12 volt coffee maker

The problem with percolators is you have to boil the coffee-212*F, which is too hot. Ideally you want to be between 195 - 205 degrees Fahrenheit for optimal extraction, you can't do that with a percolator. Some of the better quality drip machines will hold these temps...but then you need electric.
French press or aeropress, or any of the cone filters will allow proper brewing temps. A slow process, allowing the grounds to soak, will yield more robust coffee than a quick process. And none of these require electricity.