Running a chest freezer as a chest refrigerator on a trailer

[vexter0944]

Hello everyone - total newbie here - but been doing enough reading to make me join up and do some posting and see if I can get some ideas/thoughts/help

I have a concession trailer which is parked on a lot with no electric available when stored. I have a freezer on board that I plan on using as a chest 'refrigerator' with one of the Johnson controls - http://www.amazon.com/KegWorks-Freez.../dp/B0002EAL58

I'd like to setup a solar panel/battery/inverter system to run the freezer while it's in storage such that when I go get it to do some catering/vending the chest freezer would already be cooled down and ready to go. This way I wouldn't have to store the trailer where electric is available or wait on the freezer to cool down when I get the trailer out of storage.

I'd like to permanently mount the panels to the top of my trailer and then I can build something to store the battery(ies) and inverter and other equipment needed to do this. Once on site, I would plug in to normal electric or my generator to run the freezer.

If someone could help me put together the parts needed or point me to a premade system that would help a lot. I can try to get specs off the freezer (as I'm sure that will help a lot) if needed. I understand the theory, but I'm not 100% on the parts needed and/or the wattage panels needed and amount or size of batteries needed.

Thanks and I'll be watching the thread - appreciate the help!

[Sunking]

Well all depends on how much energy the fridge will use in a day and your location. Chances are you trailer is not large enough to hold all the panels and batteries required to do this. All depends on how much power it needs and location.

[vexter0944]

Well all depends on how much energy the fridge will use in a day and your location. Chances are you trailer is not large enough to hold all the panels and batteries required to do this. All depends on how much power it needs and location.

Thanks for the response! Much appreciated!

My location is very close to St. Louis, MO. As far as space...I have 26' of trailer with a fair amount of room left over to figure something out if it will work....of course it would depend on what equipment is deemed necessary. I believe this is my freezer - http://www.samsclub.com/sams/shop/pr...055&navAction=

The only way I know to get an idea of what power it needs is to put a Kill-a-watt on it and run it in fridge mode and see what goes on there. Which I have no problem doing - but I wasn't sure of how many panels and other equipment/batteries I'd need to swing this.

Based on something like this - http://mtbest.net/chest_fridge.pdf - I wouldn't think it would use too much power - but I'd have to confirm obviously as my model and the author's could be quite different. The freezer would be mounted on the trailer inside out of weather.

Thanks again!

[Mike90250]

1) if you have to have "approved unit" to meet food health codes, it will likely fail. If all they care about it, is that it's cold inside, likely OK.

2) Condensation. Where will it go ? Bottom of the unit, you either have to bail or sponge it out daily. Yucch.

3) it will still take 12 hours to chill down. And it will take a long time to chill warm foods. May need an air circulation fan to assist.

4) power requirements. Ah - the good stuff. You will have to ask an electrician to measure the Peak Starting Amps of the motor, with a $400 meter. Most won't have that, you will have to try 3 or 4 of them. Then you chose an inverter that can supply the starting surge. The batteries and cables have to be able to pass that surge, without dropping voltage below the inverter shut-off voltage. You can use any plug in watt meters (kill-a-watt) to measure power over a several day period.
Generally, you need to harvest 1 - 1.5Kwh a day to keep a unit cold. If that's an area with 4 hours of good sun, you need 500W of PV. Likely you will need a 24V inverter to make things easier.

Or you get a Co2 fire ex, and blast away inside the cabinet each time you need to use it, the Co2 snow will chill it right down. Or drop a block of dry ice inside the day before you need it. A lot more simpler.

[Sunking]

The only way I know to get an idea of what power it needs is to put a Kill-a-watt on it and run it in fridge mode and see what goes on there. Which I have no problem doing - but I wasn't sure of how many panels and other equipment/batteries I'd need to swing this.

The only way to determine is to know how much power it uses in a day. Run the Kill-A-Watt for a week or more to get accurate data.

[vexter0944]

1) if you have to have "approved unit" to meet food health codes, it will likely fail. If all they care about it, is that it's cold inside, likely OK.

2) Condensation. Where will it go ? Bottom of the unit, you either have to bail or sponge it out daily. Yucch.

3) it will still take 12 hours to chill down. And it will take a long time to chill warm foods. May need an air circulation fan to assist.

4) power requirements. Ah - the good stuff. You will have to ask an electrician to measure the Peak Starting Amps of the motor, with a $400 meter. Most won't have that, you will have to try 3 or 4 of them. Then you chose an inverter that can supply the starting surge. The batteries and cables have to be able to pass that surge, without dropping voltage below the inverter shut-off voltage. You can use any plug in watt meters (kill-a-watt) to measure power over a several day period.
Generally, you need to harvest 1 - 1.5Kwh a day to keep a unit cold. If that's an area with 4 hours of good sun, you need 500W of PV. Likely you will need a 24V inverter to make things easier.

Or you get a Co2 fire ex, and blast away inside the cabinet each time you need to use it, the Co2 snow will chill it right down. Or drop a block of dry ice inside the day before you need it. A lot more simpler.

Some great thoughts there - thanks so much!

1. I think I have this one covered - myhealth dept allows ANSI certified equipment which GE units are - so I think I'm good here.

2. I had read about that but didn't think about it daily...which leads to 3...

3. I'm ok with the 12 hours to cool down if I could swing buy the lot the day before (which is usually not an issue...) - I'm planning on basically using it to hold raw meat that will already be cold from the
distributor or my comissary fridge - I do BBQ (like on a smoker) - but the health dept won't let me hold raw meat on ice all day until I'm ready to put it on the pit - so I have to have something to keep it cold - but I don't want to freeze it - hence the chest freezer into a fridge plan - because I can fit a lot more into the chest 'fridge' than I can a normal fridge due to the fact that I'm stacking raw meat in cryovac on top of each other.

4. Duly noted That sounds like a lot of PV - could be more than I could mount on the trailer...

The dry ice idea sounds rockin...and easy....I'm liking that one..

[TnAndy]

Yep...it will work. Got a couple of those external thermostat controllers, and did test run on a 9cuft freezer running as a fridge. Took about 200-225 watt/hrs per 24hr day, (per Kil-a-Watt meter) using it in a "normal" manner.....that is, part full, opening several times per day. I saw the idea on some guy's website in Australia where he claimed 100watt/hrs/day, but didn't list the spec on the freezer he was using, so it's either smaller or way more energy efficient than the one we tried.

I bought these external thermostats in case of permanent grid down situation, I'd have a way to convert one of my chest freezers to an ultra low consumption fridge.....this was when I had only a 2.1Kw solar power system. Now that I've expanded the PV system, that is less of an issue.

Given how you want to use it, which I take it is only between permanent power locations ( like in transit ), I doubt I'd bother with going with panels. I'd set up a small battery bank ( like maybe 200amp/hr), put a good charger on it ( like an Iota smart charger ) and put in a good enough inverter to handle the start load of the motor, and call it good....the whole shebang would fit in a pretty small area.

By the way, I also built a 6x6 walk in cooler, and run it with a 10,000 BTU window AC unit. Company called "Coolbot" makes a neat over ride thermostat that allows you to use a plain ole window AC, and keep the cooler at 34 degrees. I use it a couple times a year when we slaughter pigs or beef, which is why I didn't want to sink a fortune in a commercial unit.

[vexter0944]

Yep...it will work. Got a couple of those external thermostat controllers, and did test run on a 9cuft freezer running as a fridge. Took about 200-225 watt/hrs per 24hr day, (per Kil-a-Watt meter) using it in a "normal" manner.....that is, part full, opening several times per day. I saw the idea on some guy's website in Australia where he claimed 100watt/hrs/day, but didn't list the spec on the freezer he was using, so it's either smaller or way more energy efficient than the one we tried.

Given how you want to use it, which I take it is only between permanent power locations ( like in transit ), I doubt I'd bother with going with panels. I'd set up a small battery bank ( like maybe 200amp/hr), put a good charger on it ( like an Iota smart charger ) and put in a good enough inverter to handle the start load of the motor, and call it good....the whole shebang would fit in a pretty small area.

Ahhh....I gotcha....sounds like you read the same site I did - Australia as well - LOL! The web makes us all closer than we think huh - LOL!

Anyway...how many and what kind of batteries would make up the 200amp/hr bank? How would it be wired? I'm not new to 12V but I'm used to single battery applications and car audio.

Could you give me links to the iota (a quick google showed a lot of different models..) and batteries? I think I can pick the inverter.

Keep em coming - I sure do appreciate it!

[Mike90250]

my health dept allows ANSI certified equipment which GE units are - so I think I'm good here.

A certified freezer, modded to a fridge, is no longer certified.

[vexter0944]

A certified freezer, modded to a fridge, is no longer certified.

I would normally agree - but I did ask and they said as long as it kept cold, they didn't care how (and I explained how I was going to) - yes - I need this in writing

[TnAndy]

Ahhh....I gotcha....sounds like you read the same site I did - Australia as well - LOL! The web makes us all closer than we think huh - LOL!

Anyway...how many and what kind of batteries would make up the 200amp/hr bank? How would it be wired? I'm not new to 12V but I'm used to single battery applications and car audio.

Could you give me links to the iota (a quick google showed a lot of different models..) and batteries? I think I can pick the inverter.

Keep em coming - I sure do appreciate it!

Given what you're gonna do, I'd probably go 12v. Shop around locally for batteries, look for a Trojan or Deka dealer, and tell them what you're doing, and get their recommendation.

The charger, a 30 or 45amp one will do what you want...this is gonna be a simple deal with a fairly small bank, and you want something you can leave plugged in at home ( or on the site ) to keep the batteries up, so I'm thinking you won't need a huge charger, or go up to 24v.....those get pretty expensive.

[vexter0944]

Given what you're gonna do, I'd probably go 12v. Shop around locally for batteries, look for a Trojan or Deka dealer, and tell them what you're doing, and get their recommendation.

The charger, a 30 or 45amp one will do what you want...this is gonna be a simple deal with a fairly small bank, and you want something you can leave plugged in at home ( or on the site ) to keep the batteries up, so I'm thinking you won't need a huge charger, or go up to 24v.....those get pretty expensive.

OK - this is making some sense to me - as I want to be able to go out like the night before an event, turn on the fridge/freezer and have it cool down overnight. So how would I keep the batteries charged inbetween uses? This is something I do 1 to 2 times a month max during the summer. I can see removing the batteries during the time of year when I'm not using the trailer, but what keeps them charged?

Sorry, I got to thinking about this after reading and starting to look up the equipment noted in your response and maybe I'm over thinking it or just plain not understanding. Thanks once again - this is giving me some good ideas!

[TnAndy]

I was assuming you had someplace to plug in an extension cord from the trailer to where you park it....that not the case ?

[Naptown]

So if you go there the night before and there is power available just plug into that and be done with it. No need for the Solar aspect. If no power available that's a different story.

[vexter0944]

I was assuming you had someplace to plug in an extension cord from the trailer to where you park it....that not the case ?

No - that's the problem - no power in my lot to utilize the night before.