12 volt fridges and boondocking?

do an energy audit

find a spreadsheet here:

https://freecampsites.net/adding-solar-part-four/

Doing an audit can be largely guesswork especially if you have not had any experience running that 12v compressor refrigerator. You can start by checking the specs for amperage. A small 4 cuft unit will pull about 3.5 amps. If you camp in cool weather and don't try to cool down room temperature items, you might get by with 30 AH/day. More typical use would be twice that especially when camping in warmer weather. A larger unit is likely to pull well over 100 AH/day.

You also need to be realistic about how much energy you can expect from your solar unit. I am in NY, at this time of year if we ever have a clear day the maximum output for 600 watts of solar would be less than 100 AH. Lots of my camping in done in the woods with little or no solar even on a good day. You did not mention the size of the battery bank but certainly that needs to be sized appropriately also.

It's going to depend A LOT on exactly what 12V fridge you have.

12v refrigerators will likely use 30-60AH/day.
Your propane refrigerator does use some 12v power, but let's assume it is small enough compared to the amount the 12v refrigerator uses and you can ignore it.

Your two 100AH lithium batteries gives you probably 20-30 extra useable AHs compared to your two 6V batteries.

The 600w of solar gives you 120w more than you have now. In a sunny environment that will give you 25-35AH/day more than you had.

From the above, it seems like it is about a wash and if you were okay before with your battery life/use you will probably be ok with this new rig.

If the new rig has a generator, then you've always got that as a backup. My suggestion would be to try it out and see if you are satisfied. If needed, you can always add one more 100AH lithium down the road and another solar panel or two.

Good luck!
Chris

12v compressor fridge? Get the make and model #

Thanks for the advice so far.
The 12v fridge is a Norcold. The trailer came with an 8 CF fridge and from what I understand people are replacing them with 10 CF 12v fridges?

We have a 2000 watt Honda generator that worked well with the PF9280 I put in the old trailer but since I added the panels I rarely use it to charge the GC's in the old trailer, best mod ever.

The owner of the ORV put 3 100Ah Lithiums in it, was going to keep one for his slide in camper but is willing to keep it with the trailer, negotiable.

First, You need to determine whether it’s a dc 12v compressor fridge OR a 12v heater element fridge…A compressor fridge is more efficient and typically has better insulation…

For solar, the method I use for real world ‘calc purposes’ (obviously region dependent) is to de-rate the panels by 50%, and to assume a 60% refer duty cycle - add to this your normal usage, and battery’s starting SOC (state of charge*), then plan for a day or two of minimal harvest..

* will require a Lithium capable battery meter like a Victron (smart shunt or BMV 12) or equivalent…

3 tons

ScottG wrote:
It's going to depend A LOT on exactly what 12V fridge you have.

BINGO I've read the specs on several including both Dometic and NoCol.. er. Norcold

Now at one time (Do not know if they still do) They made what I call "Danfoss" class Compressor units (Danfoss is one of the companies that makes the compressors) if there is a proper name for that class

PLEASE: TELL ME

They draw (Door closed) less than 50 watts and work very well (I have a chest freezer.. my 2nd.. that uses that technology.. first one lasted from 2005 till last year)

Then I've seen some that use more traditional compressors and draw around 150-200 watts. (3-4 times the power) Door closed.

Door open you add in ye old light bulb. Or better yet Ye New Light Bulb (LED).

time2roll wrote:
12v compressor fridge? Get the make and model #

Norcold N10DC

Norcold Link

I've had several different types of RV fridges. My current one is the 10 cubic ft Norcold 12V compressor type.

The downside to 12V compressor fridges is they consume more power per day than an absorption type fridge running on propane. The upside is they cool better, and much faster.

The Norcold has a night mode, which draws less power. They expect the fridge to be used less in the middle of the night, so they run the compressor less.

The temperature of the RV, and how often the fridge door is opened, will play a big part in how often the compressor runs. Looks like the 8 cu ft fridge draws ~5A/HR.

Just a wild guess, a 50% duty cycle of 5A/HR, is 2.5A/HR x 24 hours = 60 Amps x 12V = 720 Watt Hours per day. 600W of solar, with a derating factor of 25% = 450W of actual production. During peak sunlight, you'll replenish all the energy used by your fridge in 1.6 hours.

Short of measuring your actual usage, and actual collection, hard to give accurate numbers.

If power consumption becomes a big deal, consider using a portable Engel refrigerator. It only has one moving part, and is incredibly efficient. I added an external thermostat to mine, details here: http://2manytoyz.com/engel-thermostat.html