just playing about i need to try lower heaters like 100 or 50 to see if it still keeps the edge on it, as there is a drain on the battery with higher watts, it will only suit trolley not vans as i can warm the drums up indoors the heater is to just keep the edge off it while im working, ive replaced the pump to the outside so another battery can fit where the pump was, i using a 350watt inverter, but weather is warming up here so no need for it at mo, but still lots to play about with over xmas