Refrigeration options for a mac

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whgoffrn
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Refrigeration options for a mac

Post by whgoffrn » Sat Jul 15, 2017 2:56 pm

I've seen several people put the Engel 35s under the starboard seat with the cooler and that was my original plan also but it would require me to buy another solar panel and figure out just where and how to mount that and I'm wondering if anyone knows if it's more energy efficient to get a much smaller freezer to freeze water bottles solid and then switch over into the cooler (Or a better more insulated cooler)
Usually when I go out for extended trips I don't use ice I freeze water bottles and Gatorades ...as the ice takes up space when I could just freeze the things I drink to use as my cooling element

So I can't help but wonder if I could find a small portable freezer capable of freezing 10 -12 bottles of water per day to put in a more Insulated cooler and get by with 100 watt solar panel?

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eodjedi
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Re: Refrigeration options for a mac

Post by eodjedi » Sat Jul 15, 2017 3:38 pm

I think the Engel is one of the most efficient fridge's you can get. I have an Engel 35 on my :macm: . I use a 160 watt solar panel mounted to my Mast Carrier which supplies enough power for the fridge, Autopilot, and battery charger.

whgoffrn
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Re: Refrigeration options for a mac

Post by whgoffrn » Sat Jul 15, 2017 4:02 pm

I leave for the keys on Friday and contemplating ordering the Engel 34 quart fridge ...on Amazon says it will show up by wednesday..... do you think 100 watts is enough I have no autopilot .....the fridge chart plotter and radio is all the power I would use.

I kinda using this trip to the keys as a testing ground for what I need to work on for a trip to the exumas next year and refrigeration is top on the list now

whgoffrn
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Re: Refrigeration options for a mac

Post by whgoffrn » Sat Jul 15, 2017 4:20 pm

Spur of the moment purchases Is why my bank account hates boating lol.....engel 34qt fridge on its way....hopefully 100 watts is enough cause it's all i got

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kadet
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Re: Refrigeration options for a mac

Post by kadet » Sat Jul 15, 2017 5:19 pm

Usually when I go out for extended trips I don't use ice I freeze water bottles and Gatorades ...as the ice takes up space when I could just freeze the things I drink to use as my cooling element
I see you have purchased your fridge but thought I would comment on this in case others had the same idea, as once I did :)

The problem with freezing water onboard to use in a cooler is the energy required to turn water from a liquid to a sold is very high, not just lower the temperature but to overcome the energy water gives up when it freezes. This energy that is given up is the latent heat of freezing which is about 334kj per KG of water or 300kcal per gallon of heat as it freezes. This is why ice is so good at keeping other things cool because to turn ice back into water that energy has to be given up from the surrounding environment. Remember we cannot transfer cold only heat we take heat away something gets cold, we give something heat it gets hot.
I'm wondering if anyone knows if it's more energy efficient to get a much smaller freezer to freeze water bottles solid and then switch over into the cooler (Or a better more insulated cooler)
So simple answer is no it is way less efficient.

You are better off having a large fridge and stock it with some frozen items that were frozen in an AC freezer before relying on your solar. Or as I do set my portable up as a freezer at home and freeze most of all the stuff I can then stock it up on the boat as a fridge. I also carry a 7 day cooler full of ice for more essential items like beer if going on a long trip :P

I should be able to run mine as a freezer now as I have installed 400watts of solar now but this is untested 8)

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sailboatmike
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Re: Refrigeration options for a mac

Post by sailboatmike » Sat Jul 15, 2017 5:28 pm

Another sailing forum Im on has a engineer who is right into all this stuff, he recons his compressor driven fridge / freezer draws around 40 watts of power for around 5 to 6 hours a day, of course that depends on temp of stuff you put in it, how often you open it, the outside temp and the temp you have the unit set on.

That being given it draws between 200 and 240 watts per day

Working on a 100watt panel giving around 80 watts average for 5 hours for a total of 400 watts you have power to spare

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jimmy alonso
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Re: Refrigeration options for a mac

Post by jimmy alonso » Sat Jul 15, 2017 11:09 pm

The Engel MT-35 when running pulls 2.5 amps from the battery, depending where you set it is the amount of time it runs. On setting 2 it will start to freeze stuff. I have a total of 140 watts now of solar but did get by with only 80 watts. From sunset until morning my 102AH AGM house battery discharges to about 75% to 70% running the fridge, anchor light, fan and maybe a cell phone charger. Some nights I turn it down to about 1 and a quarter to save some amps. During the day when the battery is about 100% I turn it up to almost 2. On a cloudy or rainy day at anchor solar may charge but not much.

whgoffrn
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Re: Refrigeration options for a mac

Post by whgoffrn » Sat Jul 15, 2017 11:37 pm

I have 2 group 29 deep cycle batteries and have a cheap 2000 watt generator so with 100 watts hopefully I'll be ok ...i originally was going to take the handled off and drop it down where the cooler goes but I've been reading where others say they don't run very efficiently even with vent holes cut out of the liner .....so I may just put the fridge under the table and take the cooler liner out and have the bilge area be where I store water and heavier stuff to keep weight down low

whgoffrn
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Re: Refrigeration options for a mac

Post by whgoffrn » Sat Jul 15, 2017 11:38 pm

Where do u store your 35? Under the rear starboard seat where the cooler is or under the table?

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sailboatmike
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Re: Refrigeration options for a mac

Post by sailboatmike » Sat Jul 15, 2017 11:45 pm

jimmy alonso wrote:The Engel MT-35 when running pulls 2.5 amps from the battery, depending where you set it is the amount of time it runs. On setting 2 it will start to freeze stuff. I have a total of 140 watts now of solar but did get by with only 80 watts. From sunset until morning my 102AH AGM house battery discharges to about 75% to 70% running the fridge, anchor light, fan and maybe a cell phone charger. Some nights I turn it down to about 1 and a quarter to save some amps. During the day when the battery is about 100% I turn it up to almost 2. On a cloudy or rainy day at anchor solar may charge but not much.
Thats some good numbers to work off, is your anchor light LED or old school incandescent?

Lets assume the anchor light is incandescent and draws 15w and is on for 8hrs = 120w or 8amps
phone charger normally runs around 15w so say 6 hrs = 90w or 6amps
Fan maybe 20w for 4hrs = 80w or 5 1/2amps
Total drawn without fridge = 19 1/2 amps out of 102amp battery for maybe using 20%

That being given the fridge is taking very little maybe 5 or 6 amps

Of course all that changes is the anchor light is LED and only drawing 2 or 3 watts or 24w for the time its on

kurz
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Re: Refrigeration options for a mac

Post by kurz » Sun Jul 16, 2017 4:18 am

Well, why do it so complicate?
If you need more fridge place, get two 35l waeco or engels.
When the watts are rare, shut one off, if you have enough pump the energy in cooling both.
No hassle with sorting out the ice packs.

And: Take the fridge at the marina in a hot day. Put 5l bootles to get ice in it. Put the fridge at 220V and wait. I tuess it will last a very long time to get ice on it.

In home/kitchen fridges they say it will get 2kg of ice in 24h. So think about a hot day on the boat...

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ris
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Re: Refrigeration options for a mac

Post by ris » Sun Jul 16, 2017 7:27 am

We put our engel 35 on the port side aft of the galley. There is plenty of room to open the top all the way up if you need to. This is where we put it for our 9 month cruise. We had 4 trojan 6 volt 105's which is about 425 amp hours. We could run the whole boat including the engel for 4 or 5 days without any recharge to the batteries. Our only charging was the boat motor. But we used the Mac as a cruiser so we ran the boat every 3 or 4 days as we moved around. Check out our boat mods under ris on this website, we have a 26X also. The biggest amp saver is changing all lights to led bulbs, running lights anchor lights, and interior lights. We bought a cheap 9 dollar attwood anchor light and replaced the bulb with a 10 dollar led bulb, that is so bright you need sunglasses at night when up on deck!!! Have a great trip.

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Sumner
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Re: Refrigeration options for a mac

Post by Sumner » Sun Jul 16, 2017 10:41 am

kadet wrote:....The problem with freezing water onboard to use in a cooler is the energy required to turn water from a liquid to a sold is very high, not just lower the temperature but to overcome the energy water gives up when it freezes. This energy that is given up is the latent heat of freezing which is about 334kj per KG of water or 300kcal per gallon of heat as it freezes. This is why ice is so good at keeping other things cool because to turn ice back into water that energy has to be given up from the surrounding environment. Remember we cannot transfer cold only heat we take heat away something gets cold, we give something heat it gets hot.
I'm wondering if anyone knows if it's more energy efficient to get a much smaller freezer to freeze water bottles solid and then switch over into the cooler (Or a better more insulated cooler)
So simple answer is no it is way less efficient...
Yep, this comes up now and then. I took our 63 quart Edgestar and put a 1 gallon container of water in it alone and ran it to see how long it would take to freeze it.

http://purplesagetradingpost.com/sumner ... -23-a.html

Energy used was about 84 amp-hrs (24 hrs. X 3.5 amps) or about 3 times what would of been needed to keep the box at 38-40 degrees filled with food/drinks for the same time period.

When we had 180 watts on the boat on a 7 week trip we ran the gen/set about 3-4 hours total for the trip if I remember right. I also ran the computer a lot, a CPAP machine at night, LED anchor light and we were anchored a lot so not much input from the outboard and it is only 6 amps. I then upped the solar to 200 watts and feel that would take care of the fridge and the rest of the loads probably pretty much indefinitely baring a lot of cloudy days in a row.

Image

Considering the Edgestar 63 is about twice the size of the Engle you bought 100 watts might do the trick most of the time. Before I bought I read lots of reviews between the different makes and saw very little difference in how efficient they were compared to one another. A couple drew less amps but ran longer in the same test situation. The Edgestar has given me good service and at the time was a lot less expensive vs.s the name brands. They all have gone up since. At the time we paid about $430 and they had free shipping as part of a Christmas deal. I think the 63 quart now is about $600.

Another consideration is how often you add hot items to the box. We usually add about 2 12oz containers a day and then other hot items when we have to restock during a trip or put in leftovers. If you are adding a number of water bottles, pop or beer a day you are going to need more solar. If temps inside the boat are high you will need more solar vs. spring/fall trips.

Image

The fridge I made for the Endeavour is almost twice as big as the Edgestar yet seems to use about 2/3's the electricity and ...

Image

... it has a small freezer section. The reason is that it is so much better insulated with 3-4 times the insulation of the portable. There again the freezer section is not that cold so we don't try to make ice in it. We try and put frozen food in it or food that will freeze fairly quickly. We have used this fridge/freezer now for months at a time while working on the boat and living in it at the same time,

Sumner

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DownSouth
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Re: Refrigeration options for a mac

Post by DownSouth » Sun Jul 16, 2017 5:09 pm

Every time a fridge on a boat topic comes up I feel compelled to put the alternative view...

Sailing since the 70's we of course never had a fridge and still don't - we seem to have survived quite nicely.

In fact with the range of foods available now inc long life 'UHT' milk & custard, and everything in tins/feeze dried etc etc it's now much easier.

Save yourself the hastle and the thousand $/£ + and buy a new sail!

Yours in alternate thinking,

DownSouth

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sailboatmike
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Re: Refrigeration options for a mac

Post by sailboatmike » Sun Jul 16, 2017 5:33 pm

DownSouth wrote:Every time a fridge on a boat topic comes up I feel compelled to put the alternative view...

Sailing since the 70's we of course never had a fridge and still don't - we seem to have survived quite nicely.

In fact with the range of foods available now inc long life 'UHT' milk & custard, and everything in tins/feeze dried etc etc it's now much easier.

Save yourself the hastle and the thousand $/£ + and buy a new sail!

Yours in alternate thinking,

DownSouth
We try to do this but find a nice cold drink at the end of a warm day is just awesome.

We have tried ice but its just not economical and is very messy and gets everything wet, we use as much long life stuff as we can UHT milk, canned goods etc but the overwhelming desire for a cold drink is our driving factor, that being said there are some brilliant Eskys (cool boxes for you USA residents) that are supposed to keep ice for 48hrs

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