I have an MP3 player that uses a single AAA battery. I use NiMH AAA battery and it lasts a long time, many hours. You could easily design the Reader to use 3 or 4 AAAs and still be able to play music for a long time while turning pages. Self discharge is higher in typical NiMH, while LiIon is much lower, hence the choice of LiIon. However, he new Eneloop and hybrid type NiMH batteries also have a very low self discharge rate. That provides the best of both:
1) can be left alone for months and batteries won't drain
2) can provide a lot of current for MP3 playing and other needs
3) still has plenty of juice for music and page turns
4) can recharge
L1Wulf,
Batteries produce electricity via chemical processes which invariably slow down a great deal at low temps, such as 0 C and below freezing. The meter is simply telling you that the battery is unable to produce the necessary current and is not actually empty. After it warms up the meter will bounce back up.
Thus you really cannot use the reader outside during winter and there is no easy solution
