Newbie question about battery life

[cothrige]

Hello all.

I recently installed rockbox on my Sansa e260R and have things working pretty well.  But, I am looking for a better understanding of how the battery life can be impacted by use.  I noticed that there was a page at the wiki (SandiskE200BatteryMeasurements) and it had two battery benchmark files.  One went for just over 11 hours and the other for almost 16.  It appears that the 16hr run used ogg files (the other seems not to mention), which surprised me as I had thought, from browsing online, that ogg files would use more power not less.  BTW, I ran a battery benchmark on my player, starting fully charged and playing an audiobook which is an mp3 at 128kb bitrate, and it ran for 10 hrs 48 minutes.

So, this has me wondering what directly affects the battery life of such a player.  I have gone through the settings to attempt the obvious.  I have turned off the wheel light, and set the backlight brightness to a very low setting.  I also lowered the timeout on it to just a couple of seconds.  I did all this, btw, after the above benchmark and so I am not sure if it has had any impact yet.  But, what else may have help?  Does the theme or wps perhaps have anything to do with it?   And what about things like the actual music files?  Do oggs take more power, or does it matter?  I assume that lower bitrates are better for power, but I do not know, and what about file size itself?  Some of mine, being books, can be larger, but is that better, worse or indifferent to power usage?

Just curious about these things, and hoping somebody can help me out.

Many thanks,

Patrick

[scharkalvin]

Lots of things can make a difference.  Including on how good the battery is.  I got my Sansa reconditioned, it might not have come with a new battery??

Since the audio amplifier in the player is probably a class B output stage, the volume you play at will make a difference in the power drain.  The bit rate of the encoded music might make a difference (amount of cpu power needed to decode).  The codec itself (I'm not sure that ogg needs more power to use, I'd suspect the actual bitrate the music is encoded at.  A variable bit rate might use less power.  Finally the ambient temperature makes a difference as it effects the battery chemistry.  

[cothrige]

Thanks for the tips.  I had never given any thought to how volume level may be involved, or variable bit rate.  Very helpful.