If you have an APU, do you need an inverter

That inverter seems nice. They also sell inverters at truck stops. I don't know anything about them because I've either had no inverter or the truck already had one. I worked my first 3 years OTR without an inverter, they weren't common back in early 1990s. I did eat almost every meal from a 12 volt oven, which heated tv dinners. It took 45-90 minutes. I also had a 12 volt electric cooler, which worked well if I put lots of effort into getting it cold enough and monitor it like a mother hen. I had a wired thermometer mounted on the dash that had a temp probe in the cooler. These days I would not bother even trying to use a Igloo/coleman 'thermoelectric' cooler like are sold in truck stops. They can only cool 30-40 degrees below the temp of the truck interior and I replaced power cords or fuses frequently. I probably spent more on power cords than the coolers. There are compressor-based units that use 12 volts and those work as well as the fridge in your home. They are double the cost of the Igloo but reliable and effective. You could even limp by with using a cooler full of ice. for weeks or months by just buying ice every other day.

 

The Coleman's I had kept things pretty cold, sometimes freezing things.
One trick is to place it on an inch of Styrofoam for insulation from the heat of the floor.

My biggest problem with them was melting the 12V plug and/or socket in certain trucks. More with the more recent coolers than when I started back in 2010.

 

Short answer. Yes.

 

Tripac's have either a 65 amp or a 120 amp alternator, but an inverter is an add-on option. Carriers come with a built in inverter. One that can easily run a 700 watt microwave.