Caravans and fridges
Read our tips to make sure your food will always be hygienic, even in summer
See helpful adviceCold comparisons
The Club’s technical team answer your questions on fridges
Q Surely a fridge is just a fridge? Why are caravan and motorhome ones different?
A Leisure vehicle fridges, particularly in caravans and larger motorhomes, have looked like domestic units for some time, but their strengths and weaknesses are quite different.
Types of fridge
Sleek and sophisticated, but not quite like your domestic fridge
Fridges use two different technologies:
- Absorption: these tend to be fitted to larger vehicles and are usually powered by 12V from battery or towing vehicle, 230V from site hook-up, or LPG.
- Compressor: 12V, running either directly from a battery, perhaps also with solar panel(s), or indirectly from the mains via a 12V power supply.
Compressor fridges are efficient, cooling quickly and staying cool very effectively. They tend to make a little noise and usage off-grid needs some consideration of power management.
Absorption fridges suit on- and off-grid (via gas) usage. They’re quiet and on mains or gas tend to be relatively powerful. However, they’re less efficient and may struggle to keep cold in high ambient temperatures.
This latter point’s worth considering. All fridges can reduce temperature by a certain amount, though not necessarily to a certain level. So as outside temperature increases, their ability to achieve low temperatures diminishes. Compressor fridges often seem rated for effective use in higher ambient temperatures than absorption ones, although clearly they’ll then use more power to stay cold.
Until relatively recently, larger fridges have tended to be absorption. Large compressor fridges are now available, which combined with better (eg lithium) battery technology and solar panel fitment, means we’re likely to see their wider use in coming years.
Longer journeys
Smaller vehicles like campervans have tended to use compressor fridges
A common misconception about absorption fridges is that they work seamlessly on 12V while travelling. Unfortunately, the reality is more complex. If the voltage reaching the fridge falls too low, it won’t work. Longer cables and intermediate connections tend to increase voltage drop, making caravans more vulnerable than motorhomes. Over the past decade, ‘smart’ alternators have added another problem, as these reduce the vehicle’s alternator output whenever possible to improve efficiency and emissions. They don’t know that you have a fridge to run (or an auxiliary battery to charge). It’s often hard to know whether the fridge is still running – while it’s probably running when you set off, it may stop after a while.
Sometimes you can fool a smart alternator into keeping a high output just by turning on other things, like dipped headlights or rear screen heater. For a few pounds, you can buy a voltmeter to plug into a cigar lighter-type socket which shows the voltage level. If the readout drops from around 14V to 12.5V or so while the engine’s running, it’s quite likely your fridge will stop. You can see whether turning things on makes the voltage rise again.
Another option (at significant expense) is fitting a DC-DC charger, which takes the variable alternator output and produces a stable supply for auxiliary circuits. But – and it’s a big but – even running continuously, 12V may not deliver enough power to cool down an absorption fridge (let alone the freezer section). It’s only likely to keep an already cooled fridge cold.
Does this really matter? If your fridge is cold when setting off (several hours on mains or gas), it should stay cold for hours if you don’t open it. Keeping it full helps, even if you use lots of water bottles; that way, if you do open it, less warm air will get in. If you really need your fridge to cool while travelling, though, a compressor one may be a better future choice.
Please address your questions to: Technical Information,
Email: technical@camc.com
Tel: 01342 336611
...and quote your membership number
