Fastest cooling of 3-Way Refrigerator

ADRawli

Ok folks.  I should know this, but I don’t.  I know that putting already cold items in any fridge helps to cool it down faster, but... does anyone know the definitive answer and hopefully have some data to back up your response to this question:  if I am sitting at a campsite with all 3 options available to me to cool my 3-way refrigerator, which of the 3 will cool the interior the fastest and by how much?  I would guess its not 12V (but again, just a guess), but if that is true, is LP faster than 110v, or vice versa?  

Thanks in advance.

Verna

@ADRawli, with the 3-way I had in my former 2014 T@B S Max, I always used propane, or electric, if available.

I always felt propane was the best. I have no technical data to prove this, just the fact I pre-cooled on propane. 

I always kept frozen water bottles in the bottom.  When they thawed, I froze them in my ARB 50 quart Fridge/Freezer. 

(Yes, I do realize my 3-way was much smaller than yours.)

ADRawli

Thanks @Verna, I ask because I am in the exact predicament.  I am sitting at a campsite, with full hookups, and watching the interior of my fridge slowly, and painfully, get cooler.  It was 37-39 degrees when we loaded and left home this morning, but the 3 hour ride here saw the temp rise to 50+ while running off the 12v from the TV.  It was running, I made sure of that, but still warmed up during the ride.   And then with dinner and water bottle retrieval after camp set-up, I’ve been waiting to see it drop, and it just has not much.  I have been running it on LP, with less than a few tenths change, and so I just switched back to 110 to see if that moves it down faster.  Guess the Norcold just does not like 90+ degree weather with 70% humidity.  I think we’ll leave home with as much ice in there as we can squeeze in for future summer trips.  

RFraer

With my experience propane cools it quickest, then 120AC, then 12V. 12 V is kind of a joke. Even when towing 12V kills the house batteries and I have a high output alternator and solar.

MuttonChops

Found a Fridge cooling test on youtube.
Larger 6.0 cu ft unit.
Based on the test, that expert states 1-hour to cool 10F.

So if 90F at start, getting down to 40F would take some five hours.

He also claims difference between propane and 120VAC electric is minor.

https://www.youtube.com/watch?v=xnuChDFqKXM

ADRawli

Thanks @RFraer and @MuttonChops, that is very helpful info.  I was laying in bed last night contemplating if I should be worried with about a 48 degree temperature reading when all of the sudden, the whining of the unit stopped, as it does when it reaches temp.  I opened the fridge and got a water bottle out and sure enough, almost ice cold.  I guess my thermometer sensor was not updating correct temps.  But.. when we got up this morning it read 36 degrees as I it should, and nothing was frozen. So, I don’t know what to think as it appears I can’t exactly trust my temp readings.  I just bought a new 3 sensor unit that allows me to put one sensor outside, one in the fridge, and one at each end of the trailer cabin.  They all seam to be reading and getting updates, but now I’m not sure I trust them.  Oh well, at least that is a much smaller problem than a fridge not cooling.

By the way, I think I agree on the LP and 110 cooling at close to about the same rates.  I am not convinced that LP is faster, and I completely trust the 110, so I usually defer to that when I have the option.  Besides, 110 comes with the hook-ups, where as LP is my own cost (be it a small one).  

Thanks again to all for providing the info.  This forum continues to be a very valuable source of knowledge and better understanding. 

TNOutback

@ADRawli a fan installed in the exterior vents would probably be the best performance booster in hot weather, or even a fan plugged in and blowing into the lower vent would help.  The lack of temperature delta in hot weather makes it hard for the refrigerator to dump its heat - no matter what mode you are in.  A permanently-installed fan in the exterior “stack” really helped the performance of my 3-way in our old travel trailer.

db_cooper

Propane is definitely faster at cooling the fridge, for the same reason propane will heat the Alde faster.  More BTU's than the electric element.  Also, adding a small fan inside the fridge, and adding computer fans to move the hot air out will increase performance.

So, to cool quickly use propane and once down to temp switch to electric if available.

ADRawli

db_cooper said:

Propane is definitely faster at cooling the fridge, for the same reason propane will heat the Alde faster.  More BTU's than the electric element.  Also, adding a small fan inside the fridge, and adding computer fans to move the hot air out will increase performance.

So, to cool quickly use propane and once down to temp switch to electric if available.

Thanks, that’s good insight, and makes some sense. I was trying both but not patient enough to stick with one.  I’ll have to do some objective testing on my unit next chance I get. 

Dutch061

ADRawli said:

 It was 37-39 degrees when we loaded and left home this morning, but the 3 hour ride here saw the temp rise to 50+ while running off the 12v from the TV. 

Unfortunately this has been my experience with the 3 previous RV's that I have owned including my most recent which was a 2017 TAB 320S. Always scared me to be hauling stuff that is supposed to be cold at 50+ and then eat it wondering if there would be future problems. I put in fans to help move the air (both inside and out), I pre-chilled everything, it simply didn't matter for me I ended up with the same situation all the time. I never used the 12 Volt while traveling, I always used propane to operate the refrigerator but no better results as mentioned.

On our current 2020 TAB 400 BDL I opted for the smaller 12 Volt Compressor Refrigerator. All I can say is this is the very first RV that I have had that the refrigerator just works, it gets cold faster, it stays cold while moving, it doesn't have the wild temperature fluctuations that ALL absorption style refrigerators have, "set it and forget it". The only draw back is the fact that it is smaller but the positive trade off is the additional closet space. Some would say the amperage draw to run a 12 volt compressor refrigerator is a draw back but I would simply ask you "how important is your health"? I assure you that almost everyone who had food get to 50+ at home in their refrigerator would toss it out but when they go camping it is okay?

It is time the RV industry ditched the over priced and inefficient absorption style refrigerators once and for all.

Happy 4th of July to all, God Bless America!!!!

Brad

gulfarea

Dutch, I have had 3 rvs with the gas and totally agree with you. I removed one 2 door gas in my motor home to find it almost caught fire in the wood near the burner! Art

Dalehelman

@ADRawli

Your  experience is pretty much the same as mine over the last 5 years. I find propane and 110 to be about the same. 12 volt is pretty useless. Are you using the auxiliary fan? The more air circulation the better. I installed this screen in mine to improve air flow.

Denny16

The fastest way to cool a 3-way glass-matt refrigerator, in my opinion— is to replace it with a two-way compressor fridge, and Bob’s your uncle! 

Cheers

AirBoss

Good one, @Denny16

Question for the group:
When underway with 400 battery swtitch engaged and built-in Voctron solar, if I'm running the 3-way fridge on 12V, I presume the twin 6-volt AGM batteries are running it and the Victron is keeping them charged (also assuming a decent day with at least partial sun.

It's not relying on the TV alternator to any degree via the 7-pin.

Correct...or all wet? 

Denny16

No, sounds correct to me.  How is the refrig cooling when on battery only?

Cheers

AirBoss

Works well enough. Don't travel with it on gas. Not been on long (5hr+) road trip yet. Have one coming up next week in warm to hot temps. 

Tundra57

I have a 2019 Tab 400 wirh a Tundra TV and 12v battery charger. I do have factory solar.

I precool my 3 way fridge on 110v before stocking with food. I also use the frozen compartment. I have not had the cooling problem you guys mention running 12v while traveling. However, until I fitted the 12v charger and uprated wiring, my Tab batteries would deplete on a long run with a lot of dark running.

Once on site I switch to 110v if available or gas.

My Tab does have the additional Fan.

I have camped in 90+ heat also with no problems. I do keep the fridge pretty full with little air room.

I prefer having the larger fridge, even with the loss of storage.

I do not have a temp measure inside the fridge, but whenever I take out a bottle of water it is cold and the freezer compartment stays cold enough to keep my frozen sausage and bacon frozen.

My longest trip was 12 hours driving with at least 4 hours in darkness.

AirBoss

@Tundra57
That's pretty much how I run. Keep mine in storage facility. They stage it day before and do all the "pretrip" stuff for me...start fridge on gas, fill H20, give it a bath, etc. So when I show up to head out all I do is stock the fridge/freezer as much as possible, switch to 12V, turn off gas, hook up, and we're off. 

Victron seems to keep up pretty well, tho I do monitor it while underway. I'll 110V every time if it's available. Paid for it already! 

I was mostly curious about how the T@B AGM's are being charged while underway. I suspect that regardless of the 7-pin connection they're charged by Victron and not TV Alternator. 

Don't think it's an issue for me as the TV is pretty stout on all things towing...just one of those things that make you go, "Hmmmm....I wonder?" 

Denny16

AirBoss, the TaB batteries are getting charged from solar, and your TV, when underway.  So you are apparently getting enough charge to keep up with the fridge.

We have the compressor two-way fridge, and the solar keeps up with it during daylight hours.  
cheers

KAR

Fascinating reading. Thanks for all the insight! we'll be taking a trip across CO, NE, IA and MI sometime this summer so we'll see how our fridge does. Wish us luck! And good luck to you! Stay healthy!

CruiserCamperChris

Great thread. Ive learned a lot. Does the 2021 T@B 400 w/3 way Norcold already have the cooling fan to help get rid of the fridge exhaust? Or do i need to add one? Where would i put it?

And does everyone agree that you should never run the Propane while towing? The reason being that in an collision, or crash, it would lead to a fire or explosion?? 

Thanks!

bergger

The 2021 400 with the 3-way fridge has a cooling fan already.  It is thermostatically controlled and will turn itself on and off as needed. 

Our 3 way fridge has been great.  We also pre-chill it on 120v the day before we leave and pre-chill any food or drinks we put in it at the start of the trip.  We never use propane when towing but use the 12v option.  Our truck has a 200 amp alternator and between that and the solar does a pretty good job at keeping the batteries from depleting too much as we travel. 

 If we are going on a long trip, 6 or more hours of driving, I'll monitor the batteries with the victron app and if needed turn the fridge off every once in a while if the batteries get close to 80%.  After they quickly charge back up I'll turn the fridge back on 12v.  The fridge holds a cold temp for a good while even when turned off as long as it is prechilled and the food is frozen or prechilled as well.  If you have left over space in your fridge I also recommend placing some freezer packs in it to help keep the temps even colder.  We usually put 2-3 ice packs in the fridge anyway as we re-freeze them overnight and use them in our day trip cooler when on vacation.   

pthomas745

Most likely, your propane fridge flame will blow out, so running on propane isn't possible (some people have managed this, however).

If propane tanks "blew up" at the pace and ease that people think they do, they would never be installed in trailers, portable BBQ's, homes, etc.

CruiserCamperChris

Of course the big factor is if you are towing in 100 degree weather, or 60 degree weather. Glad we have a Dometic fridge/freezer in the TV

Denny16

The issue with towing whilst running a propane appliance is not the propane tank danger, they are very safe, and all current certified tanks have an auto count off valve if the gas lines become severed or any fast leak occurs.  

The danger is, a slow leak (which is not detected by the tanks build in safety valve),  that could develop whilst towing, which goes undetected and could cause a fire.  

Motorhomes have an additional safety auto cutoff valve installed (in addition to the tanks build in valve) to allow them to rind propane while underway.  But they are not unattended, as most are open to the cab.
 Cheers 

Marceline

Sharing this in case anyone else is in a similar situation.
When I kept my T@B in storage yard with no power I would get a chunk of dry ice and throw it in the fridge to accelerate the cooling process. 

CruiserCamperChris

this is a good article on the subject. There are some good comments in the comments section too: https://camperreport.com/can-i-tow-a-travel-trailer-with-the-propane-fridge-running/