thats right... but If there are 4 one-way AA Batteries inside which can be changed it should work. Back in civilisation after 3 days I have to buy new ones... Not eco-friendly I know... But an acceptable solution for for exceptional circumstances.

I`ve never seen an external charger for a BP-4L battery. But you are right - http://cgi.ebay.de/Akku-Ladeger%E4t-...100312138004r5... Now the parts for my diy-project are ordered. Doesn`t matter... I surely will have fun building it

Another possibility could be this: http://nokiaport.de/index.php?mid=5&pid=akkuersatz - on this site is a circuit diagram for externaly powering Nokia devices without a battery inside. Do you think that it ist possible to use 3 AA reuseable AA batteries with 1,2V (maybe a bit more...) each - 3,6V together and this diagram but without the diodes D1 and D2? Or will the current be to high without the low drop regulator?