I also use a 1kV generator. It weighs about a third of a big deep cycle battery and is only the size of a shoe box. Exhaust noise is 52dB (bugger all) and you can hold a normal conversation standing right next to the exhaust and when running my laptop, heaters, camera's, mounts etc it just idles away giving 8 hours on a single tank of juice. They cost a little more (if you want the ones with clean enough power to run a laptop/PC) but are far better then any battery option I could find. You can also use it to power a small fridge or kettle or both whilst taking your pics
. Oh did I mention how quiet they are......
Mark