[Matt[_6_]]

2 - When you have the recorder in hand, you will be able to find
someone to build a battery pack for you capable of any capacity that
you want

So pick out a recorder that offers the capacity you need at the
quality that you can tolerate. I'd suggest making some test recordings
using the settings that tive the smallest file size before buying.
Then come back here stating your location ("UK" is too general if you
don't know where your local electronics repair shop is) and I'm sure
someone will have a good suggestion.

I have one already that I've used in the past. It's a small 1GB Medion
MP3 player (MD80527 is the model number) that can record in 8 bit 32kb/
sec .wav format. It takes a single AAA battery.

I set it recording yesterday to test its battery life, and so far from
a fresh battery I've just gone past the 24 hour mark. The batter
indicator has an almost empty display, so it's not got long left.

I'm in Cheshire in the UK (just south of the Manchester area) if that
is of any help.

Kind Regards,

Matt