Only using fridge to make ice...?

[dreadlocks]

normal fridge power consumption can easily double, triple or more your needs when your trying to actively remove a bunch of heat instead of just maintain temps.. your plan sounds like your gonna run your fridge at basically full duty cycle trying to freeze a bunch of stuff.. at that point you can run two or three fridges, start w/pre-chilled contents and get better results.

Beer is my biggest consumer of energy, just tossing a warm 6 pack in every other day nearly doubles my power needs.. no amount of insulation or anything can fix that.

Making ICE boondocking, thats not for drinking, is a huge waste of energy.. basically pointless.

 

[Charles R]

The only thing I've read that was remotely similar to what you're going for, but not really at all, was someone who used the fridge as the icebox part of his system. Basically he keeps frozen foods and some ice packs in the 'freezer'. He then uses a cooler as the 'fridge', where he keeps more ice packs, and his cold foods. But the big difference here, that is drastically different than your plan, is that the freezer runs 24/7. It needs to, because he swaps out the ice packs every morning to keep the food cool. Like others have noted, these things are best at maintaining a set temp, not a constant freezing and thawing cycle.

Another downside you didn't mention is the extra space needed to carry both a fridge and a cooler. Maybe you have room to spare, though. I also think noise is an overestimated thing, too. But I don't know if you're basing that from real experience with a specific unit. For my Dometic, when it was new, it was dead quiet. Like, "can't even tell when it's cycling on, even when the vehicle is not running" kind of quiet. Now after running basically non-stop for 5 years at 36°f, you can certainly hear it. But I've never had a problem falling asleep with the level of noise my fridge produces... And I sleep RIGHT next to it.

 

[dreadlocks]

noise can be easily handled when sleeping, unplug it.. it'll run a lil harder in the morning but if its well packed full of cold mass it'll easily maintain safe refrigerator temps overnight.. popular hypermiling technique for solar users is to burn that excess unused energy when batteries absorbing to chill the fridge down as much as it can, and then let it coast overnight til the next day and repeat.. so in the afternoon you just turn the set temp way down so it runs continuously, and then when sun goes away you crank it up til morning and its basically off all night and uses very little battery as long as sun cooperates.

Fridges are generally well insulated, I had an ARB in a VW BUS w/no AirCon that would keep drinks frosty cold when it was sitting in the sun and 130F inside.. even then power consumption was less keeping that box cold than it is chilling a bunch of warm drinks.. and unlike a cooler I could use the sun against its self w/a solar panel on the roof.. same time it was heating up the bus it was cooling down my drinks so extra energy needs of ambient temps were moot.

 

[tanuki.himself]

Beer is my biggest consumer of energy, just tossing a warm 6 pack in every other day nearly doubles my power needs.. no amount of insulation or anything can fix that.

found the same problem in Oz - solution was to drink red wine at ambient temperature, and it tastes better than Australian beer.....

I'm planning on doing a similar thing, using a compressor unit in freezer mode (probably Webasto) on solar, load it up with pre-frozen food in portions, then use the food as ice packs to keep a larger cooler down to temperature as it thaws ready for cooking. If you start from a decent butchers and fishmongers they will usually vacuum bag and hard freeze whatever you want so you can eat quality stuff, and most of what is in the cooler needs to be kept above freezing anyway. Both compressor unit and cooler will be off the shelf but then i will cast PU foam around them to add extra insulation in the space they occupy . Will probably add an extra 12v fan and ducting where the compressor motor blows out to make sure the heat output is sent straight outside

and I can always throw a bottle of white wine in the freezer if i need a cold drink......

 

[DaveInDenver]

Seems like a decent idea, but I've never heard of anyone doing it, so maybe not! What I'm thinking is having a small fridge (15-20L) and using it only to freeze icepacks... and only when there is sun or the truck is running. It'll be turned off the rest of the time. Food and frozen icepacks will go in a good cooler.

Advantages:

a) lower battery requirements with the ice providing a buffer
b) not having the fridge noise at night
c) better insulation of the cooler
d) easy to just buy ice in town if you are looking at a week of rainy weather
e) if it's sunny you can make ice for other people

Downsides:

a) fridge will have lower efficiency at a lower temperature... but may be offset by the higher efficiency of the cooler.
b) futzing around exchanging icepacks and monitoring temperatures
c) temperature control is less precise

Anything I missed?
Anyone tried it?

It'll use more energy freezing ice compared to cooling but it's possible the smaller volume and potentially reduced duty cycle could make it work. I've heard of people doing this indefinitely (rotating ice blocks to a cooler) but I think the reason is just because they want a freezer mostly.

Since my Engel is an MT45 (huge) I've only tried it leading day trips so I could bring ice cream to hand out at lunch. If you test it and find the energy consumption is workable over time doing that will make you the king of summer trips...

 

[Rbertalotto]

I know folks with kids do this. Use the frig to freeze sport drinks and bottles of water every night. In the morning, water and drinks needed for the day and frozen foods needed for dinner are transferred to cooler. Keeping other foods cool. No messy ice to deal with. Frig is not opened until next morning.
Kids opening and closing frig dozens of times a day really hurts energy use.
They claim their aux battery lasts much longer with this method.

 

[DaveInDenver]

Frig is not opened until next morning.
Kids opening and closing frig dozens of times a day really hurts energy use.
They claim their aux battery lasts much longer with this method.

I can believe a small freezer such a 15L as @rruff is talking about opened just twice a day could end up being pretty efficient, especially compared to a larger fridge opened a dozen times. Not sure if the overall system is going to be more efficient since opening the cooler often and having the ice blocks melt faster will negate any system advantage. I think it's an interesting idea when you consider real world use, though.

 

[rruff]

Making ICE boondocking, thats not for drinking, is a huge waste of energy.. basically pointless.

The energy it takes to freeze ice is the same as it takes to melt it. Nothing lost there. Cooling down beer every day *is* a big load, but you'd have that whether you made ice or just used the fridge to do it.

I know folks with kids do this. Use the frig to freeze sport drinks and bottles of water every night. In the morning, water and drinks needed for the day and frozen foods needed for dinner are transferred to cooler.

I guess they are keeping a good amount of frozen food, but I don't plan on having any. I'd only run the freezer to make ice during the day using excess solar energy. If they are freezing at night they'd be using 100% battery. Night time will be cooler though, so the efficiency of the freezer would be a bit better, but still...

I can believe a small freezer such a 15L as @rruff is talking about opened just twice a day could end up being pretty efficient, especially compared to a larger fridge opened a dozen times. Not sure if the overall system is going to be more efficient since opening the cooler often and having the ice blocks melt faster will negate any system advantage. I think it's an interesting idea when you consider real world use, though.

Considerations for total energy use (solar power), comparing 1) Freezing icepacks in a tiny freezer during the afternoon (freezer is off the rest of the time) and transferring them to a good quality cooler at dinner time, vs 2) Running a larger refrigerator that is on all the time, would be:

a) Efficiency difference running the tiny freezer at freezing temp vs the fridge temp (say 25F vs 35F). About 15% based on some Secop data, in favor of #2.
b) Energy loss to the environment of the cooler+tiny freezer (only on a max of ~6hrs per day) vs the larger fridge. #1 should be better, but don't know how much. I need some real cooler vs fridge numbers to determine this.
c) Energy loss associated with cooling down the freezer once per day and exchanging icepacks twice per day (freezer to cooler in evening, cooler to freezer ~noon). Not a lot, but in favor of #2.

I figure I'd split the icepacks into 2 or 3 groups; on sunny days the oldest ones would go in the freezer. I'd have enough icepacks to last 4 cloudy days typically. That buffer is the main reason for doing this (plus I really don't want the fridge noise at night), as it greatly reduces the battery storage requirements to keep food from spoiling. If you figure at least 250W-hr/day to run a fridge, then that's 1,000W-hr of battery I wouldn't need. Note that this is for fulltime in the boonies, not trips.

The heat of fusion of ice is 333 J/g. 1 W-hr is 3600 J, so it's .0925 W-hr/g. 1,000 W-hr cooling would need 1000/.0925= 10,810g or 10.8 kg or 23.8lb of ice to last 4 days with a 250W-hr/day cooling load... but the cooler may have a smaller load than this.

 

[DaveInDenver]

I'm hoping you try this. As Deming said, "In God we trust, all others must bring data." Keeping a small freezer constant full making ice blocks does strike me as potentially a better use of energy than a larger fridge that is opened a lot and often not ideally packed. I think the cooler holding the chilled food will experience more temperature variation than a similar fridge but that would be an acceptable practical trade-off.

 

[Ozrockrat]

I have done this in a relative emergency when we caught more fish than would fit in the fridges. Only for a couple of days and it kept everything cold enough. The fish went into fridges. Another fridge did freezer/ice making duty and the food and beer went into the cooler.

Probably wouldn’t recommend it as a long term solution. The main reason it actually worked was because we kept consolidating the cooler as the beer and food was consumed.

 

[Dometic]

The only thing I've read that was remotely similar to what you're going for, but not really at all, was someone who used the fridge as the icebox part of his system. Basically he keeps frozen foods and some ice packs in the 'freezer'. He then uses a cooler as the 'fridge', where he keeps more ice packs, and his cold foods. But the big difference here, that is drastically different than your plan, is that the freezer runs 24/7. It needs to, because he swaps out the ice packs every morning to keep the food cool. Like others have noted, these things are best at maintaining a set temp, not a constant freezing and thawing cycle.

Another downside you didn't mention is the extra space needed to carry both a fridge and a cooler. Maybe you have room to spare, though. I also think noise is an overestimated thing, too. But I don't know if you're basing that from real experience with a specific unit. For my Dometic, when it was new, it was dead quiet. Like, "can't even tell when it's cycling on, even when the vehicle is not running" kind of quiet. Now after running basically non-stop for 5 years at 36°f, you can certainly hear it. But I've never had a problem falling asleep with the level of noise my fridge produces... And I sleep RIGHT next to it.

Which Dometic cooler do you have? We love hearing stories of hard-core use like this!

DOMETIC
mobile living made easy
shop.dometic.com
Use promo code Expedition20 for $25 off your order of $75+

 

[IAm_Not_Lost]

When my 35L Dometic CFX fridge is set to a temp that will freeze/make ice it uses 3-4 times the energy then it does when set a comfortable 37 degrees F. I think you will definitely find that it would be easier to just have a moderate sized fridge. The 35L-50L sized fridges seem small, but when you factor in the fact that there is no ice taking up space and making it difficult to fit things in then they turn out to be able to hold just as much as comparable sized ice chest (meaning a 70-100L ice chest).

 

[The Artisan]

As stated get a small genset and small icemaker should not use that much gas. Nice thing reuse water to make more ice
No 12v fridge to buy and offsets cost of small genset
Kevin

 

[rruff]

When my 35L Dometic CFX fridge is set to a temp that will freeze/make ice it uses 3-4 times the energy that it does when set a comfortable 37 degrees F.

That's because you are actually making ice, yes? The relevant comparison would be steady state consumption at 27F vs 37F... for instance. Based on the compressor data that should be more in the 15-20% range.

 

[IAm_Not_Lost]

That's because you are actually making ice, yes? The relevant comparison would be steady state consumption at 27F vs 37F... for instance. Based on the compressor data that should be more in the 15-20% range.

Sure, if you are only factoring in using some sort of cool pack and could use a set temp of 27F that would be different, but the OP seemed to want to make ice as well. I can't remember what temp I had to set my fridge down to for it to actually freeze ice cubes/bottles, but it was something like under 15F, maybe closer to 5-10F. Either way, I don't think it would be an efficient solution.