Advice for Dometic 12V Compressor Fridge

Olena

I know I was talking big a few weeks ago that I am going to be upgrading myself to a 2021 T@B, but I have now decided to stick with the T@B I have. The big reason? The dealer told me that if I were to order now (that was beginning of October) the new T@B would not be ready until at least July! Not interested in making a mid-season switch, I am now working on getting some new mod cons ready for next year. 

Here is my question. I just bought a Dometic CF18 12V compressor fridge. I bought this model because it fits in the space under the counter without sticking out (my T@B has no built in fridge, up until now I have used a Yeti cooler). This model is 12V DC only and does not offer a 120V regular plug. Most of the time I am boon docking and have a 120W Zamp solar panel (and am looking to upgrade my battery for next year but that's a whole other discussion), which will probably work out fine, and I can always add more solar power. My T@B does not have an Alde either, so my electrical needs are just the water pump, a bit of fan use, some lights and the parasitic draw of the carbon monoxide detector. I am using the amp usage charts that have been posted over the years to help me figure out how many amp hours I will need once the fridge is in the mix. By the way, the fridge is rated at 0.9 amp hours.

Okay so finally here is the question! Sometimes I do camp at sites with electrical hook-up and when I do, will I be able to use the 12V fridge - plugged into the 12V receptacle, and with shore power will it just run without having to monitor the battery? I don't use electrical hook-ups very much so this is kind of twisting up my brain. Does the power go through the converter and right to the 12V receptacle or does it route through the battery? Do I need to keep the battery cut off on or should it be off when I am in this situation? 

In the spring my dealer is going to install a hidden 12V receptacle so I can plug in the cooler without a big wire running across my counter. Is there anything special about that that needs to be considered (my T@B dealer is good and the technician knows his stuff). 

Denny16

Yes, the newer TaBs have a DC only fridge, and whilst running on AC, the trailer’s AC/DC Power converter supplies the 12VDC to run the trailer 12 volt systems, including the DC fridge.  It will also charge your battery too.
cheers

Sharon_is_SAM

Your new frig will be wired for 12 v and as long as the technician ties it into the existing 12 v supply, it will be powered via the converter when on shorepower and you do not need to monitor the battery.

Regarding the battery switch, if you turn it off while on shorepower, your frig will continue to run independent of the battery.  If you leave the battery switch on, the frig will still receive power via the converter and your battery will also charge.

Just make sure the tech does not wire the frig directly to the battery.  

Denny16

Good point on not wiring directly to battery Sharon.  It should be wired to one of the spare fuse positions on the converter, with its own, correct size fuse.
cheers

Olena

Thanks for the advice. I will make note that the plug should be tied into one of the spare fuse positions on the converter. 

Sharon_is_SAM

@Olena - I would add that, up to now, you have not needed to worry about excess draw on your battery.  With the addition of a frig, I would consider installing a shunted battery monitor especially since you like to Boondock.  You will want to protect your new upgraded battery system.

4ncar

@Olena: Are you saying that the fridge comes with a 12v “cigarette lighter” plug, and that the shop is installing a socket near by? If so, ask them to cut the plug off and splice the wire directly into a 12v circuit. Best if it were on its own, but one with little existing draw.  This way there isn’t any wires exposed at all.

Marceline

4ncar said:

@Olena: Are you saying that the fridge comes with a 12v “cigarette lighter” plug, and that the shop is installing a socket near by? If so, ask them to cut the plug off and splice the wire directly into a 12v circuit. Best if it were on its own, but one with little existing draw.  This way there isn’t any wires exposed at all.

If she has other uses for that cooler (e.g. tailgating, family trips) it would probably be better to keep the original 12v cigarette lighter plug.
Dometic CF18

Denny16

The OP is installing a top loading chest type unit, a compressor version of his former Yeti Ice Chest unit.  So leaving the 12VDC plug on it would be advantageous as Marceline pointed out.  See: https://shop.dometic.com/store/dometic/en_US/pd/productID.5178069600?gclid=Cj0KCQiAhZT9BRDmARIsAN2E-J0rHZ9yTtHM05DEcIRw7abpA9cguO45L7ygchqDNU8PPxABwHEaTLIaAs3cEALw_wcB
cheers

Sharon_is_SAM

 Merit or Hella 12v sockets allow a more secure, reversible connection.  We have this system for our installed ARB AC/DC frig/freezer.

CrabTab

Keep the stock 12V plug and have a socket installed instead of hard wiring. It is nice to have options as your usage evolves. We have used our Dometic CFX75DZ in several vehicles, depending on our activity. We've used it in our TV when pulling the T@B, grocery getting, picnicking and even in my old 4x4 when surfcasting (nice to have a frozen treat on a hot beach).

CrabTab

@Olena Here is some usage data from our much bigger Dometic (ours is 75L vs your 18L). This was from as extreme a test as I could do when I was trying to determine my amperage needs. The fridge was placed in a completely closed T@B, in direct sun, in late July. Temps inside the trailer went over 100 degrees during the day.

One side of the cooler was set as a freezer at 7 degrees and the larger section was set to 39 degrees. The white line shows the freezer temp over 24 hours. The orange bars are the corresponding current draw over that period of time. The average draw was over 2Amps/Hour.


The next day, same conditions, I set both sides of the Dometic to 39 degrees. The current draw drops to about 1Amp/Hour



Hope this helps...

4ncar

Ahhh, didn’t realize it was a top loader....

Olena

Thanks for all the advice. My motto is always "keep it portable". Portable fridge, Porta Potti - you get it. I like options for different scenarios. Initially, I bought the Dometic with the intention of only using it when I have an electrical hook-up, and going back to the Yeti when boon docking.  But, of course, now I am thinking I could probably get used to this fridge thing (no block of ice melting into my cheese!).

The plan is to try out the fridge with my current solar and battery set up to see where it takes me, and once I have an idea of power consumption then I will invest in a new battery plus any accessories. Two 6V batteries are not an option for me, they just add too much weight (I drive a Ford Escape and do not want a bigger car).

I want to thank Crab T@B for the info. It makes me feel confident that my 18L Dometic with no freezer compartment should in fact come in at around 0.9 Amp/hour as the manual states.