If you're looking to get the type of battery longevity that you would from a Kindle or other device that is solely an eReader, then I don't think that is possible. The eDGe uses more capable/powerful (and thus less efficient) hardware than something like a Kindle. It's not a matter simply a matter of a less efficient operating system, the hardware itself is more capable (by design) and thus it uses more power even if the only screen being used is the eInk. It *may* be technically possible to do some tweaking like undervolt the CPU if an eInk-only mode were possible in order to conserve power... but even then, I would imagine that the battery longevity would still be inferior to a dedicated eReader like a Kindle.