How to power a fridge in camper van?

Finding the right way to power a fridge in a camper van starts with one big decision: run on 12 volt direct current or step up to 120 volt through an inverter. For most travelers, a 12 volt compressor fridge wins by a wide margin. It cools quickly, uses less energy, and avoids the overhead of converting battery power to alternating current. The rest of the system is a simple puzzle of energy in, energy out, and safe delivery.

Sizing power for a van fridge

A good plan starts with daily energy use. Fridge makers often publish average draw in amp hours per day at 12 volts. Many 12 volt compressor units use about 30 to 60 amp hours per day in mild weather. That translates to roughly 360 to 720 watt hours. Hot climates or frequent door openings can push that number higher, while pre chilling food and limiting door time can lower it.

To translate daily energy into battery size, multiply your estimated watt hours by the number of days you want to sit without charging. Then divide by the usable fraction of your battery type. Lithium iron phosphate typically allows about 80 percent usable capacity. Absorbed glass mat is closer to 50 percent. For example, if your fridge needs 500 watt hours per day and you want two days without charging, that is 1000 watt hours. On lithium, divide by 0.8 for about 1250 watt hours. At 12.8 volts nominal, that is about 97 amp hours. Add a cushion for inverter loads or hot weather and you may land near a 120 to 150 amp hour lithium bank. On absorbed glass mat you would double that figure to keep depth of discharge healthy.

Ambient temperature matters. A well ventilated cabinet and some airflow around the condenser can reduce duty cycle. Keep the fridge out of direct sun, away from heat sources, and provide intake and exhaust paths so the compressor can breathe.

Choose the right fridge type

There are three common approaches. A 12 volt compressor fridge is the most efficient and practical choice for vans. Two way household style fridges on 120 volt can work, but they require an inverter and draw more energy during start cycles. Absorption fridges favor propane use in stationary campers, but they are sensitive to leveling and are less efficient on electric settings in a van. For mobile use, a 12 volt compressor unit balances performance, safety, and energy use.

Charging sources that keep food cold

Your fridge runs as long as your battery has energy. That makes charging essential. Mix multiple sources to cover different conditions and trip styles.

Solar is the silent workhorse. Panel output varies with sun hours and tilt, but a rough estimate is panel watts times four to six hours per summer day, multiplied by about 0.7 to account for losses. A 200 watt array might yield around 560 to 840 watt hours in good conditions, enough to cover most fridges during bright seasons. In shoulder seasons or shade heavy camps, solar alone may not keep up, so pair it with engine charging.

A dc dc charger ties your house battery to the alternator while protecting both systems. Smart alternators used in modern vans need a dc dc charger rather than a simple isolator to maintain proper charging. Common sizes range from 30 to 60 amps. At 30 amps, one hour of driving can deliver roughly 360 watt hours into a lithium bank. That is a meaningful top up for a fridge heavy day.

Shore power is a nice safety net. A quality charger rated around 20 to 40 amps can recover the bank overnight at a campground or driveway. If you carry a small inverter generator for other reasons, the shore charger can make quick work of a low battery in poor weather.

Battery chemistry and capacity math

Lithium iron phosphate brings stable voltage, fast charging, long cycle life, and usable capacity near 80 percent. That means a smaller footprint for the same autonomy. Absorbed glass mat can work if cost is the main concern, but it is heavier, charges slower, and prefers shallow cycles. Aim for a battery with an integrated battery management system that protects against over current, low temperature charging, and cell imbalance. Add a shunt based monitor so you can see real state of charge rather than guessing from voltage alone.

Wiring and install best practices

Delivering clean power is as important as storing it. A fridge is sensitive to low voltage, especially during compressor start. Keep the wire run short and size it generously to keep voltage drop under three percent. Many under counter installs benefit from 12 gauge wire for short runs, while longer paths may call for 10 gauge or even 8 gauge. Always confirm with a voltage drop calculator that uses your exact length and expected current.

Fuse placement is critical. Place a properly sized fuse or breaker within about 7 inches of the battery on the positive lead feeding your distribution block. Fuse each branch circuit, including the fridge, according to the device rating and wire size. Use marine grade crimp connectors, adhesive lined heat shrink, and secure all cables to avoid chafe.

Ventilation often gets overlooked. Fridges reject heat from the condenser coil. If you trap that heat behind a cabinet face, duty cycle rises and power use climbs. Provide a low intake opening and a high exhaust opening. A small fan on a thermostat can help in hot weather.

Solar and alternator pairing

Solar is great when parked. Alternator charging shines while driving. Together they smooth out the highs and lows of travel days and layover days. A practical setup for many two person vans is a 120 to 200 amp hour lithium bank, 200 to 400 watts of solar, a 30 to 60 amp dc dc charger, and a 20 to 40 amp shore charger. That mix supports a 12 volt compressor fridge, lights, fans, and device charging with headroom for cloudy spells. If you add an induction cooktop or air conditioning, revisit the math and scale up storage and charging accordingly.

Cold storage habits also stretch your energy. Pre chill food at home, set the thermostat a bit warmer for items that do not need deep cold, and fill empty space with reusable ice packs or water bottles to stabilize temperature. A portable thermometer helps you verify that food stays in the safe zone.

At this point you can see the pattern. Estimate the fridge load, choose a battery that handles your preferred number of idle days, then add charging sources that fit your driving and parking rhythm. Tie it together with safe wiring and thoughtful airflow and the fridge becomes a set it and forget it part of your travel.

OZK Customs builds these systems daily and has seen the difference that clean design makes. Our team sizes lithium banks to real world use, installs dc dc charging that plays nicely with modern alternators, and routes short, heavy cables to keep the compressor happy. We integrate solar arrays that fit your roof plan, add shunt monitors for precise readouts, and finish with tidy distribution that is easy to service. If your van is due for a dependable cold chain, we would be glad to map and install the full package for you in Fayetteville Arkansas.

For more on our adventure ready builds, explore Recreational vans. If you want a from scratch power system inside a tailored rig, visit Custom build van. Looking for a finance friendly platform with a reliable electrical plan, see Mainstream vans.

Tell us how you travel and what you power. We will design the right battery capacity, charging mix, and wiring so your fridge stays cold without a second thought. Submit the form to start your build plan with OZK Customs.