I love operating my little FT 817 portable. Being limited by a stealth antenna at home it is really fun to get out in the foothills with my ATAS 25 and hear this little antenna outperform my patio antennas. My problem is working QRP. I'm relatively new to operating QRP and quite frankly it is laborious to both me and the stations I'm attempting to contact. Yes it is true that every now and then I hit paydirt and I intend to keep the 817 as it really requires little power (backpacking batteries is not fun). I enjoy taking the rig into the foothills outside of Denver and include my dog on the trips which means I have to pack in amenities for the dog also...food...water..tether and ground screw (for the dog tether...but it would probably make a good grounding point also). So I'm looking at the FT-891 as a possibility for more power in a portable rig. It draws 1-2A on receive and has cooling fans so it's specified amp draw of 23A means significantly more battery than the 817. I'm thinking that the amp draw could be reduced while operating on a battery between 11.7 and 12.7V Spec amperage is @ 13.8V. Also...I could crank the power output down to 50% and still have 10X the output of my 817. My question is this...how big a battery would be required for the FT-891 operating at 50% power? I'm using a 5AH SLA with my 817 and get quite a few hours of operation. Unfortunately a lot of time is spent calling stations that hear me calling but can't quite copy me. I might be able to accommodate a 10-12AH SLA in my pack but how much operating time would that allow me with the FT 891? Comments and suggestions appreciated.