By Grant Spolander & National Luna / Camping Fridge Guide
Many of us operate with the ‘set and forget’ mindset when it comes to camping fridges. Set the thing to a low temperature and then hope like hell we’ve got enough battery power to keep the beers cold and the provisions fresh during the days in camp. But with a little understanding, and a little active management, it’s possible to reduce the amount of power your fridge requires. The first thing to understand is this, the greater the difference between your fridge’s internal temperature and the ambient temperature (the temperature of the environment in which your fridge is located), the more the two temperatures will strive to equalise.
Good insulation slows this process, but eventually the fridge’s internal temperature will rise. Which will prompt the fridge’s compressor to “cycle” or switch on in order to bring the internal temperature back down to the selected temperature setting. To illustrate this, we used a 60-litre test fridge set to 4°C and recorded how often the compressor cycled on when the ambient temperature was adjusted to 21, 32 and 43°C respectively. The following graphs paint a clear picture.
To be clear, it’s not that the compressor is working “harder” or “faster” at 43°C ambient (as opposed to at 21°C), but rather that the compressor is cycling on 3 times as often. It’s worth noting that the actual energy consumed – per cycle – is mostly the same at the various ambient temperatures. It’s the number of cycles which are the meaningful measurement. This experiment clearly demonstrates that higher ambient temperatures lead to more frequent compressor cycles, and thus, greater energy consumption. But what happens if – using the exact same test fridge – we fix the ambient temperature at 32°C, and then change the fridge’s internal temperatures to 4°C, -6°C and -16°C? This experiment allows us to exclude the effects of ambient conditions and focus solely on how internal temperature settings affect a camping fridge’s energy consumption.
So, to recap, the greater the difference between the fridge’s internal temperature and the ambient temperature, the more these two temperatures will want to equalise.
The insulation in your fridge is the only factor that can slow this process. Given that insulation is never 100% effective, some loses will eventually occur and the fridge’s compressor will have to cycle on in order to lower the internal temperature. Lowering your fridge’s internal temperature has the same effect as raising the ambient temperature. The worst-case scenario would be an internal temperature set very low while the ambient temperature is very high. In such an instance, it wouldn’t be surprising for the compressor to run 100% of the time.
TOP TEMP TIPS
There are few things more satisfying than an ice-cold beer consumed in the noon day heat. However, it pays to be mindful of how “ice-cold” temperatures impact the energy consumption of your camping fridge. Most household fridges operate within a range of 4 to 7°C, so setting your camping fridge any lower than this may be unnecessary. That said, it can be a good idea to set your fridge’s temperature super low while you’re driving – during which time the fridge is drawing power from the vehicle’s alternator – and then adjust the fridge temperature to a more sensible setting once you get to camp and are running off battery power. This will ensure that your drinks are super chilled after you’ve finished putting up the tent, and will also reduce the compressor’s workload for a decent period thanks to residual cooling.
In much the same way, if you have a dual-compartment fridge, it can be helpful to deep-freeze ice bricks and/or meat in the freezer section while you’re driving, then once in camp adjust the temperature setting upwards (approximately 7°C), and move the ice bricks / meat to the fridge section where they can slowly defrost and assist with keeping things cool.
Bear in mind that in the short term (the duration of most camping trips) it’s often unnecessary to freeze food beyond -6°C. The efficiency of your fridge is more dependent on its insulation, than it is on the performance (or amp draw) of its compressor. However, the benefit of a more powerful compressor is that it can pull temperatures down more quickly.
A fridge protection jacket can assist in maximising your fridge’s insulation. Besides protecting your fridge from physical wear and tear, it also acts as a barrier against direct sunlight reaching and heating the surface area of the fridge’s outer casing. In the same vein, you also want to pay attention to fridge location, it should be placed in the coolest (or least hot) place in the camp. Even just making sure the fridge is always in the shade can make a difference. In closing, perhaps the most important lesson of all is that optimum fridge performance or energy efficiency requires a hands-on approach. You need to mitigate the effects of high ambient temperatures and actively adjust your fridge’s temperature settings to suit the conditions of the day.