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Keeping food cold

Refrigeration is the most common form of food preservation for 'dwellers , although drying and canning also work for some foods.

Note that many 'dwellers choose to use no refrigeration at all.

upright vs chest

Upright fridges stand up and have a door that opens off the side.

  • Pro - easier to load and unload for many people. Fewer “hidden” foodstuffs. Space above refrigerator remains usable.
  • Con - items may shift and fall out when the door is opened. Cold air “spills” out when the full-height door opens.

Chest fridges lay down like a beer cooler.

  • Pro - Can be filled to capacity. Items do not fall out. Possibly better cold retention due to lack of bottom seal and no air “spillage”.
  • Con - May have to dig for food. Space above top door unusable unless placed in a slide-out or similar.

using a cooler

* Pro - low cost, low empty weight, zero power consumption and widespread availability.

* Con - constant need to add frozen material and the requirement to dispose of any melted ice.

Tips to make cooler use more effective and simple:

  • store your cooler out of direct sunlight and in the coolest place available
  • small coolers (L'il Oscar, etc) are often found in thrift stores for a few dollars
  • ice-free methods
    • if you have regular access to a freezer at work or elsewhere rotate blue freezer packs in/out of the freezer and into your cooler. This removes the ongoing cost of buying ice but requires a number of packs so you can always have them in rotation.
    • nearly-filled bottles of water1) are free and work much like the freezer packs above.
  • if using ice
    • block ice will last longer than cubed ice
    • store food in a tub or other container to keep melted ice off it
    • use a cooler with a drain at the bottom. This makes cleaning/draining easier and may allow you to reclaim any clean water for washing or other purposes.
    • you may be able to harvest ice from trays or an icemaker at work. If doing this, remember to leave enough ice for others, refilling ice trays, etc.
  • use cold weather to your advantage (see below)

using a refrigerator

A refrigerator (refer or reefer) is used to keep items at a given cool temperature, typically ⇐40F.

Refrigerators give off heat and must be ventilated; ensure any vents exhaust into open area. Cooling performance may be enhanced by adding fans to move more air across the condenser2) and dusting components regularly.3) Cold retention can be enhanced by adding insulation in the form of foam sheets or insulative covers made for the cooler.

front vs. top loading

Front loading refrigerators are square or tall rectangles shaped like residential refrigerators. Advantages include:

  • direct access to the contents from a walkway
  • can use vertical space over the unit without have to build a slide-out

Top loading refrigerators are usually low rectangles shaped like insulated coolers. Advantages include:

  • items don't fall out when vehicle moves
  • space can be filled more completely
  • cold air doesn't spill out when opening the door, which may reduce power consumption if the door is opened frequently.4)

absorption refrigeration

Absorption (ie, propane-powered ammonia cycle) fridges were popular in RVs because they used minimal power to run the ignitor, control board, fans if any. This type of fridge had to to be quite level so the ammonia cycle cooling would work by gravity; there is no pump.5) Using one out of level could damage the $$$ cooling unit.

Absorption units are rare in vandwelling setups due to size, expense, and need for exterior venting.

Over the last few years RV refrigerators have been going to 12v or, more commonly, 110v residential style units.

compressor refrigeration

Words of Wisdom: “Check amps drawn [by the compressor fridge] over 24 hours, much more important when boondocking than purchase price.” – John62CT6)

12v compressor refrigerators become the standard way to chill food in solar-equipped vans. The main types of compressor fridges common in 'dwelling setups are:

  • Danfoss-style compressor – Now made by Secop, these compressors have a reputation for quality. Brands include:
  • Sawafuji-style compressor – this compressor has one moving part and is energy efficient with low startup current.14) This kind of fridge is least likely to be damaged by rough use in the outback. Downsides: initial expense, the oscillating piston can be noisy. Brands include
    • Engel used by Luciano15115) and Arctic Cat16)
    • undertheaxles uses a Engel MT35F, and reports it consumes 12A each day.17)
    • Engel MT45 used by goldendinnerplate18)
  • non-Danfoss-style compressor brands include:

Note that using a compressor fridge for refrigeration vs. freezing can have vastly different power requirements:

“I use a pair of 65 qt Whynter units, one as a fridge, one a freezer. The freezer uses somewhere around 4 to 5 times the power that the fridge uses. Keeping the fridge at 40F is fairly easy, keeping the same unit at 0F is another story.” – Almost There22)

The Engel MT series (MT35, MT45) are reported to have very low current draw due to clever cooling airflow design.23)

Secessus describes the interior size of the Alpicool 15L (flat lid) version:

I store leftovers in pint and quart mason jars, which stand up fine in the [Alpicool] 15L. Longneck beers are slightly too tall. Since glass is heavy and harder to compact for trash removal I buy beer in cans anyhow. 16oz tallboys do fit. ←- the info discerning gentlemen need to know24)

Peltier refrigeration

Peltier cooling doesn't get used much in solar setups because it uses a lot of power and does so 100% of the time. A typical Peltier cooler might run 4-5A continuously whereas a compressor cooler might run 5A 30% of the time and turn off the rest of the time. The 100% duty cycle issue can be alleviated by wiring in a 12v thermostat.25)

This kind of device cools to ~30-40F below ambient, which may not be a problem if the ambient is 80F or less. For best results avoid putting hot or even warmer-than-ambient items in the cooler. Use a fan on the item until it is room temp before placing in cooler.

Most lack thermostats and so can accidentally freeze food if ambient temps are low enough.

Read the manual before purchase to see how long it can be run at a stretch; fans are a common failure point when run 24/7.

possible use cases

  • you have a surplus of power: you are hooked up to shore power, have a large solar install, or are running your heavy loads on an opportunity circuit.
  • you are in an area where ambient is less than 80F and the cooler has a thermostat (or you wire in a thermostat/relay). Most snowbirds stay in areas that are <80F.
  • you want to chill nonperishable items like water, beer, etc or semi-perishables like cheese and salami.
  • you already own one and run it on a Low Voltage Disconnect so it doesn't run down your batteries

using nature

In low humidity areas with a significant day/night temperature differential you may be able to cool or even freeze cooler packs and water bottles. Leave them outside overnight and put them back in the cooler in the morning.

leaves room for expansion
assuming it would ever get cold enough to shut off.
food/refrigeration.txt · Last modified: 2021/10/14 12:29 by frater_secessus