Power saving tips & tricks


_wb_

Microbe
Staff member
Joined
Apr 5, 2012
Messages
5,390
Age
42
Location
Brussels, Belgium
As we all know, the Pandora has great battery life. But even if it's great already, there's always ways to improve it even more. There is no such thing as "too much battery life".


In this other thread there's a breakdown of Pandora's power consumption in broad categories. It's probably a good idea to check that thread first.


This thread can be used to share some tips & tricks to improve the battery life of your Pandora.


Here are my tips:


- Set the backlight brightness as low as possible. Use a brighter gamma setting than default: I use the simple gamma setting and put it at 150%. The gamma setting does not affect battery life, but the backlight has a big effect on it, so you want to get your brightness from the gamma setting, not from the backlight. Of course too high gamma will make the contrast too high, so don't overdo it.


- Disable the power indicator led. It is kind of useless (I never power off, so I know it's on, no need for a led to tell me that), and it consumes about 17mW, which is not much, but in lid-closed mode, that is the difference between 143 hours and 170 hours of standby time.


- Don't overclock higher than needed - if everything you need works fine at 500 MHz, don't run your cpu at 900 MHz all the time. The extra clock speed does have a (small) impact on power consumption.


- Don't overvolt higher than needed - if OPP2 is enough, don't set it to OPP5.


- Make sure you don't keep using the cpu unnecessarily when the lid is closed. E.g. if you were playing music, stop playback (or quit the player), don't just set the volume wheel to zero.


- Tiny effect, but still: use the stylus, not the nubs.
 
Last edited by a moderator:
If you are using wifi, especially ad-hoc with a cellphone, you might want to power that down when not in use.


On the other hand, if it takes a full minute to reconnect (as mine sometimes does), that can be too much of a bother. The updated wifi drivers did help me a bit there.
 
I always use an low LCD brightness and do not OC, so my Battery time is always pretty decent. ^^


Since I've found out, that the newer Firmwares are running the CPU always with OPP5, it may be an Idea to set it back to OPP3, should be enough for 600MHz and maybe even a little bit more. :)
 
- Tiny effect, but still: use the stylus, not the nubs.
In XFCE, I primarily use the Pandora button and DPad to navigate the menu. Then I press enter when I'm at the program I want to launch. To me this is fastest way to navigate, just wondering what thoughts are on using the DPad vs Nubs in the world of power consumption?
 
Last edited by a moderator:
- Set the backlight brightness as low as possible. Use a brighter gamma setting than default: I use the simple gamma setting and put it at 150%. The gamma setting does not affect battery life
This is interesting, thank you, will try it out.


EDIT Can you please explain how to? I see no "100%" which could be slided up to 150%...

- Disable the power indicator led.
Can this be done from the Settings Menu? Will try that, too. I never power completely off either, so I know it is in Sleep Mode :) and no real need for a LED reminding me of it.


EDIT Can´t find such an option either. I guess I have to manually edit some config file then?
 
Last edited by a moderator:
- Tiny effect, but still: use the stylus, not the nubs.
In XFCE, I primarily use the Pandora button and DPad to navigate the menu. Then I press enter when I'm at the program I want to launch. To me this is fastest way to navigate, just wondering what thoughts are on using the DPad vs Nubs in the world of power consumption?

Using the keyboard is the best option of all. Using the nubs is a bit worse than using the stylus because there are much more events that wake up the cpu (you're moving the mouse cursor around, instead of directly registering one click at the spot you want). But if you can avoid the mouse completely, that's even better.

- Set the backlight brightness as low as possible. Use a brighter gamma setting than default: I use the simple gamma setting and put it at 150%. The gamma setting does not affect battery life
This is interesting, thank you, will try it out.


EDIT Can you please explain how to? I see no "100%" which could be slided up to 150%...
It's in Settings > LCD Settings > Manage LCD Gamma (simple).

- Disable the power indicator led.
Can this be done from the Settings Menu? Will try that, too. I never power completely off either, so I know it is in Sleep Mode :) and no real need for a LED reminding me of it.


EDIT Can´t find such an option either. I guess I have to manually edit some config file then?
No, there's no GUI option for it. You can manually change it by writing a "0" in /sys/class/leds/pandora::power/brightness (as root).


I modified the script in /usr/pandora/scripts/op_power.sh to switch the led off when the lid is closed (and also to set cpu speed to 125MHz when the lid is closed).
 
It's in Settings > LCD Settings > Manage LCD Gamma
Thanks, I think I have it now. Now the brightness is tuned down to 5, indoors, looks fine so far with the higher Gamma settings.

You can manually change it by writing a "0" in /sys/class/leds/pandora::power/brightness (as root).
I can´t manage this right now, opened the correct file with AbiWord, wrote "0", trying to save it as txt-file but it doesn´t save. Will try again tomorrow, tho this isn´t so very important :) Thanks again.
 
Might need to be ROOT, Use terminal - Nano or VIM (Leafpad is ok, but not root).
 
I can´t manage this right now, opened the correct file with AbiWord, wrote "0", trying to save it as txt-file but it doesn´t save. Will try again tomorrow, tho this isn´t so very important :) Thanks again.

(emphasis mine)


It's a text file, not a word processor document. You really should be using a text editor like Mousepad.


I think the problem is you need root privileges. Instead of choosing Mousepad from the menu, open a terminal and type:



Code:
sudo mousepad /sys/class/leds/pandora::power/brightness
 
Last edited by a moderator:
I modified the script in /usr/pandora/scripts/op_power.sh to switch the led off when the lid is closed (and also to set cpu speed to 125MHz when the lid is closed).

Would be interesting to see that script.


Does it automatically turn the LED back on when you open...and automatically clock back up to whatever your default is? I set mine to 800.
 
hum:


-Activate the "audio click between music and game" feature, it's said to save battery :D
 
I modified the script in /usr/pandora/scripts/op_power.sh to switch the led off when the lid is closed (and also to set cpu speed to 125MHz when the lid is closed).

Would be interesting to see that script.


Does it automatically turn the LED back on when you open...and automatically clock back up to whatever your default is? I set mine to 800.

It sets the clock back to what it was before, and at first I made it to turn the LED back on, but then I decided I don't need the LED at all, so now it also switches it off when you open.


It's really not hard to modify that script, all the lines you need are already somewhere in there, you just have to put them in the functions that get executed when you close the lid.


The power you save by clocking down is really not that much though (maybe 10 mW), and it does take noticeably longer (1 second instead of 0.3 seconds or so) to turn the led back on - I suspect that's just because executing the code to turn on the display just takes longer because you're downclocked. Another disadvantage is that you may not have enough horsepower left for music playback with the lid closed. But of course you could use a higher value than 125MHz, and still get some power saving, maybe even a lot if you're using it for music playback, because I think it will consume less power to keep the cpu 90% busy at 200MHz than 30% at 600MHz.
 
I modified the script in /usr/pandora/scripts/op_power.sh to switch the led off when the lid is closed (and also to set cpu speed to 125MHz when the lid is closed).

wow, I like that! I managed to change the LED settings for the different modes, but was totaly unable to change the CPU settings for lid-closed mode.


Do I have to add some lines there? I`m absolutely afraid of messing this op_power.sh file up. Please _wb_ be so kinde and help with some lines!


any chance to change the OPP level (its always at OPP4 at my 1Ghz)


musik is playing well at 350MHz at an avarage of 50% (adacious + Firefox + claws mail + system info running)
 
I modified the script in /usr/pandora/scripts/op_power.sh to switch the led off when the lid is closed (and also to set cpu speed to 125MHz when the lid is closed).

wow, I like that! I managed to change the LED settings for the different modes, but was totaly unable to change the CPU settings for lid-closed mode.


Do I have to add some lines there? I`m absolutely afraid of messing this op_power.sh file up. Please _wb_ be so kinde and help with some lines!


any chance to change the OPP level (its always at OPP4 at my 1Ghz)


musik is playing well at 350MHz at an avarage of 50% (adacious + Firefox + claws mail + system info running)

Same here. I'm totally afraid of screwing up the file.


Now, me...I DO frequently play music with lid closed...so I would need the minimum clock setting to play Audacious at full volume.


also, I'd still want the LED to come back on with lid open. And I ALWAYS want the red LED light indicate charging...to come on when it is charging...lid closed or open.
 
I can´t manage this right now, opened the correct file with AbiWord, wrote "0", trying to save it as txt-file but it doesn´t save. Will try again tomorrow, tho this isn´t so very important :) Thanks again.

(emphasis mine)


It's a text file, not a word processor document. You really should be using a text editor like Mousepad.


I think the problem is you need root privileges. Instead of choosing Mousepad from the menu, open a terminal and type:



Code:
sudo mousepad /sys/class/leds/pandora::power/brightness
Of course - you are so right! :oops: Consider me a total newbie in this. I can play around with emulator setups but modifying a scripts is new to me, or rather, I haven´t done a similar thing since the autoexec.bat and config.sys days.


Will try this out tonight from Terminal.
 
Last edited by a moderator:
Now, me...I DO frequently play music with lid closed...so I would need the minimum clock setting to play Audacious at full volume.

try it, as I said, everything is gooing well for me at 350Mhz with several other programs running as it would be useless for me to quit all running programms just to listen to musik and start them again when I`m back for desktop use


Otherwise Adacious runs without any clicks at 125Mhz, but CPU usage will go UP and responding time when you open the lid again will be also bad...


depending on how many programms you are running while you are listening to music I think 200-300Mhz will be good for you.?.


(I get a CPU usage of around 80% at 200Mhz with audacious and system info to check ... wondering how much System Info is using...)
 
Does setting the OPP level really make a difference? I always thought it just sets the maximum allowed level, and in fact the Pandora would use eg. only OPP3 if it does not need more?


Also not sure if setting the CPU clock to a too low value may again have a negative effect on battery life? I think I read something about this here a while back ... certainly would need confirmation by someone who actually *knows* though. This is just what I think I remember ... handle with care.
 
I thought that clever power management automatically underclocks/volts when the cpu isn't much used...?


edit: isn't this how the new kernel achieves low power consumption when idling?
 
Last edited by a moderator:
Now, me...I DO frequently play music with lid closed...so I would need the minimum clock setting to play Audacious at full volume.

try it, as I said, everything is gooing well for me at 350Mhz with several other programs running as it would be useless for me to quit all running programms just to listen to musik and start them again when I`m back for desktop use


Otherwise Adacious runs without any clicks at 125Mhz, but CPU usage will go UP and responding time when you open the lid again will be also bad...


depending on how many programms you are running while you are listening to music I think 200-300Mhz will be good for you.?.


(I get a CPU usage of around 80% at 200Mhz with audacious and system info to check ... wondering how much System Info is using...)

OK...so how do I go about editing the file, so that it is set for say 200 mhz, led off when lid closed, but on when open...and batt charge always goes on when charging.
 
I thought that clever power management automatically underclocks/volts when the cpu isn't much used...?


edit: isn't this how the new kernel achieves low power consumption when idling?
No, the low power consumption is achieved mostly by putting the cpu in idle states (C1-C5). Underclocking is not done automatically, because switching frequencies turns out to take too long and consume too much power of itself to be worth it to change the clock speed automatically all the time. At least that's my understanding.


I don't have time now to write a tutorial on how to change that script, but anyone with some knowledge of bash should have no problem with it.


CPU usage of System Info depends a lot on which panel you have opened: number 5 takes almost nothing, the others take between 2% or so and 5% or so. Of course the nyancat theme uses more.
 
Back
Top