Input rating DC12V - 2.7A

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I am looking at adding a freezer to my newly purchased houseboat. I was all excited but knew I needed to do my homework to make sure I could support it. after talking to a man who had one on his saliboat he said it was doable but suggested I change my system to two 6volt's that would give me 440amps and add solor panals. I have been reading old posts and read one about the amp's may total 10 times the expected when going from ac to dc, buyers supprize. I have been lead to believe this unit draws 2.7 amp dc and runs about 1/2 to 2/3 of the hour, consuming about 25 to 35amps a day. I have a gen set and can recharge a little with that but was thinking solar to cover some of the re-charging too. Plus when the boat moves it charges.

???my question's are
am I understanding this power consumption correctly? and what would be a good option for the recharging of this loss charge.

The Engel 45 is a medium/large sized powerful freezer capable of freezing almost anything. It is ideal for long term freezing. As a refrigerator it can hold a steady interior temperature. They are great for people on the move - as this unit can be taken anywhere! - all you need is either a 12 Volt power supply or household 110 Volt supply. Features super low power consumption.

http://www.bigfrogmountain.com/engel/Engel%2045.htm

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,476 admin
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    Re: Input rating DC12V - 2.7A

    A suggestion... Do you have bottled gas on the boat (for stove)? If so, a gas powered fridge would probably be worth a look. The smaller ones use much less than one pound of propane per day (if I recall correctly).

    Solar on a boat can be a bit problematic... Unless you are docked, how are you going to keep those panels facing south. Is wind going to catch on those panels and cause you problems? If you are docked, can you insure that you will not be moved and/or shaded by somebody else in the future?

    Regarding power use, 2.7 amps * 24 hours per day * 2/3 duty cycle would be about 43 amphours (or 12v*43amphours=518watthours per day).

    Power wise, 250-518 Watthr per day is not all that hot (and the capacity is very small maybe a cubic foot or so)... Look around here and see that a couple people converted a plain old AC chest freezer into a fridge--uses about 150-250 watthrs per day, and is 7+ cu.ft. in capacity.

    My 17 cu.ft. cheapo Home Depot upright freezer uses about 1,000 watthours per day. You can get a chest freezer that does better than that.

    Solar wise, you certainly can power that size load (500 WattHrs) with a few hundred watts of panels--assuming good orientation and such (also need batteries, generator backup, and such)... But is this what you want?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
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    Re: Input rating DC12V - 2.7A

    i might suggest you do some reading in the catagory of Energy Use & Conservation as there are a few discussions on refrigerators there that may interest you. do know they are a high draw item so it may be tricky for you to come up with enough solar power on a boat to do this. keep in mind too that the sun doesn't shine 24hrs a day, but that frig will run in that 24hr period.
    as to the amps being higher for 12v that is because it is watts that is consumed. (defined-voltsxamps=watts) to make matters worse is that there is also a conversion loss in upping the 12vdc to 115vac(sinewave and not modified sinewave) so there may be 10-20% more power needed depending on the efficiency of the inverter used.
  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
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    Re: Input rating DC12V - 2.7A

    Bat21,

    The Engel 45 draws 2.7 A when the compressor is running, and 0.7 A in “standby”, both at 12 V nominal. If the duty cycle is 67% (2/3 day with compressor running, 1/3 day standby), the daily energy consumption will be (24 hrs x 67% x 2.7 A) + (24 hrs x 33% x 0.7 A) = ~49 Ah at ~12 V.

    You'd need a 120 VAC-to-12 VDC converter if you wanted to run the Engel from a 120 VAC source. The output from the converter would be 0.7 A or 2.7 A at 12 VDC, but, allowing for converter loss, the 120 VAC input current to the converter would be in the 0.08 A to 0.32 range.
    ...suggested I change my system to two 6volt's that would give me 440amps...

    This guy gave you technically incorrect advice. When wiring similar batteries in series, you add the individual voltages but the Ah capacity doesn’t change. Accordingly, when you wire two 6 V x 220 Ah batteries in series, you’ll get a 12 V x 220 Ah battery bank.

    You might want to consider VRLA (gel or AGM) batteries for your boat instead of staying with flooded-cell batteries. In general, VRLA batteries are maintenance-free (no checking electrolyte level or pH, no adding water, no equalization) and they’re ~10% more efficient (W out / W in) than flooded-cell batteries. They can also be installed on their sides, which may be helpful in tight quarters. See Concorde, Deka, MK, and Trojan for quality VRLA batteries.

    The downside is that VRLA’s are generally more expensive than flooded-cell batteries, and they’re sensitive to overcharging.

    HTH,
    Jim / crewzer