Originally Posted by TechniSol
I think you have to perform the occasional deep discharge for the battery metering to properly determine the remaining power capacity of the battery. The normal method is to account for power usage levels and uptime and build up a total current or watts available profile and then subtract during discharge. You can get fancier, but it's probably not worth the work.
The occasional deep discharge to shutdown should only help to recalibrate the profile. The shutdown should occur prior to any internal low voltage shutdown circuitry in the battery kicking in as long as Kobo left the proper wiggle room.
As to how the chapter size might effect current draw during sleep mode, what if the RAM being used is segmented and can be independently powered down if not being used? Buffer a small amount of text in memory and you have minimal current draw during sleep mode. STUPIDLY buffer multiple chapters and keep a lot of dynamic RAM refreshing and kiss your battery life goodbye. It's just a theory from a hardware dinosaur, but it might be relevant...
OTOH, if you're trying to get maximum battery life out of a device like these, and the processor is fast enough, why even bother to buffer text in between page turns? Just preserve a few pointers and grab the text and render on the fly. It would seem like the lowest power consumption based method?
It seems to me that, by paging forward as fast as you can, page turns slow down after some number of pages - perhaps indicating that they buffer a few pages ahead, but that might be just rendering buffer, the whole or any part of the file itself may or may not be held in main memory.
One small nitpick, you mention watts available when speaking about battery life. Watts are the rate of energy usage, and what you actually want to know is watt-hours, the energy left in the battery, I think.