Something drawing on my battery

It is easy to add a battery cut off switch to the engine battery. Any auto supply store has them. It is just a switch put on the battery terminal that you then connect the wire back to. Get a good one. This will shut off your engine battery completely from the electrical system for the van. Just don't forget that it is there and off or you will be thinking that your battery is dead when the engine won't start. Of course, when you do this you lose any radio pre-sets, etc.. This will eliminate drain. Your engine battery should certainly last a month without driving but it is always a good idea to go out and start the engine once a week if the van is sitting. Let it idle for a few minutes or sit for awhile charging.