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  1. #21
    Join Date
    May 2001
    Location
    North Wales, sailing Aegean Sea or Menai Strait
    Posts
    21,340

    Default

    Quote Originally Posted by neale View Post
    That might be OK if it is only used for beer, but if there is food in there as well the fridge will almost certainly get above safe storage temperatures if left off overnight. Care is needed with this approach although it is well worth considering.
    In Greece in the summer months, beneath an awning that extends from the mast aft to the stern of the boat, the overnight temperature in our saloon is quite often 35C in port, less at anchor. The temperature in the fridge when turned off overnight reaches 20C. Food in the freezer section defrosts, probably not up to 20C but well above freezing.
    Answers to some technical queries at new website http://coxeng.co.uk

  2. #22
    Join Date
    Mar 2004
    Location
    Butts Ash Near Hythe,Hants,UK
    Posts
    554

    Default try a keel cooler

    I have a compressor fridge with an external cooler.
    Often spend 3 or 4 days at anchor with fridge on all the time
    and the battery drain is no problem.
    This is a link to a previous thread.
    http://www.ybw.com/forums/showthread.php?t=225572
    You know you are getting old when your back goes out more than you.www.actionoptics.co.uk[/url]

  3. #23
    Join Date
    Jan 2011
    Location
    Hayling Island
    Posts
    704

    Default

    Quote Originally Posted by blackbeard View Post
    Bomb proof ploy which keeps food cool over a weekend without flattening batteries or costing money.
    Save some drinks/fruit juice bottles - maybe half a dozen, each of a litre or so.
    Fill with water - not quite full as water expands on freezing
    Place in freezer at home, allow some space between them (see above).
    Even better: Fill the bottles with a saturated salt solution (as much salt as the water will absorb). Freeze that down and then much better at cooling. With these even had ice in a bottle of water the other day. My bottles came from the chemist. 2 litre polythene bottles that syrups are supplied in.

  4. #24
    Join Date
    Sep 2006
    Location
    West Yorkshire
    Posts
    2,679

    Default

    We now have a ridiculously large Coleman 36l coolbox, but it works as it seems to have good thick lagging. We have only bought about 6 bags of ice for it while we were away for Easter.
    It will probably use more when it's warmer but even if it takes 2 bags in 3 days it'll be much better than the previous cheap coolbox we had.
    For a W/E we don't bother with ice, taking cold/frozen food is enough and it's not going to go off in 2 days.

    No battery drain, and we have ice cubes for the GnT (cider if you like).
    Bob.
    Any bull in this post may be composted.

  5. #25
    Join Date
    Oct 2004
    Location
    I know how fast I'm going, but not where I am
    Posts
    6,812

    Default

    Quote Originally Posted by Mark M View Post
    --------------------------------------------------------------------------------

    I am thinking of buying a the WAECO TropiCool TC-35FL, coolbox which cost around 200.00
    That is a thermo-electric cooler. It will chomp your batteries quickly. They are inefficient.

    A much better bet is the Waeco CF35 CoolFreeze. It costs twice as much. But it is more than twice as useful. I have a smaller one in the range - the CF18. It uses 10Ah per 24 hour period in a UK summer (at 12V).
    Andersen 22. The best winch never made.
    miniwinwm.wixsite.com/miniwinwm

  6. #26
    Join Date
    Sep 2010
    Posts
    5

    Default

    Thanks for your replies
    The "fridge" is a thermoelectric cooler, the type that heats aswell. There is no thermostat control, it is either on or off. Well its off permanently now unless hooked up to electric. Its now warm beer and food poisoning!

    PS. It drained the batteries to less than 10v so probably didnt do them much good

  7. #27
    Join Date
    Jul 2002
    Location
    Farnham, Surrey
    Posts
    20,809

    Default

    Quote Originally Posted by oddynoki View Post
    Thanks for your replies
    The "fridge" is a thermoelectric cooler, the type that heats aswell. There is no thermostat control, it is either on or off. Well its off permanently now unless hooked up to electric. Its now warm beer and food poisoning!

    PS. It drained the batteries to less than 10v so probably didnt do them much good
    I think you need to read up on the subject of batteries and charging and fridges. Some of the replies you have received have made some guesses and assumptions... and the advice is perhaps not the best.

    A few thoughts based on what you have said:

    10 volts is FLAT - its so flat that its 'damaging the batteries flat'. The problem with flattening the batteries to this degree is that you get into a vicious circle. The batteries lose capacity when they are regularly run down to this sort of voltage and this means that it become easier and easier to flatten them... The whole subject of charging is often discussed on these forums, but ideally you need to make sure that you only discharge the batteries by perhaps 50% of their 'capacity' and to re-charge them up to at least 80% or 90%. When you do the sums, you can see that this means that 'usable capacity' of a battery bank is actually quite small. This is why Vyv added another battery to his domestic bank. FWIW we have over 400 Ah of capacity in our domestics on our current boat and I am thinking of increasing this even more for when we live on board. I don't want to go into the debate about charging systems, but one hour of engine running with an engine using an unsophisticated regulator is not very likely to bring your batteries back to anywhere near fully charged. It isn't just a matter of changing the regulator either. The batteries will only accept charge at a certain rate. The chemistry/physics can't be FORCED to accept charge faster then it will allow according to the design of the plates etc etc.

    The fridge you mention is particularly power hungry and this doesn't help much either! Depending where you are in the world, a modern air cooled of keel cooled fridge would be much more efficient. Water cooled is inherently more efficient, but air will work ok so long as you are not in the tropics. Even in warm climates, air cooled will work - and there are those who debate the difference. We changed to water cooled so I am biased.

    If you can't change the fridge type you might do something about the insulation as one of the key parts of the equation for the efficiency of a fridges is how it is made. I recently rebuilt our fridge with as much insulation that I could pack round it. As the boat had come from the manufacturer, there was only 1 inch of insulation in some places and NONE on the top beneath the work surface. We have gone from using 60 Ah overnight to less than 30 Ah (This includes all other uses - our battery monitor measures power in and out, but doesn't measure the fridge separately.) We have problems turning the fridge down enough now - if we are not careful we freeze everything in the cool box or the milk is just so cold it hurts your teeth when you eat your breakfast cereal! One of my jobs is to add a door to the freezer compartment so that frozen and fridge don't get quite so mixed up...

    All the talk about packing the fridge out making it more efficient is true to the degree that you are minimising the amount of heat lost when you open the door/lid. By making sure its packed out you reduce the 'volume of warm air' you let in whenever you open the lid/door. Switching the fridge off at night doesn't make a huge amount of sense unless the insulation is fantastic and you don't open the door/lid during the dark hours. Personally I would rather leave the fridge on and ensure that the meat etc doesn't become a hazard to our health by being warmed up and cooled down every day.

    Hope this helps - and all IMHO as ever.
    Semper aliud

  8. #28
    Join Date
    May 2001
    Location
    North Wales, sailing Aegean Sea or Menai Strait
    Posts
    21,340

    Default

    John Morris uk has it exactly right, especially about that fridge. I had one a long time ago and found it very demanding of power. You are almost better off using it as a cool box, filling it up with ice and only turning it on when the engine is running.

    I had the bright idea of filling it wath cardice (CO2 ice) before going on a summer cruise. Not recommended - it damaged the thermostat when the temperature fell below its range.
    Answers to some technical queries at new website http://coxeng.co.uk

  9. #29
    Join Date
    Jun 2001
    Location
    Home Shropshire 6/12; boat Greece 6/12
    Posts
    10,416

    Default

    Interesting the apparent gaps in knowledge about fridges.

    Quality of insulation is the most important factor - I know mine uses 40-45 AH in 24-hours at 28C ambient - with 1 85 watt PV panel I used to be able to go 4-5 days before having to recharge the two 100 ah batteries when they got to 12v unloaded. It's infinitely more efficient when full - and if on supercool for a long time freezes weak beer.

    IMHO water cooling is a diversion - with a ducted air system, the theoretically lower efficiency is minimal and power is saved by not having a water circulating pump.
    The fan is a 100mm computer cooling fan using 0.4 watt and that only comes on at 1/2-speed >13.0v and full speed at >13.8v.

    It takes about 24-hrs, with no compressor, for the contents to get to near ambient.

    The compressor unit is a bog-standard Danfoss, with additional controls by the Italian firm ASU-Isotherm - the Waeco uses exactly the same unit with the same solid-state inverter - power usage, 4.5 amps on start-up, 1.8 in economy and 2.8 in supercool. The holding plate thermostat is set in the range -10C to 4C.

    We're all guessing, because the OP has given so little relevant information - it's probably an absorption device, but we don't know - what's certain is that (like Vyv's fridge) it's badly insulated or never full - or constantly being looked in - or it's front-loading...
    Last edited by charles_reed; 08-05-11 at 15:46.

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