Hi
Lots of useful stuff in this site!!
I like to share this idea, I have for years used the H4n with external batterypack, and I chose to buy a 6600 mah and a 10000 mah pack for ab. 10 USD from dx.com in Hongkong.
See my blog how it is done. I cut the plug (Size iss odd on H4n!) from the 110/220V transformer and joined it with a USB-cabel. Works for 10-15 hours in cold condition (I live 320 kms North of the Arctic circle
), I often leave it out all night for recording owl and elks feeding.
Have a look at
http://tromsofoto.blogspot.no/2012/03/recording-birdsounds-with-telinga.htmlYours Stein