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thriftydutch

Ontario, Canada

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Posted: 01/13/19 02:34pm Link  |  Quote  |  Print  |  Notify Moderator

Okay here goes. I have a 12v-120v fridge. It is a Norcold DE 704D model. What I want to know is how much solar do I need to run this fridge. Ask any question you want about the fridge and I will try to give that information. I have 2 12volt house batteries.
I am not concerned about winter time. Just spring, summer and fall when the sun is higher in the sky.
Please leave this in the class B section.


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donn0128

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Posted: 01/13/19 02:45pm Link  |  Quote  |  Print  |  Notify Moderator

The name plate on the refer should give you all you need to know. Amp/hour rating for each power source is? Multiple that by 24. You have the amps necessary to run it for 24 hours. Amp/hour rating for each battery is? Since you do not want to draw a battery below 50%, half of the battery capacity is? Is that more or less than your refers draw? 125 amp solar panel should be OK for 2-12V batteries. But again, the rating of solar panels is kind of ambigious. That rating is based on full sun and tracking the sun. Since neither of those is really practical you really need to assume less output. Whether a panel can fully charge a battery or not is questionable at best. And based on how discharged the battery is.





Lwiddis

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Posted: 01/13/19 02:51pm Link  |  Quote  |  Print  |  Notify Moderator

Since the fridge isn’t the only item drawing 12 volt juice, do an energy survey. Multiply by 1.5. Then we can recommend battery AHs, then solar panels, then controller and lastly wiring.


Winnebago 2101DS TT & 2020 Chevy Silverado 1500 LTZ Z71, 300 watts solar-parallel & MPPT, Trojan T-125s. TALL pole for flags. Prefer USFS, COE, BLM, NPS, TVA, USF&WS, state & county camps. Bicyclist! 14 year Army vet - 11B40 then 11A - (MOS 1542 & 1560)


pianotuna

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Posted: 01/13/19 03:41pm Link  |  Quote  |  Print  |  Notify Moderator

Hi thriftydutch,

We would need to know the consumption in watts and the duty cycle of the fridge.

In my case that works out to 5.7 KWH per day. That means I'd need about 1000 watts of solar panels.

Your fridge is likely to be a LOT more efficient than mine.


thriftydutch wrote:

Okay here goes. I have a 12v-120v fridge. It is a Norcold DE 704D model. What I want to know is how much solar do I need to run this fridge. Ask any question you want about the fridge and I will try to give that information. I have 2 12volt house batteries.
I am not concerned about winter time. Just spring, summer and fall when the sun is higher in the sky.
Please leave this in the class B section.



Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp hours of AGM in two battery banks 12 volt batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

time2roll

Southern California

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Posted: 01/13/19 05:11pm Link  |  Quote  |  Print  |  Notify Moderator

Manual just says max 15 amp fuse
I assume this fridge draws 10/12 amps at 12v near continuous.

The minimum I see is 6 batteries and 600+ watts solar.

Plan to have a small generator to use as needed. With a generator you can get by with less battery and solar until you see what works.

This is why most use a propane fridge.


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crosscheck

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Posted: 01/13/19 07:10pm Link  |  Quote  |  Print  |  Notify Moderator

time2roll wrote:

Manual just says max 15 amp fuse
I assume this fridge draws 10/12 amps at 12v near continuous.

The minimum I see is 6 batteries and 600+ watts solar.

Plan to have a small generator to use as needed. With a generator you can get by with less battery and solar until you see what works.

This is why most use a propane fridge.


Read the yachting forums. These 40 year old fridges are thrown overboard and replaced with modern Danfoss compressor, 12V DC fridge/Freezers that are much more reliable and use 1/3 the amps. 200W solar and 2 6V GC2,s are what you would need extra for a modern 12V compressor fridge. For what the OP has, at least 3 times that amount. My 5 years experience with a similar sized 12V fridge as the OP is that 50% cycling was the max for us depending on as many as 6 factors which adds up to around 65AH/day being the highest draw/day.


Dave


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thriftydutch

Ontario, Canada

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Posted: 01/14/19 08:07am Link  |  Quote  |  Print  |  Notify Moderator

I just found this info on the fridge.
120 volts 0.4 amps
12 volt 4.0 amps
The batteries I have are 115 amp hours each.

pianotuna

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Posted: 01/14/19 08:38am Link  |  Quote  |  Print  |  Notify Moderator

Does the fridge work well on the 12 volt setting?

12 x 4 = 48 watts x 24 hours = 1152 watt-hours.

1152 watt-hours / 5 = 230 watts of panels. However one needs to be able to recharge the battery bank, too! I'd go with at least 400 watts on a flat fixed installation.

twin 115 amp-hour batteries would yield about 1300 watt-hours usable.

That would allow for only one "grey day" before another source of power for the fridge would be needed.

time2roll

Southern California

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Posted: 01/14/19 10:34am Link  |  Quote  |  Print  |  Notify Moderator

thriftydutch wrote:

I just found this info on the fridge.
120 volts 0.4 amps
12 volt 4.0 amps
The batteries I have are 115 amp hours each.
OK you have about 100 amp hours usable and assuming 50% duty cycle you need 50 amps hours per day. So you need 10 amps to the battery for 5 hours so 200 watts solar minimum in good conditions. That is just the fridge. I would still be at 3 to 4 batteries and 400+ watts solar to do this comfortably. Not an exact science, lots of variables. Solar will need to produce more than you use. Very easy to come up short doing a minimum calculation.

pianotuna

Regina, SK, Canada

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Posted: 01/14/19 06:32pm Link  |  Quote  |  Print  |  Notify Moderator

Duty cycle (measured) on my rv is 2:3 (on 40 minutes per hour) with the door never being opened with ambient temperature of about 16 c (61 f).

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