Battery Saving - Revision history

imported_>amigadave: redirect to Make your battery last longer

2011-05-31T13:40:23Z

redirect to Make your battery last longer

← Older revision		Revision as of 13:40, 31 May 2011
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	This page aims to document "power user" techniques for extending battery life, i.e. automating various aspects of the phone's behaviour with a view to extending battery life. '''It is currently a stub/work in progress; the aim is not to reinvent the wheel but to draw together a variety of approaches to battery saving.'''		#REDIRECT [[Make your battery last longer]]

	~~= Before you start =~~

	~~== Set sensible defaults ==~~

	The techniques here all involve automating the process of turning various things on or off according to the activity of the phone. Before there's any point in doing this, you'll want to have set the phone up more or less the way you like it, turned off anything you don't use, set reasonable defaults and made such optimisations as you can. You'll want to have had your device for a while, and be familiar with [[Kernel_Power]] and [[DbusScripts]].

	~~== Use the Kernel for Power Users ==~~

	~~Not just for [[Overclocking]], the~~ [[Kernel_Power]] package helps to save battery power and makes it easy to configure CPU frequency scaling. You should be using this for power saving purposes even if you never choose to go over the stock 600MHz.

	~~=== Enable SmartReflex ===~~

	Reports are mixed on SmartReflex; some users report crashes, while others use it with no problems and report improved battery life. There seems to be general concensus that it limits overclocking to 805 MHz and will cause crashes in combination with overclocking above that figure. The author uses SmartReflex on VDD1 and VDD2 without problems, at CPU speeds from 250-805MHz.

	~~=== Undervolted kernel ===~~

	~~Follow the information on the [[Overclocking]] page, but don't just grab the "ideal" profile and assume it'll be ideal in terms of battery life. If~~ your ~~device is happy and stable on the "starving" profile, with SmartReflex on, then you're onto a winner.~~

	~~=== Powersave bias ===~~

	The powersave bias setting modifies the behaviour of the ondemand governor to save more power by reducing the target frequency by a specified percentage. This can be used to limit the extent to which the phone will overclock, according to user-specified criteria.

	~~= Background power saving techniques =~~

	Techniques in the "background power saving" section should have little or no negative impact on the performance or usability of the phone but should save power in the background when the phone is not actively being used.




	~~== Actions on phone lock/unlock ==~~

	~~One of the simplest uses of [[DbusScripts]] is to detect when the phone is locked or unlocked and run scripts to reduce the cpu frequency, system load, etc.~~

	~~=== Suspend user processes ===~~
	~~See Xagoln's post: http://talk.maemo.org/showpost.php?p=1005668&postcount=1~~

	~~=== Change kernel powersave bias ===~~
	Over on the [[Overclocking]] page, Fecn describes a set of scripts to modify the [[Kernel_power]] settings on phone lock/unlock, basically to underclock the CPU (or at least, undo overclocking it) whilst the device is locked.

	~~= Invasive power saving techniques =~~

	Techniques in the "invasive power saving" section save power by intentionally limiting the activity and/or functionality of the phone. This can have unintended consequences, so be sure you understand what you are instructing the phone to do before you do it.

	~~== Take IM / e-mail / other connections offline ==~~

	~~== Change radio mode ==~~

	~~Keeping the phone in 2G mode except when 3G is needed for data will seriously enhance~~ battery ~~life at the possible expense of~~

	* not having 3G connected per default when you launch a 3G application
	* interrupting any Internet connections/phone calls when radio mode is changed
	* forcing any background Internet traffic to GPRS
	* impacting on viability of some messenger services, notably MSN

	Therefore, many users drop to 2G mode manually, using something like qwerty12's [http://talk.maemo.org/showthread.php?t=39725 3G/2G Mode Selection Applet] or [http://blog.dawid.lorenz.co/2010/05/saving-n900-battery-power-with-simple_445.html David Lorenz's power saving script.] These work fine if you remember to use them before remaining battery life becomes a problem. An alternative approach is to attempt to automate this such that the phone spends most of its working life (and makes and receives most calls) in 2G mode. We should then switch to dual mode when it is useful to do so, and switch back when it is no longer ~~required.~~

	The first part of this, the downgrade to 2G, is easy to script. We can do this any time the phone gets locked, provided we check that we're not on a call at the time. It's also nice to add a delay so that the phone only bothers to downgrade the radio mode if it gets locked and stays locked for a minute; we don't want it changing radio modes every time I throw the phone in my pocket to change buses. So, to achieve this:

	* from our existing "on lock" script, we call a "try to set 2g" script
	* have that script sleep for a while, to see if we unlock again
	* have that script check for any good reasons it should not change radio mode
	* have that script downgrade the radio mode to 2G

	~~So, getting the phone to auto-downgrade to 2G is not hard (scripts to follow).~~

	Slightly harder, though, is getting the phone to upgrade the connection again automatically when we do things that might require 3G. We certainly don't want to change the radio mode every time we unlock the phone, but we can do so on detecting the launch of known 3G applications (again assuming that we're not on a call at the time). However, these applications run within the user session, so you'll need to set up a second instance of DbusScripts running on the session bus in order to process the relevant events.













	~~[[Category:Power users~~]]

94.174.1.22: /* Powersave bias */

2011-05-17T15:01:15Z

Powersave bias

← Older revision		Revision as of 15:01, 17 May 2011
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	=== Powersave bias ===		=== Powersave bias ===

			The powersave bias setting modifies the behaviour of the ondemand governor to save more power by reducing the target frequency by a specified percentage. This can be used to limit the extent to which the phone will overclock, according to user-specified criteria.

	= Background power saving techniques =		= Background power saving techniques =

94.174.1.22: /* Use the Kernel for Power Users */

2011-05-17T14:33:58Z

Use the Kernel for Power Users

← Older revision		Revision as of 14:33, 17 May 2011
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	Follow the information on the [[Overclocking]] page, but don't just grab the "ideal" profile and assume it'll be ideal in terms of battery life. If your device is happy and stable on the "starving" profile, with SmartReflex on, then you're onto a winner.		Follow the information on the [[Overclocking]] page, but don't just grab the "ideal" profile and assume it'll be ideal in terms of battery life. If your device is happy and stable on the "starving" profile, with SmartReflex on, then you're onto a winner.

			=== Powersave bias ===

	= Background power saving techniques =		= Background power saving techniques =

94.174.1.22: /* Before you start */

2011-05-17T14:27:09Z

Before you start

← Older revision		Revision as of 14:27, 17 May 2011
Line 6:		Line 6:

	The techniques here all involve automating the process of turning various things on or off according to the activity of the phone. Before there's any point in doing this, you'll want to have set the phone up more or less the way you like it, turned off anything you don't use, set reasonable defaults and made such optimisations as you can. You'll want to have had your device for a while, and be familiar with [[Kernel_Power]] and [[DbusScripts]].		The techniques here all involve automating the process of turning various things on or off according to the activity of the phone. Before there's any point in doing this, you'll want to have set the phone up more or less the way you like it, turned off anything you don't use, set reasonable defaults and made such optimisations as you can. You'll want to have had your device for a while, and be familiar with [[Kernel_Power]] and [[DbusScripts]].

	~~== Install the relevant applications ==~~

	~~You'll need [[DbusScripts]] and [[Kernel_power]] and you'll also want to have installed the status menu applets for manually adjusting screen brightness, radio switching, etc.~~

	== Use the Kernel for Power Users ==		== Use the Kernel for Power Users ==

94.174.1.22: /* Set sensible defaults */

2011-05-17T14:26:42Z

Set sensible defaults

← Older revision		Revision as of 14:26, 17 May 2011
Line 5:		Line 5:
	== Set sensible defaults ==		== Set sensible defaults ==

	The techniques here all involve automating the process of turning various things on or off according to the activity of the phone. Before there's any point in doing this, you'll want to have set the phone up more or less the way you like it, turned off anything you don't use, set reasonable defaults and made such optimisations as you can.		The techniques here all involve automating the process of turning various things on or off according to the activity of the phone. Before there's any point in doing this, you'll want to have set the phone up more or less the way you like it, turned off anything you don't use, set reasonable defaults and made such optimisations as you can. You'll want to have had your device for a while, and be familiar with [[Kernel_Power]] and [[DbusScripts]].

	== Install the relevant applications ==		== Install the relevant applications ==

94.174.1.22: /* Enable SmartReflex */

2011-05-17T14:24:33Z

Enable SmartReflex

← Older revision		Revision as of 14:24, 17 May 2011
Line 17:		Line 17:
	=== Enable SmartReflex ===		=== Enable SmartReflex ===

	Reports are mixed on SmartReflex; some users report crashes, while others use it with no problems and report improved battery life. There seems to be general concensus that it limits overclocking to 805 MHz and ~~causes~~ crashes in combination with overclocking above that figure. The author uses SmartReflex on VDD1 and VDD2 without problems, ~~but does not overclock above~~ 805MHz.		Reports are mixed on SmartReflex; some users report crashes, while others use it with no problems and report improved battery life. There seems to be general concensus that it limits overclocking to 805 MHz and will cause crashes in combination with overclocking above that figure. The author uses SmartReflex on VDD1 and VDD2 without problems, at CPU speeds from 250-805MHz.

	=== Undervolted kernel ===		=== Undervolted kernel ===

94.174.1.22: /* Use the Kernel for Power Users */

2011-05-17T14:20:58Z

Use the Kernel for Power Users

← Older revision		Revision as of 14:20, 17 May 2011
Line 13:		Line 13:
	== Use the Kernel for Power Users ==		== Use the Kernel for Power Users ==

	Not just for [[Overclocking]], the [[~~Kernel_power~~]] package helps to save battery power and makes it easy to configure ~~the kernel~~. You should be using this for power saving purposes, even if you never choose to go over the stock 600MHz.		Not just for [[Overclocking]], the [[Kernel_Power]] package helps to save battery power and makes it easy to configure CPU frequency scaling. You should be using this for power saving purposes even if you never choose to go over the stock 600MHz.

	=== Enable SmartReflex ===		=== Enable SmartReflex ===

94.174.1.22: /* Before you start */

2011-05-17T14:20:11Z

Before you start

← Older revision		Revision as of 14:20, 17 May 2011
Line 15:		Line 15:
	Not just for [[Overclocking]], the [[Kernel_power]] package helps to save battery power and makes it easy to configure the kernel. You should be using this for power saving purposes, even if you never choose to go over the stock 600MHz.		Not just for [[Overclocking]], the [[Kernel_power]] package helps to save battery power and makes it easy to configure the kernel. You should be using this for power saving purposes, even if you never choose to go over the stock 600MHz.

	== Enable SmartReflex ==		=== Enable SmartReflex ===

	Reports are mixed on SmartReflex; some users report crashes, while others use it with no problems and report improved battery life. There seems to be general concensus that it limits overclocking to 805 MHz and causes crashes in combination with overclocking above that figure. The author uses SmartReflex on VDD1 and VDD2 without problems, but does not overclock above 805MHz.		Reports are mixed on SmartReflex; some users report crashes, while others use it with no problems and report improved battery life. There seems to be general concensus that it limits overclocking to 805 MHz and causes crashes in combination with overclocking above that figure. The author uses SmartReflex on VDD1 and VDD2 without problems, but does not overclock above 805MHz.

	== Undervolted kernel ==		=== Undervolted kernel ===

	Follow the information on the [[Overclocking]] page, but don't just grab the "ideal" profile and assume it'll be ideal in terms of battery life. If your device is happy and stable on the "starving" profile, with SmartReflex on, then you're onto a winner.		Follow the information on the [[Overclocking]] page, but don't just grab the "ideal" profile and assume it'll be ideal in terms of battery life. If your device is happy and stable on the "starving" profile, with SmartReflex on, then you're onto a winner.

94.174.1.22: /* Before you start */

2011-05-17T14:19:30Z

Before you start

← Older revision		Revision as of 14:19, 17 May 2011
Line 13:		Line 13:
	== Use the Kernel for Power Users ==		== Use the Kernel for Power Users ==

	Not just for [[Overclocking]], the [[Kernel_power]] package helps to save battery power and makes it easy to configure the kernel. You should be using this for power saving even if you never choose to go over the stock 600MHz.		Not just for [[Overclocking]], the [[Kernel_power]] package helps to save battery power and makes it easy to configure the kernel. You should be using this for power saving purposes, even if you never choose to go over the stock 600MHz.

	== Enable SmartReflex ==		== Enable SmartReflex ==

	Reports are mixed on SmartReflex; some users report crashes, while others use it with no problems and report improved battery life. There seems to be general concensus that it limits overclocking to 805 MHz and causes crashes in combination with overclocking above that figure. The author uses SmartReflex on VDD1 and VDD2 without problems, but does not overclock above 805MHz.		Reports are mixed on SmartReflex; some users report crashes, while others use it with no problems and report improved battery life. There seems to be general concensus that it limits overclocking to 805 MHz and causes crashes in combination with overclocking above that figure. The author uses SmartReflex on VDD1 and VDD2 without problems, but does not overclock above 805MHz.

			== Undervolted kernel ==

			Follow the information on the [[Overclocking]] page, but don't just grab the "ideal" profile and assume it'll be ideal in terms of battery life. If your device is happy and stable on the "starving" profile, with SmartReflex on, then you're onto a winner.

	= Background power saving techniques =		= Background power saving techniques =

94.174.1.22: /* Actions on phone lock/unlock */

2011-05-17T14:04:49Z

Actions on phone lock/unlock

← Older revision		Revision as of 14:04, 17 May 2011
Line 34:		Line 34:

	=== Change kernel powersave bias ===		=== Change kernel powersave bias ===
	Over on the [[Overclocking]] page, Fecn describes a set of scripts to modify the [[Kernel_power]] settings on phone lock/unlock.		Over on the [[Overclocking]] page, Fecn describes a set of scripts to modify the [[Kernel_power]] settings on phone lock/unlock, basically to underclock the CPU (or at least, undo overclocking it) whilst the device is locked.

	~~=== Change radio mode~~ (~~non-invasively~~) ~~===~~

	= Invasive power saving techniques =		= Invasive power saving techniques =