The Dometic CFX3 Mega Thread

It’s irrelevant which tip you have on the 12v plug, whether it’s the two prong or the cigarette outlet style tip, they both supply the same 12v to the fridge. I prefer the two prong because in can be screwed into some power receptacles making for a more secure connection.

 

Agree.

 

I use a Jackery 500 or 240 to power my Dometic. Cigarette lighter DC outlet on the JACKERY. Works great.

 

Ended up getting that used

$780 CFX3 45 -Liter Portable Refrigerator and Freezer, Powered by AC/DC or Solar

CFX3 45, and also picked up a Jackery 550 (the box store-version of the 500). Worked great throughout Colorado and Utah (driving several hours daily), and in the Sierras from Thursday until yesterday (truck was off from 1PM Thursday to 3:30PM yesterday - fridge was set at 37 degrees and the Jackery was still at 22% when I turned the truck back on). It's a total gamechanger, and I'm loving it. Probably will end up getting a 100W portable solar panel for it at some point.

 

@essjay Good for you.

 

Thanks to everyone who replied to my question about the Dometic CFX 2-prong vs. standard DC plug!


I have another question.


I have a 180amp hour lithium battery stack (Inergy APEX + FLEX) with the CFX fridge connected via the standard DC plug tip. I have the fridge set to on low battery protection mode. My understanding is that protection mode cannot be shut off entirely (I'd love to do that!).

I did a test and the fridge cooled down to the set temp (37 degrees) and eventually got the "Low Voltage warning" on the fridge LED display.

Here is the voltage readout at the time of the voltage warning:

Fridge display: 11.3v
Battery display: 11.4v

My understanding is that in low protection mode the compressor won't start if the voltage unloaded voltage (on the fridge display) is below 11.4v, so as far as I can ascertain the CFX appears to be performing as designed.

However, my battery stack at this time was at 65% capacity. The prior poster (@essay) said his CFX fridge was still running when his Jackery 550 was at 22%, and if I do the math correctly that is a 45 amp hour battery, so much less than my 180amp hour stack.

Does anybody have any idea if what I experienced was "normal" (fridge shutdown at 66% capacity on 180amp hour battery) and if so, how to square that with a Jackery 550 (45 amp hour) running a CFX at 22% capacity?


Note: when doing this test, I was putting other load on the battery stack from other devices. I was trying to drain the battery rapidly to see when the CFX was going to shut off. As far as I know that shouldn't affect when the CFX would shut off as those are all separate circuit's but am mentioning it in case I am mistaken.

 

I don't know about the math, but I should probably note that I pre-cooled the fridge at home overnight from a wall outlet before putting it in the truck for the trip. I also use the medium protection mode setting, rather than the low.

 

You can change the cutoff threshold/sensitivity on the CFX. So if your fridge is powered by your one and only house battery you’d want it to shut off and not drain your starting battery. In my case I run it off a PLB40 so I shut the protection mode off. Would be the same concept using a Jackery or any other similar device.

 

Thanks, your reply gives me some hope! Do you know how I would go about shutting off the protection mode on the

$761 CFX3 35 Portable Refrigerator and Freezer - 36L - Powered by AC/DC or Solar Portable Refrigerator, Smokey Gray

CFX3 35 fridge?

The battery protection menu on the CFX3 35 only gives 3 options "High, Medium, Low". I've spent hours scouring the manual and Google and can find no information on how to totally turn off battery protection on any Dometic CFX fridge models.

 

I could be wrong but I think low is essentially the same as off. That’s how I run mine and it doesn’t cut out.

 

Thanks for the reply. Unfortunately, for my

$761 CFX3 35 Portable Refrigerator and Freezer - 36L - Powered by AC/DC or Solar Portable Refrigerator, Smokey Gray

CFX3 35 setting battery protection to low is not the same as off. My fridge shuts off when my 180amp hour battery stack is at 66% capacity, which seems ridiculous to me if that is "normal" behavior.

 

I just checked the manual for mine and you are right, only options are low medium or high. It says at low it will shut off at 10.1V. I’m not familiar with your battery setup. Is it lithium cells? I thought one of the advantages of a lithium unit like the PLB40 over a second battery is that they can be run down all the way to 0% without dropping in voltage so the fridge can run it all the way down to zero without any loss of function.

 

Thanks for checking!

Yes my batteries (Inergy APEX and FLEX) are lithium cells.

Do you recall how low (percent or voltage) you've run down your PLB40 battery? And, do you use your PLB40 for anything other than the fridge?


The reason that the fridge shutting off at 66% is a problem for me is the battery stack it's connected too is used for lots of other things (interior lights, sink pump, roof fan, charging laptops / phones, etc.). My normal usage for that stuff (i.e. without the fridge) drops the battery down to around 60% if it's a cloudy day (no solar) and I'm not driving (no alternator charging), which would cause the fridge to shut off if it was also drawing power.

The more I research this, it looks like the only way to make the CFX fridge happy is to put it on it's own battery, that isn't used for anything else significant, and then the CFX's refusal to use over half the battery capacity doesn't matter. But, I am hoping I am wrong and I can learn from somebody something I am missing in this picture.

 

I've run it all the way down to zero percent during tests.

It's the only device hooked up to it.

 

Test it with only the fridge, and run the fridge as a freezer.

I believe that should be 10.1v shut off at low setting.
If it keeps doing that contact @Dometic

I keep 2 Jackery batteries. 2 is 1, 1 is none, 3 is better.
I cover mine with a folded fleece blanket.

 

Thanks, that is very helpful to know. The PLB40 is 40 amp hours, so if you can run it down to zero, and @essay can run his 45ah Jackery 550 down to at least 22% then it makes no sense to me why my fridge is shutting off when my 180ah battery reaches 66% regardless of what the manual says about battery protection.

Thanks for the reply. I plan to call Dometic tomorrow. For low setting in my owner's manual it says 11.4v for ON and 10.1v for OFF. And they don't define what ON or OFF means.

After lots of research I pieced together that the voltage for the battery protection is based on the voltage at the tip of the power cable (reported on fridge display), and ON (11.4v) is the unloaded voltage and OFF (10.1v) is the loaded voltage (i.e. when the compressor is running). Once I found that info it explained why the voltage on the fridge display jumps up and down all over the place rather than the volts going down in a straight line as the battery's power gets used: ever time the voltage suddenly jumps higher, I can hear the compressor shut off.

So if the above is correct, that actually does line up with my test scenario as the low voltage message displayed when fridge voltage was 11.3, the battery display reported 11.4, and the compressor was off, so it seems like the unloaded voltage spec of 11.4 would apply. Unless I've misunderstood something.

What doesn't make sense to me is a) if the above is correct, why would a company design a fridge to use less half of the batteries capacity and b) and if the above could be correct how can a PLB40 can be run to zero and a Jackery 550 could be run down to at least 22%.

I'll post back here with whatever Dometic has to say.

--

Thanks again to all for all the replies!

 

I am following up on my post above. I contacted Dometic and they said that the PLB40 is a Lithium Iron Phosphate battery which delivers a stable 12V output until the battery is at nearly 0% capacity They suspect that my house battery stack is a regular Lithium Iron battery as those types of batteries gradually output a lower voltage the lower their % capacity is. I did some research about batteries and this seems to check out. I suspect the Jackery is also a Lithium Iron Phosphate battery which would explain why it is able to be run down to a low % capacity as well and still run the CFX cooler.

So, looks like I'll be buying a PLB40.

Thanks again for the help brainstorming on this issue.

 

A good option. They are expensive but, for the capacity, they seem comparable in price.

What I did was buy several Jackery units. If one fails, I have another. I do not like relying on one.
2 is 1, 1 is none, 3 is better.

 

Thanks for the perspective. Do you know the size dimensions on your Jackery units? I've had a hard time finding that precise info and the PLB40 seems like it's smaller. I've got a very tight space situation.

I should be covered on redundancy though even with one fridge battery because when I bought it my van was wired up to run the CFX via the starter battery, so if my fridge battery failed (PLB40 or Jackery) i could cut back over to the starter battery temporarily.

 

I’ll parrot that for the money, you can get better options as far as watt hours per dollar spent. Check out Ecoflow, I just bought one and am wholly impressed.