you do find that bottom limit where stuff goes bad, set the undervolted value to 50 above it and move to the next slot with the same procedure...
> 
> ...


Great post! Looks like my explanations.









I do have to say one thing because I laughed when I read it... "...all silicone is not created equal..." Silicone is what Pam Anderson is made of and silicon is what your CPU is made of. So yeah all silicone is not created equal.









(No hate meant by that. Just think it is funny.)


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## SOTK (Jul 25, 2011)

I wouldn't say undervolting isn't worth it. I've tried Faux and Franco without user custom undervolting, and experienced quicker battery drain. For example, with LTE enabled and syncing on (twitter, Gmail, Facebook, tapatalk, etc), I can get through a 12 hour work shift with 70% or better left of my battery. That's with sending a few texts and checking my email and stuff during work breaks. When I've tried no custom user undervolting kernels, I've left shift with 45% battery remaining.

Sent from my Galaxy Nexus using Tapatalk


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## sandfreak (Jun 11, 2011)

2defmouze hit the nail on the head. Exactly my thoughts on undervolting.


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## 2defmouze (Oct 12, 2011)

abqnm said:


> Great post! Looks like my explanations.
> 
> I do have to say one thing because I laughed when I read it... "...all silicone is not created equal..." Silicone is what Pam Anderson is made of and silicon is what your CPU is made of. So yeah all silicone is not created equal.
> 
> (No hate meant by that. Just think it is funny.)


Lmao I wasn't even sure so i trusted autocorrect haha









Sent from my GalaxyNexus


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## GSUS969 (Jul 19, 2011)

SOTK said:


> I wouldn't say undervolting isn't worth it. I've tried Faux and Franco without user custom undervolting, and experienced quicker battery drain. For example, with LTE enabled and syncing on (twitter, Gmail, Facebook, tapatalk, etc), I can get through a 12 hour work shift with 70% or better left of my battery. That's with sending a few texts and checking my email and stuff during work breaks. When I've tried no custom user undervolting kernels, I've left shift with 45% battery remaining.
> 
> Sent from my Galaxy Nexus using Tapatalk


I agree with you. I did underbolt my phone last night. And throughout 9 hours of sleep. I lost only 1% on my battery (I was losing about 8% prior to undervolting)


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## pedxing (Jan 15, 2012)

GSUS969 said:


> I agree with you. I did underbolt my phone last night. And throughout 9 hours of sleep. I lost only 1% on my battery (I was losing about 8% prior to undervolting)


Holy crap! Was that with no other changes or does that include installing a new kernel and Rom. The best I can get is a half a percent an hour with WiFi and phone services still on.

I'm trying to find out the actual effect of under volting by itself.

Sent from my Galaxy Nexus using Tapatalk


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## dirtmaster88 (Oct 10, 2011)

Probably already well known but I've always found that CPU Spy is an awesome tool when under/overclocking. It'll show you down to the second statistics for the time spent at each CPU speed level. I was suprised to see my phone running at 350mhz pretty much whenever it's not in a deep sleep.


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## PURGATORY (Jan 20, 2012)

The lowest I have gone on my gnex is

1350-1180
1200-1120
920. -1020
700 -900
350. - 840

On apex v5 in lower even by 2 or 3 volts I had problems. It will take a dump in less then an hour. I have tried 820v on 350hz and it will stay on for 10 sec. Just some time to adjust the problems. I was in fear.

I have tried lower Hz like 180hz (I used 860-880) and 250hz(I used 850-870). I noticed the volts had to be higher to stay on for idle and the other higher Hz needed to be higher to support the low idles.

I have Franco kernel 13.1
Running:
1350-1280
1200-1180
920. -1080
700. -980
350 -880

It has great stability. No problems. It can go lower but a safety net is always good.

I have seen great battery life. I can go 10-11hours with out charge.

Sent from my Galaxy Nexus using Tapatalk


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## PURGATORY (Jan 20, 2012)

****Let me clarify 10hours straight playn Words with friends with 5 people tell the battery dies. That is how I test









Sent from my Galaxy Nexus using Tapatalk


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