Not sure if this is a good idea after all. Inverter to block heater

In preparation for the cold snap this weekend my boss wants all the trucks plugged in if possible. But since my truck sits out in a field, I thought it'd be brilliant to turn on the inverter and plug the block heater into that, with the tri-pac monitoring battery life. (Supposedly the apu and the main engine share coolant but I'm not so sure. I think the guy who installed them in our fleet didn't do that for some reason, it's come up in the past)

Now my spidey senses are tingling, I'm overlooking something. Does the block heater use some inordinate amount of wattage? Will the inverter over heat from prolonged use?

I'm going to check it in an hour to make sure everything is kosher, but I want to leave it for the weekend.

Am I overlooking something?

 

Apu and main engine are NOT connected coolant systems.

They are SUPPOSED to be, but for some reason they aren't on our fleet.

 

Yeah it's a big inverter but I don't know the rating on it. I'm out now but I'm going to check it tonight.

 

Well, it sort of worked.

The block heater stayed warm but the APU ran all weekend. But there wasn't enough juice for the rest of the truck. A voltage saving circuit turned off my interior lights (that's how I knew there was a problem) so unplugged the block heater, turned off the inverter, left the APU running and went back inside for breakfast & a latrine break.

Started just fine when I came back.