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Old 06-02-2014, 02:10 PM   #1
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12v freezer

Been looking to replace my 12v freezer... (yes it can do 120 VAC also)...

Found these 2... obviously built from the same people under different names...
EdgeStar 12V DC Portable Fridge / Freezer - 43 Qt. - FP430
Whynter 45 qt. Portable Fridge/Freezer-FM-45G at The Home Depot
BUT... if you read the specs.. both say 120VAC 65 Watts.. but one says .75 Amps and the other 2.5 Amps on AC and 4.5 on DC !!!

why such a huge disparity? or am I missing something????
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Old 06-10-2014, 11:58 AM   #2
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wow... not one response. figured someone had to know the difference
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Old 06-10-2014, 12:04 PM   #3
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wow... not one response. figured someone had to know the difference
Perhaps if you had somehow phrased the question so that anchors were involved . . . :-)
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Old 06-10-2014, 12:05 PM   #4
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Perhaps different cooling units? Perhaps one uses an inverter to change AC to DC (hence greater amperage on AC), and the other has 2 separate power systems?
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Old 06-10-2014, 01:45 PM   #5
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I heard the anchor part so I'll chime in. I believe the first says 5.4A @12V At 24V (double the voltage thus half the amps, 2.7A) Watts = Volts x Amps. at 120V consumption is .65A. I believe the Specs on consumtion are screwed up by a typo. 65W at 120V is .78A (0.75A is close) they probably used 115V instead of 120V The line above lists the input voltage as 115V/120 Hz. It's not particularly efficient but it will probably only run 25% of the time. If you've a big battery bank, charger and alternator so what. It will probably consume 35AH per day.

The second says 120V (or in this case 110V used) is 65 Watts. The 2.5A doesn't make sense. Another typo. 2.5A is most likely th 24Vdc consumption. 2.5A @ 110Vac would be 275 Watts.

The unit is most likely foriegn, the specs were listed by someone who didn't have elctrical term translation skills, and rewritten by a copy writer who wasn't an electrical engineer either. They are obviously the same unit by different importers.

Now what was that anchor question?
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Old 06-10-2014, 01:48 PM   #6
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wow... not one response. figured someone had to know the difference
Ok Mr tmiller, I can let you know what I "think" I know. I put a CF-110 Dometic on my bridge and did a lot of research before I did. First I think all these type cooler/freezer use Danfoss BD 35 or BD 50 compressors. It looks like the bigger BD 50 are used in the units bigger than 40 quarts. The units you mentioned have both AC and DC cords. I looked up the BD 50 specs and they run .75 amps on 115 AC and 7.5 amps on 12 VDC. The load on these compressors varies with temp. Its a wide range from -20F to 50F. I have verified my units load and power consumption with a battery monitor and data logger for temperature. Mine runs 15 minutes every hour maintaining 33F, with outside temps in the mid 80s. I like my beer COLD! It draw 7.5 amps with 12.5 VDC. It is advertised as holding 113 cans.
During my research and discussions with suppliers they always told me it could not be left outside. I built a box and insulated it so we could leave it on the bridge. Hope you get a nugget of info out of this.
Dave
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Old 06-10-2014, 05:59 PM   #7
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I have been using a Engle unit for a couple of years. Just before I bought a new boat I stumble across a second unit too cheap to pass then another came with the boat, built in. These things have 2 moving parts, seem tough and draw between 2-3 amps @12 volts. They also work on 120volts. Keeps my ice cream rock hard. conversely also on the new boat there is a 110 frig-freezer that pulls 90 watts. After inverter supplied 110 I can run All 3 Engles for the same juice. That 90 watts requires 7.5 amps operate the unit, 10% penalty for inverter 8.25 amps. I think the 120 volt unit is short lived on this boat.
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Old 06-10-2014, 06:02 PM   #8
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If you were to buy better beer, it would not have to be kept so cold! I have a Waeco, just like yours, that I am putting on upper deck. Have the insulated cover for it, but no box. Thanks for the current draw info. Do you run it off the invertor, or just run it 12 volts. DS
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Old 06-10-2014, 10:37 PM   #9
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If you were to buy better beer, it would not have to be kept so cold! I have a Waeco, just like yours, that I am putting on upper deck. Have the insulated cover for it, but no box. Thanks for the current draw info. Do you run it off the invertor, or just run it 12 volts. DS
If AC and DC are both plugged in it runs on AC. Soooo, when I am at anchor it still runs on AC off the inverter. Everything I read says the compressor is more efficient on AC. My Tundra frig/freezer has the same setup with a Danfoss BD 50
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Old 06-10-2014, 10:47 PM   #10
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What about the built in ineffiency of the inverter, that has to count?
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Old 06-11-2014, 08:06 AM   #11
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If AC and DC are both plugged in it runs on AC. Soooo, when I am at anchor it still runs on AC off the inverter. Everything I read says the compressor is more efficient on AC. My Tundra frig/freezer has the same setup with a Danfoss BD 50

NovaKool told me our units run on DC all the time, even when fed an AC source. If given both AC and DC at the same time, each unit shows preference for AC but then also converts that AC to DC first.

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Old 06-11-2014, 08:10 AM   #12
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What about the built in ineffiency of the inverter, that has to count?
Probably does, I just take the small hit for the convience of not having to open breakers and pull plugs when anchoring. House bank is 940 amphrs so we are not squeezed for power.
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Old 06-11-2014, 08:30 AM   #13
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An option, fairly easy if you do any of the electrical work on the boat. You are able to rewire the distribution panel so that AC goes to the outlet for the freezer only when on shore power or the generator. Thus when at anchor and the inverter is on the freezer will not be getting AC power. I use this for the water heater, chargers and the refrigerator / freezer. I have also done this for one outlet into which I plug in radios,lights, cell phone IPODs etc which need to be charged, thus charging them while the generator is running each day.
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Old 06-11-2014, 08:39 AM   #14
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Sooo, it comes from the house bank to an inverter, where goes to 110 from 12, hits the refer and goes to its inverter back from 110 to DC. Double the loss would be my guess, each time the current is converted there is a loss. How much? From DC to DC count on 10%. AC to DC, I don't know but likely another 10%.
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Old 06-11-2014, 09:13 AM   #15
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Ok Mule, you are correct and now the engineering side of me is curious. I have a good battery monitor. I will get the data for AC vs DC.
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Old 06-11-2014, 03:56 PM   #16
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My Xantrex Prowatt 2000 inverter eats -.39 amps just sitting by itself. The load increases to -.55 amps when tied to the 120vac bus with no loads.
The Tundra T80 frig consumes -3.12 amps on DC only and -4.8 when powered by the inverter. The -4.8 amps includes the base inverter load.
The Dometic CF110 eats -4.32 amps when DC only and -5.82 amps when on the inverter. When both units are supplied by the inverter they eat -10.03 amps. We are probably losing 20- 30 amphrs a day running refigeration on the inverter.
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Old 06-11-2014, 04:13 PM   #17
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I would run them on DC only. Properly size your house bank and if possible add alternative charging be it solar and or wind. You might find out that alternative charging can keep up and exceed the draw over a 24 hour period. Taking the numbers above the AC inverter load on the house bank combined is -10.03 amps if they were run strictly on DC the draw would be -7.92 amps
If running it on AC your losses will be higher. The AC load is 240.72 for 24 hours.
Your DC 24 hour load would be 190.08 thats a savings of 50.06 amps.
These numbers are worst case I doubt either unit runs constantly we need to know what the average amps per hour the units are using be it AC or DC. I think a DC source would win every time. You have less components when you fed them with DC.
Am I missing something here?
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Old 06-11-2014, 04:24 PM   #18
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They run 9-10hrs in a 24hr period. I have a house bank that is >900 amp-hrs. My alternators are two high output alts at 120/150 amps each. I can charge the bank up easily after two days of mooring out and consuming around 380 amp-hrs.
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Old 06-11-2014, 06:06 PM   #19
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I am becoming a bit fanatical on 12 volt current conservation I guess. I have 735 watts of Solar with a 400+ watt wind generator feeding 10 golf cart batteries for 1125 amps. Pretty robust. Just got the boat and am learning the systems, last night I was down to 12.8 volts so I fired up the charger, was cloudy yesterday and today. Charger off all day now at 14.2. Boat seems pretty independent. All on the batteries are 2 Engles and water pumps both bilge and house water + lights, on demand 12 volt water maker (140 GDP). I want only 12 volt refers, led light + some 12 volt fluorescent. On 110, air conditioner, battery charger, inverter for TV and microwave, so that 110, 90 watt refer bugs me.
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Old 06-11-2014, 07:38 PM   #20
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12.8 volts with no charging source is fully charged. 735 watts of solar would support all my battery needs and thats assuming 50% output for 8 hrs a day. I burn just under 200 amp-hrs a day.
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