Start With a Load List
Every reliable overland power system starts with a simple list of what you will run and for how long. Add up daily amp-hours at 12 volts:
- 12V compressor fridge, 40 to 55 quart: about 30Ah a day in mild weather with a sensible thermostat setting, and 50 to 60Ah in heat or set very cold
- LED lights and a roof fan: about 10 to 20Ah
- Phones, headlamps, and a laptop: about 10 to 30Ah
- Water pump: only a few amp-hours, since it runs in short bursts
Most weekend trips land around 50 to 90Ah a day. Measure your own fridge with a battery monitor once the system is in, because ambient temperature changes the numbers more than the brand does.
The Battery: Why Lithium Wins in a Truck
A 100Ah LiFePO4 lithium battery typically weighs around 22 to 30 pounds and delivers most of its rated capacity. A lead-acid bank with the same usable energy weighs two to three times as much, which matters on a truck where payload is already tight. Mount it low and forward in the bed, in a secured box, away from water.
If you camp more than two nights without driving, or run a fridge in desert heat, consider 200Ah. Otherwise 100Ah plus charging is the right size for most builds.
Charging Three Ways
- DC-DC charger from the truck: sized around 20 to 40 amps, it limits the current a lithium battery pulls from the alternator and applies a lithium charging profile. Hooking lithium straight to the alternator can overheat it, especially at idle.
- Solar: 100 to 300 watts on the camper roof or a portable panel, through an MPPT controller. Many DC-DC chargers include one.
- Shore charger: optional, for topping up at home before a trip.
Wiring It Safely
Put a properly rated main fuse within about seven inches of the battery's positive terminal, then a main disconnect switch. Run tinned copper wire sized for the current and the run length, crimp with proper tools and heat-shrink terminals, and fuse every circuit at a fuse block. Add a battery monitor with a shunt for an accurate state of charge. If you are not confident with DC wiring, hire a 12V or marine electrician, because a short on a lithium battery can start a fire in seconds.
Do You Need an Inverter?
Run as much as possible on 12V and USB, which wastes less energy. If you need to charge a laptop or camera batteries that only take wall power, a small pure sine wave inverter is the safe choice for electronics. Size it for what you actually plug in, often 300 to 1,000 watts, and switch it off when not in use, since inverters draw power even when idle.
Water: Keep It Low and Simple
Water weighs about 8.3 pounds per gallon, so a 15-gallon tank is more than 120 pounds. For weekends, two jerry cans or a 10 to 20 gallon tank mounted low and near the rear axle is plenty. A 12V demand water pump feeding a tailgate faucet gives you running water for dishes and hand washing, and it draws power only while the tap is open. Add an inline filter on the intake, and drain everything before freezing weather.
Condensation in a Hard-Shell Camper
Pop-up and wedge campers have thin walls, so breath and damp gear condense on the cold shell overnight. Crack a window or vent on each end for cross-flow, run a roof fan on low, keep wet jackets out of the sleeping area, and never cook inside. A small WiFi temperature and humidity sensor helps you learn how your camper behaves in different weather, so you know how much ventilation it needs. Aim to keep relative humidity under about 60 percent to prevent mold in mattresses and fabric walls.
Safety Devices Are Part of the System
Install a combination carbon monoxide and propane detector, especially if you add a diesel air heater. Mount a vehicle-rated fire extinguisher within reach of both the bed and the tailgate. Store propane outside the sleeping space, and route heater exhaust outside according to the manufacturer's instructions.
Related Reading
- Pickup Truck Overland Camper Build: The Payload-First Plan
- How Much Does an Overland Truck Camper Build Cost?
- Minivan Camper Condensation, Ventilation, and Power
See the complete build in the pickup truck to overland camper guide, and estimate your system cost with the cost calculator.
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