Compressor v absorption fridge - HELP!

[Petermac]

OK myswaggers, I really need your help.

I'm in the market for a fridge.  Yes, I know that Engel are the best, but having just sprung for a new camper and a bunch of other accessories, we are feeling a bit budget conscious right now.

The 3 way fridge concept is extremely appealing.  I have a 100 amp hour AGM mounted into the trailer, but let's face it - that won't get me far with a 45 or 50L fridge which is what I'm chasing.  At this point I don't have an Anderson plug on my vehicle ($300), I would probably need another battery ($250), solar panels to get me through a week or more camping at Frazer ($500?), and I still need to buy the damned fridge!

A 3 way unit will get me over this hurdle with gas.  My main concern is how cold a 3 way fridge will get as opposed to a compressor unit.  My research is telling me that the best I can hope for is 25 degrees below ambient, so if the mercury gets up to 35 then we're looking at 10 degrees in the fridge, and my steak's not going to last too well under those conditions (not to mention the impact on my beer consumption).

I know that many would have grappled with this issue, so I'm looking for your collective wisdom - bite the bullet and go with a compressor unit (along with the associated costs) or take the 3-way option?

Petermac

[D4D]

Without a doubt compressor, set the temp and pretty much forget

[MR MAC GU]

X 2 on the compressor fridge...3 way fridges are generally a waste of money unless you only plan on using them in cooler climates.

Although more expensive than an Engel you could look at an Auto Fridge, they are the most power efficient fridges on the market, once they are cold you only need to run them for about 3 or 4 hours per day making the power drain very low. They have a gel in the cabinet which freezes keeping the inside cold and they work extremely well. I have one in my camper and it will last at least 4-5 days without charging even at around 35c+ they are still pretty efficient.

The Engel in my car is half the size and lucky to last 1.5 days so spending more on the fridge may save heaps in solar, extra batteries etc although we still have these for extended stays...

Hope that helps

[mystq]

Compressor, had them for years, wouldn't go camping without one 

[barnray]

Mate a 3 way will pop the coke on gas and if left on 12v will freeze over night but the batteries will be stuffed, they do freeze. I have used a 3 way on Frazer for a week on gas and kept meat frozen. Barnray

[morgue]

Without a doubt compressor, set the temp and pretty much forget

x3

Good quality compressor and you will not go wrong.

 

[Petermac]

Although more expensive than an Engel you could look at an Auto Fridge, they are the most power efficient fridges on the market, once they are cold you only need to run them for about 3 or 4 hours per day making the power drain very low.

Good tip Mr Mac - I'll look into the Auto Fridges.  I just had a quick scan of the net and found their web site but no prices - any ideas what they're worth?

This is great feedback guys - thanks for your input.  At this stage it looks like compressors are the way to go (damn it).

But I'd be pleased to hear any other views on the subject - if only to enforce what's already been said.

[Patr80l]

I've got a 39 litre Engel which has been trouble free for about twenty years.   Can you say that about the fridge in your kitchen?  
I've got a Jayco Hawk which came with a three-way Domtec.   It takes a while to get cold (but I don't turn it on until I get to my destination; the perishables are in the Engel for traveling).   It's great for longer camps, running on gas.   (I've got 2 x 9kg bottles on the Hawk)
My Engel cost me about $1000 all those years ago.   That's $50 per year or $1 per week.   A good investment (and it's still going).

[Joff]

Although more expensive than an Engel you could look at an Auto Fridge, they are the most power efficient fridges on the market, once they are cold you only need to run them for about 3 or 4 hours per day making the power drain very low.

I don't get this logic.. don't get me wrong, I believe the Auto Fridge to be a good'n but,,,, once cold, as you say, if they didn't need to be run then surely they would just not cycle back on?? Bit like people who unplug their fridge at night.. If it doesn't need to run at night then it won't turn itself on..


Anyhoo,, I agree with the basic premise that the compressor fridge dumps all over 3ways.. I've had 2 Dometic 3ways and both worked well on 240v and gas but lousy on 12v.. bloody lousy actually..

I have two compressor fridges these days; an Evakool (~2004) and an Engal (Jan 2009). both are great. Aside from a rheostat in the Evakool at 3 years old and a complete refrigeration system replacement in the Engal at 3 months old  (yes, the whole shootin match) they have both been great.
 

[mystq]

Something wrong with an Engel,,,,,,,, well I never

[SteveandViv]

While you can get some god results from the 3 way fridges they are not much chop in warmer climates as the above say and I have never ever seen a three way on 12 volt be able to freeze any thing. They will hold temp while you travel but that's about it. The issue with that is that they are then usually tucked away n the camper or car where the temps are so much hotter than they can cope with and just don't do well. Most will advise to turn it on 240 a few days before you go and get the thing down as low as you can go. The you switch it to 12 while you travel but take care as they use 7 to 14 amps which you will need a dedicated outlet for if in the car as the factory jobs won't like it one bit. Again you will need to make sure the fridge has a clearing around t and on top so it can vent. The when you get to camp you get the spirit level out and set the fridge up, out of the wind as wind will effect the pilot light which needs to hit the bottom of the gas chamber spot on to get the max effect...Anyway, you get the idea...

So when looking at the compressor fridge there are a few that use a lot of the same parts. Waeco, ARB and others all use the Danfoss compressor which are the best on the market aside from the Engle which uses the swing motor. And, as noted once set up you can almost set and forget. We have two. One 60 ltr and a 50 dual zone. We don't use the freezer much but did while up the Cape this year as the bread doesn't last long in that heat and moisture, same up our way. anyway it's great to have the option. If we don't want to use the freezer you take out the divider and then it's a fridge - easy.

While every one loves to say Engle are the best they fail like all the others and can be quite noisy. Don't be put off by the plastics that Waeci and ARB and another use, we had our 5 years and taken it across and every where else in Aus and it's fine. It's in the insulating bag and it's used as a seat at camp. Also Engles will flatten your battery if your not careful, they can run at low voltages which is good if you don't care about your battery state. They don't have a cut out option so you should consider that. The Waeco does as an example so you can be sure your battery is not being wrecked by dragging it to low. In an emergency you can hit the override switch and it will run until the motor stalls but  that's another discussion. You can also change the controller so that the cut out protection is not used. I have done this and set up a switch to allow me to use it or not. I'm certainly not bagging the Engles as they are a great fridge as well. All I'm saying is choose what's right for you. it may even come down to what fits in the space you have. Plenty have bought just for that reason and it maybe the most important of all as they are all great these days.

Anyway, you'll have to do a bit of work on the set up as you mentioned, no matter which way you do. Do it right first time around and it will last you for ages.

Good luck.

[Estelle]

We run a compressor fridge (waeco 35l) in the tug and a 90l 3 way in the CT.

The 3 way will freeze in a hot environment with gas. Gas is very efficient with these beasts. You don't care if it is overcast for a week. No generator, starting tug etc. They can be a bit of a pain to get the setting right so that it doesn't freeze until you are used to it.

We have an invertor to run our 3 way in transit on 240V. Use 240 before setting out, uses the same element (no need to start from scratch by heating the 12V element) in transit and takes advantage of a thermostat.

Each type has advantages and disadvantages.

Camping in the one spot for a week you don't need to think about recharging the battery(s) to run the three way.

On our last trip, the  waeco (compressor model) temp increased on a few occassions because I hadn't noticed the power plug had 'disconnected' from its source. So you need to keep an eye on it unless you replace the cigarette lighter connection with something that will not just 'pop out'.TKes a long time to get back down to the set temp.

[Petermac]

Anyway, you'll have to do a bit of work on the set up as you mentioned, no matter which way you do. Do it right first time around and it will last you for ages.

Good luck.

SteveandViv,

thank you for taking the time to give me such a detailed answer.  To be honest I was never really in the market for an Engel - if I head down the compressor path then I was going to head off to the Waeco seconds factory to see what we can lay our hands on.  Sounds like that's a smart move.

Again, thanks for taking the time.

Pete.

[Petermac]

The 3 way will freeze in a hot environment with gas. Gas is very efficient with these beasts. You don't care if it is overcast for a week. No generator, starting tug etc. They can be a bit of a pain to get the setting right so that it doesn't freeze until you are used to it.

Estelle,

nice to see the counter arguments for the 3-way.  Not being able to get the temperature down in heat was my big concern - sounds like you have had good experience there.  You didn't mention the brand of the 3-way - I'd be interested to know...

Cheers.

Pete.

[Mighty80]

I believe it is all about your intended use for the fridge.

I have a 2 year old dometic/chescold 55L 3-way fridge/freezer and love it. However it is more suited to longer stays where you can put it on gas and forget about it. I run a little fridge thermometer that sits on top to keep an eye on the temperature. Believe me I have run this thing in very hot weather and it still freezes very well. A 4.5kg gas bottle will last for approx 2 weeks.

If it is shorter trips where you will be stop starting like touring then a compressor fridge would be the go due to the car or solar charging it every day or so.

I wouldn't trade my 3-way as it suits me.

Good luck with your choice.

Cheers Scott

[Straitened Out]

We've had two 3-ways [slow learners!]. You mentioned Fraser and we live nearby. The ones we had just can't cope with conditions up this way or further. We now run two Engels, one of which is about 30 years old.
Cheers
S.O.

[Estelle]

Estelle,

nice to see the counter arguments for the 3-way.  Not being able to get the temperature down in heat was my big concern - sounds like you have had good experience there.  You didn't mention the brand of the 3-way - I'd be interested to know...

Cheers.

Pete.

Hi Peter,

The Dometic 90l.

They can be a fiddle to get right, but they can also be very good. Gave up trying to get it right on 12V. 'Tis why we run it on 240V in transit.

We set ours between 3 and 4 on the dial in temps in the mid twenties and find it about right on gas. We have had it working quite well in the high 30° temps. We aim for about 4° C. The temp does wander a bit, but... .  The compressor models seem to maintain a more stable temp.

You can help the fridge by the use of 'extractor fans' to move the heat away from the cooling fins (both versons).

The gas option for us is a bonus as you can go wherever and not worry about the battery.  Nice to have both types for versatility.

Maybe rent/borrow a three way as a trial?

One better than the other? Depends on circumstances.

[maurerless]

Estelle,

nice to see the counter arguments for the 3-way.  Not being able to get the temperature down in heat was my big concern - sounds like you have had good experience there.  You didn't mention the brand of the 3-way - I'd be interested to know...

Cheers.

Pete.

And another vote in support of a 3-way here. We have a Dometic 90 litre in the CUB. On a 4.5 hour trip home after camping we had it on 12v and the leftover meat half froze while it hadn't while on gas camping. Thermostat setting was just about 2/3 high. Admittedly it wasn't summer heat, but it counters the argument that running on 12v while driving is not efficient. (Caveat is that the CUB travels nearly level and was relatively smooth highway travel. We haven't gone long distances off the tar... yet.)

Tony

[SteveandViv]

And another vote in support of a 3-way here. We have a Dometic 90 litre in the CUB. On a 4.5 hour trip home after camping we had it on 12v and the leftover meat half froze while it hadn't while on gas camping. Thermostat setting was just about 2/3 high. Admittedly it wasn't summer heat, but it counters the argument that running on 12v while driving is not efficient. (Caveat is that the CUB travels nearly level and was relatively smooth highway travel. We haven't gone long distances off the tar... yet.)

Tony

"but it counters the argument that running on 12v while driving is not efficient"

Well I don't think it does. I don't think it's efficient to be using that much power to keep stuff cold but you do because the benefits are that you can use gas when camped. It's great your fridge can freeze on 12 volt, most can't. And again, they are fine up until it get hot and humid. When you get to 40, the fridge will be 12, that's the way they are. You make a great point. they travel well on tar but due to their design are crap off road as they rely on the separation of ammonia and water. When shaking the sh1t out of the fridge this is hard to do - well we found that the be the case anyway when we had the three way.

I guess though as many have said it depends on what your going to do. Dragging the camper up the CREB as we did would not suit the  three way while the angles almost cause the compressor to have palpitation.. Probably no wrong or right here but I know what didn't work for what we did and that was the three way under stress.

[gronk]

I like my beer cold....1deg......found the only reliable way to do that was a compressor fridge......

[Petermac]

OK guys this discussion has been fantastic for my edification on car fridges.  Here's where I think we've gotten to so far based on general consensus:

• A good three way will probably do the trick in a fixed position (i.e. camp site) providing that they are set up properly.  Performance may be compromised at 40 degrees C given that the quoted performance on most absorption (3 way) units is 25 degrees below ambient, but for most conditions we should be OK.  This opens up the option of using gas, which is of course the primary attraction of these fridges.
• 3 ways are power hungry on 12v and probably not all that effective either - the most we can hope for here is that the temperature that was previously obtained on either gas or 240v is maintained.  Forget using 12v to cool the unit from room temperature.  There may be an option of using an inverter while driving to run the fridge off 240v to overcome the 12v limitations in transit.
• In transit 3 ways can be problematic because of their need to separate ammonium and water, and shaking the hell out of them doesn't help (i.e. off-road).  But on the black top they will probably be OK.
• Compressor fridges will get colder under higher ambient temperatures and a range of travel conditions, and run more efficiently on 12v.  But you'll need to find a way to charge your battery bank when you're stationery for any extended period, and of course you'll need an Anderson plug in the tow rig during transit.

So if you're the kind of camper that likes to travel to the one location and stay put for a week then a 3 way is probably going to suit you best as it provides a cheap energy supply solution for an extended stay in the form of gas.  But if you are touring, particularly 4x4ing, then the compressor units are the only choice.  Compressors are undoubtedly more versatile, but you'll need to invest more heavily in power supply.

It would indeed appear to be correct when people say "horses for courses" when it comes to fridges.  But I think the above logic will help most people define what kind of horse that they are. 

As for me, a 3 way is very attractive as most of my camping is in south east QLD and only a couple of hours travel from home base.  But because I want the versatility of using my camper for touring in the future I think it will have to be a compressor unit...

Cheers.

Petermac

[D4D]

3 way can do 25 degrees below ambient temperature worst case. Therefore at 30 degrees ambient you're already over the safe storage of food temp of 5 degrees. Food poisioning whilst camped is not fun.

http://www.health.vic.gov.au/foodsafety/downloads/safe_storage.pdf

[jwb]

Got it in a nutshell Petermac

I have seen 3 different 3 ways freeze items on many occassions ( on gas/ by accident)

cheers

[Captain]

...The Waeco does [have a low voltage cutout switch] as an example so you can be sure your battery is not being wrecked by dragging it to low. In an emergency you can hit the override switch and it will run until the motor stalls but  that's another discussion. You can also change the controller so that the cut out protection is not used. I have done this and set up a switch to allow me to use it or not. ...

Just a quick note on the low voltage cut-out switches. While they are good at preventing you running your battery too low, please be aware they are actually there for the fridge MOTOR PROTECTION. Running a motor on too low a voltage can burn the motor out, hence the protection. If you bypass this motor protection, there is a good likelyhood that in warm/hot weather you will burn the motor out.

The Engel doesn't have this protection as its a "solenoid" motor and doesn't have a motor as such. It can run on very low a voltages and then simply stalls.

Cheers

Captain

[SteveandViv]

Just a quick note on the low voltage cut-out switches. While they are good at preventing you running your battery too low, please be aware they are actually there for the fridge MOTOR PROTECTION. Running a motor on too low a voltage can burn the motor out, hence the protection. If you bypass this motor protection, there is a good likelyhood that in warm/hot weather you will burn the motor out.

The Engel doesn't have this protection as its a "solenoid" motor and doesn't have a motor as such. It can run on very low a voltages and then simply stalls.

Cheers

Captain

Yes Captain, thanks mate, you are right however while I have bypassed the low voltage cut of the Danfoss controller the controller still controls the low motor cut out that cannot be bypassed and will error if this is reached (Three Flashes I think). Happy to discuss further if you need. This is clear in the engineering document I have but again your right if the 9.6 low motor cut out was not there then you could burn it out. Actually it is the Danfoss specs that show you how to by pass the low voltage with tables and the resistance values to set solid cut outs or as I did in my case set it at the lowest possible which is the motor protection voltage.

I don't agree though that the voltage cut out is just for motor protection, Waeco sells it as other do as a battery protection option and as you can set it a H - M - L or 12.5 to 11.4 or close, none of these voltages are close the the Danfoss stall voltage.

As a note I don't use this much, it's me mucking around and as such have built it as a turn off turn on feature like my additional fan that kicks in when the heat in the condenser housing get to 100c as after that the over temp circuit will cause a temp error (5 flashes) which is quite likely up here in 45 and the van while I work. It also increases the efficiency of the fridge 30% from warm to cold which I find helpful.

Anyway all good. thanks again for the input. It's helpful for others as well to hear both sides of the story.

I thought the Engle was called a swing motor based on the design and it will certainly run to very low voltages.

Steve

A few bits from the manual

The compressor overload and start protection cuts off power to the compressor if the compressor speed
drops below approximately 1,850 rpm (BD35F/BD50F/BD35K) or 2,450 rpm (BD80F/BD250GH/BD100CN)
or if this motor speed is not reached during the start sequence. Possible reasons for overload protection
activating could be excess refrigeration system pressures during operation or an excessive pressure differential.
The fan overload protection stops the compressor and fan if the fan current exceeds 0.5Aaverage
or 1Apeak .
If the electronic unit heat sink senses a temperature >100°C it will cause the compressor to stop. Restart
will occur automatically when the temperature has dropped. (<90°C, with 66 seconds additional delay).
If a fan is installed, it will continue to run if the compressor stops due to overload or electronic unit
overheating.
If a voltage outside the specified range is applied to the electronic unit, the compressor does not start

The low voltage limits can be established if a connection is made between the terminals C and P, please
see also the passage Optional battery protection settings page 9.
The electronic unit will calibrate to the applied voltage. This means that if the battery voltage is less than
17V, the electronic unit assumes that it is working in a 12V system. If the voltage is higher than 17V, the
electronic unit assumes that it is working in a 24V system. Consequently, the compressor does not run
at power supply voltages between about 17V and the desired battery protection cut-out voltage for
24V systems. A continuous voltage range from 9.6V to 31.5V can be established if a 220k? resistor (wiring
diagram item 9) is connected between the terminals C and P. This wide voltage range makes the BD
compressors very suitable for photovoltaic powering.