Silly Question - Webasto Heater Runs On Electricity Or Fuel?

First night in my truck, I left the heater on all night and the battery was unable to turn over the engine in the morning. I thought the Webasto heaters ran off the diesel fuel. Was this just coincidence or something else? I am paranoid to run the heater!

The heater runs off of diesel. Perhaps your batteries need to be looked at. Did you leave any appliance plugged in on the truck all night? The bitter cold doesn't help the batteries at all but that shouldn't happen. I would take it to the shop because it's definitely not the heaters fault.

Diesel is the fuel for the heat in the Wabasto heater, but the fan runs off the batteries. Sounds to me like your batteries need to be replaced. They should be able to run that fan all night without straining them like that.

Also, if you have an "iceless" cooler, it's best to turn it off overnight. The goodies, including milk, will stay cool enough.

Right after I got my truck, the batteries were dead several mornings. Turns out two of the four were kaput. I was at a Petro, so I got 700 points for four new batteries!

APU:

Auxiliary Power Unit

On tractor trailers, and APU is a small diesel engine that powers a heat and air conditioning unit while charging the truck's main batteries at the same time. This allows the driver to remain comfortable in the cab and have access to electric power without running the main truck engine.

Having an APU helps save money in fuel costs and saves wear and tear on the main engine, though they tend to be expensive to install and maintain. Therefore only a very small percentage of the trucks on the road today come equipped with an APU.

It was my first night in the truck after it was assigned to me. I don't know how long it sat before I got it, so that and the cold could have contributed to the batteries being low.

I am not sure if I left anything plugged in, but it's possible that I left my phone and satellite radio tuner in.

I have been idling at night and while no one has said anything it seems wasteful. I'll try again when I have some flexibility in the morning in case I need a jump. I'll be sure to unplug everything too.

Once you drive for 10-11 hours then spend the night you'll know. The chargers & radio won't hurt but the cooler sucks amps while it's running. My cab has an on/off switch just for the cooler outlet.