Technical
Which fridge for your camper: compressor, absorption or cool box?
The fridge is the only appliance in your camper that runs day and night, which makes it the biggest single draw on your battery. The choice between compressor and absorption decides how much battery you need, how many vents you have to cut into your side wall, and whether it still works on a campsite in Spain.
Updated on 11 min read
The three types side by side
| Compressor | Absorption | Cool box | |
|---|---|---|---|
| Runs on | 12 V, and 230 V via the charger | Gas, 12 V, 230 V | 12 V |
| Use per day | 25 – 50 Ah | Barely any power on gas; unusably much on 12 V | 30 – 60 Ah |
| At 35 degrees outside | Keeps cooling, uses more | Stops keeping up | Cools poorly |
| Needs to be level | No | Yes, within three degrees | No |
| Noise | Audible when it cycles | Silent | Audible |
| Ventilation needed | An air gap around it | Two vents in the side wall, mandatory | Free-standing |
Absorption was the standard in factory campers for years, and that is where its good name comes from. The principle has no moving parts and is therefore silent, but it works with heat rather than a pump — and that is exactly its weakness. When it gets hot outside it can no longer shed its own heat, and it stops cooling. Which is precisely when you need a fridge.
Running an absorption fridge on 12 volts while driving works, but it draws around 10 amps continuously — twice what a compressor uses across a whole day. Parked on 12 volts it is not an option: your battery is flat in half a day.
How big, and where
For two people shopping every few days, forty to sixty litres is ample. Bigger sounds attractive until you see what it costs: every extra litre is cabinet space taken from your galley, extra weight, and more power. A hundred-litre fridge in a three-metre van is a fridge you drag around half empty.
- Under the worktop is the usual place and also the best: low weight, and you reach it standing without bending to the floor.
- Not beside the hob and not against a sunny wall: every extra degree he has to shed costs you power.
- A drawer model is nicer to use than a door, because with a door the cold air falls out every time you open it.
- Budget for the weight of a full fridge. Fifty litres of shopping is roughly thirty kilos on top of the appliance itself.
Ventilation: where most fridges come unstuck
A fridge does not create cold, it moves heat — from inside to outside. If that heat cannot escape, the fridge runs without result, and that is the most commonly reported fault. A compressor needs an air gap of a few centimetres all round, with space below and above so warm air rises by itself. Absorption is stricter: it needs two vents in your van's side wall, one low and one high, exactly as the manufacturer prescribes.
On a gas absorption fridge those two vents are not a recommendation but a condition. The appliance burns gas and the combustion gases must go outside; box it in and they end up in your living space. If you choose gas, have the installation checked by someone qualified.
What it asks of your battery
A fifty-litre compressor fridge uses about 25 amp-hours a day in spring and double that in a hot summer. In most self-built campers that is more than half the total daily use. So put it first in your battery calculation rather than last: a hundred amp-hours of lithium is already tight with two sunless days and a fridge.
- Set it to the most economical setting that is still cold enough. One degree lower already costs noticeably more.
- Fill it with already-cold shopping before you leave. A fridge cooling warm bottles runs for hours on end.
- Insulate the housing. A fridge in a warm cabinet ends up cooling the cabinet too.
- A separate fuse close to the battery, and 2.5 mm² cable up to four metres. It briefly draws far more than its rated figure when it kicks in.
Work out your battery from your daily use
What you need for this
We do not (yet) sell these parts separately. The list is here because this is what should be in your basket before you start.
- 40 – 60 litre compressor fridge, 12 V, drawer or door
- Ventilation grille for the housing
- Separate fuse and 2.5 mm² cable
- A battery monitor, so you see what it really draws
Frequently asked questions
- Compressor or absorption in a camper?
- For a self-built camper, almost always compressor. It works regardless of outside temperature, does not need to be level, needs no gas connection and no two vents in your side wall. Absorption is silent and runs on gas, but cannot keep up above thirty degrees — exactly when you need it.
- How much power does a camper fridge use?
- A fifty-litre compressor fridge sits at 25 to 50 amp-hours a day, depending on outside temperature. In most self-built campers that is more than half the total daily use, so count it first when sizing your battery.
- How big should the fridge in my camper be?
- Forty to sixty litres is ample for two people shopping every few days. Bigger costs cabinet space taken from your galley, extra weight and more power — and in a three-metre van a hundred-litre fridge travels half empty.
- Why is my camper fridge cooling badly?
- Almost always ventilation. A fridge does not make cold, it moves heat, and if that heat cannot escape it runs without result. A compressor needs an air gap of a few centimetres all round, with space below and above. An absorption fridge needs two vents in the side wall, one low and one high.