12V mini-coolers are not very effective at chilling food or keeping it cool long-term. Their Peltier pads are very power hungry being on 24/7 drawing 4-6 Amps every hour with little result. Cool-boxes are also a pain in the ass getting ice for them every couple of days so here is another relatively affordable and effective solution.
My efficient solution that I developed for my small boat not only gives you an extremely low power draw fridge but also provides AC electric as a side-benefit.
You can put together this setup for around $230 [assuming you already have a leisure battery] which will drain less than 15AH per day and consists of the following:
• $111 – Walmart Igloo 1.1Cu-Ft white freezer [good price] or other 1.1 – 1.2 Cu-Ft cube type variants. For maximum efficiency, make sure it’s a freezer you buy, not the similar sized 1.6 Cu-Ft fridges as the extra insulation is a major factor here] http://ift.tt/1TOEeMF
• $80 - 1000W BESTEK 12V Inverter [although a 600W+ pure-sine is recommended if the budget allows]. For peace-of-mind before purchase; connect the freezer to an AC wall outlet and monitor it for a day using a kill-a-watt meter logging its maximum peak start-up wattage to size-up the minimum Inverter size needed. Smaller = cheaper but leave some overhead] http://ift.tt/1XsNEN7
• $9 – SUNKEE DC-DC Wide-Input to 12V Stabiliser – provides a steady 12V feed to the Digital Thermostat relay Controller. http://ift.tt/1TOEefE
• $16 – Inkbird 12V Digital Temperature Controller – This has a small built-in 10 amp relay which in-turn, controls a larger heavy-duty relay wired in series to the Inverters 12V positive cable. This controller remains on all the time and is wired to the SUNKEE providing its steady 12V power supply. It consumes next to now power [<1W or <0.01A] and has a temperature probe which is stuck through the freezer door seal and tapes to its inside wall. The LCD display temperature should be set at around 38°F and opens the 10A relay when the temperature goes above this figure http://ift.tt/1XsNCot
• $11 - 100A Heavy-Duty ‘Normally-Closed’ 12V Relay – This is wired in-line to the Inverters positive 12V cable and controls the Inverters on/off state. It is switched on & off by the thermostat controller [the Inverter’s built-in on/off toggle switch must be left on] http://ift.tt/1TOEefI
• $4 – Torpedo switch – This overrides the Inverter’s shut-off 100A relay to manually keep it on so that you can briefly use other AC items though you may need to unplug the fridge when using higher draw items or the inverter will trip-out on an overload spike when starting up. For wiring the system, see the diagram below http://ift.tt/1XsNEN9
Wiring Diagram: http://ift.tt/1TOEeML
I did some power meter testing running this setup for a couple of days with the freezer in a 70°F environment and it consumed less than 0.5 amps per hour including running the temperature controller and relay constantly and used only 11-12 amps over 24-hours [not opening the door]. It usually ran for around 6-minutes every hour [about 10% on-time] had a 650W surge and settled down to 52-Watts whilst running though other fridge power levels might very well be 10-20 Watts higher.
An effective 12V compressor fridge such as an Engel, Dometic or Waeco costs much more, holds less and is actually less power efficient. Due to their lightweight and portable nature; these top-access 12V fridges have thin insulation. You also don’t have the side benefit of access to an AC power supply.
I found it was important to toggle the inverter on and off manually as when the inverter was on but not having a load being drawn, it was taking 1-Amp every hour just sitting there on it’s own. Hope this info helps as it should translate to vans well. Oh and the Bestek 1000 Inverter can also power this 600W microwave http://ift.tt/1XsNFjV too so this combo will be perfect for quick-cook stored microwave meals .
Submitted April 12, 2016 at 05:33PM by CaneyJ http://ift.tt/1TOEeMN vandwellers
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