This will come as a shock to many of you, but it is actually possible to camp without electricity.
Reliable visual records from the Middle Ages (1950—1985) clearly show families surviving—even, at times, apparently enjoying themselves—in campsites lit only by white gas or propane lanterns, retrieving food from insulated boxes cooled only with ice, and engaging in such non-electrically dependent activities as fishing, swimming, climbing trees, and reading books manufactured in the ancient Gutenberg manner, on paper. (A few disputed images even purport to show family members talking to each other.)
Of course it’s easy to idealize scenes in vintage Kodachrome transparencies. What isn’t so apparent are the tragic effects of those primitive times: respiratory problems from second-hand kerosene smoke, salmonellosis caused by eating chicken stored at above-optimal temperatures, blindness brought on after repeated attempts to read Field and Stream by the light of a candle lantern (not to mention the devastating tent fires also associated with open flames), ugly cases of fratricide sparked when siblings were forced to interact directly with each other. (“Where’s Timmy?” “I don’t know, mommy. Maybe a bear ate him.”)
We can thank the advances of civilization—the Cree, the Engel, the earbud—for the blessedly longer median life expectancies now enjoyed by overland travelers. But LED lanterns, 12V fridges, and the myriad of electronic entertainment and communication devices now virtually grafted to our persons—they all require electrical power. Those of us who’ve moved even farther upmarket with such things as truck-mounted campers need yet more, for water pumps, vent fans, heater blowers . . . although personally I’ll draw my line of sympathy this side of anyone who wants to power a flatscreen TV in the wilderness.
An auxiliary deep-cycle battery has become nearly standard equipment for a well-sorted overland vehicle, and with good reason. It keeps the starting battery free for its critical duty, and serves as a starting backup as well if connected with a selectable isolator such as the National Luna (although the advent of the brilliant Micro-Start and similar products has made this function nearly redundant). With a battery monitor it’s easy to keep track of usage and voltage.
However, depending on load (especially that fridge), you can run down even a high-quality Group 34 AGM battery in anything from six or seven days to less than one. If you’re on the move day to day, it’s likely your engine’s alternator will be more than adequate to bring the voltage back up to an ideal float level of 13.4 volts or so. But what if you’ve found the perfect beach or forest campsite and don’t want to move for a week, or two? Idling the engine is a notoriously poor (slow) way to recharge a battery, irrespective of the fact that you’re pointlessly burning fuel, causing pollution, and spoiling your ideal campsite with noise. You need a different power source—and the finest one you could ask for is a mere 93 million miles away.