I noticed that they base their run times on using 100% of the battery amp-hrs in their calculator. Divide the run time in half and you'll get a better picture of how long you should really use a particular device.
Bruce
2009 6.5'X11' TTT - Boxcar All it takes is a speck of faith and a few kilowatts of sweat and grace. Boxcar Build aVANger Build