Electrical system to run a refrigerator?

[TMG51]

Considering a refrigerator for my (as of yet to be acquired) van. I'm not keen on draining my battery and leaving my home stranded though. I'm weary of any electrical item which will demand a constant draw.

I'm aware of deep cycle marine batteries, switches which automatically change the current over when the alternator cuts out.... I don't know what all is involved in installing a setup like this. What modifications would I need to perform in order to plug the above refrigerator into your average cargo van without killing the battery? Or simply have it on while driving, use a cooler the rest of the time?

What setups do you guys run?

 

[SternWake]

There are 3 strategies for refrigeration.

First the 3 way absorption/ propane fridge. These use the least electricity, but modern ones still consume a fair amount of battery to run the circuit board, They are energy hogs when the heating element is run on electricity. the 12v option was designed only for use when the engine is running. the 12v option will deplete a fully charged battery in hours and cannot keep safe temps in hot ambient temperatures. The 120v option will eat up the kilowatts too. These must have dedicated ventilation so no byproducts of propane combustion can enter living quarters.

2nd is the Dorm/household/residential fridge powered by an inverter. This is popular as it is INITIALLY cheapest. But these fridges are not very efficient, and the inverter must be kept on 24/7, and the inverters will draw energy just turned on powering nothing, like when the fridge compressor is not running. They will use ~ 2x the electricity as the next option, and the least expensive dorm fridges will use 3x. Many find they need more battery, more charging sources( solar) and more daily driving to get one of these to run indefinitely.

Least popular among newbies but venerated among veterans, the most efficient, the best performing, is the 12v compressor fridge.

No inverter needed, they were designed to be efficient running on battery power, they were designed for rough usage in heeled over Sailboats beating upwind.

They cost about 4x as much as a residential/dorm fridge, but require half the battery capacity, solar and/or other charging sources. which make up a portion of the cost difference initially and ultimately are cheaper as batteries will likely last longer, longevity wise.

12v compressor fridges come in front loading and chest style and a Van sized fridge will run 400 to 800$

Van sized 12v compressor fridges will use between 15 and 35 amp hours per 24 hours. 60 watts of solar in a sunny environment sould be the baseline minimum for worry free running, just for the fridge. rare exceptions exist. More solar is always better. Aim for lots initially. It is cheaper and easier than adding more later.

Marine batteries say deep cycle on them, but true deep cycle batteries are constructed differently. They are heavier, more durable and more costly.

Lots of refer info on this forum, do a search

 

[DC Fuse]

Start here.These are very efficient.You are going to need a dedicated house battery. Look under your vans hood to see if you have room for another battery (mine does). If not consider a AGM battery as these won't gas off like a wet cell and you can put it inside. Users of this refrigerator report good performance. http://www.whynter.com/productdetail/refrigeration/portable_freezers/308

 

[AltTransBikes]

http://www.expeditionportal.com/for...ke-a-cheap-isolated-dual-battery-setup-for-50

Great link there, I'm one of those 'pictures worth 1000 words' learners.
Looks like a great adventure site over there as well.

 

[TMG51]

I am going with solar because i dont want to drive every couple of days. I also want to keep the vehicle and solar systems separate but if you want to use your alternator to charge the house battery cheap, then read this...

http://www.expeditionportal.com/for...ke-a-cheap-isolated-dual-battery-setup-for-50

Good info there. Some folks on here have great knowledge on this stuff too.

That's exactly what I was looking for, thanks much. Very useful information there. Especially the prolific encouragement of beer consumption. Speaking of which, how does everyone legally knock back a few in the van when you're parked for the night?

 

[MrNoodly]

I had the big refrigeration test today. I'm running a small Dometic fridge that I've encased in 2" foam insulation with Reflectix on the outside. It runs off two 104Ah deep cycle batteries charged only by a 270W solar panel. When I drive more than a few miles I plug the fridge it into the van's 12V outlet to give the batteries a rest. Otherwise it runs off the two big batteries. Of course, it doesn't run constantly, only whenever it needs to cool back down to the chosen temperature. Well, today it was 109°, and still over 100° at 8:00PM. The van is parked so the AC isn't running. The inside of the van is as hot as outside. But the fridge was 33° without cycling on, and the batteries were still putting out 12.9V. Amazing.

 

[christine]

I've been running two Edgestar compressor fridges for several months now, no problems at all. Love it. I have 440 AH of battery capacity, and 600 watts of solar. The batteries are always fully charged when I check them around noon. The batteries are not connected to the alternator or anything, just solar panels.

 

[Zil]

Most vehicle alternators are not designed for the heavy use required to charge a house bank. They may handle a second light battery such as marine or starter, but will struggle with the heavy demand of a proper deep cycle house bank.
The answer is solar.

 

[Willy]

My buddy Nick was running a Waeco CF-50 off a Unisolar 64W panel (I lent him both) and a 12v marine battery with no problems. Wasn't quite enuf juice to also charge his phone and have an inverter going to run his 120v light. 'Course, he had to locate the panel where it didn't get a full day of direct sunlight. ..Willy.

 

[SternWake]

Capable alternators can make excellent bulk chargers IF:

a: the battery is less than 80% charged
b. The wiring is of sufficient thickness between alternator and depleted battery
c. the engine rpms are high enough to spin the alternator fast enough where it can make as much as the battery can take.
d. The vehicle is actually driven every day and for a fairly good distance.

Unfortunately far too many people act like the alternator is some magical instantaneous battery recharger that produces free energy. It consumes 1 engine HP to produce 25 amps. Idling to recharge can be extremely inefficient and slow, depending on the chassis.

Having the alternator take the battery to ~80% quickly in the morning and letting solar complete the job is a recipe for a happy battery.

Having enough solar to to the job without alternator assistance is even better.

Extra insulation and making sure the cooling unit can transfer the heat removed from the box efficiently are keys to running a fridge on battery power. Proper ventilation of the condenser and compressor is paramount. properly done this can yield the biggest efficiency increase. Danfoss/Secop compressor controllers can handle 0.5 amps of fans which switch on with the compressor. The fans which come with most danfoss compressors are less than 0.12 amps, so adding another fan to exhaust the heat generated from the condenser compressor will more than make up for the electricity the extra fan uses, especially a highly efficient fan like a noctua Nf-f12.

 

[MrNoodly]

There are high-output aftermarket alternators. There are also kits to mount double alternators. But relying on only the alternator to charge batteries would require a lot of driving and gasoline burning. One of the general rules for low-cost van living is to drive as little as you can.

 

[SternWake]

Many of These aftermarket alternators usually do not state the rpm at which they make their "rating"

Very possible that two alternators of the same physical diameter/size, the higher rated one might very well put out less amperage at lower RPMs than the lower rated one.

Relying on an alternator to FULLY charge a battery requires lots of time and driving, but getting a depleted battery to ~80% can be done very quickly with an actual high amp alternator and thick cabling between the two.

In my experience and observations over the last 7 years, my batteries love all the high alternator amperage I can feed them when depleted, even if the solar by itself could have gotten the batteries to the same level of charge come the next discharge cycle.

But when the batteries are over 80% the alternator does not need to feed them much, can't feed them much, as they cannot take much, and this is where solar shines and often in this range I do not even bother allowing the alternator to contribute, if the sun is shining.

With Lead acid batteries, Any and all charging sources should be used to keep the battery as near 100% as possible.

But this does not mean idling the van for 8 hours in a possible futile hope to reach 100%. if you are driving from A to B anyway, let that battery drink all it can.

 

[Dino]

http://www.amazon.com/gp/aw/d/B005X97OHA?pc_redir=1409891821&robot_redir=1


What do you folks think about a Dometic cdf-11? I have an opportunity to buy one new for $249. I know they are tiny at 11 quarts but I would mostly be using it for keeping milk a bit of cheese and a few eggs cold.

 

[SternWake]

It has a danfoss bd-35 variable speed compressor which can power a fridge upto 8 cubic feet at max compressor rpm, so it will just be cruising along on that little fridge, At the slowest most efficient rpm.

If the size is adequate for you, I see no downsides. It should be quite efficient, just keep it out of direct sun and make sure the vents for the cooling unit can breathe freely.

A quality ciggy plug receptacle wired to and fused directly at the battery can help avoid issues. But it should only draw about 3 amps when it first fires up and will taper to 2.2 amps at the end of the compressor cycle. Most ciggy plug receptacles in vehicles can handle this without issue. But if you hear the fan come on, but the compressor does not come on, it is a voltage issue. Either the battery is too low or the wiring between battery and compressor controller is too thin or the connector itself is causing excessive voltage drop.

 

[Dino]

Thank you SternWake. It sounds like a good deal and I wouldn't need much solar power. Now I just have to figure out exactly what I can cram into 11 quarts. ..

 

[akrvbob]

I've had a Dometic cf25 for 4 years and it is a good solid device. That really is a very, very small fridge but the price is great!! It may not be easy to put a gallon of milk and a dozen eggs in there. The milk might be too tall to the let the eggs fit on top so they will have to go in at an angle.
Bob

 

[Dino]

I would have to buy smaller less economical packages of foodstuffs which might make the purchase more expensive in the long run. I'll have to think this one out and maybe see if they'll let me open one up and put some groceries inside!

 

[Optimistic Paranoid]

I would have to buy smaller less economical packages of foodstuffs which might make the purchase more expensive in the long run. I'll have to think this one out and maybe see if they'll let me open one up and put some groceries inside!

If you have the internal dimensions ( H x W x D ) it should be easy to fold and tape some cardboard to the same size for your experiments.

Regards
John

 

[akrvbob]

Inside dimensions are tricky because the compressor takes some of the inside space. On my Dometic, the area above the compressor does not stay very cold. I keep cheese slices and margarine there and nothing else because they don't take much cold to be good.

I have a 65 quart Whytner fridge, and it stays just as cold over the compressor. Another way it is better than my dometic.

Bob

 

[MrNoodly]

I've had a Dometic cf25 for 4 years and it is a good solid device. That really is a very, very small fridge but the price is great!! It may not be easy to put a gallon of milk and a dozen eggs in there. The milk might be too tall to the let the eggs fit on top so they will have to go in at an angle.
Bob

You can split an egg carton down the middle and stack the two halves. You can even fit the halves on the small shelf that's at the hinge end of the compartment. I've done it with mine.