Sage Sage battery life

[Quoth]

I removed KOReader on the Sage & Elipsa once they added PDF cropping that worked. Currently the crop is also per document.

It's much the fastest of my ereaders, and it & Elipsa are much faster to transfer than the Libra on USB. The battery life isn't as good as some eink ereaders, but better than some. It's adequate and none of the three people I know also with a Sage have complained.

[xor_]

I finally got my hands on a quasi-new Sage after giving up hope that Kobo will release a newer version anytime soon.

One thing I noticed is that the Sage uses power management governor "interactive" per default. This is in a way desirable for responsiveness but clearly doesn't maximize battery life. I searched the forums for discussion about this option of playing with governors, but was a bit surprised that I couldn't really find anything.

So I experimented with using governor "powersave" instead. This keeps CPU speed fixed at the minimum supported frequency. And in my completely anecdotal experience, it does increase battery life somewhat. I don't have a lot of experience for comparison, and "measuring" by watching the battery percentage indicator in Koreader obviously isn't reliable. That said, the values I get seem to be quite a bit better than a lot of the values reported in this thread. I only did basic reading in Koreader, and in a way this result is surprising because I would have expected that even governor "interactive" would keep the CPU frequency low for that. So I'm not ruling out that a part of the effect could be measuring imprecision.

Obviously there is a tradeoff between battery life and responsiveness, but I didn't notice any unnerving delays during normal reading. Page-turns are still instantaneous. Only once in a while when the reader loads a new chunk into memory, there is a short delay. And importing books does seem to take longer.

In any case, there is no harm trying. You can switch quite easily between governors from nickelmenu with a configuration entry like this:

menu_item: main :governor powersave :cmd_spawn :echo powersave | tee  /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

menu_item: main :governor conservative :cmd_spawn :echo conservative  | tee  /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

While "powersave" keeps the CPU at minimum speed, "conservative" does speed up, but more slowly than "interactive".

If you try it, please report back with your results. I'm curious whether it makes a real difference.