Thanks for all the great input everyone!
I apologize for not providing more info up front, didn't really know what I should include... I also apologize for the delay in responding, I was travelling for work and just got back to civilization today.
So the prevailing theories seems to include the inverter not running the outlet(s), lack of battery power, lack of battery capacity, undersized cables limiting power transfer, and excessive draw above the 800W rating of the coffee maker...
Outlets: I guess that's a fair response, as I did let the secret about my lack of electrical knowledge be known right up front. However, even with my pea brain, I did manage to verify the outlet in question (and several others) are in fact providing A/C power when the inverter is switched on.
Battery power: I will verify voltage at the battery bank the next time I try it. I do know that the generator had run for several hours the day prior (running A/C to combat the 95+ temps), and that we had little to no (known) electrical draw throughout the night once the genset was shut down.
Battery capacity: (2) new 12-volt "deep cycle RV" batteries from the local tire shop, both July 2018 dated.
Cable Sizes: Difficult to verify based on only being able to see the external cable insulation, cannot vouch for how thick the insulation is or how thick the copper is hiding inside?
Excessive Draw: I'd put this as a very likely culprit after reading this discussion and many others about similar type issues. I will research lower wattage single-serve coffee makers.
As far as what the inverter does when I say it won't work, there is an audible "beep beep beep" and the coffee maker simply shuts off, as if the power switch has been pushed again to physically turn it off. No fuses or breakers blow, as I can push the ON button again immediately and it will "beep beep beep" again.
With regard to how I make my coffee, which clearly was not the point of this thread, I have done it all over the years and suffice it to say would very much prefer to simply utilize the inverter to make a cup or two early in the morning, quietly and without adding heat inside the coach.
