LordThornber Posted July 25, 2014 Share Posted July 25, 2014 Yes, that's me :D Ok, here goes, on our new van, the fridge will run on 12v when the engine's off. Our last van didn't, only when the engine was running. We're very much hook up merchants, (apologies to the purists), so are curious about this, we're going on a 6.5 hr ferry crossing, would leaving the fridge on 12v be a yes or a no? In terms of flattening the battery that is.. Thank you as ever for your help. Martyn Link to comment Share on other sites More sharing options...
sshortcircuit Posted July 25, 2014 Share Posted July 25, 2014 It would help if you give the fridge model number, as Baily's site not to specific. Link to comment Share on other sites More sharing options...
Tracker Posted July 25, 2014 Share Posted July 25, 2014 Not a numpty at all Martyn - very valid question - and there is probably a very simple answer once we discover what it is!! My knowledge base is old fashioned so I don't know and am guessing but maybe the fridge is wired to switch itself to leisure battery use when the engine is not running? Apologies if you have already looked / asked but does the handbook / dealer / converter know !!! Is it a self switching fridge which chooses it's power source according to what it senses is available? If so maybe it will only use 12 v if there is no gas or mains available, using the battery most appropriate? It's clever stuff all this electronics gubbins!! Or it could be wired up incorrectly and you have the very real risk of flattening the engine battery if you forget to switch the fridge off - although being new I doubt that? Is it a compression or absorption fridge and do you know the power - watts - it consumes on 12 volt? Do you have one or two leisure batteries? Link to comment Share on other sites More sharing options...
lennyhb Posted July 25, 2014 Share Posted July 25, 2014 It's quite normal for a AES fridge to be wired that way, Hymer have been doing it for about 8 years & it is the way Dometic recomend wiring AES fridges. I pulled the fuse in the Elecktroblock that controls it in my van it now works the old fashioned way. Downside is if the gas is off it's starts squrking at you with that silly alarm I just turn the fridge off when I go on ferries. If you have the 150 or 160 Lt fridge they draw about 15 amps on 12 volts so will completly bu**er your battery in a few hours. Also with the latest fridge/freezers the frame heater is permantly on when running on 230 or 12 v drawing even more current. Link to comment Share on other sites More sharing options...
Robinhood Posted July 25, 2014 Share Posted July 25, 2014 ....I would be surprised if you have the Dometic standard absorption fridge that is installed by Bailey to find that the cooling functions work on 12V (any control circuits will) - though stranger things have happened). At the size of fridge installed, the maximum current draw is usually in excess of a nominal 10 amps, which in 6.5 hours running could draw around 65% of the standard (105AH) installed battery - leaving it at severe risk of "death". If you've doubled your battery capacity, then you might just get away with it, but I don't think I'd choose to try. Whilst I wouldn't like to risk frozen food for that duration, if the fridge and contents are well chilled down before the crossing, and not opened during it (which is, of course, very unlikely ;-)) then it should keep any non-frozen perishables adequately cool. Link to comment Share on other sites More sharing options...
colin Posted July 25, 2014 Share Posted July 25, 2014 As Robin says, it will severely deplete your battery, although there is a cutout which should stop it ruining them. AFAIK it's only there to keep the fridge on 12v for 15mins whilst at a fuel pump in case you have a CS reg with the gas on. Link to comment Share on other sites More sharing options...
LordThornber Posted July 25, 2014 Author Share Posted July 25, 2014 Thankyou for your replies boys. We've decided it's getting switched off, I'm definitely not even remotely flattening a brand new battery, I'd rather replace, or not take some fridge items first. It's got me thinking though, perhaps the fridge doesn't work when switched on to 12v and engine not running, I've just assumed it does as the lights come when you open the door. I can't see the manual as it's in the van and it's storage spot. In answer to the questions that my query raised, it's not AES, its manual switching and we only use 1 leisure battery, due to being hook up merchants. Martyn Link to comment Share on other sites More sharing options...
Guest Had Enough Posted July 25, 2014 Share Posted July 25, 2014 LordThornber - 2014-07-25 11:12 AM Thankyou for your replies boys. We've decided it's getting switched off, I'm definitely not even remotely flattening a brand new battery, I'd rather replace, or not take some fridge items first. It's got me thinking though, perhaps the fridge doesn't work when switched on to 12v and engine not running, I've just assumed it does as the lights come when you open the door. I can't see the manual as it's in the van and it's storage spot. In answer to the questions that my query raised, it's not AES, its manual switching and we only use 1 leisure battery, due to being hook up merchants. Martyn The fact that the light comes on is nothing to do with whether or not the fridge operates on 12v. You may have noticed that the light comes on when it's set to use gas. My fridge light appears to be wired separately from everything else and it still comes on even if I switch off all the 12 volt power at the control panel. The only way to stop my light coming on is to completely turn off the fridge. I suspect that your fridge doesn't work on 12v when your engine is off. Link to comment Share on other sites More sharing options...
Robinhood Posted July 25, 2014 Share Posted July 25, 2014 LordThornber - 2014-07-25 11:12 AM We've decided it's getting switched off, I'm definitely not even remotely flattening a brand new battery, I'd rather replace, or not take some fridge items first. ...as I posted above, we've happily taken perishables on longer ferry journeys than this, just not frozen food. It helps to have a fairly full fridge, and to chill it well down before travelling. A couple of ice packs in the freezer can help as well, but if you're taking an initial supply of milk for the journey, it's also possible to freeze this down (in plastic bottles) and simply let it slowly thaw out (again, helping to maintain the fridge like a cool box). My 'van is the same as Frank's, and my light also works unless the fridge is completely turned off. The installation instructions define the connection to the cooling circuit (which is really a heating circuit), and the electronics/light as being separate. The latter must be a permanent connection, and on my 'van I have a suspicion this is to the vehicle battery, not the leisure battery (which has an isolator on it which doesn't cut the fridge light). Link to comment Share on other sites More sharing options...
colin Posted July 25, 2014 Share Posted July 25, 2014 LordThornber - 2014-07-25 11:12 AM I've just assumed it does as the lights come when you open the door. Martyn, you've just made an ASS out of U and ME :D Link to comment Share on other sites More sharing options...
Guest pelmetman Posted July 25, 2014 Share Posted July 25, 2014 My new fridge has a sexy blue light B-)........................I know how to keep up with the Jones's :D........... Link to comment Share on other sites More sharing options...
LordThornber Posted July 25, 2014 Author Share Posted July 25, 2014 Had I actually thought about this for for a minute I'd have found my own answer. Everything is switched off and still the lights come on, I've just assumed (there's that word again Colin), that switching it to "battery" lets it draw power from the battery, well of course it does, providing the 12v supply is switched on, what a pillock. As for the light and its power source well it must come from the vehicle battery 8-) Can't wait to read the manual . Thank you again everyone. Martyn Link to comment Share on other sites More sharing options...
lennyhb Posted July 25, 2014 Share Posted July 25, 2014 LordThornber - 2014-07-25 1:13 PM As for the light and its power source well it must come from the vehicle battery 8-) Martyn Nope still powered from the leisure battery, has to have a permenant supply for the fridge to work when the habitation control panel is turned off. Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 25, 2014 Share Posted July 25, 2014 LordThornber - 2014-07-25 1:13 PM..............Everything is switched off and still the lights come on, I've just assumed (there's that word again Colin), that switching it to "battery" lets it draw power from the battery, well of course it does, providing the 12v supply is switched on, what a pillock. As for the light and its power source well it must come from the vehicle battery 8-) ................Martyn Not sure Martyn! :-) The 12V fridge energy supply is connected to the starter battery, but only functions when the engine is running. So, selecting 12V on an MES fridge when the engine is not running, results in no energy to the fridge, so no cooling. The fridge control panel, and its interior light, also run on 12V, but these are supplied from the leisure battery, so have power 24/7. This applies whatever main energy source is selected; 12V, mains, or gas. Link to comment Share on other sites More sharing options...
Tracker Posted July 25, 2014 Share Posted July 25, 2014 If you switch the leisure battery off at the control panel, or disconnect it by pulling a fuse or removing a battery clamp does the fridge light still work? If it does the light is powered by the engine battery - Simples!! Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 25, 2014 Share Posted July 25, 2014 Not necessarily! If the supply is switched off at the control panel the fridge light/panel is not necessarily isolated. None of ours have had this kind of switching. If the fridge auxilliary fuse is removed, or the habitation battery terminal disconnected, and the lights etc still work then yes, the supply is from the starter battery. Link to comment Share on other sites More sharing options...
Tracker Posted July 25, 2014 Share Posted July 25, 2014 Which is why I started with the easy to do and worked towards the less easy to do as proof!! Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 25, 2014 Share Posted July 25, 2014 Sorry, but so as not to further confuse Martyn, if you turn off the control panel and the fridge light stays on, it surely only proves that the control panel does not switch the fridge light - not where it is powered from? Link to comment Share on other sites More sharing options...
Tracker Posted July 25, 2014 Share Posted July 25, 2014 Yes Brian, but turning off the 12v supply at the control panel is a simple first step which involving no delving in lockers or fiddling with cables, connectors, terminal or fuses. However if it did not prove or disprove anything the next step would be the only way to prove or disprove the power source for the aforementioned light and that is to remove a fuse close to the battery as long as Martyn knows which fuse to remove or better still release and lift off the connection to one terminal of the leisure battery. I trust that clarifies it? Link to comment Share on other sites More sharing options...
Pampam Posted July 25, 2014 Share Posted July 25, 2014 Hello lord thornber i bet if you googled it the instructions for your fridge would be found ont 'internet , ours was a large dometic fridge with seperate freezer and worked on gas or mains , i dont know if it actually worked on vehicle battery when van was running but it always stayed cold pp:) thats a good idea about freezing milk i used to freeze water too and put it in fridge to "thaw out and keep fridge chilled if you wrap frozen food in newspaper it stays frozen for ages too : Link to comment Share on other sites More sharing options...
Brian Kirby Posted July 25, 2014 Share Posted July 25, 2014 Tracker - 2014-07-25 8:11 PM Yes Brian, but turning off the 12v supply at the control panel is a simple first step which involving no delving in lockers or fiddling with cables, connectors, terminal or fuses. However if it did not prove or disprove anything the next step would be the only way to prove or disprove the power source for the aforementioned light and that is to remove a fuse close to the battery as long as Martyn knows which fuse to remove or better still release and lift off the connection to one terminal of the leisure battery. I trust that clarifies it? I follow your logic, Rich, I just don't agree with it! To me, stage 2 provides proof, whereas stage 1 is fallible. I just hope the manual provides Martyn a clear answer, as I suspect that between us we have totally confused him! :-) Link to comment Share on other sites More sharing options...
LordThornber Posted July 26, 2014 Author Share Posted July 26, 2014 Thankyou again boys and girls :D Ok, here goes. Firstly, there's more chance of me wearing a toupee than removing fuses and/or delving in lockers. The light comes on only when an energy source is selected, as Frank and John et al helpfully pointed out. Fridge turned to off = no light on. The manual, as far as I can see doesn't comment on the light, except to say it has a 2 minute cut off if the door is left open. It does say though that the fridge should only be operated on 12v whilst the engine is running, to prevent battery discharge. But in the fridge itself, an idiots guide states that 12v cooling only works with the engine running! Martyn Link to comment Share on other sites More sharing options...
Derek Uzzell Posted July 26, 2014 Share Posted July 26, 2014 Dometic provides general installation guidance for current-model fridges, but leaves ’nuts and bolts’ decisions to whoever installs the appliance. For example, the “Battery connection” advice in the downloadable installation guide for an 8-Series fridge/freezer includes the following: "Provide a 16 A fuse to protect on-board 12 V circuit. In order to ensure that the 12V power supply is shut off when stopping the engine (otherwise the battery would discharge within a few hours), perform the power supply to the heating element (cf. page 30, connection A/B in wiring diagram) in a way to have the 12V supply only live while the vehicle ignition is switched on. The connection C/D (interior light, electronics, cable black / violet) must be permanently provided by a 12V DC power supply to be protected by a 2A fuse.” Dometic do not say “Take the 12V power-supply from the vehicle battery and fit a relay where appropriate” or “Connect C/D to the leisure battery”. They just leave the installer to do their best (or worst!) Link to comment Share on other sites More sharing options...
Robinhood Posted July 26, 2014 Share Posted July 26, 2014 ....indeed Derek; Dometic set out the generic requirements for connection, but leave the actual detail (which could consist of a number of different methods) to the converter. As I've posted here before, I know to my cost that Auto-Sleepers used to (and may still do) connect the fridge cooling circuit across the leisure battery, switched via a sensing relay from the alternator feed to ensure it only functions with the engine running (and the battery thus being on-charge). A blown fuse in the leisure-battery charging circuit and a long drive to the Lake District with the fridge in use resulted in a "dead" battery on arrival on-site. I have remedied a similar issue for an Auto-Sleeper owner on a site in Ireland, so it wasn't a one-off. ....and, contrary to my perceptions set out previously, the light/control circuitry in my current fridge is connected to the leisure battery, not the vehicle one - I went and checked. ;-) Link to comment Share on other sites More sharing options...
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