>>231648This.
Leaving the car's engine running is a terrible idea. Car engines are designed for moving, not making electricity. Airflow through the radiator/grille keeps the vehicle cool, you risk overheating the engine by letting it run without moving. You're also wasting a lot of mechanical energy when all you need is the stator.
Spend some $$ and get a small generator. For a battery charger to keep the van's battery charged and running an electric blanket, a generator will work a LOT better than the van's engine. My 2kW goes about 6 hours on a 1-gallon tank of fuel with a battery charger and some other equipment on it.
Looks like electric blankets are about 200 watts.
My 15-amp battery charger is about 200 watts.
Running those two together, 400 watts. You could probably get away with a 1kW generator; those are a little better on fuel, smaller, lighter, quieter, and cheaper.
Pic related. The Honda or Yamaha units are better gens overall, but to be honest I've had real good luck with this 2kW Generac. I found two of these for $300, one runs great, the other I keep for parts.
