Hello,
I want to share some experience with searching long energy support for my Canon Powershot SX100is, which I use for time lapse.
After some google search I decided to make my own battery pack. Here it is:
2x 8000 mAh "D" (LR20, R20) battery
battery holder
DC conector
cable and solder
it works fine, no need to add any other components, cheap. But charging is a little bit longer :-) I took about 1200 pictures in a row, last 200 pictures was with the exposition 1 min (night sky, which needs a lot of energy) and batteries was not still dead (I was).
My experience with night sky and Eneloops 2000mAh was just about 200 pictures (with 1 min exposition) so I am very satisfied with this pack.
my first day to night video wih battery pack is here (sunsetF16 script)
http://www.youtube.com/watch?v=oJ9kw08nYyg#
