"Refrigeration" off the grid

Hi,
I am designing my truck to work almost completely on 12v. There will be a small inverter for specific non-12v things.
I was leaning heavy towards just using removable coolers to store product in. Used in conjunction with re-freezable plastic ice blocks, I figure this would be a very economic way to keep my product as cold as it needs to be throughout the day of sales.
 
Since looking at some of the discussions about "plate freezers" on here, and thinking about the idea of re-freezable plastic ice blocks to another level, I have considered another option that I wanted to get some opinions on.
 
I was thinking if I have the space, to install a 7 cu chest freezer in the corner of the truck. When the truck is parked overnight, this freezer would be emptied except for the reusable ice blocks. It would be plugged along with my battery bank for recharging, in and the somewhat defrosted ice blocks would re-freeze. In the next morning, everything is unplugged and the chest freezer, along with included ice blocks acts as an insulated cooler.
I suppose on one hand, this is a glorified and more expensive insulated cooler. But I think I could set up the inside so that it is not only spacious and organized but efficient at keeping cool product on a daily basis. Maybe the most beneficial aspect of this is if I happen to do a 3 day event where there is energy, I can keep the freezer plugged in and use it to keep product frozen day after day.
 
It may not be a silver bullet arrangement, but it seems like it has promise and may have some benefits over an insulated cooler setup.
 

Only one question, will your HD allow you to do this? Ours would not for 3 or 4 reasons.
jack

I don't know specifically, but I can't see why not as it would operate the same as an ice cooler at the very least as long as the temps stayed below 40.

I'd check before I even planed it.
 
We can only use coolers as a temporary storage device for transportation from point A to point B.

And if your moving a truck or trailer from point A to Point B all food must be taken out of a cooler (reach in type) and put in a cooler (portable type) during the move.
 
We may not move food from a service unit to another unit (home) and back to the service unit.
 
I'd bet (never tried it) but I'd bet our HD would make us throw out food in a freezer if it were not completely frozen. Just because it said freezer on the out side, they'd want the temp to be low enough to freeze the food.
 
And finally if you have food on board at an event and it's frozen how are you going to cook and serve it ?

Home (unit) for me is a licensed commissary. Regardless, I am not sure our rules are as strict as yours.
The "freezer" not being a freezer is a good point, but really, I can't see the problem if they know the routine and know that the food is never getting into the danger zone temps unless its on the grill.
 
I have dealt with frozen food before. Sometimes its not completely defrosted. I defrost it on site.
 
On top of all this, I am not dealing with meat. I serve soy and wheat gluten based meat substitutes. I am sure it sounds wonderful to a BBQ type like yourself. :) But it is popular in these parts and certain events.
 
Thanks for the feedback. I'll definitely check with the local HD before making any investments.

We use a couple "Nordic Ice" packs in an "extreme" 5 day cooler. These ice packs are fantastic and work better than any ice blocks or "blue" ice packs. My daughter gets them in with the chocolates the store she works at gets. You can also buy them from Cabala's and on Amazon or eBay. They are well worth the $$. We place them back in the upright freezer overnight.  They are still mostly to completely frozen at the end of the day.
 
I will keep my opinion about the freezer to myself.

"I serve soy and wheat gluten based meat substitutes."
 
Oh hell I'm sorry I even tried to help. I didn't know you served fake meat,
I don't know anything about that stuff, in fact never even tasted it. None
of the rules that I work with daily apply so forget my post.
jack

Well, your experiences may help regardless of what I am serving. I just thought it was worth mentioning that since meats are considered some of the most high risk foods for food borne pathogens and often have more strict guidelines. Beans can be hazardous as well. So, vegetarian foods aren't necessarily less susceptible pathogens and should require proper food handling protocols.
Much the way processed meat hot dogs are exempt from a lot of scrutiny when it comes to strict food handling protocols compared to raw meat products, the products I sell, while completely animal product free, are pasteurized and packaged similarly to meat hot dogs.

not sure what you plan to charge your battery bank, but I will tell you this, One deep cycle marine battery take about 4 hours to charge on a 75amp speed charger in my parts of the world... I'd  be more interested in your battery bank than anything else
 

I would think about upping to a 24v system, 2-12v batteries wired together.  Get a better true sine wave inverter/charger, and use Golf Cart batteries, not marine batteries. 
 
al

Golf Cart batteries= $$$$$$$$

I have a nelson cold plate freezer in my ice cream truck. I plug in at night and it'll stay cold over 24 hours and hold ice cream after it's been unplugged. Nelson also sells portable cold plates. I havent used them but if they work as well as the cold plates in their freezers these would be well worth it. http://www.cnelson.com/frozen-dessert-carts/cold-plates-re-useable
 
My health dept also will not allow the use of coolers to store product in the service unit as the only means of keeping product. Mechanical refrigeration is required for licensure of the service unit. And all equipment including freezers in the service unit must be NSF or equivalant. (CSA,UL, Intertek)

Dr of BBQ


Golf Cart batteries= $$$$$$$$

I dont usually post, because I dont have anything to contribute. Im still learning, and I learned years ago to do more listening - then talking. (or maybe the wife told me that).
That being said, I did a really fast search on Golf Cart Batteries and I was surprised to find that there really IS a difference between a Marine & Golf Cart battery. Performance, life span and cost. Plus, Golf carts use 6-8 battery's, to last a 18 hole round of golf.  I have no idea how many you would need, to accomplish what you talking about. BUT.......they start at $200 ea.
 
See? We (I) never stop learning....

I don't know about that. I can find Trojan t105s here locally for $115 a piece. The marine/rv battery I have now retails about $80 or 90. Its rated at 180 amp/hours, I'd say the t105 is comparable in price at 225 amp/hours.

Plus the t105 is a true deep cycle whereas the rv/marines are just hybrids and shouldn't be run down so much.

I noticed my costco selling golf cart batteries, but I couldn't find any amp hr info on it. I should ask them in the tire area.

The Class C has a 12 volt Deep Cycle Marine battery from Wal-Mart (Everstart Maxx DC--- DC stands for Deep Cycle.... there is a difference) put in it when we first got it as the "house" battery. It powers all the lights and the water pump. Dumb vintage converter (1980's?) charges it while plugged into shore power. That was back in the summer of 2006. Same battery is still going strong. Makes it almost 6 yo (will be 6 yo in June).
 
If you really want good info on batteries you need to read the Ample Power Primer and Phred's Poop sheets on batteries. The Poop Sheets are easier to understand for me.
 
The best recommendation I have ever heard for batteries is to buy cheap and kill a few sets as learners before buying a decent set. Thing about batteries, the cheaper they are the more instrumentation you need on them. The more you learn, the more you are happy that you got the instrumentation to use on the good batteries when you finally get them. 
 
House battery bank in our bus conversion will be deep cycle marine  batteries on a 3 stage smart charger system. I cannot fit the tall golf cart batteries in the bay. My marine batteries should have a life span of 5 to 7 years  (similar to golf cart batteries) and will cost roughly half the price of a single 6V golf cart battery. BTW, you have to buy golf cart batteries in pairs to get 12vDC bank. I did the math  and FOR US the standard Deep Cycle Marine batteries were far cheaper.
 
David uses the starter battery from the bus in his cart (just for lights & water pump). Puts it on the charger about every other week. Makes more sense to use it than to let it sit doing nothing and draining down. In freezing weather, he charges it more often... a fully charged battery is less likely to freeze.

Dry Ice might be another option...
 
Yes, it will take TWO T-105 batteries to make 12vdc...that's your basic building block of off grid electricity...and this SERIES of two batteries wil put out about 225 amps...
 
BUT...
 
You do NOT want to drain these ALL THEY WAY DOWN...(I've spent a lot of time off grid, on grid, and half and half, so I know a bit aboiut this)...
 
This is how the pro's do it...
 
To properly size a SYSTEM you need to start at th eend and work your way forward, because it all has to work together as a system, not just some stuff cobbed together...
 
1)...You calculate your loads...maximum draw, worst case scenrio, and will the loads be 12vdc or 120vac...???
 
Lets assume you're going to use a quality true sine wave inverter to convert 12vdc to 120 vac...
 
How many hours a day does it need to be working...???
 
What is your charging source...???
 
We'll get to these in just a moment, so follow me on this:
 
2)...calculate how large of an inverter you'll need, kmowing that nothing is 100% efficient, and you risk damage to an inverter running at 100% all the time, so add in some margins, and remember SURGE power required when some things are first turned on...
 
So for example, IF I needed 1,000 watts at 120vac, I'd want a true sine wave inverter of at least double that capacity minimum (2,000 watts)...
 
3)...in this example, to produce 2,000 watts at 120vac, that equals roughly 17 amps current...this tells me what size wires I'll need (and don't forget that you'll need fuses on this output circuit)...for the Inverter OUTPUT.
 
4)...In order to get 2,000 watts at 120vac OUT of the inverter, you'll need to stuff 2,200 watts at 12vdc IN the inverter...and that's 184 amps current (this is why battery cables are so large) and of course, you'll also install appropriate size fuses between the battery bank and the inverter input.
 
5)...To produce 184 amps of current at 12vdc for extened periods, you'll need to add a few more batteries, so this is where you calculate how many hours a day, how many days a week
 
Remember to add a margin for reserve, inefficiency, and that you *never* run your batteries all the way down...
 
I'd never run my batteries down more than 50%. How can you tell...???  There are meters you can install that tell you this.
 
Why are two t-105 SIX volt DC batteries used instead of just one TWELVE volt DC  battery...???  Plate size...plate size (area) determines the true output of a battery, and for how long.
 
T-105 type are rated as 225 amps, come in golf cart, marine, and AGM versions...
 
We know that TWO of these, wired in SERIES is tha basic building block...see below...
 
 

 
 
So it's the combination of series and parallel connections that make up a battery bank of any desired voltage and amperage...and so far I've used a 12vdc battery bank as an example. The calculations will be different if you wanted 24 volts to run a quality 24vdc inverter...
 
6)...ok, so lets say that you've gotten this far in systen design...you know you want a certian output from the battery bank for a certian period of time...and this now takes us to charging method and time period to charge the batteries.
 
Certain types of batteries have different charging limits, so an el chepo car/automotive charger ain't gonna cut it here...this, like the inverter, will come from a quality solar power shop...this is important because the wrong type of charging method can and will damage some types of batteries...
 
To get power out of a battery bank you must recharge it as soon as possible and do a 100% complete charge, not a partial charge. So this will drive the specs for your charger. gonna plug it in at night where (for some) the electric rates are cheaper (if on a T.O.U. meter)... ???
 
You'll want the charger hardwired onboard so all you need to is plug it in to "shore power" at home oe elsewhere.
 
Remember that batteries will be heavy so they need to be located someplace low to keep your center of gravity low, and also in a place that distributes the weight favorably front to back, especially if this is going into a towable trailer where tongue weight is a concern...
 
Batteries also need to be accessable so you can inspect the water level (at least once a week), get to the fuses, and also remember that chargingg batteries emit hydrogen gas, so the battery compartment should be well vented to the outside, and sealed from any flame source inside the rig
 
Distilled (de-ionized) water should be kept on had for the batteries...use of any other kind of water (tap, well, spring, bottled drinking water) will kill your batteries overnight...
 
You can mitigate the power used while on location with solar panels on the roof and have a sunny place to park...
 
You'll want your SYSTEM to be installed by a professional who understand code (such as IBC or UBC) and hopefully has done  a mobile install before, and ask your county HD of they need the electrical system on board to pass an electical inspection as well...
 
BTW, while I wish you luck...are you sure you don't want to at least cook up some cajun hot links...???
 
PS...you can learn a lot about solar electric systems in general, and available equipment, by reading Home Power Magazine, Ashland, OR, USA

You forgot to mention that the setup you described is not an install & forget it thing. You mess with the batteries all the time.
 
For a mobile install, try finding someone who does installs for RVs.
 
There's a reason we are buying a generator over a battery bank. Less hassle. We got better things to do than test batteries, check the fluid levels & specific gravity all the time... or whatever is done. I just know enough to know what would work best for us. You need to do the same.
 
For just powering a freezer, a 12vDC battery bank seems excessive.  We will be powering a chest freezer & small air conditioner. For that, we are using a generator. Some of the Honda EU's & Kipor inverter generators would suit your needs. Unless you must be generator free. We don't have that problem, at this point.

Lorna - if you go back and read his original post, he says he wants to run the mobile part on 12 volts DC...that DOES require batteries, and why much of this thread talks about batteries...
 
Also, if you go back and read MY post, you'll notice that I said the batteries need to be accessable to check them once a week.
 
Flooded batteries do need the water levels checked. With a good meter you shouldn't ahve to compare cells with a hydrometer but once a month to see if it's time for an "equalizing charge"...
 
Sealed (valve regulated) and AGM batteries don't need ot have water checked...they're sealed...but the also have voltage restriction in their charging specs: 14.5vdc MAX...and thisis why I said SOME batteries have special chargingneeds and an automotive type charger will damage the batteries...auto chargers typically put out more than 16 volts dc, and while a novice might think that 1.5vdc difference doesn't make a difference...believe me...it DOES and will damage AGM and valve regulated sealed batteries.
 
Treat your battereies like the major investment that they are, and you'll get maximum life out of them...and for T-105 type 5 to 7 years is typical IF you treat them nice...I know...I've been doing this for 35 years...in an area where many are beyond power lines...
 
 

PS...same about charging rate for Gel Cell batteries ... if you charge them at too high a voltage gas bubbles will form on the plates and can't be removed...in a flooded cell, any gas bubbles formed will float up to the top of the water electolyte...that can't happen in a gelled electrolyte...and in gel cells bubbles remove that surface area of the plate from ever functioning again in the electro-chemical conversion process we call "electricty"...

Hi. First time poster. I designed my truck to run on batteries for (what I hoped would be) extended periods. I wanted to be able to work without running a genset, either recharging off the truck's alternator or off shore power at night. All my cooking is done with propane. I had originally planned a propane fridge as well, for the purpose of reducing the electric load. But I ran out of money and put in an electric fridge instead.
 
I carry four Optima blue-tops and a 5000 watt inverter which can drive every electric appliance I have for as long as the batteries will bear it. No 12-volt stuff, except for my water pump. Not sure why you chose to run everything off 12v DC, it is very inefficient.
 
My experience with this stuff, I hope this helps you:
 
--I can run one of my 1100 cfm exhaust fans, my lights and my fridge for 2 - 2.5 hours before the batteries die. There are times when this is desirable, mostly in situations where I want to run silently yet shore power is not available at the site. This situation does not occur often.
 
--I can easily run my fridge all night off the battery bank if for some reason I can't get overnight shore power. This does beat the hell out of running a generator all night. Advantage: batteries.
 
--A 200 amp-hour battery bank will cheerfully pull as many amps when recharging as you will give it. You can not charge the batteries with your vehicle's alternator, it will overheat. You will burn up lots of A/C battery chargers trying to push enough electricity into it to charge it quickly. Eventually you will either get a specialized ultra-duty shore powered charger with temperature probes (marine industry = $$$) looking for the magic 4-hour charge or you will just learn to wait for it to charge off a 6-amp POS charger from the Wal Mart which can take days. I burned the clamps right off a 15-amp Sears charger--I don't mean the insulation melted off the leads, I mean the stranded copper cables burnt through. Consumer-grade chargers just can not handle loads like this.
 
--I can keep the fridge running while I am driving, for free, without running the genset. This is mostly what I use the batteries for. It is nice to be able to do this I must admit. But I almost never drive the food truck for more than 30 minutes at a time so it is more a conversation piece than a money-saver. Not sure what it costs to run my Aurora genset for 30 minutes but it is surely well under one dollar.
 
--I would not do it this way again. I would install a quiet, reliable diesel generator and run it when I need electricity and shore power is not available. I would do it just like all the other food trucks whose operators have enough sense to realize the wheel has already been invented. =^}
 
Hope this helps,
 
Ken
Tamale Trolley Food Truck
Memphis, TN

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Tamale Trolley,
Welcome to Roadfood!
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http://tamaletrolly.com/
http://twitter.com/TamaleTrolley
If & when in Memphis, check out his Batteries as well as his Tamales!

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Wow! Thanks man. Didn't expect that. That's not really my web site--we would be at www.tamaletrolley.mx if I had bothered to build a web site but I have not. =^)

just a thought......but what about covering your roof with solar panels? Could be a sales gimmick and ease your load.

That is a good idea and I think I will consider it down the road.