I am reasonably sure the SDC is power regulated so it gets the same power from 100% batteries or 5%. You can detect without performance loss right up until they are dead flat. Once the battery "alarm" sounds its game over. I usually check mine if I stop for a quick break in the arvo. If I'm planning on doing a few more hours & they're getting low I'll change them, otherwise I just continue. I haven't noticed that there is any power/performance drop if the batteries are getting low. I was heading back to the car once with only one battery LED on & picked up 2 of the smallest bits of the day so it certainly doesn't lose sensitivity at the last LED of battery power left.
Mine last a full day (both the Powerizer & Tenergy's) & I'd estimate 10-12 hours running time. Both sets fully charged have lasted me on a 3 day trip. I do carry at least one set of alkalines though for backup.
I have only used some Kodak Xtralife alkalines & they only lasted about 4-5 hours but would be ok if needed. No performance boost in using them.
Mine last a full day (both the Powerizer & Tenergy's) & I'd estimate 10-12 hours running time. Both sets fully charged have lasted me on a 3 day trip. I do carry at least one set of alkalines though for backup.
I have only used some Kodak Xtralife alkalines & they only lasted about 4-5 hours but would be ok if needed. No performance boost in using them.