If you understand German language here is a thread about that:
http://www.e-reader-forum.de/ebook-r...n-prs-650-350/
Otherwise use Google translation:
http://translate.google.at/translate...n-prs-650-350/
For I have had troubles charging my PRS350 with a solar charger, I played and frickled with my reader in a very uncommon way (loading with batteries over naked cables and voltage up to 12V), trying to load the battery. I'm very surprised, that the reader is still living ;-)
Seems to be rugged, but sometimes refuses beeing charged from distinct chargers.
A normal cellphone charger will do I guess. At least in my case.
A.