You can change out a propane bottle a lot faster than a battery and they are usually serviced out by some one who is desiginated to do so. With batteries there is always the war between the shifts as to who changes out the battery and who waters the battery. You can have all the rules and regulations in place for the battery issues but you always have either non compliance with the rules or you have some one who figures how to screw over the next shift on a regular basis. Real world. I have yet to see a battery lift run as long as a LPG unit in the real world.