A pair of AAs?
The killer feature of the Psion Series 3 and 5 was the battery life. A full month on the 3, and a week on the 5, from a pair of alkaline AAs. That's *using* them, not sitting idle under a good book.
Phones seldom last a full day. Use them, and they lose charge so fast you ca
<that was my joke>
Even the solid old Nokias only lasted two days before needing to be plugged in. Kindle Fires are somewhere between the two. The Paperwhite lasts a good couple of weeks.
Make it twice the weight and give me a battery I can work with. This is going to need a good deal more than an 8 Ah battery if you want me to do work on it. Give me four times that, then maybe we'll talk.
Until then? If you're going to make me work tethered to a cable, I'm already not on my feet, so I may as well use a laptop.
32 Ah battery or gtfo.