Using a Freezer in an off road caravan or off road camper trailer

Posted by Bruce Loxton

Apr 19, 2013 4:32:00 PM

need ice for drinks when in off road caravansVirtually every home has quick access to a freezer. It is therefore easy to imagine the benefits of a scaled down freezer as part of your off road kit. When travelling off road, gas fridges (3-way) are not practical so you will be using some form of 12V compressor based refrigeration. 12V freezers can consume up to three times the amount of energy compared to a fridge. Freezer design and size will dictate both larger battery and solar capacities. This adds to both cost and weight. Is it worth it? 

Firstly lets consider the lightest weight solution: An Alternative to using a Freezer is to take Cyrovac prepared food.

This is far better for long term storage than frozen food with a camper trailer. Here is more information on Cryovac processing:

Long Term

The air is replaced in a sealed bag with food grade CO2. This removes the oxygen (which is what spoils the meat) in the vacuumed pack. The result can be kept cool (slightly chilled) for 12 months in a dark area.

Short Term

The air is not replaced in a sealed bag but just “sucked out”. This is typically what the butchers do or if you have a machine at home.

This perishable food must be kept chilled in the fridge and will usually keep for 3-6 months.

  • There is a caution on cryovac meat. You cannot guarantee that it will be free from pathogens (these grow even without oxygen), which may have been introduced when slaughtering. Larger cuts of meat are safer with a smaller surface area than say mince-meat, which deteriorates rapidly. In general, meat is sterile below its surface, provided the animal was healthy at the time of slaughter. 
  • Never eat meat that is swollen, as this is an indication that gas-forming anaerobic bacteria are active. The good thing is that harmful bacterium tell you when they are active - gas, foul odour, and slime. 
  • Finally, always cook the meat right through - don’t take chances with rare meat as this means the temp has not penetrated the whole slice and killed any bacteria present. It may be all right in a restaurant but not in the bush. Cook until the juices are clear. If in doubt, chuck it out.

Off road camper trailer fridgeIf you want ice for drinks, then there are low weight solutions. Kimberley change the compressor speed on the fridge and double the insulation in the Kimberley Karavan so you can make ice in Darwin. For off road camper trailers, fridges like the eutectic one used in Kimberley’s Platinum Model can be set to have a bottom layer of ice with fridge space above.

If you do want a freezer with your camper trailer then consider either:

  • Dual-zone fridges are popular but they are more power hungry than single-zone units 
  • Small freezer in the back of the vehicle. This will use more power than a large fridge in the camper trailer

Lithium vs AGM InfographicEither way you will need more battery capacity and solar output. The lightest weight option here is using Lithium Batteries and Super Thin solar. You can option up to 250Ahrs of Lithium and 156W of solar for less than 25kgs. If your current AGM battery is 105Ahrs then it weighs close to this so the swap-out won’t increase your weight.

Drawer Freezer in off road caravanAt the other end of the spectrum are fullsize off road caravans for long trips. There is a big advantage of large freezer space in these. However, the battery capacity and on board solar has to always be available.

In these rigs, the secret is to have a very well insulated chest or drawer type freezer. At Kimberley we double the top insulation and double the air movement through the condenser. The result is less energy use but remember freezers still use a lot of energy.

The weight here is not much more than the camper trailer solution if you use Lithium batteries and Super Thin solar.

 Glass vs Super Thin Solar InfographicIn the top of the line full size off road caravan: the Kimberley Kruiser T3, there are 480 Ahrs of Lithium and 540W of solar for a total weight of less than 70 kgs.

 

off road caravan lightweight solar panels on roof

 

 

 

 

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Table below is a guide to assist in design decisions and requirements.

 

 

Absolute Lightest weight with eutectic fridge/freezer

Small Long term freezer in vehicle or Dual Door
“Fridge/ Freezer”
in camper trailer

Large Fridge (133L) with increased compressor speed and added insulation for ice tray

Absolute the best with 55L Drawer freezer

Use a cryovac strategy rather than freezing food for long term storage

Yes

Yes

Yes

Yes
(in separate fridge)

Makes Ice for Drinks

Can on bottom layer with mid depth divider

Yes

Yes

Yes

Holds frozen food below minus 10 degrees c for long term storage

Only if switched to 100% freezer mode

Yes, the second zone should hold temp except for the “flow over” design used which would require the whole unit to be in freezer mode

Only a small volume generally used for ice and ice packs for bushwalking

Yes

Power consumption range

20 Ahrs per day

35-80 Ahrs per day

30-40 Ahrs per day

50-60 Ahrs per day

AGM Battery and Glass Solar Size Suggested
(assumes other loads as well)

140-200Ah AGM

100-120W
Solar

200Ah+ AGM

180W Solar

200Ahr AGM

220W Solar

400Ahr AGM

180-400W solar

Weight of AGM battery and Glass Solar Panels

87kgs

96kgs

100kgs

185kgs

Lithium Battery and Super Thin Solar Size Suggested

(assumes other loads as well)

120-160Ah Lithium

120-150W
Solar

160Ah+ Lithium

180W Solar

160Ahr+ Lithium

220W Solar

250Ahr Lithium

180-400W solar

Weight of Lithium Batteries and Super Thin Solar Panels

22kgs

24kgs

26kgs

48kgs

For the technically minded, the way the power consumption varies with fridges and freezers is firstly by the size of the compressor and secondly by the cycling time. The cycling time has a big impact on the energy consumed.

To reduce overall power consumption, insulation is the first priority, then a strategy to optimize compressor speed and cycling time. The same model and size compressor in 2 completely different brands will perform quite differently. A Waeco 80L Freezer draws close to 70 Ahrs/day whereas the eutectic Freezer in a Kimberley draws 40 Ahrs/day. They both have the same compressor but with different strategies and insulation.

Topics: lithium batteries, off-road caravan kitchen, light weight off-road caravans, portable solar panels, freezer for off-road caravans, freezerfor off-road camper trailers

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The Kimberley Karavan, a lightweight folding off road caravan that can go anywhere. Kimberley Karavans are unique with their internal shower and toilet, comfortable internal seating and luxury finishes.