Can't really help with the petrol powered side of things but I think it comes down to the size of the highbanker your running, spray bar setup ect. I use a 2000 gph 12v which is ample for my highbanker, a 90 amp deep cycle battery gives me around 6hrs run time. I also been using solar panels (80watt) which also keeps a bit of charge in the battery. Mick