Keeping Refrigerator on when Traveling?

[Cate&Rob]

I did some pretty extensive studies on smaller RV refrigerators and published my findings. I like to use data to manage risk. . . . The data tells me that if I'm going to be operating for most of the day in a warm environment, that I would have a greater risk of food born bacteria. I run with the propane on to mitigate this risk

When we got our Reflection a few years ago (our first RV!) we followed the instructions and towed with the propane off. These fridges don't insulate very well, so after a 6 to 8 hour travel day, everything was beginning to thaw. Based on Jim's research, we switched to running with the propane on and are much happier with this risk vs the spoiled food risk. (not to mention the warm beer at the end of the day )

Some anecdotal observations . . .

For a while, I would turn off the propane before crossing the bridge between Canada and the US . . . although, there is no sign requiring this, like there is for tunnels. Entrance in to the US goes through thermal (and who knows what else) full vehicle scanners. Then, I forgot to turn off the propane ! No comment at the booth. We have now crossed the border many times in both directions with the fridge operating on propane.

Since I drive a gasoline truck, I am very cautious around refueling. If the trailer is "way back there" and no where near the pumps, I will leave the fridge on. If anywhere near the pumps, I shut the fridge off. Fueling one time across from another trailer, I can hear the ignitor clicking on the back of his fridge right beside the gasoline pump. I yell to the owner that his fridge is on. He replies "no problem . . . I turned off the propane" . . . which was why the igniter was trying to ignite something. The point being that if you turn off the propane, turn off the fridge too.

Rob

[TucsonJim]

Any reliability issues with the Dometic LP gas checker? My brother had another brand and he said sometimes it went nuts?
Thanks
Keith

Other than being a little inaccurate when the batteries get low, it always works fine for me. If I see a reading that doesn't make sense, I change the batteries which is about every year or two.

Jim

[Guest]

I travel with the propane on and the fridge lit. Not overly comfortable with this but without the propane on there is a much higher risk for food poisoning than a fire (nice report Jim). One thing that is important if you live in a heavily wooded area like we do. My fridge chimney cap is collecting a fair amount of pine needles and leaves in the fall. I clean this up as best as possible but need to go further to make sure this debris is not getting into the chimney flue. I will be making up a screened cover to sit over the chimney cap when the rig is sitting at home.

Jim

[TucsonJim]

This thread is why I'm so interested in GDRV's assessment of 12VDC refrigerators.

Jim

[Cate&Rob]

This thread is why I'm so interested in GDRV's assessment of 12VDC refrigerators.

Jim

12VDC refrigerators are not a “new invention”. These have been used on boats for years. They have also historically been “power hogs” so I am also looking forward to learning about new technology for these.

(Propane use on a boat is very restricted by ABYC specs. Propane is heavier than air. A propane leak on an RV drops out the underbelly and blows away. A propane leak on a boat fills the bilge with explosive gas)

Rob

[howson]

12VDC refrigerators are not a “new invention”. These have been used on boats for years. They have also historically been “power hogs” so I am also looking forward to learning about new technology for these.

(Propane use on a boat is very restricted by ABYC specs. Propane is heavier than air. A propane leak on an RV drops out the underbelly and blows away. A propane leak on a boat fills the bilge with explosive gas)

Rob

IF GD continues to head down this path it will be very interesting to see the recommended aH (amp-hour) battery capacity for a trailer with a 12V refrigerator. I hope they won't stick with the one wet-cell battery. I don't have numbers, but would find it incredulous if one battery is considered sufficient.

[Bigjaike]

I've read somewhere that you should not travel with the refrigerator running on LP. I understand the thinking on this, but aren't they designed to do this. Else besides ice how do you keep the refrigerator cold?

I went with a solar, inverter and large battery bank so I can run the fridge on AC power going down the road, I recently went on 12 hour drive time (unhook to hook back up) and had about 16% left in battery power. I isolate my propane tanks before I leave the camp ground.

[Canyonlight]

I went with a solar, inverter and large battery bank so I can run the fridge on AC power going down the road, I recently went on 12 hour drive time (unhook to hook back up) and had about 16% left in battery power. I isolate my propane tanks before I leave the camp ground.

Does this mean that the truck is not charging the RV batteries while driving ? I thought most trucks with 150 amp +/- alternators or more capacity would keep the RV batteries charged while driving with the AC fridge running (and possibly additional AC usage as well.)

Dan

[TucsonJim]

12VDC refrigerators are not a “new invention”. These have been used on boats for years. They have also historically been “power hogs” so I am also looking forward to learning about new technology for these.

(Propane use on a boat is very restricted by ABYC specs. Propane is heavier than air. A propane leak on an RV drops out the underbelly and blows away. A propane leak on a boat fills the bilge with explosive gas)

Rob

The primary difference between these new models and the ones from the past is that the new models operate on a compressor instead of a heating element.

Jim

[howson]

Does this mean that the truck is not charging the RV batteries while driving ? I thought most trucks with 150 amp +/- alternators or more capacity would keep the RV batteries charged while driving with the AC fridge running (and possibly additional AC usage as well.)

Dan

My '17 F-350 with it's 225 amp alternator provides a whopping 9 amps of 12vDC through the 7-pin connector. Converted, without accounting for any loss, that's a mere .9 amp of 110vAC.

You may recall I have 400aH of battery capacity with my four Battle Borns. On average we consume 30aH of that capacity in addition to what the truck provides for every hour we tow (refrigerator on). That's why I want to run additional power from my truck back to the trailer. (Project on my "To Do" list.)

[Canyonlight]

I always suspected (w/o knowing or thinking about the actual #s) that our HD trucks were putting out more than adequate power to operate the residential fridges while on the road w/o draining the RV battery(s) what so ever. Thanks, Howard for enlightening me.

Under normal operation of the residential fridges, what is the power draw ?

Dan

[howson]

I always suspected (w/o knowing or thinking about the actual #s) that our HD trucks were putting out more than adequate power to operate the residential fridges while on the road w/o draining the RV battery(s) what so ever. Thanks, Howard for enlightening me.

Under normal operation of the residential fridges, what is the power draw ?

Dan

I don't have actual (from experience) numbers on a residential refrigerator (my Dometic is an absorption, "RV" refrig) but from what I've read it is significantly less.

This (old) video by Gone with the Wynns is probably the best I've seen on the topic. (Over 11 hours he only used ~205 aH. That's a LOT less power than my Dometic! Complete text of the test is here: https://www.gonewiththewynns.com/rv-...igerator-power)

[Cate&Rob]

Over 11 hours he only used ~205 aH.

I would agree that this number is "in the ballpark". On our boat, we have a residential 9 cu ft apartment size 120VAC fridge. It draws about 2.8A (after the compressor start-up spike) and typically runs about a 50% duty cycle. Powered through an inverter with some inefficiency, this 2.8A at 120V becomes 30A at 12V. In 12 hours at 50% duty cycle, that would equate to 180 Ah. (30 x 12 x .5). In warm weather this could easily be over 200 Ah with the fridge requiring a longer duty cycle.

A key part of this investigation/comparison should be insulation capability. The relatively inexpensive residential fridge on our boat will stay cold inside without power for far longer than the similar size but much more expensive fridge on our RV under similar circumstances. The small portable 12V fridge/freezer units operate with very low power consumption because they are very well insulated. The bottom line is that the key problem with RV absorption fridges is not their system for cooling . . . it is their lack of adequate insulation.

Rob

[howson]

. . . it is their lack of adequate insulation.

WHY????? Space? It can't be cost--can it? Insulation can't be that expensive!

[Cate&Rob]

WHY????? Space? It can't be cost--can it? Insulation can't be that expensive!

Agreed . . . it has to be trying to get the maximum interior volume inside the smallest possible outside dimensions.

Rob