I was being a bit conservative, assuming other things in the car might be on taking power at the same time... ( dome lights, radio, internal electronics, DC/DC converter itself )

It's literally 235 watt-hours, but to be safe, count on 150 out your power port between charge cycles. ( IE 1 hour at 150w Max. )

5.5Ah pack x 330v x 13% useable ( Engine on at 40% SOC, off at 53% SOC ) Typ.

 

Ok

 

That is true and I deserve that ...

However, my question was two fold and also applies to football tailgating where I normally run a 1100W generator for a TV to watch some other football games while we pregame. If I can cut out the noisy generator that would be great.

 

Keep in mind, if you need more power, you can always buy a larger inverter and connect it with alligator clamps on your 12v battery itself.

150w built-in inveter, run the engine 3-5 minutes each 60 minutes.
300w inverter means you should run the gas engine 3-5 minutes each 30 min.
600w inverter means you should run the gas engine 3-5 minutes each 15 min.
900w inverter or larger, and you should probably leave the key in run the whole time and let the car do it's own thing. It will probably automatically cycle on for 5, off for 10. On for 5, off for 10.

1200w is the maximum anyone should attempt.
I don't think the car would keep up with 1200w continuously, but intermittant is ok.