Refrigeration with Very Little Power (or No Power)

[churchmouse]

I have built up, used and sold a few 4 to 6 battery invertor packages to friends with off the grid cabins. These have the ability to run most anything residential in nature including a gas furnace. I am gathering materials now to build an 8 battery multi inverter bank and genny package. This is an expensive build but when done it would have the capacity to run 2 houses if properly monitored and usage was kept under control. A fridge like OP lists would not hit that bank very hard at all.
I am looking at solar options to keep the banks topped off but that ain't cheap either.

 

[SkinNFluff]

RV fridge, runs off propane, cheap and plentiful.

If the grid were to go down for 6-8 weeks or longer, gas were to become scarce, propane sold out, and natural gas was not available, what alternatives would you seek during warm months for refrigeration? Yes, you can cure meat. Yes, you can root cellar. But if you must refrigerate, such as to store insulin in addition to food, what approach would you use?

propane is only good if you can get it.

 

[churchmouse]

RV fridge, runs off propane, cheap and plentiful.

I think the OP is stating his idea may outlast supplys such as propane. If the S does HTF then you will be hard pressed to find and acquire Propane.

 

[Spudgunr]

I think the OP is stating his idea may outlast supplys such as propane. If the S does HTF then you will be hard pressed to find and acquire Propane.

Why would you wait until the SHTF to acquire the propane? A small propane fridge and a 1000 gallon tank would last quite some time. You can store up to 2000 gallons residentially, a quick search showed at least one propane fridge running 1/3 of a gallon a day. A couple years worth at least (though you'd have no redundancy). It would also only be a few thousand dollar proposition, probably around the same though as an electric option with gas and solar backup. You'd need maybe 200W worth of solar panels to possibly not have to run the generator, though several days of bad weather and you would still need to. I like the electrical version because more can be done with it, but if we are talking 6 months plus then it is pretty much going to HAVE to be primarily solar and supplemented with generators/chargers just from a fuel storage standpoint (unless you go propane and trifuel, which is also an option).

 

[churchmouse]

Why would you wait until the SHTF to acquire the propane? A small propane fridge and a 1000 gallon tank would last quite some time. A couple years maybe? It would also only be a few thousand dollar proposition, probably around the same though as an electric option with gas and solar backup. You'd need maybe 200W worth of solar panels to possibly not have to run the generator, though several days of bad weather and you would still need to.

I have found that properly managed the package I build can run a cabin for 3 or 4 days with out a recharge. A house with woman and kids is not easily managed as they do not think past the light switch.
I put bass boat multi-circuit chargers on these to maintain charge levels if you are on the grid. In the woods a good charger is required and depending on how far you drop the level they will charge up in a good couple of hours genny run time. The advantage to these is you can have lights/convenience at night and not run a genny to attract the zombies in a SHTF situation.

 

[6mm Shoot]

The propane system is a easy way to go. You just need to get a 300 gallon tank or bigger for propane storage. I have four 40 pound tanks for our 32' travel trailer and in less you are using the heat it last about 2 months running the fridge and stove. If you are using it for heat it will last about a month.

So if the grid went down in the winter we can go for four months before we have to refill tanks. That would take us through winter. That is the plan if the grid goes down due to a storm or what ever. That is also why I bought two extra tanks. Most travel trailers come with two tanks.

I must say that it isn't a cheap system. The fridge cost some where around a grand. The tanks go for around $100 each. Then you have to get all the stuff to hook it up. That probably cost around $100 more for the regulator, tubing and fittings. If you get one that runs off electric also it will cost about $200 more for the duel powered fridge. Then you will have to have the voltage converter and that goes for a couple $100 with the wiring.

Good luck with what ever you decide.

 

[BigBoxaJunk]

My families cabin in Canada has an old Servel Fridge that my grandfather took up there in the mid 1950's. It was a natural gas unit that he'd had converted to propane; it's been serviced once and still works fine after more than 50 years of use up there. Since I was a kid, I always thought it was fascinating how that gas flame could be harnessed to make things cold, and the freezer compartment gets darned cold.

I've always wondered how hard it would be to use an alternative heat source for that type of fridge. Maybe heat from a solar collector, or heat from burning wood or charcoal.

 

[churchmouse]

My families cabin in Canada has an old Servel Fridge that my grandfather took up there in the mid 1950's. It was a natural gas unit that he'd had converted to propane; it's been serviced once and still works fine after more than 50 years of use up there. Since I was a kid, I always thought it was fascinating how that gas flame could be harnessed to make things cold, and the freezer compartment gets darned cold.

I've always wondered how hard it would be to use an alternative heat source for that type of fridge. Maybe heat from a solar collector, or heat from burning wood or charcoal.

In a servel the flame is used in place of the heat generated from compressing refrigerant in a direct displacement mechanical pump. In a camper refer that is dual such as Propane/electric the resistance heater powered by electricity replaces the heat of the flame.
You could not possibly use anything that burns and control it closely enough to keep the system flowing. Just to hard to do.
Those old servels were so well made.

 

[BigBoxaJunk]

In a servel the flame is used in place of the heat generated from compressing refrigerant in a direct displacement mechanical pump. In a camper refer that is dual such as Propane/electric the resistance heater powered by electricity replaces the heat of the flame.
You could not possibly use anything that burns and control it closely enough to keep the system flowing. Just to hard to do.
Those old servels were so well made.

The whole place is a family treasure, but that fridge has always been one of it's jewels.

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60 years old and still in good shape.

 

[buckstopshere]

Set up your battery bank now and look up a guy named Steven Harris on google. He has some information on a super efficient ice maker that you can use to cool your fridge that will run on way less power than the actual fridge. Insulate it with a blanket after you put the ice in. An ice box so to speak.

 

[Clarity]

I think that the combo of a small, efficient freezer or refrigerator, and a small battery bank to store energy, combined with a modest solar set up to charge the batteries, and a gas or propane sipping generator to top off the batteries in the event of extended periods of overcast, is the way to go. We have stored up enough insulin for quite a while, and I have gathered, although not digested and understood, reading materials on the making of insulin from pig pancreas, as was done in war time in China long ago to save lives when insulin became more valuable than gold. I need to develop enough expertise to assemble this cooling system myself, or find someone knowledgeable to help me. Such as system would also be, albeit not easily, portable.

To me, it is all about staying flexible, as much as you can. You never know what will fail, or when you will need to leave. Backups for backups are needed.

 

[churchmouse]

I think that the combo of a small, efficient freezer or refrigerator, and a small battery bank to store energy, combined with a modest solar set up to charge the batteries, and a gas or propane sipping generator to top off the batteries in the event of extended periods of overcast, is the way to go. We have stored up enough insulin for quite a while, and I have gathered, although not digested and understood, reading materials on the making of insulin from pig pancreas, as was done in war time in China long ago to save lives when insulin became more valuable than gold. I need to develop enough expertise to assemble this cooling system myself, or find someone knowledgeable to help me. Such as system would also be, albeit not easily, portable.

To me, it is all about staying flexible, as much as you can. You never know what will fail, or when you will need to leave. Backups for backups are needed.

My 1st 3 battery bank/invertor packages were mobile to a point. They were on a skid like construction and fully boxed. Everything was contained with in. They worked very well. No solar but we used to cycle them often to keep the battery's fresh.
The one I am putting together now will have 8 deep cycle marine battery's (gell sells) with 2 RV rated invertors and a clean power invertor for electronics. This will run 2 houses.
We are no longer interested in mobility.

 

[RobbyMaQ]

My wife's uncle and aunt live out of a 5th wheel (traveling north america in their retirement). I am amazed at how efficient their system is (all propane). Of course, it's a trailer, not a 2000+ sq ft house...

 

[CountryBoy19]

My choice would be a good battery/inverter/generator system and a lot of gas. All parts are easy to come by, well documented, and would be very useful anyway in normal operations. You could run a small inverter off your car, run an extension cord to your battery bank, and then use a 30A charger for recharging, so you could even forgo the generator.

That is the most ridiculously inefficient way to power something. Auto engine > alternator is terribly innefficient > inverter has losses > battery charger has losses > batteries have losses > inverter (if using AC power at the end) has losses. I'm not even going to do any research, I'm just going to throw out a wag that your suggested system would be roughly 5% efficient. You would be much better off buying the worst of generators...


As far as what I've seen a lot of people do for low-power consumption refrigeration is they buy a small, high-effic. chest freezer and add a controller that keeps it above freezing. Freezers are more efficient and better insulated which is why they choose freezers. Then add in solar panel, inverter, & battery bank. Do go DC on the freezer/fridge. The money you save by getting a modern, HE, AC freezer on sale at the local big box store can be put towards extra solar panels or batteries. You will be much better off that route and your battery bank will be AC powered giving you a little more versatility on the days when the sun is shining strong and you need just a little power for something else...

 

[Spudgunr]

That is the most ridiculously inefficient way to power something. Auto engine > alternator is terribly innefficient > inverter has losses > battery charger has losses > batteries have losses > inverter (if using AC power at the end) has losses. I'm not even going to do any research, I'm just going to throw out a wag that your suggested system would be roughly 5% efficient. You would be much better off buying the worst of generators...


As far as what I've seen a lot of people do for low-power consumption refrigeration is they buy a small, high-effic. chest freezer and add a controller that keeps it above freezing. Freezers are more efficient and better insulated which is why they choose freezers. Then add in solar panel, inverter, & battery bank. Do go DC on the freezer/fridge. The money you save by getting a modern, HE, AC freezer on sale at the local big box store can be put towards extra solar panels or batteries. You will be much better off that route and your battery bank will be AC powered giving you a little more versatility on the days when the sun is shining strong and you need just a little power for something else...

You are right that it is pretty inefficient, but its easy and cheap to throw together. It is WAY worse than a honda EU, but its not much worse than some of the cheapie generators and it is a lower consumption alternative. You CANNOT charge a battery bank with less than a couple hours, so with the battery bank option you aren't looking at watts per gallon, you are looking at gallons per hour (unless your charging rate exceeds the output capacity at idle of your generator). My cheap generator uses a gallon on hour for 4000 watts, or it can put out 2000 watts and use almost that much (3/4 or so, I don't remember, and with no load at all it'll use a gallon in 2 hours). I didn't say you had to or even should, I said you COULD use it hooked to your alternator. Did you even read the post? The second paragraph says that a generator would give you more output for the same amount of fuel, or in the case of the inverter generators (Honda EU, yamaha, etc) you can get a LOT of runtime from a gallon of fuel but they are $1000+. An inverter is $50 (and you could use the one that is in the system to begin with) and cars will just be lying around come SHTF. I'd hazard a guess you have access to at least a couple right now. When it is time to replace my alternator I MAY (haven't decided yet) replace it with a high output unit that puts out over 100 amps at IDLE (200+ at speed), that is 1400 watts with nearly 3 hours per gallon, not nearly as efficient as a honda eu generator (they can do two to three times better), but not nearly as costly either, and it is two to three times as efficient as my generator with a similar load.

For long term reliability I think if I were going to hack a controller into the system I'd get a couple. Though that is true of every part of this system, I would not just have one generator, or just have one inverter, or even just one battery bank. I would rather have 2 sets of 4 than one set of 8 in case there were some component failure and they went into meltdown. Fusing at the battery cables should help to prevent that, but isn't guaranteed.

I would not worry about a dc fridge too much (that decision would primarily be driven by price), but if you do, get TWO of them. In this immediately life or death type situation, redundancy is absolute key. Or, a DC one, and a normal fridge and inverter. I was going to make a comment about how many more amps 12v dc uses than 120 and so your fridge would need to be near the batteries, but if you have a small super efficient fridge it really shouldn't use much. My 15 cubic foot deep freeze that is full only uses 90 watts while running, I suspect the 12v fridges would be even less due to (I HOPE) increased insulation and smaller size.

It seems that the consensus is one of two ways: Inverter/battery system or direct propane/kerosene fridge. Based on some of the longevity claims on the combustion fridges that would seem to be a good option, but it would be quite expensive to have redundancy (though it is less likely to be needed).

I think either way, you could have a pretty sweet system for $2000-4000 depending on what infrastructure you can put in place and how many redundancies you want.

I was going to compare some usage figures from a 12v fridge (which uses more power than my freezer), but comparing a fridge which gets used FREQUENTLY to a deep freeze that didn't get opened in the test period isn't exactly a fair comparison. I will say that my deep freeze, in the basement in the month of March, used 0.66 kwh per day over a 5 day stretch. You would want to add insulation (gluing on foam panels would suffice) and turn the temp down and you could likely get that down to under 0.5 kwh per day. It does look like though the low voltage specific fridge uses a small amount less energy, it would likely be much cheaper to just buy one extra small solar panel than to buy the dedicated 12v fridge. Those are statments about one specific 12v fridge maker though that the off grid community seemed to regard as shady in their advertising, so there may be others that are better and cheaper.

Don't forget, you wont HAVE to refrigerate (or at least significantly so) for 3+ months a year, though I could see some merit in keeping the meds and fridge in one location such as a basement and not trying to fool with ice/snow and such, particularly if you have an excess of solar energy anyhow. If you DO choose to refrigerate in the dead of winter, don't forget to size the solar for the reduced solar hours in winter, or plan to run the generator.

 

[churchmouse]

Not that hard to set up 12V lights as back up. The cabins I have mentioned are 12V lighting period. The 120V side is for the coffee pot and other appliances. Propane forced air furnace and such. It is nice to have ample power during sleep periods without the thrum of a genny and having to fuel it up.

 

[Spudgunr]

Also, if you are considering a 120v system, a meter will be invaluable. Kill-a-wat meters are a great tool to find out how much an appliance is using. It will tell you current usage (both current as in amps drawn and current as in the watts iti s currently using) and energy over time, I think up to a week or so?

 

[churchmouse]

I have access to parts and pieces from Motor homes. A lot of folks will buy one and rune it until they need brakes and tires and realize they do not want to put that money out. Some of these units only have 30K on them and have been sitting for a while. Many are headed for the scrapper. These have decent invertors and genny's on them. Many have a nice DC/genny control panel as well. 12V lighting and other systems that still work well. A few hours work and this gear goes a long way in setting up for off the grid.
Look around. If you are crafty and posses the skills it is not that hard to put together something that over time can be expanded and improved upon.

 

[CountryBoy19]

Did you even read the post?

Hmmmm... did you even read the OP?

You would want to add insulation (gluing on foam panels would suffice) and turn the temp down and you could likely get that down to under 0.5 kwh per day.

Be careful with that. Most freezers and a lot of fridges have their condenser lines on the exterior panels of the unit. Adding insulation on the outside of those will increase power consumption by a very large amount and burn your freezer up. If you look at how the off-grid people are running freezers as fridges they are #1 trying to find freezers with external condenser coils (nearly impossible), #2 Running the freezer with water bottles in it to get down to temp and freeze the bottles then covering with heavy blankets with the freezer disconnected from power for extend periods of time. #3 No doing anything to the walls and only insulating the lid (almost never has condenser coils in it).

 

[armedindy]

didnt some old school fridges use propane?

http://home.howstuffworks.com/refrigerator5.htm

those of you with rv's and what-not