AC/DC Fridge

I have to feel sorry for anyone who asks for advice on this forum, because when it's all over, he (or she) will walk away more confused than when the question was asked in the first place.

A lot of "information" has been posted in this thread, some correct, some slightly off, and some decidedly incorrect. Assumptions have been made that lead to wrong conclusions.

There are two schools of thought on this subject. One, use an "off the shelf" purpose built marine AC/DC refrigerator, install it, turn it on, and just use it.

The other group believes there is a cheaper way that can be cobbled up from parts available at Walmart that will do the job just fine.

I'm not going to change the mindset of anyone who is in the second group and they will not change my mindset. The OP and anyone else who is on the fence will have to make up their own minds. It's your boat.

rwidman said:

The other group believes there is a cheaper way that can be cobbled up from parts available at Walmart that will do the job just fine.

I'm not going to change the mindset of anyone who is in the second group and they will not change my mindset.

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+1

rwidman said:

I have to feel sorry for anyone who asks for advice on this forum, because when it's all over, he (or she) will walk away more confused than when the question was asked in the first place.

A lot of "information" has been posted in this thread, some correct, some slightly off, and some decidedly incorrect. Assumptions have been made that lead to wrong conclusions.

There are two schools of thought on this subject. One, use an "off the shelf" purpose built marine AC/DC refrigerator, install it, turn it on, and just use it.

The other group believes there is a cheaper way that can be cobbled up from parts available at Walmart that will do the job just fine.

I'm not going to change the mindset of anyone who is in the second group and they will not change my mindset. The OP and anyone else who is on the fence will have to make up their own minds. It's your boat.

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Cobbled up or a MUCH better solution than an industry that has lagged behind every other industry on the planet that I can think of.

Many innovations in the 20th century and before came from someone's garage...and some of it turned out just fine...like Apple Computer products....and for that matter a couple of bicycle guys got the airplane off the ground.

You want to shop at marine stores, pay their prices and the whole process require NO thought on your part...fine..

But to look down your nose and post that snide flavor at people smart enough to innovate and solve problems whether the be to save money or solve the problems of cruising thatmost boat manufacturers only dream of....well I have a pet name for those that do that also...

Unless you are here for entertainment...many are here to hear ideas...not just West marine Advisor articles.

psneeld said:

Cobbled up or a MUCH better solution than an industry that has lagged behind every other industry on the planet that I can think of.

Many innovations in the 20th century and before came from someone's garage...and some of it turned out just fine...like Apple Computer products....and for that matter a couple of bicycle guys got the airplane off the ground.

You want to shop at marine stores, pay their prices and the whole process require NO thought on your part...fine..

But to look down your nose and post that snide flavor at people smart enough to innovate and solve problems whether the be to save money or solve the problems of cruising thatmost boat manufacturers only dream of....well I have a pet name for those that do that also...

Unless you are here for entertainment...many are here to hear ideas...not just West marine Advisor articles.

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Oh come on, I completely agreed with his post.

Nobody here was looking down on anybody for cobbling up a repair or modification to their boat, and there is nothing innovative about installing a cheapo dorm fridge in a boat.

To stay on the subject, installing a dorm fridge isn't something I would have done on my smaller cabin cruisers, and its not something I would do on a larger boat either.

I'm all for saving money, but cheaper isn't always better, its just cheaper. On my boats I've always been in the "do it right" camp, even though at times it was difficult to write the check.

Maybe only in your mind it's the right thing.

After a year or so on this forum there are a few that never think outside the box and for those ...have a cup of coffee and shoot the shi* in the local West Marine Store lobby.

There are some like me that come here to think completely outside the boat show box...exchange ideas...right or wrong and explore possibilities.

Some of my ideas have failed miserably and I have switched back to conventional wisdom. But for the most part my boats wind up better than what the manufactures have put out for sale, have saved tens of thousands over the years and NEVER have I encroached on safety.

Like I said..if a poster doesn't have much more to offer than what the West Marine or Boat US Tech has to offer...why waste the bandwidth?

And I have been around the block to know the difference in posting tone.

psneeld said:

Maybe only in your mind it's the right thing.

After a year or so on this forum there are a few that never think outside the box and for those ...have a cup of coffee and shoot the shi* in the local West Marine Store lobby.

There are some like me that come here to think completely outside the boat show box...exchange ideas...right or wrong and explore possibilities.

Some of my ideas have failed miserably and I have switched back to conventional wisdom. But for the most part my boats wind up better than what the manufactures have put out for sale, have saved tens of thousands over the years and NEVER have I encroached on safety.

Like I said..if a poster doesn't have much more to offer than what the West Marine or Boat US Tech has to offer...why waste the bandwidth?

And I have been around the block to know the difference in posting tone.

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Ok, possibly I missed something in this thread, along the lines of innovative thinking.

Was there some new gadget suggested, that would make fridges more efficient? Was there some new way of cooling suggested that could possibly be the next "apple computer" (to use your example from above)? Possibly I missed this, and if thats the case my sincerest apologies.

What I read was not so innovative. It was walk into walmart, or target, buy the $70 dorm fridge on sale (since its back to school time). Install that in a otherwise nice boat.

Now, if someone wanted to put a second stand alone fridge, or a standalone deep freeze on their boat, thats another story. We all see that frequently.

Not yet...but that doesn't mean someone isn't going to post something next that won't be if they are not shut down by the "conventional book thumpers"...and while maybe this thread's not the best example...there are plenty more that are.

By late fall I hope to do a flybridge, freezer conversion from a low dockbox and the guts of a cheap home freezer that should be 1/3 the cost of off the shelf marine store ones...Maybe it will work...maybe it won't...but at least I'll try and pass along success or failure to those that may be in the same situation that I am.

If I didn't say it loud and clear...I don't mind the two camps and their ideas...it's just how the thread pans out that can be the issue more than the topic....and the fact anyone can walk into a marine store and buy off the shelf...if the other camp doesn't suggest alternatives...why even have these forum discussions?

psneeld said:

Not yet...but that doesn't mean someone isn't going to post something next that won't be if they are not shut down by the "conventional book thumpers"...and while maybe this thread's not the best example...there are plenty more that are.

By late fall I hope to do a flybridge, freezer conversion from a low dockbox and the guts of a cheap home freezer that should be 1/3 the cost of off the shelf marine store ones...Maybe it will work...maybe it won't...but at least I'll try and pass along success or failure to those that may be in the same situation that I am.

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Please post the results of that conversion. Thats the kind of thinking that will help everybody!

I'm looking at adding a built in deep freeze myself, and if I can save some $$$ I'm all for it.

ksanders said:

Please post the results of that conversion. Thats the kind of thinking that will help everybody!

I'm looking at adding a built in deep freeze myself, and if I can save some $$$ I'm all for it.

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My son actiually suggested it....he has a nice, several year old freezer he got and doesn't need. He said to me why don't I just sawsall the compressor and plate out and add it as a component within another insulated box that fits and is attractive on the bridge, add ventillation to the compressor area and add a new insulated wall between the compressor and plate (he knows I'm good with composites).

The trick is the dimensions of the compressor and plate...I'm not sure his freezer will work until I take a few things apart and measure. But if the dimensions are good...the rig would cost between 1/2-1/3 of what the equivalent off the shelf stuff would be saving at least 2-300 dollars for a weekends work and the end result would look the way i wanted it...so this is the kind of stuff I'm talking about for those that don'yt have $1200-$2000 to drop into a professionally made, custom freezer.

"The benchmark for energy consumption is standard household equipment, which now has excellent insulation...

However this insulation is so thin that it must be heated frequently to remove the moisture. Simplt place your hand on a newer house unit when the unit is cooling.

The "best" in class has been made for decades , Sun Frost,

but the size (because of thick insulation) and the price scare off the budget minder.

Even tho many alt energy folks claim a 4-1 savings by NOT having to create and store energy , for some the math never works.

Our NO Cold switches from DC to AC automatically , when ever AC is powered.

Since Aug 8, the Walmart chest freezer has run a total of 50 hrs and 19 minutes. This is maintaining 28 degrees at the brine brick. The basket in the upper part of the freezer hovers around 40. My beer stays deliciously cold in the bottom and refrigerator items don't freeze in the basket.

It's interesting to note that the brine brick, designed to melt/hold 28*, will make ice even when the freezer isn't powered.

We know the brine brick will provide refrigeration for 6 days without power. Never buy ice even on long weekends on the road/water. This was the original intent - to replace an ice filled cooler...and the freezer even has a smaller footprint.

I'll gather some data on inverter/generator cycles during the 2000 mile tow to Lake Powell and while on the lake, to see if inverting power for the freezer can be managed with our normal generator run time, using a Freedom 30 and single dedicated AGM battery.

And by the way, it's my job to support unconventional thinking. Don't take it personally and don't try to put me out of work.

jeffnick said:

And by the way, it's my job to support unconventional thinking. Don't take it personally and don't try to put me out of work.

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How much does it pay? I know some out of work pontificators who might like some extra income.

jeffnick said:

Since Aug 8, the Walmart chest freezer has run a total of 50 hrs and 19 minutes. This is maintaining 28 degrees at the brine brick. The basket in the upper part of the freezer hovers around 40. My beer stays deliciously cold in the bottom and refrigerator items don't freeze in the basket.

It's interesting to note that the brine brick, designed to melt/hold 28*, will make ice even when the freezer isn't powered.

We know the brine brick will provide refrigeration for 6 days without power. Never buy ice even on long weekends on the road/water. This was the original intent - to replace an ice filled cooler...and the freezer even has a smaller footprint.

I'll gather some data on inverter/generator cycles during the 2000 mile tow to Lake Powell and while on the lake, to see if inverting power for the freezer can be managed with our normal generator run time, using a Freedom 30 and single dedicated AGM battery.

And by the way, it's my job to support unconventional thinking. Don't take it personally and don't try to put me out of work.

Click to expand...

Now that's some out-of-the-icebox thinking! Got any pics? Never heard of a brine brick before.

We have an built-in AC/DC Norcold box that, while not efficient, runs well. It sits low so that you need to get onto the floor to see what's inside. We recently added a 120V apartment size unit on the countertop run off the inverter. When we're on shore power or generator, it gets its power from those sources. The Admiral loves it since we don't have to bend over to get into it. I love it for the extra capacity and no longer a need for ice in a cooler for drinks.

Is it marine? No. Is it a bit redneck? Yes! But it looks like it's staying! We'll be adding a marine style hook/latch to the side to secure the door while underway, change to a granite countertop to accomodate the door swinging open above the fiddling and secure the unit from tipping. If the next owner doesn't like it, he can remove it with minimal effort or scarring.

The benefit of a forum like this is to give and receive different opinions on various topics and allow the individual to decide which works best for him. I know I've made suggestions in the past that turned out to be bad ideas, as pointed out by other posters. It's a good thing that they pointed this out.

I've also posted ideas or experiences with products that have worked well, only to be blasted by other poster(s) that it's a terrible idea or it doesn't work. I know it's frustrating when you share your experience with someone asking for help and others feel the need to contradict most if not all you post.

There is no one-size-fits-all solution to all problems. When it comes to safety and sound practices, the issue should be WHAT is right, not WHO is right. The sooner we all get that idea and allow each other to contribute without the personal attacks the better.

When our Vitrifrigo AC/DC quit working I replaced the control unit with a DC only unit. I don't see the point of AC operation. If I have AC I also have DC from the battery charger charging the batteries.

Bob

BobH said:

When our Vitrifrigo AC/DC quit working I replaced the control unit with a DC only unit. I don't see the point of AC operation. If I have AC I also have DC from the battery charger charging the batteries.

Bob

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Agreed. If my AC/DC fails, that's probably where I'll be headed. True 12V DC only (not 12V DC to power an internal inverter for AC) is more efficient.

The brine brick is a Walmart (marine) flexible 5 gallon camping container with enough salt to lower the freezing temp to 28*. I started out just using plain water but my beer was always above 34 and the basket temps climbed to the high 40's...needed to reduce both so introduced the salt.

Right now, I put in a case of 16oz plastic bottles (along with the brick) which will be solid tomorrow. I'll then relocate the frozen bottles to the cooler in the van to keep my soft drinks cool for the road - and anything else that needs refrigeration.

While on the road, I'll zero the power on timer and use the inverter to maintain the brick. We'll see if the single (smallish) AGM is up to the task until I run the gen for the evening meal, and overnight a/c if required. If the AGM dies, at least I'll know how many hrs/mins it lasted and can make adjustments.

What ratio of salt to water do you use to make your brine solution Jeff? Any special prep at all?

I used one carton of salt for a little less than 5 gallons of water. Heat a couple gallons to help disolve the salt, let it cool and fill the 5 gallon container almost full. If you put this in your freezer it will go solid and as it melts it will stay around 28*. Plain water will only hold the temp at about 34.

Note the quantity on the carton of salt...it's more than a pound.

Thanks for that. I'll try it out next weekend on a road trip I have planned.

To round out my earlier posts on this topic with some hard data: I measured the amp draw and cycle time of my two fridges. One is a Vitrifrigo marine model running 12v direct. It is a 2-door, with the freezer below. It has a capacity of 240litres total. It draws 4.7A when cycling-on and at 17.5C ambient, it cycles on for 6 minutes out of every 12..so a 50% duty cycle. This means it uses 4.7A x 50% x 24hrs = 56.4A over 24 hours, even without the door being opened.

The 2nd fridge is a domestic bar fridge, single door with a small freezer compartment. AC only, it it powered by the inverter. It consumes 7.2A on average over its 5 minute on-cycle...but it cycles on only once every 30minutes..so its duty cycle is 10/60. This means it uses 7.2A x 10/60 x 24 = 28.8A over 24 hours. This fridge is just 140litres...60% of the Vitrifrigo & with a much smaller freezer, so I'm not suggesting that the two are in any way comparable. But it does draw attention to the importance of cycle time in assessing the energy efficiency of refrigerators.