how to maximize battery life for ipod video + rockbox?

[doublea71]

battery life is unbelievably short when playing .flac files at volume. is there a theme that is less of a drain on the battery or are they all the same? obviously brightness can be turned down, but what else can i do to keep this thing portable? as it is now, i have to plug it in often to recharge it and that pretty much defeats the purpose. or is it possible that i'm in need of a new battery?

[torne]

Enable display sleep if it's not on already, so that not only the backlight but also the display itself turns off when you aren't actively using it. Other than that, not really; once the screen is off, the vast majority of power being consumed playing back FLAC will be the power to run the hard disk to refill the audio buffer every time it runs out, which is far more frequent with FLAC due to the files being rather large

[doublea71]

got it - thanks! can the battery capacity be upgraded in ipod videos? there's a shop here that I think can do it.

[gevaerts]

If these flacs happen to be 96/24, that will only make things worse (possibly a lot worse)

[doublea71]

Is a player with a flash drive better on battery life? I'm pretty disappointed in the battery life with flac right now. Hopefully I can find a way to make it worthwhile. Having to charge it every few hours is a bit of a nuisance and I'm beginning to feel tethered to AC outlets.

[torne]

Improved batteries do exist (and even one of the same capacity may work better as all original ipodvideo batteries are now quite old...) but the capacity numbers on them are often optimistic overestimates :p You can probably get one that's 10-15% higher capacity than the original battery; numbers much higher than that are probably being very generous in advertising.

[dreamlayers]

Disk DMA might help here. It doesn't help much when playing MP3 files, but there's a lot more disk access when playing FLAC. It was disabled due to instabilities. I think those instabilities were due to a CPU cache bug, and I have a workaround. First apply this patch. Then edit firmware/export/config/ipodvideo.h and uncomment or add "#define HAVE_ATA_DMA". Finally, recompile.

I think your battery might be worn out. When I was playing FLAC, the battery life wasn't too bad, even without DMA. Note that some cheap batteries overstate their capacity.

When the battery is very cold, you're only able to make use of a small fraction of its capacity. When going outside in winter, I put my iPod under clothes to avoid this.

If the problem is hardware cutting off power during disk activity instead of an orderly Rockbox shutdown, it may be possible to avoid that by decreasing the hardware shutoff threshold while the disk is active. I thought about creating a patch, but I'm not sure if it's a good idea. This problem normally means the battery is worn out and/or too cold.