For Christmas I received an unexpected but very welcome gift - a Kenneth Cole KC-1816. I know it's a fashion brand, but I quite like the style. Reminds me a little of a TAG Heuer Micro TourbillonS. Anyway, down to the nitty-gritty of my post. It has a Seiko calibre 7T92 (12 hour chronograph in 1/20 second increments). I'm wondering how long I can expect the battery to last if I use the chronograph function regularly? Does it take a lot of energy or not much at all to power the 1/20 second hand?