3-way fridge and power inverter

Have a 3-way fridge on Avan Sportliner that works very well at 240V and with gas. The 12V never worked (bough used). I am trying to test if I can operate it with an inverter (extra battery) on long travel daily trips. Tried with a small 150W I got but it did not work.
Problem of not enough power?
Does it need to be pure or modified sine wave?
On a 2 month long trip the cost of ice may be well invested on a good inverter or something like this:
http://www.ebay.com.au/itm/WAECO-FRIDGE-COOLER-PORTABLE-12V-VOLT-CAMPING-CAR-CARAVAN-BOAT-BRAND-NEW-TB08G-/400811651139?hash=item5d523c7043
Thanks in advance
Carlo
Note: Had a compressor fridge before with solar panel, etc. Won't go back to that.
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Reply By: Member - cherrywipe - Tuesday, Sep 29, 2015 at 10:28

Tuesday, Sep 29, 2015 at 10:28
Hi,
Our first van had a 3 way fridge which didn't work. The heating element was never installed in rear of unit..
Wired in a new 1 and was ok.
Good luck. Cherry.
AnswerID: 590843

Reply By: Bob Y. - Qld - Tuesday, Sep 29, 2015 at 13:17

Tuesday, Sep 29, 2015 at 13:17
Carlo,

I'd suggest you'd need a bloody big inverter, ample battery storage and then have the risk of your Avan being at mains potential while you're driving along.

Those little coolers, fridge is a bit tongue in cheek, are okay as a drinks fridge while travelling, but are very power hungry once you turn the engine off. Also they struggle to keep internal temps low, except in ideal conditions eg. airconditioned car interior. We've had a couple of them and they were handy for cooling drinks while travelling. The cooling fan can be a little annoying too, until you get used to it.

What dramas did you have with the compressor fridge and solar panel?

Bob

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Follow Up By: garrycol - Tuesday, Sep 29, 2015 at 14:03

Tuesday, Sep 29, 2015 at 14:03
I a confused by your followup - the OP is talking about a 3 way fridge not a thermoelectric cooler.

Why would he need a "bloody big inverter" - my 3 way uses 120w on 12v so not a real big inverter would be needed. When travelling surely the inverter is taking power from a battery being charged by the tow vehicle - when camped is running on gas.

To the OP - yes the 3 ways work worst on 12v and if it does work OK on 240v a inverter may the solution though inefficient and possibly dangerous in case of accident. For just the fridge any one inverter of the power capacity would suffice but if you also want to use it for anything else a Pure Sine Wave unit should be purchased.

Before I did anything I would check the size of the 12v wiring to your fridge because if it is too small this may be the cause of the problem - likewise the heater could be playing up so get it checked.

Garry
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Follow Up By: garrycol - Tuesday, Sep 29, 2015 at 14:05

Tuesday, Sep 29, 2015 at 14:05
Ooops - my apologises - did not look at the link that the Op put up - yes agree with Bob - dont bother.
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Follow Up By: garrycol - Tuesday, Sep 29, 2015 at 14:06

Tuesday, Sep 29, 2015 at 14:06
If we could amend posts on this archaic site I would have just amened my follow up.
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Follow Up By: ferrarofilms - Tuesday, Sep 29, 2015 at 14:18

Tuesday, Sep 29, 2015 at 14:18
Got it Bob.Thanks.
I think I'll keep it as it's now, ice on the Waeco for the day and gas/240V for the night.
An old say: if it's working, don't fix it.....
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Follow Up By: Gramps - Tuesday, Sep 29, 2015 at 14:29

Tuesday, Sep 29, 2015 at 14:29
"garrycol posted:
If we could amend posts on this archaic site I would have just amened my follow up."

If we read posts/links before commenting we would'nt need to amend followups etc :))))

Sorry garrycol, could'nt resist.

Regards
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Follow Up By: Bob Y. - Qld - Tuesday, Sep 29, 2015 at 15:01

Tuesday, Sep 29, 2015 at 15:01
No worries, Garry.

I didn't do the maths on the inverter thing anyway. :-)

Bob

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Follow Up By: Bob Y. - Qld - Tuesday, Sep 29, 2015 at 19:54

Tuesday, Sep 29, 2015 at 19:54
Just on these "coolers" Carlo. We have 2 that we used, like 30 or so years ago, and apart from the heavy power use and sometimes noisy fan, they were a handy item when only Engels or 3-way fridges were available as an alternative.

One little blue fridge fitted comfortably between 2 kids, on the back seat, and kept beer and coke cold for long driving days in last century diesel powered vehicles, ie: slow.

A bigger, about 40L fridge was a Koolatron, and seemed to be much better, due to its design. Left it going in our caravan while we were away for a couple of nights, and all the Veges were frozen. Case of if you have ample power, then they are a low cost choice..

Bob

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Follow Up By: Members Pa & Ma. - Wednesday, Sep 30, 2015 at 15:08

Wednesday, Sep 30, 2015 at 15:08
Hi Garrycol,
I was reading this article out of interest for our situation with a heater.
I'm not trying to be smart but there is a preview button where you can edit.
Anyway, according to the newsletter the site is receiving an upgrade at the moment and maybe there will be an edit button put in for after you've hit the submit button out of habit & it's gone .
I hope so.
Take care, safe travels. Ma.
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Follow Up By: garrycol - Wednesday, Sep 30, 2015 at 15:56

Wednesday, Sep 30, 2015 at 15:56
Hi Ma - as I understand it once you have hit submit there is no editing - I do not see a preview button on my posts already submitted.

And before submission you can edit all you want anyway. The issue above was something I became aware of after the post was submitted not a simple typo.

For ages this has been a complaint by many on this site but doesn't worry others.

In my view the ability to edit/correct an error in your own post is a must on a modern forum. Not all errors are simply a lack of attention in drafting before posting.

Cheers

Garry
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Reply By: Frank P (NSW) - Tuesday, Sep 29, 2015 at 14:08

Tuesday, Sep 29, 2015 at 14:08
Carlo,

I had an Avan Cruiseliner and had the 12V part of the fridge working as well as it can on 12V.

The secret is BIG cable from the tug charging system (preferably via an isolator) all the way back to the fridge in the van.

I used 6B&S to an Anderson at the rear of the car, then re-cabled the van with an Anderson to connect to the car and 6B&S going back to a junction box at a convenient location (under the bed in our case), from which other 12V stuff branched out. I then made sure the cable from that junction box to the fridge was as short as possible and a reasonable size (6mm from memory).

AFAIR that fridge pulls about 12 amps, maybe 15, when on 12V. That causes a big voltage drop if cabling is too small and the fridge wants a good 12V when it is running. 6B&S cabling fixes that.

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Follow Up By: Frank P (NSW) - Tuesday, Sep 29, 2015 at 14:17

Tuesday, Sep 29, 2015 at 14:17
Just to add to that, Carlo, the reason I fixed the 12V side of it is because I'm not a fan of using an inverter and having live 240V in a towed van.

I found the 12V, one working properly, to be perfectly adequate to maintain fridge temps while towing, and that's about all you want and about all it's designed for. 240 or gas once set up in camp.

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Reply By: Member -Pinko (NSW) - Tuesday, Sep 29, 2015 at 14:22

Tuesday, Sep 29, 2015 at 14:22
Carlo
I do what you are talking about.
I had a modified sine wave inverter and it played havoc with my HF radio on 8022Mhz.while mobile.
I have swapped it for a 360 w. pure sine from Jaycar and all is good now.
The 240v element in the fridge has a higher heat output than the 12v.
The fridge is now fine and holds the fridge temp from an overnight stop.
The fridge / inverter setup whilst mobile keeps the fridge fluids on the boil whilst mobile and when I stop at the end of the day swap over to gas and there is no recovery time.
I also have a relay installed to switch of the 12v to the inverter when the ignition is off for smoko or shopping in a town. When I am mobile again the inverter comes on.
The current draw is very similar to 12v. but much more efficient.
Stan
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Reply By: Member - Keith C (NSW) - Tuesday, Sep 29, 2015 at 17:51

Tuesday, Sep 29, 2015 at 17:51
Have you tested to see 12v at back of fridge?could be as simple as a broken wire somewhere ,also carefully check the selector knob on the control panel, could be a slight misalignment, when turned to 12v it may be just missing the contact surface in the switch,move the knob a little each way and then try 12v. Keith
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Reply By: gelatr - Tuesday, Sep 29, 2015 at 18:00

Tuesday, Sep 29, 2015 at 18:00
Like others have said the issue is most likely your cable size. My 3 way works fine on 12 volt because I made sure the cable was fit for purpose. In fact it will freeze if not watched carefully. I personally wouldn't like to run 240 volt in my van while I'm on the road. I think it's is fairly obvious why.

I bought one of the Waeco CoolPro coolers and again it works just fine as a cooler. It tends to be a bit noisey but it works okay for drinks and picnic items. It's not something I would rely on as a fridge.
AnswerID: 590863

Reply By: TerraFirma - Tuesday, Sep 29, 2015 at 21:33

Tuesday, Sep 29, 2015 at 21:33
Correct me if am wrong but typically the 3 way fridges never worked as well on 12v. Personally I would stick with Gas or buy a compressor fridge for 12v if you don't want to use Gas. The inverter scenario is not worth it vs the option of buying a 12v compressor fridge IMO. Cheers
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Follow Up By: Member -Pinko (NSW) - Tuesday, Sep 29, 2015 at 21:52

Tuesday, Sep 29, 2015 at 21:52
The main minus for a compressor fridge is that if camped on the Cooper, as we do for three or four days and it becomes overcast the solar does not keep up or it is only a short run to the next camp spot.
They are fine if you only travel between caravan parks.
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Follow Up By: The Bantam - Tuesday, Sep 29, 2015 at 22:09

Tuesday, Sep 29, 2015 at 22:09
the problem there is not the fridge .... its the solar and battery system ..... but people don't want hear that they need bigger/more pannels and bigger batteries.

cheers
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Follow Up By: garrycol - Tuesday, Sep 29, 2015 at 22:17

Tuesday, Sep 29, 2015 at 22:17
In that situation run your car engine to recharge - no load situation results in little fuel being used. Not ideal but is a reasonable stop gap.
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Follow Up By: The Bantam - Tuesday, Sep 29, 2015 at 22:51

Tuesday, Sep 29, 2015 at 22:51
couple of problems with that

#1 car alternators do not output anywhere near full capacity at idle.

#2 no matter how big the charger or alternator involved lead acid batteries will take hours to realh a high state of charge from a low one.

SO ya could be running your car engine for 3 or 4 hours ... and still not reach full charge.

cheers
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Follow Up By: garrycol - Wednesday, Sep 30, 2015 at 00:00

Wednesday, Sep 30, 2015 at 00:00
As I said - a stop gap and not ideal.

Alternators may not put out a lot at idle but they do put out a big proportion of their capacity at not a lot of revs above idle.

Even on an overcast day solar panels still produce - maybe not enough but a car alternator may just make up the difference.

Not suggesting charging batteries from flat this way - just adding to the charge already there - plus if there is no other way to get charge it is an option.
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Follow Up By: Member -Pinko (NSW) - Wednesday, Sep 30, 2015 at 07:02

Wednesday, Sep 30, 2015 at 07:02
An overcast day ?
I have 12 panels on my house roof.
On a day of full sun = $7.80
On an overcast day = $2.80
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Follow Up By: TerraFirma - Wednesday, Sep 30, 2015 at 08:43

Wednesday, Sep 30, 2015 at 08:43
I'm confused. You say the solar panels won't keep up when running a 12v compressor fridge? How will they keep up running 12v via the 3 way fridge? No matter the cable size compressor fridges are more efficient via 12v than 3 way fridges via 12v. By co-incidence I was talking about this the other day at Cool Factor a well respected service and sales outlet for refrigeration. Are you wanting to run your fridge on gas and then 12v after the gas runs out?
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Follow Up By: garrycol - Wednesday, Sep 30, 2015 at 10:48

Wednesday, Sep 30, 2015 at 10:48
He is not running the 3 way on 12v when camped will have changed to gas. The issue re solar panels in this post was with respect to a 12v compressor fridge. The OP sites this as a reason for not wanting to go back to a 12v compressor fridge.
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Follow Up By: TerraFirma - Wednesday, Sep 30, 2015 at 10:53

Wednesday, Sep 30, 2015 at 10:53
Cheers Garycol that makes sense.
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Reply By: The Bantam - Tuesday, Sep 29, 2015 at 22:18

Tuesday, Sep 29, 2015 at 22:18
This hasben dealt with in the past ....... the reality is .... there is no free lunch.

The reason that three way fridges in general do not work well off 12 volts is voltage drop due to cables too small.

therr way fridges run continuoulsy .... they do not stop and start like compressor fridges .... and they simply are not energy efficient.

SO ya have this 3 way fridge sitting there drawing about 10 amps continous and most likly it is a 10 to 15 meters away from the alternator as the cable runs.

if the cable aint big enough the fridge will be prodidgeoulsy inefficient on 12 volts ...... it is that simple.

if you try to run it of an inverter ... that voltage drop will still be there .... and you are introducing extra losses in the inverter ...... if the fridge is operating poorly on 12 volts ... so will the inverter .. if it runs at all.

the answer is heavier cable ...... like starter motor size cable ..... without going into calculations ...... over that distance 10mm2 cable will probably not quite do it .... if you want efficiency ya probably talking 20mm2 cable all the way back to the cranking battery and a 50 amp anderson.

cheers
AnswerID: 590871

Reply By: Nomadic Navara - Wednesday, Sep 30, 2015 at 01:36

Wednesday, Sep 30, 2015 at 01:36
Three way fridges do work well on 12 V if the wiring is heavy enough. Most tow bar installers only use cable that has about 1/4 of amount of copper in the cable that is required (or probably even less.) Same with the van makers, I am yet to see their wiring that is sufficient for the job. You need 8 gauge cable of bigger to do the job properly.

If the 12 V power cable is not large enough to run the fridge efficiently then it will probably also have too much voltage drop along it to run the inverter as well. First of all upgrade the cable and see if you can make the fridge work properly, if you can do that then there is no point in adding the inverter.

When you have your fridge working properly on 12 V, don't run it off a battery without the alternator running. You will flog the battery too much if you do. I have seen 3 way fridges flatten a Falcons starting battery in half an hour.
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Reply By: Member -Pinko (NSW) - Wednesday, Sep 30, 2015 at 09:11

Wednesday, Sep 30, 2015 at 09:11
Carlo asked if he could use an inverter to run his 3 way.
I answered YES.
Because I use one and it works.
A family member has a jayco swan and it also works for them in practice.
There are probably many others that do the same, we would not be the first.
And the latest chinese made Dometic 3 ways perform better than the made in Denmark ones.
To convert to a compressor fridge of equal capacity with the required batteries (which may need replacing after 4 years) and solar panels will cost in excess of $2400.
Just try the inverter Carlo.
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