12v / 120v fridge question

In my experience with a similar fridge, 2 days no sweat with no solar. If you are getting reasonable solar output add a day. Really I think it will still be going on day 5 but I'll be conservative...and your batteries will be in better shape.

Mote wrote:
Could he run the fridge on propane instead ? I would think his batteries would last longer then.

He is talking about an all electric fridge.

Dave

Could he run the fridge on propane instead ? I would think his batteries would last longer then.

Kevin,

There are a lot of variables when it comes to the amount of amp/hr used by your batteries in a day.

Just the fridge by itself will use somewhere between 25- 60 amp/hr per day depending on ambient temps, door openings, inside temp settings, replacing cold food with warm etc.

What are your other non - fridge draws? These all have an impact how often if any you will need to use other power sources other than solar to replenish your batteries( genny, shore,alternator).

We have 4 years experience with the 7.5 cuft NovaKool 12/120V fridge/ freezer.
Started out with 4 6V AGM with 190W solar. Our camping style is 98% dry or Boondocking. Ran our genny only a few times in those 4 years. We found that with 190W solar, if the desert temps got over 90F in the day, it was touch and go so we added another 140W and never have a problem with batteries being run down.

To answer your original question, between 2 and 5 days depending on conditions.

I would recommend that you install a minimum of 190W of solar. If you have more room or even if you don't(portable system), go with 300W and add 2 more batteries but this is maybe more than you are willing to invest at this time.

The 12V compressor fridge is the largest single draw of electricity in our camper but we are 100% happy with its performance and would not go back to an absorption fridge.

Dave

I have a NovaKool R5810 5.8 cu ft fridge, DC only. It draws about 4.5 amps while running, but it runs less than 50% of the time even on hot days. I figure I'm running around 35-50 Ahr per day during the summer. That is about 420 - 600 Whr.

You could feed that with a 85W - 150W solar panel so your 95W panel is a little small, given that you will have other loads.

I have 400W and a 220Ahr battery but that is probably overkill for most folks. I run all summer long, almost always without hookups, and I use my computer and a tablet for music (don't worry - I use headphones!) a lot. I also run an Engel 12V cooler (same type of compressor) for beer.

If you add another 95W panel you will likely be in good shape.

The Novacool is a marine 12vdc compressor fridge. 3-5 days with good sun and little other draw.

Going to 24v from 12v DC provides no discernible difference in voltage drop with a 4 amp load. It will be 0.10 volts drop with a 10 foot run (20 feet round trip) with 8ga wire. Higher voltage helps with high draw motors and inverters but not for something like a fridge drawing 4-5 amps.

In the real world with a 220 AH 12v battery bank I have never been able to draw the batteries down to more than 78% DOD and that was with a test where I had all the lights, the TV, and the fridge running.

Good idea to invest in a Trimetric or similar device so you know exactly what your battery charge level is at any point in time and can accurately monitor the draw down from the fridge, furnace, lights, and anything else in the camper.

The RV fridges are designed to use 120v AC or propane for power. The DC is to power the electronics. Want a fridge that is designed to operate on DC then get a marine fridge.

Guys I think he is talking about a compressor fridge, not a propane 3-way running on the 12V heater element.

Our NovaKool 9.1 cuft fridge uses about 600 watt-hr per 24 hour period (I actually wired it to run on 24V for lower wire losses).

One 12V 125AH battery can supply 600 watt-hr without draining below 50%.

Two would provide about 2 days with no other loads on the battery.

95 watts of solar is a bit light. We have 1080 watts.

You need at least twice the battery and 4x the solar.
Otherwise 12v is for transit only.

No propane?

I looked at the chart.

4.4 x 24 = 106 amps

That's NOT ever opening the door & doesn't take in consideration what else in the coach is using 12 volts like the furnace, lights, LP detector etc.

You won't reach 24 hours before you're below 50% SOC. Even with the 95 watts solar.

Correct me, if I'm wrong.