Refrigerator on 12v while driving

[slonecker]

I have a 2018 Casita and tow it with a ‘21 Ridgeline. If I have the refrigerator on DC while driving the house battery doesn’t seem to keep up so I eventually use the propane default. Is that a common situation?

[jgilliam1955]

Originally Posted by slonecker

I have a 2018 Casita and tow it with a ‘21 Ridgeline. If I have the refrigerator on DC while driving the house battery doesn’t seem to keep up so I eventually use the propane default. Is that a common situation?

Yes, I drive on either one. Propane is good for most people. However, we have a couple of tunnels that require you to cut off the propane.

[Casita Greg]

A lot depends on the size of your tow rig's alternator. A lot of people who tow with smaller rigs don't have heavy duty alternators, and suffer the same fate. We tow with a full sized pickup with the "tow package" which includes a higher output alternator. We have always run our trailer fridge strictly on the 12 VDC 7-Pin Bargman plug-in, and it keeps our trailer fridge below the food danger zone. (Under 40 degrees or less.) And we sometimes have traveled for as much as 12 1/2 Hrs. continuous, stopping only to fuel up and make a bathroom pit stop.

If your rig isn't equipped with a "tow package" set-up, then your smaller alternator probably won't give you all the power you need to run both the tug and the trailer at the same time.

I've never had the fridge not stay cold while towing with our rig.

[Lynn Eberhardt]

For many (most?) people, while the alternator may be fine, the wiring between tow vehicle and trailer isn't heavy enough to keep up with the electrical demand. The fridge may stay cold but the trailer battery probably won't charge or may even discharge while driving. Some have installed much heavier wiring, others run on propane.

[slonecker]

Lynn
I think what you are describing is my situation. Both of the vehicles I have had this issue with have had heavy duty alternators and the reefers stay cold but the house battery gets down to lower battery charge than I want it to.

[justa25thTA]

I tow with a 2015 F150 with a tow package. I could not run my fridge on dc while traveling, it would run the trailer battery down fairly quickly.


I put 300W of solar on the roof with a victron blue tooth controller. Took a long trip to Big Bend earlier this year and was able to monitor the battery via the victron app from the truck. With the solar, no problems running the fridge on dc.

[Jon in AZ]

Originally Posted by slonecker

I have a 2018 Casita and tow it with a ‘21 Ridgeline. If I have the refrigerator on DC while driving the house battery doesn’t seem to keep up so I eventually use the propane default. Is that a common situation?

Very common. As others have said, the alternator and/or wiring gauge and length will not support the amperage required to run the fridge AND maintain the battery.

Propane is a viable alternative. There are a few situations in which you will have to shut off the fridge: auto ferries, a few longer tunnels, and- the biggie- gas stations. Technically you should stop and shut off the fridge before you enter the pump area and pull out of the pump area before you relight. I’d say not many do, but I’ve been in several situations where a gas pump failed to shut off, with fuel all over the ground. I’d hate to be nearby with an open flame.

Biggest downside is the flame may blow out due to turbulence. That depends on weather conditions as well as the aerodynamics of your rig. A few people find they just can’t get it to stay lit reliably, while many have no issues. Assuming the fridge is working properly, there’s no fire risk if the flame blows out. The thermocouple will shut off gas flow. It’s just inconvenient, and food can spoil if you don’t catch it in time.

[thrifty bill]

Switch to a compressor fridge and you will likely be fine.

[Lynn Eberhardt]

My work around used to be to start with the fridge cold, power off. Turn the fridge on when leaving the first rest stop, off at the next. Repeat. That worked for food and the battery. Now, I run 115 volts AC to the trailer from an inverter in the car to keep the fridge cold on AC. That also works.

[Chilliwack Murray]

Originally Posted by Jon in AZ

Very common. As others have said, the alternator and/or wiring gauge and length will not support the amperage required to run the fridge AND maintain the battery.

Jon is correct. The DC supply wiring to the trailer is small compared to the alternator output wiring. The larger the draw, the more voltage drop on the wire... Add to that trailer connectors and more connections in the trailer and you will find the 14.5V at the alternator is down to 12 or 12.5 at the trailer battery when you add the extra 8 or so amps to supply the fridge. You need about 13.8 V to keep a lead acid battery fully charged so you are actually discharging the battery down to 80 or 90% when the fridge is on.

On our old Trillium with just a 4 pin trailer connector I ran a separate 10 gauge wire and connector from a solenoid to charge the trailer battery so there was much less voltage drop and I could run the fridge with minimal effect on the battery. The 12V element provides far less heat to the absorption unit so you get a lot less cooling compared to 120VAC or gas, it's really just meant to maintain the temperature and it won't really keep up in hot weather.

[John in Santa Cruz]

Originally Posted by Lynn Eberhardt

For many (most?) people, while the alternator may be fine, the wiring between tow vehicle and trailer isn't heavy enough to keep up with the electrical demand. The fridge may stay cold but the trailer battery probably won't charge or may even discharge while driving. Some have installed much heavier wiring, others run on propane.

yeah, I had exactly this problem, towing a Casita 16 with a Tacoma with the fridge on DC. voltage under the hood was 14.2V indicating the alternator was working just fine. Voltage at the trailer battery after an hour or two of driving was 12.0, and the trailer battery (a fresh Interstate 27M) was nearly dead. And, the Casita 16 had a pretty small fridge.

I switched the fridge back to propane, and never tried to run it on DC again.

With my Escape and F250, I tried running a 18A DC-DC converter to charge my lithium batteries, same problem. Voltage at the input to the DC was down to about 10V, while the DC-DC was outputting 13.6V at 18 amps, thats about 24 amps at 10V... The voltage was fine under the hood, that diesel truck had a big alternator. I tested the voltage *at* the 7 blade with the engine running, and it was at about 1/2 the total drop. I gave up on trying to use a DC-DC to charge my lithiums, anyways, my 360W Solar outputs around 30A on a sunny day at lithium charging levels so I've never had any real problems keeping my batteries charged. With 5200 watt*hours of lithium, I can go at least a week without *any* charging..

[Mike Kelley]

Originally Posted by thrifty bill

Switch to a compressor fridge and you will likely be fine.

I used to spend hours reading endless threads trying to solve numerous refrigerator problems.
Since I installed my Nova Kool compressor fridge I have much more free time. More time to camp.