12 V Marine Refrigerators

[davecalvert]

We have a Belize 43 catamaran with separate Sea Frost fridge and freezer. This is engine driven and 110 Volt. Can anyone recommend a good way to convert this to 12 V for both fridge and freezer? We would like to use the same holding plates and keep the 12 volt drain to a minimum.
Any good recommendations would be appreciated.
Dave

[Cheechako]

it's engine drive AND 110 volt? That would imply you have two compressors. If so... you could just use an invertor to drive the 110V compressor.... most "12V" marine compressors are actually 110/120 volt anyway aren't they? If you have a really BIG compressor then it may draw too much though.

[davecalvert]

I did try using the 2,500 watt inverter to run the 110 volt compressor. It used way too much power. I need low draw 12 V compressor and hope to use the same cold plates.

[djmarchand]

Your holding plates won't work with 12V Danfoss compressors. The engine or 120V compressor systems are rated at a much higher btu/hr value than the small Danfoss compressors are. The evaporator (holding plate) for your big compressors is the wrong size to use with a Danfoss compressor.

That is why they are holding plates so the compressor can stay off for hours and let the holding plate carry the load. Danfoss compressor systems rarely use holding plates.

If you want to change them, change the whole system.

David

[Vasco]

Originally Posted by djmarchand

Your holding plates won't work with 12V Danfoss compressors. The engine or 120V compressor systems are rated at a much higher btu/hr value than the small Danfoss compressors are. The evaporator (holding plate) for your big compressors is the wrong size to use with a Danfoss compressor.

That is why they are holding plates so the compressor can stay off for hours and let the holding plate carry the load. Danfoss compressor systems rarely use holding plates.

If you want to change them, change the whole system.

David

I have a 12v holding plate system. It's an old EZ-Kold. uses a Danfoss compressor.

[Hudson Force]

I also have a holding plate with my Danfloss compressor on my Technautics "Cool Blue". I'm very pleased with what I have, but I'm looking forward to hearing from anyone with experience using the very small Aspen rotary compressors.

[goboatingnow]

Danfoss compressor systems rarely use holding plates.

funny , I have one too.


Dave

[goboatingnow]

but realistically , why not talk to Seafrost

[neptunesjester]

If you can find the btu/hr rating of the 110 compressor, you can attempt to match it to a 12v compressor.

I did a complete 110v to 12v conversion on a household style fridge on my boat. It's been running for over 2 yrs in Florida without issue. I went with the BD50 after chasing down the 110 compressor specs through part number searches on google. The BD50 is about 2/3 of the btu/hr of the original compressor, but still pulls down the freezer to 0. I'm happy with that since it isnt supposed to be a deep freezer to begin with. Food stocks turn over about every two weeks.

Between the compressor, the cooling fan, and the evaporater fan, it pulls about 7.5 amps while running. I had to make a 12v auto defrost system to replace the 110 system and it pulls about 12 amps while running. It kicks on for 30 minutes every 12 hrs.

The whole system uses about 100 amp hrs a day.

[Richard Kollmann]

Seafrost sold those Hybrid holding plate systems set up with two different size 110 volt compressors. If the 110 volt compressor in your system is the small one it can easily be replaced with a Danfoss 12 volt compressor powering plates. If your compressor is their smaller one, I think 1/6 HP, the Coeficient Of Performance daily energy consumed will be somewhat better with the Danfoss unit. Do not look for less engine alternator running time unless you keep engine drive in operation also. You will probably need to upgrade the boat’s DC power grid to support 12 volt refrigeration with alternative energy wind and solar this will slow down battery aging as well as reduce engine run times. Your engine drive system is producing around 20 times the capacity in one hour than a Danfoss BD 12 volt compressor would. Suggest you do the math recommended in my web site slide show and adjust end figures by cruising climate ambient air and water temperatures 2% for cooler per degree as the slide show is based on worst case tropical conditions with two people onboard.

You should contact Cleave at SeaFrost for a conversion to his system from 110 volt hybrid to 12 volt hybrid. I made these conversion at one time and his advice is would be the best.

You could buy a large 12 volt unit replacing all parts of Seafrost system but you will be running engine alternator twice as many hours per day.

[Dulcesuenos]

We had almost exact same system , We went with Cleve at Seafrost, replaced ours with a Danfoss 12v Bd80 compressor, 2 stainless plates and the digital thermostat and it was easy to install. Runs great. We use 440 watts solar , a Xantrec 40 PWM controller. 650 ah of house bank and have never run low on juice even w 3 days of overcast. Not sure you box set up but we Have an 8 cu ft flow through both plates are on freezer side. Works great!

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[davecalvert]

Thanks very much for the good impute from Richard and Dulcesupnos.
I did call Sea Frost yesterday but Cleave was out on lunch break. I'll call him today. I was just looking at all options. as well as going to another brand.
I do have 420 watts of solar panels, an Outback controller, and new 500 amp house battery bank. I am also looking at higher output alternators.
I do plan to retain the engine driven compressor but, rarely use the 110 volt compressor. Converting this to a 12 volt compressor sounds like the best way to go.
Cheers,
Dave

[Akka]

Our boat came with a 110V system in parallel with our engine-driven system, both by Cool Blue and with both systems using the same holding plates. We're rarely at a dock and the inefficiency of the 110 system using the inverter was staggering, so we changed to a Danfoss BD50 12V DC compressor. Worked great for years, although we just developed a tiny leak we can't find, even with UV dye . We bought the compressor on EBay, and had to solder it into the existing system. No change in any other parts, such as the ambient-air condenser, filter, receiver, tubing. I don't know anything about BTUs, but our freezer makes ice and the refrigerator keeps the beer cold in 96-degree weather, so ... seems OK to us .

[Akka]

Wait! Where did that ad for Modelo beer come from? I certainly didn't put it there (though we are in Mexico and I like Modelo). Does this forum monitor postings and picked up on the word "beer"? Not sure I like this ...

[Neptune's Gear]

Dave, I have both engine driven and 12v/mains systems on my boat (in the same fridge/freezers). Gives two completely separate systems. Have a look on my website, www.neptunes-gear.com or send me an email if you are interested.

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