What Size Power Station Runs a Camping Fridge?

Short answer: for a weekend with a National Luna 35L or 45L, get the Sasquatch 1800W. It holds 1229Wh. That's two and a half days of fridge with the freezer side running, and about five without it.

My truck has a house battery, so I don't run my fridge off a power station often. I have done it, though, and most of the time a power station will run a fridge for a weekend, no problem. The math is below, so you can pick a size without guessing.

/HOW MUCH POWER A 12V FRIDGE USES

A compressor fridge doesn't run all the time. It cools down, shuts off and kicks back on when the inside warms up. What it costs you is how often that happens over 24 hours, not the amps on the label.

National Luna doesn't publish a daily figure for the 35L or 45L. They have published two tests that get close. In one, their example fridge at 4°C used 16 to 20 Ah over a day. In the other, a 60L dual zone with a fridge side at 4°C and a freezer side at -10°C averaged 34.44 Ah over 24 hours.

At 12 volts, that's about 200 Wh a day for a fridge and about 410 Wh a day with the freezer side running too. Those are the two numbers I use below.

/12V FRIDGE POWER IN WINTER VS SUMMER

Winter is easy on a power station. A fridge in a cold truck doesn't have to cycle on and off much, so the compressor sits idle most of the time.

Summer is the other end. In National Luna's numbers, the compressor runs 18 to 20 percent of the time at 21°C (70°F) and 30 to 50 percent at 43°C (109°F), and uses about three times the energy in that heat. The station that runs your fridge for five days in October might give you two in August.

/HOW LONG A POWER STATION RUNS A FRIDGE

I count 85 percent of each station's rated capacity. Some is lost converting to 12 volts, and you don't want to run it to zero anyway. Then divide by the daily use.

These are planning numbers, not test results. A full fridge, a shady spot and a lid that stays shut will beat them. A hot day and a load of warm drinks won't.

/WHICH SASQUATCH POWER STATION TO GET

• 300W, $129. Phones, cameras and a laptop, which is what Sasquatch size it for too. It runs a fridge for about 20 hours, or 10 with the freezer on.
• 600W, $249. A night or two in cool weather, or a weekend if you drive every day and charge it on the way.
• 1800W, $569. The weekend one. Two and a half days with the freezer on, about five without.
• 3000W, $769. Base camp for a week. It also takes two solar panels at once, so it can charge while it works.

/NATIONAL LUNA FRIDGE: 35L OR 45L

Both are dual zone, so each side has its own thermostat: fridge and freezer, two fridges or two freezers. Same footprint, same 40mm of insulation. The 45L is 2 inches taller for 10 more litres, and National Luna size the 35L for two or three people.

Freezing costs more than cooling. If you don't need the freezer this trip, set that side as a second fridge and you'll sit closer to the lower number in the table.

/HOW TO MAKE A POWER STATION LAST LONGER

• Plug the fridge's DC lead into the station's car socket, not the AC outlet. Going through AC converts the power twice.
• Cool it down at home on wall power before you leave. The fast cool-down is when the fridge pulls the most.
• Keep it in the shade and open it less. Both come straight from National Luna.
• Pack it full. A full fridge holds its temperature longer between cycles.
• Charge it while you drive. Every Sasquatch takes a car input, and once you're topping it up on the road, long off-grid days stop being a problem.

/POWER STATION VS A HOUSE BATTERY

My truck runs a LiTime 320Ah house battery, about 4,000Wh, charged by a Redarc system while I drive. My interior build post has the whole setup. That's the wired-in version of the same idea. A power station gets you most of the way there without touching the truck's wiring, and it comes inside with you at the end of the trip.

Kingston