Running a fridge on a leisure battery

[vwalan]

3 way is ok till you get in to hot climates .then they dont work. if you stay in uk thats fine .you may never get it too hot if you go down to southern spain now you will have a problem. many still get it in winter in maroc, compressor fridge is tops .panels 185 quid for an 80 wt .is cheap. forget spending thousands .that was before .now in uk they are cheap. make use of them i do. at this moment i am powering my fridge in the house and during the day i power the big freezer . make use of them 365 days of the year.

 

[Deleted member 3011]

Yes, solar panels certainly have decreased in price. I put 2 24V 180watt panels on my OKA a few months ago for about the same price as I paid for each 160Watt panel on the MCI three years ago. MPPT controllers also have come down in price and make it a proposition to use 24V panels to charge 12V batteries more efficiently than a straight 12V system. I'm a big fan of solar and each of my vehicles has at least some panels with two of them being fully self-sufficient as far as electricity goes.

The issue of DC to DC battery chargers is not as straightforward as it seems.

Imagine a battery that is down to 30% and needs 80 Ah to fill it up. A charger will have to put more than this back so lets use 100Ah just to make it easy.

How big is your DC-DC charger. 25 Amps? You will need to drive for 4 hours to come close to fully charge the battery. In two hours you can put only less than 50 Ah back in so the battery will only be 75% charged. An alternator might start putting 40 amps in and of course this tapers off fairly quickly but in two hours you could actually still get around the 50 Ah without the complexity and cost of the DC charger.

Depends on the alternator characteristics and length and size of cable of course but it can be a reasonable method for some RVers

Of course if the DC charger is a little bigger or the battery is not so discharged or the drive is a bit longer then there is no question the DC charger is going to do the job better and it certainly takes a lot better care of your batteries. Without some sort of extra charging, just charging from the engine alternator will almost certainly result in chronically undercharged batteries and uneconomic battery life.

My MCI bus is a bit out of the ordinary as far as size goes but as an example of my thinking, the alternator (280Amps at 24V) will, after a few days bushcamping, put in 160Amps for at least the first 30 minutes of driving and then this tapers off gradually and is still putting in 40 amps at the end of two hours. Total over two hours - about 230Ah into my house battery. Then I switch it off to let the solar finish the job in a more controlled manner. To achieve the same thing with a DC charger, I would need a pretty big capacity and it would have a big price tag as well. I have lots of solar so it isn't an issue either way. In fact on one trip the alternator "blew up" (100kmph on heavily corrugated roads proved too much) and I couldn't get spares for a few months so I did the final 9,000km with no alternator and made do by cross feeding the starter batteries from the solar panels.

Isn't it much more convenient to walk in the front door of a regular house and switch on the light fed from the grid. Cheaper too -- but not half as much fun as trying to generate your own.

 

[mildred]

Without some sort of extra charging, just charging from the engine alternator will almost certainly result in chronically undercharged batteries and uneconomic battery life.

That bit needs adding to the earlier post that people should print out and keep in the van!

 

[vwalan]

hi tony ,you are right i use a 24v dc to 12v dc charger .but its only to give a boost when driving it certainly isnt the only wat i do it. i like to park in the sun so 240wt panels on roogf. . but i sugest any body trying to run a fridge by battery must have a so;ar panel as a starter. i,m happy with my set up .only in the darker dec /jan is it a prob .by middle of dec hopefully maroc sun will be enough. it usually is. like you i find it hard to explain how much most people use in amps etc .you explain it better than me but we both know alot can be saved by using power carefully. see you on the road somewhere .keep smiling.cheers alan.

 

[Deleted member 207]

3 way is ok till you get in to hot climates .then they dont work.

My personal experience with 3 way fridges is that they do work in hot climates (plus 30C) - on 12V they dont work well but if the fridge is cold will maintain temp if cooled on gas or 240V before use.

The big problem with 3 way installations is that people dont follow the fitting instructions and leave a lot of air gaps on the sides, dont baffle the top to the upper vent, and dont have appropriate exterior vents at the lower rear of the fridge.

The Engel 3 way chest freezers are a prime example of how well they can work.

The Dometic/Electrolux upright fridges suffer from the same as any upright - open the door and all the cold air falls out.

There are some nice fitments using chest fridges using 3 way kits.

 

[spooker]

I fitted a compressor fridge in my first self-build, largely because I didn't want to cut holes in the sides of the van. Loved the van and the fridge, but if I were to do another self build I would definitely go for a 3 way.
My reasoning:
Cost - of the fridge was similar to 3-way alternatives, but I had to fit x2 110 ah batteries at first, then upgraded to x2 130 ah and a 60w solar panel - not cheap.
Convenience - on sunny days in the winter it would last for 3 or 4 days before I needed to add extra charge to the batteries. In the south of France in 30C+ I had to run the engine every other day. The ambient temperature does affect running time quite noticeably. And so does how often you open the door, how much warm food and beer you put in and expect it to cool. I never came anywhere near the power usage as advertised in the brochure.
Alternatives - The 3-way fridge would have cost me less to buy, the space taken up by bigger gas cylinder would be similar to the batteries, and as someone else mentioned - its nice to know you can stay put without worrying about cloudy days, turning the tv off or having to run the engine.

Ultimately I would still prefer the simplicity of the compressor, but my experience of running one has (at this time) steered me towards absorption.

 

[dolmen]

Great discussion folks ... in my last van I had a compressor fridge and solar, I was more than happy ... due to having bought an Elddis with an absorbtion fridge it seems a terrible waste of money to replace it at this early stage so I'm gonna hold on to it for the time being.

Has anyone here got battery to battery charging? for me it looks like a good enough system but I'd love to hear more, before purchasing. I also plan to add solar, but this time we'll be travelling with our dog so hot hot will be out, and as we drive most days B to B sounds like a great solution.

TIA

 

[paulhag]

Great discussion folks ... in my last van I had a compressor fridge and solar, I was more than happy ... due to having bought an Elddis with an absorbtion fridge it seems a terrible waste of money to replace it at this early stage so I'm gonna hold on to it for the time being.

Has anyone here got battery to battery charging? for me it looks like a good enough system but I'd love to hear more, before purchasing. I also plan to add solar, but this time we'll be travelling with our dog so hot hot will be out, and as we drive most days B to B sounds like a great solution.

TIA

Battery to Battery charger is a good system, if you check through recent forums there is a member saying how good is system works and he explains how and why. If I decide to build a new camper this winter it will be a must for me, although you will get some members disagreeing with the system, the choice is yours.

 

[windyjools]

compressor fridges

Hi
I have experience of using compressor and 3-way absorbtion fridges. The upside of the compresor fridge is that you need no big vents in the side of the van and you only need a pair of wires to run them.
The downsides are:
they are really expensive to buy.
despite what they say, they are noisy enough to wake you up at night when they fire up.
they hammer your batteries, we run 2 x 110ah leisure batteries and get 2-3 days MAX before they start to drop below 12.2v (this is about 50% discharge limit) unless it is bright sunlight when our solar panel will compensate.
I just don't find that the pros outway the cons, having spent a lot of time researching this whole subject, I would not go the compressor fridge route again. Everyone that I have met (except one) has had the same problems as I have had. When it is warm and not sunny, even our 175watt solar panel wont supply enough, and you can buy lots of gas for the price of solar panels/batteries and the heavy duty cabling you need to set up a compressor fridge correctly.
I have travelled to Morrocco in vans equipped with absorption fridges and had no problems, use a little sense, don't park with your fridge side facing south and you will have few problems, but find a nice shady spot in Spain or anywhere warm and your batteries will soon go down with a compressor fridge! Most factory built vans use 3-way fridges because they work!!!! you have a choice of power sources, with a compressor fridge, you don't, if your 12v system hasn't enough power, you have no fridge. Face it, heating and cooling uses a lot of power......you wouldn't use 12v alone for heating so why consider it for cooling?
Good luck whichever way you decide, me personally, next time it's 3-way no question.

 

[RogerO]

Maddp:

If you have a LT35 consider looking at the brickyard forum. Excellent LT section. - - - The Brick-Yard - - - click on Forums then scroll down to the LT sections.

 

[windyjools]

Compressor fridges AAAAArggghh!!!!!!

See my previous reply....I am now on my 4th CR80 from Dometic!!!! They sent out an engineer to check out the installation and he was happy that it was all ok so I now have a new CR80 which still doesn't work properly so they (Dometic) have 'modified' it so the thermostat bulb is located in the freezer not the fridge area. It seems to work well so far but has anyone else had problems with these fridges not maintaining a reasonably constant temperature in the fridge? Ours used to let the temperature in the fridge get up to 10c-12c before the thermostat kicked in!! Turning the thermostat up to make it maintain the temperature below 10c had the effect of having the thermostat kick in so much our 2 110AH batteries would be flat in under 2 days. Any ideas or possible solutions wouldbe very gratefully received.