# Farmers Market Egg Cooler delima, a little help??



## Muleman (Nov 8, 2013)

Ok, so let me explain. I have a van that I intend to put a small 5 or 7 cubic foot freezer in and run it as a cooler using one of the Johnson Controls Thermostat units. I need this freezer/Cooler for 2 reasons. One is to pick up meat from the butcher shop and bring home or take for deliveries. The meat will already be frozen or at the very least very cold. The second reason is to keep eggs in, while at the Farmers Market. My trip to the butcher is only about 3 to 4 hours total and the FM would also be about 3 to 4 hours total. I intend to plug the freezer in while at home. I think by adding some frozen bottles of ice to the bottom to create a thermal mass it will stay cold just fine. Here is my dilemma. The rules at the FM say the eggs must be kept below 45 degrees in a "running refrigeration unit"? Therefore, simply unplugging it at home the morning of the FM with a temp of say 37 degrees and expecting it to stay cold for the few hours we are there will not work, it must be "running". My idea is to add 2 deep cycle batteries to the van and use the van alternator and/or home trickle charger to charge them if needed. Then run a power inverter from the 2 batteries to run the freezer. I can not imagine it will actually be running much, if I have it plugged in at home and already at temp before I leave the house. So does this sound like a plan or am I missing something?


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## TnAndy (Sep 15, 2005)

Sounds like a plan. 

We tested a 9cuft chest freezer using a JC external thermostat, and found it used about 200watt/hrs in a 24hr period, with frequent openings/closings, and no ice in the bottom.

My guess is you'll only use in the 50w/hr range, or less, for a 4 hr period. That's not a lot of power use. Stick a "Kil-a-Watt" meter inline and monitor your actual power use to be sure

The only thing you might watch out for is cheap, square wave, inverters.....they may, or may not, run the freezer.


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## Peasant (May 18, 2013)

TnAndy said:


> Sounds like a plan.
> 
> We tested a 9cuft chest freezer using a JC external thermostat, and found it used about 200watt/hrs in a 24hr period, with frequent openings/closings, and no ice in the bottom.
> 
> ...


200 Wh/day is exactly what this guy got with what looks like a smaller freezer (5 cf?). This guy also got 200 Wh/day with a larger freezer (7 cf).

Muleman, 200 Wh/day = 33.3 Wh over the course of 4 hours. Since it's probably hot in the van, TnAndy's rounding up to 50 Wh makes sense.

50 Wh @ 12V = 4.2 amp-hours. You'd only need a ~17 ah battery to run the fridge for this long, assuming you only run the battery down to 75%. No reason not to go a bit bigger, maybe a 35 ah battery like this.

TnAndy is right that some modified sine wave inverters may not play well with your freezer. For a dedicated set up like this, I'd get the smallest true sine inverter you can find. I would think a 200W would work, but would need to know starting surge. TnAndy, have you measured the surge on your set up?


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## Muleman (Nov 8, 2013)

Thanks to both of you for the info. I will read up on those links. I thought it was doable, just figured I may have overlooked something or mis-figured. I really do not want to wire it into the van unless I have to. I would rather be able to charge the batteries from an outside source at home, then just use the battery bank to run the system for the 3 or 4 hours required. I know charging battery banks can be hard on small automotive alternators.


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## TnAndy (Sep 15, 2005)

Peasant said:


> TnAndy, have you measured the surge on your set up?


No, we didn't. Not something I thought to do. Just plugged in the Kil-a-watt meter and recorded the results for a week or so.


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