Under 40 is about what I was thinking too. With temps in the 50's and higher I get great battery life. Which with the Moutrie D40's and my one Wildview, is still not that good. But the Moultrie will go for 6 weeks and the Wildview for 4 weeks. Back in December I had to put internal batteries in the Wildview, and bring the external battery home for re-charging. Temperatures were in the high 20's during the day and under 20 at night. When I went back a week later with the re-charged external battery, the low battery light was on, and it had only taken a few pictures. With the external it will easily go a month even with temperatures under 40 the entire time.
