Solar Powered Fridge?

Discussion in 'Motorhome Chat' started by BetweenTheWheels, Apr 10, 2013.

  1. BetweenTheWheels

    BetweenTheWheels Read Only Funster

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    Is it feasible?

    I know that it's not a good idea to run your fridge on DC while static (unless you want a flat vehicle battery quickly). However, is it possible to have a windscreen solar panel hooked up to your cigarette lighter in the cab thus powering the vehicle battery which is being used by the fridge??

    The reason I ask is that I am heading off to France/Spain on Sun as part of my full-timing ....ahem 'experiment' and would only be using gas for the fridge and some minor cooking. The solar panel I have is one of the big ones from Halfords that plugs either into cigarette lighter or using croc clips direct to battery. Obviously the charging of the battery would only take place during the day but that's when I would have the fridge on and it would be turned off (or on gas depending on contents) when it got dark.

    Am I missing something completely obvious? Not unlike me I must say!

    Any thoughts?
     
  2. Reallyretired

    Reallyretired Funster

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    You can run a fridge off solar power but:

    1. you need a condenser fridge. The normal 3 way absorption fridges are too inefficient on electric.
    2. You need a lot of solar. One of those portable ones are usually around 10watts and are only suitable for giving a trickle charge when vehicle is stored, you will probably need around 300w-500w on the roof, i.e. several large panels.
    3. you also need the sun to shine, we haven't seen too much of it this year in UK
     
  3. callumwa

    callumwa Read Only Funster

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    You would be lucky if the windscreen solar panel could charge your phone if on all day.:RollEyes:

    With a standard van fridge your battery will be dead on the first day......:cry:

    :Smile:
     
  4. eddievanbitz

    eddievanbitz Trader - Funster

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    The Dometic compressor range of portable fridge/freezers draw about 45w and are guaranteed to go 22* below ambient temperature

    I have one for beer and wine on a slide out rail in n outside locker and my solar panels easily keep up with it in the summer in the UK but I have a lot of solar capacity

    The portable one you have will not make any appreciable difference to you leisure batteries, they're more designed for battery maintenance

    Regards

    Eddie
     
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  5. Jaws

    Jaws Funster Life Member

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    If you are intending plotting up somewhere for a week+, there is a trick often missed today

    Years ago, before it was the norm to have a fridge, just about all my aunts and uncles, and indeed us, had a couple of biscuit tin ( the old ones that loose biscuits were delivered to shops in ) buried in the garden

    Just a couple of inches below the surface and even on the hottest summer day the milk was always cold.

    Today, the metal tin could easily be replaced with a plastic box.. Suitable sizes are just a couple of quidlets.

    Ok, no use at all if you are on the move, but if intending to plot up for any length of time 10 minutes with a small trowel will give you if not an ice box, certainly a cold one :thumb:
     
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  6. dave newell lvs

    dave newell lvs Trader-Vehicle Services

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    An alternative method is to get a plastic bucket with a lid, fill it with cold water and place your milk etc inside. Wrap a wet towel round the bucket and place it in the shade, as the water evaporates from the towel it draws heat from inside the bucket just like an absorption fridge.

    D.
     
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  7. Wildman

    Wildman Read Only Funster

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    JJ is your man with experience, he has been running a compressor fridge from solar in the UK and Portugal for many years, he can advise how often he needs to run the genny to keep charged as well as the solar panels.
     
  8. BwB

    BwB Funster Life Member

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    A lot of the auto three way fridges will need a 12v supply from the engine battery in order to function. Over time this small draw may indeed be topped up by your windscreen solar panel (but check the cigar socket is still live when the ignition key is removed - if not you'll need to use the croc clips directly to the battery).

    Most three way fridges will not work on 12v unless the engine is running as I believe they take a signal off the alternator. So this might need checking and possibly a bit of a rewire. But sounds like too much effort as you don't really want to be taking a long heavy draw off the starter battery.

    As an aside - when I used to go camping as a boy with my dad we used to put the milk bottle in a clean knee length sock, soak the sock in water and hang it in the shade. The evaporation kept the milk cool so long as the sock didn't dry out. The mention of the bucket method above jolted a happy memory of something I'd forgotten!! :Smile:
     
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  9. tonka

    tonka Funster Life Member

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    If you mean one of these..
    http://www.halfords.com/webapp/wcs/..._productId_927417_langId_-1_categoryId_255205

    Then..:Rofl1::Rofl1::Rofl1:

    Sorry, being serious... You do realise that this is virtually nothing in power terms, as said may just about charge your mobile phone.... Good idea to think of alternatives but be careful not to waste cash on things like this that give very little back..

    £200 - £300 spend on a DIY solar system may be better.. ie 2 x 80w panels, a regulator and another battery..
     
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  10. Chris

    Chris Funster Life Member

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    I am a newbie to solar.

    My new van has a panel and sat here in the rain in Wales it is currently showing a charge of 0.5 watts.

    Presumably that's not enough to charge even a phone?

    I am on hook up so it doesn't really matter but I would be interested to know how many watts you need for them to be of any use at all.
     
  11. bigfoot

    bigfoot Funster

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    My first built van-Devon Eurovette on a VW had an evaporation cooler. A cup or two of water a day and it kept the milk and butter from going off or melting,evaporation causes a drop in temperature. When I was in Egypt and India we had bags made of fleece type material which we soaked in water and made them damp,then placed the items we wanted cooling-it worked. One of my chums had a WW2 tropical water bottle which had a baize outer,like a snooker table,then it was dipped in water after filling it-worked a treat.
    None of these methods are any good for ice cubes,but you can buy those in supermarkets for about £1 or a Euro.
     
  12. Reallyretired

    Reallyretired Funster

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    I assume you mean 0.5A. That would be enough to charge a phone and would keep a battery charged up when the van was not in use. The little chargers from Halfords would not even produce this much in full sun.
     
  13. Chris

    Chris Funster Life Member

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    Sorry yes Amps:BigGrin:

    Told you I was a newbie:BigGrin:
     
  14. 54mud

    54mud

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    I've got a 12 volt fridge (compressor) and a 60 watt solar panel and one big (180 amp/h) leasure battery and it will last 3 days in the UK without any other charge.
     
  15. BetweenTheWheels

    BetweenTheWheels Read Only Funster

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    Thanks for the all the suggestions folks - I thought I was being optimistic alright - as they say, advice is what you ask for when you already know the answer but wished you didn't!!!!

    I have a fixed solar panel on the roof and a leisure battery bank of 3 batteries so am fairly self-sufficient otherwise while wild-camping. I just thought this could be another way of staying off the grid for longer.

    BTW the portable panel I got from Halfords is the big one - about a foot and a half by a foot - RSP600, power rating 6watts and current at max power 340mA. - it was about €70 but reckon it will come in handy for something - even the beer cooler!!!

    Thanks again and Bon Voyage - heading off to France on Sunday after 2 years in the planning (code for dreaming!). Will keep on the site for the unbelieveably helpful advice and hopefully I will get to a stage where I can contribute more than questions!!!
     
  16. 1_man_and_his_dob(lo)

    1_man_and_his_dob(lo) Funster

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    I've got a suitcase panel from Maplin - 13W but even in full sun I haven't managed 1A and that is not sufficient to replace the power used by my Waeco compressor fridge. It will extend the use of the battery though.

    The problem is, when it is summer and the sun is getting the most out of the little panel, that's when the van is at it's warmest and the fridge is having to work harder.
     
  17. Jaws

    Jaws Funster Life Member

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    To help put in to perspective, that panel could not even cope with the draw of ONE standard internal in your van light bulb in your van in perfect sunny conditions !
     
  18. Reallyretired

    Reallyretired Funster

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    These little panels are designed only to keep your battery from going flat when the vehicle is unused for a period, to compensate for all the little current drains (alarms/remote locking etc) which over a period of (usually) weeks will flatten the battery. They will not run a beer cooler as these (peltier effect) are even less efficient than absorption fridges.
    I have on order a 10w panel for my Discovery, in the hope that it will still start after being left for a month or so. The Disco is particularly hard on batteries when parked as apart from all the usual things, it checks whether it's level every 2 hours and adjusts the suspension accordingly. I am told that I can prevent this by leaving it in access height (hopefully).
     
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