Traveling with Fridge on 12V?

[Snoopwagon]

Usually boondocking in the woods somwhere I switch to propane or generator/small quiet one 😊 where hook ups are available definagtley 110 30a AC

[Glenn Baglo]

Problem is, if you've been camping for four days and running the furnace to take off the chill at night, your battery will be depleted.
Then you drive to another campsite. The tow vehicle isn't capable of running the fridge and recharging your trailer battery, so you arrive with a depleted battery.
That's no problem if you camp with full hook-ups, but if you boondock, you will have to charge that battery somehow.

[Snoopwagon]

All of that worry goes away with a good little solar system and a small genie!

[Raz]

You have two buckets, one above the other. The top one is open, the bottom covered. There is a hose between the two. It's raining. Water entering the top bucket fills the bottom bucket through the hose. No matter how big the hose, eventually both buckets fill as long as it keeps raining.

You punch a hole in the bottom bucket. It will remain full as long as the hose is big enough (wire size) and it's raining hard enough (alternator capacity).

While not perfect, the analogy gives those confused with ohms and amps a picture of the refrigerator/charging dynamic and why some are successful and others are not. Raz

[floyd]

Originally Posted by Jann Todd

Your vehicle battery should be isolated from your trailer battery. This prevents draining of the vehicle battery. The way I was told it works is when the vehicle battery is charged fully then the trailer battery is charged also while driving. I would not have 2 batteries without an isolater. Isolaters can be very cheap or very expensive depending on what you put in. We had a cheap one in a camper van and one in our truck when we had a fifth wheel. The cheap ones are just little silver canister looking things with 3 places to hook wires. Last one was about $20.00 or so. It is also a safety so that if you get a short in your wiring it won't affect the trailer and tow vehicle. My isolater saved my truck wiring once when the camper on my truck shorted out.

While this is good advice for the most part, an isolator is just that, it prevents cascading. I have accomplished the same thing manually for many years with a simple 30A switch and a fuse. Of course you must remember to shut it off yourself, rather than rely on the isolator.

[floyd]

Originally Posted by Snoopwagon

All of that worry goes away with a good little solar system and a small genie!

If you had a small genie, you wouldn't need a battery, and if he refused to grant your wishes you could just pour oil down his lamp and burn him out! At least you would still have light!
Of course we already have a a good little Solar System.

[Civilguy]

Originally Posted by Raz

You have two buckets, one above the other. The top one is open, the bottom covered. There is a hose between the two. It's raining. Water entering the top bucket fills the bottom bucket through the hose. No matter how big the hose, eventually both buckets fill as long as it keeps raining.

You punch a hole in the bottom bucket. It will remain full as long as the hose is big enough (wire size) and it's raining hard enough (alternator capacity).

While not perfect, the analogy gives those confused with ohms and amps a picture of the refrigerator/charging dynamic and why some are successful and others are not. Raz

I work with water systems. I once went to an interview and explained water systems in terms of an electrical analogy. At least I tried to...

In other words, I used something more arcane and less intuitive to explain something that was simpler and less complex.

We didn't get the job, and rightfully so. I still laugh at myself whenever I think about it.

What's that old saying? Good judgement comes from experience, and a lot of that experience comes from bad judgement.

[BARNEYCONE]

Radar one,
think inverter, however know that inverter require 10 amps dc in for 1 amp ac out.
Bbc ii

[Civilguy]

Originally Posted by floyd

Of course we already have a a good little Solar System.

Floyd, I'm kind of surprised you didn't cue up a little Eric Idle for us here...

[Markz]

I installed a 7 pin plug to my camper and use the 12v Aux terminal from the tow vehicle to power my fridge while driving. I was concerned about the fridge draining my SUV's battery so I installed a 30amp relay and breaker for the 12v umbilical that uses the driving lights to switch on the relay to the fridge and my backup camera. If my SUV's lights are on the fridge is drawing power from the tow. If my SUV's lights are off the fridge is off. I also hooked up the backup camera transmitter to the relay that serves as a reminder to turn the driving lights on when towing. If the screen is not receiving a signal, my refrigerator is off. Since my car provides an audible warning if the lights are kept on with the keys removed, it reminds me to turn the lights off when stopping for a rest.

I also can use the tow power to recharge my camper battery.

The picture is of my 7 point terminal box with itsncover removed. It contains two breakers and the relay. Been working great for years.

Someone on this forum gave me the idea. Just passing along the info.

[Peg Davis]

Originally Posted by ehoepner

I always travel with the Frig on 12v dc. It keeps the Frig cool and I have no problem with Trailer battery discharge.

The problem people have when the trailer battery is discharged is related to the size of the wiring on their tow vehicle. Their tow vehicle wiring is to small for the number of amps the Frig pulls. Because the wiring is to small the wiring restricts the flow of electricity. Therefore the trailer battery is discharged because it is making up the difference in what is supplied by the tow vehicle and the requirements of the Frig.

Wiring sizes should be 10 gage, 12 gage is very marginal. 14 gage drains the trailer battery.

Just so. Re Casita fridges, they draw 15-16 amps on 12 volts (not sure what the draw is on the 5.0 TA we now have on order). So, you're spot on with the wire sizes. But just about any TV rated to tow a Casita has an alternator that can put out nearly a kilowatt. That is ~80 amps. So, no problem there. And most trailer batteries are between 0.7 and 1.0 kwh, so eating in a restaurant for an hour or so will not drain them...

[Perryb67]

Originally Posted by Peg Davis

Just so. Re Casita fridges, they draw 15-16 amps on 12 volts (not sure what the draw is on the 5.0 TA we now have on order). So, you're spot on with the wire sizes. But just about any TV rated to tow a Casita has an alternator that can put out nearly a kilowatt. That is ~80 amps. So, no problem there. And most trailer batteries are between 0.7 and 1.0 kwh, so eating in a restaurant for an hour or so will not drain them...

We went shopping for 3-4 hours one afternoon and came back to a dead Odyssey battery. We did want a live battery with our connection so auto-off wasn't an option. We just got stuff out of the frig AFAP and never have looked back. We also keep blue ice packs in the freezer, when needed to fill the space, aiding in keeping the freeze/frig cold.

Enjoy,

Perry

[Mr Lynn]

REPORT:

I am happy to report that we just drove from Massachusetts to Virginia, in two days, with*the fridge on 12V*all the time we were on the road, and turning it off if we stopped for any length of time (say, longer than maybe 20 minutes0, and it worked fine. *As long as the Ford Expedition engine was running, the battery voltage stayed at 13.5 or so. *We initially kept the fridge at position 2, but on the second day advanced it to 3, with no ill effects.

I did notice, as claimed here, that if I left the fridge on 12V with the TV engine off, you could see the trailer battery decline visibly.

We stopped at a state park site with electric power, so no problem running the fridge overnight.

From this I conclude that, whatever problems others have encountered running the Casita fridge on 12V, Ford seems to have engineered their Expedition factory trailering package to get sufficient voltage to the trailer.

/Mr Lynn

PS Also posted on the Casita Forum.

[Mr Lynn]

Correction: I should have said "the Dometic three-way fridge," not "the Casita fridge."

/Mr Lynn

[Civilguy]

Thanks for the posting! I had mentally just sort of written off the idea of running the refrigerator on 12 volts due to the problems some folks have reported. But, I have never actually tried it out for myself.

[glamfib]

Originally Posted by Mr Lynn

would prefer to use 12V. The issue seems to be whether the fridge will draw too much current and discharge the trailer battery

Have been using a Coleman 12v. fridge https://goo.gl/skC2Zn for a while. Of course, not a lot of capacity 40 Qt. but going through Arizona did a good job

[Ziggy]

Originally Posted by Mr Lynn

REPORT:

*As long as the Ford Expedition engine was running, the battery voltage stayed at 13.5 or so. *We initially kept the fridge at position 2, but on the second day advanced it to 3, with no ill effects.

The voltage you are seeing is the output fro the generator not the battery voltage. You are seeing that because it is hooked up to the terminals of the battery. What's important is what the reading is AFTER your turn off the engine and let it sit for a few minutes without any load on the battery.

[MarkyVasquez]

Get a voltmeter at Wal-Mart. Set it to DC. Turn on the refrigerator on DC or 12 volts. Then connect the voltmeter to the trailer battery with your tow vehicle off. It should be around 12.6 volts. Have someone turn on the tow vehicle and accelerate it to 2500 rpm. If the meter goes over 13 volts it'll be fine. Don't worry about the amperage. A battery will draw different currents depending on it charge, size and type of battery. The voltage will indicate if the wire is too small by producing a voltage drop. The alternator will also have a voltage drop if it is too small.
Happy Camping
Marky

[ehoepner]

This is the best idea yet, you could take it one step further and buy a volt meter that plugs into the cigarette lighter plug, at least my Casita has one. With the Frig on DC and the trailer plugged into the tow vehicle and the tow vehicle engine running, the volt meter should be reading 13.2 volts or above.

[Joe MacDonald]

I just finished a 3 week trip, 3500 KM's moving almost daily.
Ran the fridge on DC whenever I was moving. it actually performed better on DC, had no issues with battery going low until last two days. what I found was the charge line from the vehicle had broken off the pin at the trailer plug, ten minute fix, and worked fine after

Joe