Inverters and 120Vac appliances take a lot of power out of the batteries.
So, we simply heat water on the stove and pour it through the Melitta filter system. Once the water is hot, we have coffee in seconds. We have two filter holders because my wife likes flavored coffee and I do not.
The filter holder looks like:
and the paper filters:
This system uses coarse ground coffee (fine grind plugs the filter). Use 2-4 teaspoons coffee to make one cup. I find that you can make two cups from the grounds, then either a new filter or add 1/2 the amount of coffee for the next cup. Usually I simply go for the new filter after two cups, because after the first two cups I switch to decaf. Filling the filter will fill a standard coffee cup, or you can make less.
I'm not addicted (I'm not; I'M NOT) but I do like my morning coffee. And sometimes afternoon coffee also. The Melitta filter system makes coffee easy, just boil water and pour.