It's the newbie again... So.. I have my heater that I plug into the mains in the winter to keep the inside warm. I bought a little oil heater but it wasn't that great. It hardly heated the van up at all. Then I bought a hot air blower and that really did the trick. But what happens if there is a power cut or I have to go somewhere one night when it's really cold. Are there any good heating options that anyone here uses that doesn't require being plugged into the mains but kicks out enough heat?