minimattapps
Posts: 49
Joined: Thu Aug 02, 2012 9:04 am

UnderVolting / UnderClock to save battery life.

Thu Oct 04, 2012 11:48 pm

Hi, I am working on a device which i need to run off batteries for about 4 hours, currently it is about 2 - 3 i am only moving files around so could lowering the voltage a bit and lowering the frequency to like 300mhz improve my battery life? and if so how would i do that. Also what kind of software / processes could i remove to improve the battery life.

Thanks Matt

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hojnikb
Posts: 128
Joined: Mon Jun 04, 2012 3:59 pm
Location: @Home

Re: UnderVolting / UnderClock to save battery life.

Fri Oct 05, 2012 6:58 pm

you can undervolt/underclock using config.txt with dynamic scaling to higher freq with cpufreq driver. That will save you some power but not much imho.

If you want to do some hardware modifications (which will yield more power saving)
you can follow this
http://www.bitwizard.nl/wiki/index.php? ... spberry_Pi
+°´°+,¸¸,+°´°~ Everyone should have a taste of UK Raspberry Pie =D ~°´°+,¸¸,+°´°+
Rasberry Pi, SoC @ 1225Mhz :o, 256MB Ram @ 550Mhz, 16GB SD-Card, Raspbian

ciudadverde
Posts: 20
Joined: Mon Sep 03, 2012 11:46 am

Re: UnderVolting / UnderClock to save battery life.

Sat Oct 13, 2012 3:42 pm

How connect you the batteries to the pi?

MarkR
Posts: 154
Joined: Fri Jan 25, 2013 1:55 pm

Re: UnderVolting / UnderClock to save battery life.

Fri Jan 25, 2013 1:59 pm

You probably can't save much power on Model B by underclocking. Underclocking is possible, it's really very similar to overclocking, but in reverse (Hint: Overvolt settings also accept negative numbers)

You can't save power by underclocking the CPU because the lan chip uses most of the power, so it's really a lost cause.

To save power on a battery powered application, you really need to remove the LAN9512 chip, which amazingly, there is a page describing here:

http://freneticrapport.blogspot.com.au/ ... re_24.html

It's a tricky bit of soldering, requires some special tools and can probably easily overcook your Pi. You also lose one USB port and the ethernet. (I assume that a battery powered application does not need ethernet)

According to some reports, you can reduce the power consumption of an idle Pi by about 3x without the lan chip.

drgeoff
Posts: 9357
Joined: Wed Jan 25, 2012 6:39 pm

Re: UnderVolting / UnderClock to save battery life.

Fri Jan 25, 2013 4:55 pm

Instead of removing the LAN/USB chip, wait a little bit longer for the Model A to ship.

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