tonyg3nwl Posted August 23, 2010 Share Posted August 23, 2010 Hi, Yesterday I discovered that the internal fridge light was on , even when running on Gas. I thought that this was unusual, so investigated further, and found that the only way to get the light to go off was to turn the fridge source selector to OFF. This means that the light is on, when we are on a 5 day or wild camping session, putting a (small) load on leisure battery, and is on also even when in motion ( not that that matters as engine is charging) The light is on even when door is closed so it would be on all winter if you forget to turn the fridge source completely off and this would discharge habitation battery. tonyg3nwl Link to comment Share on other sites More sharing options...
Derek Uzzell Posted August 23, 2010 Share Posted August 23, 2010 You don't say what make/model of fridge you've got but, if it's Dometic Powerfridge like mine (Model RM-7605L in my case), then I'm a mite wary of your advice. 1. If you do not turn the 'energy selector switch' to the OFF position, then 12V power will continue to be fed to the fridge's electronics irrespective of whether there's a valid energy-source available. For example, if you have selected 12V operation to run the fridge while you are driving your motorhome home and, having arrived there and stopped the vehicle's motor, you then fail to turn the selector switch to OFF (ie. you leave the switch in the "12V" position), even though there's no 12V 'motor' power to carry out fridge cooling, a small demand will continue to be placed on the supplying leisure battery to power the fridge's electronics. This demand would drain the battery eventually, though it would take quite a while to do so. 2. If you select Gas, 230V, or 12V on the energy selector switch and open the fridge door, then the interior light should illuminate. The only way to stop it illuminating is to turn the energy selector switch to OFF (or remove the light bulb). 3. It's clearly common sense that a fridge's interior light should only be on when the fridge's door is open and that's what happens with my fridge. I haven't researched what causes the interior light to come on or go off (I assume it's some sort of magnetic sensor of the type used for domestic doors/windows security systems), but there's absolutely no doubt that this happens because, when I read your posting, I went and checked! It perhaps needs saying that the light comes on when my fridge's door is only just open and, vice versa, the door must be nearly shut before the light goes off. I'm going to suggest you take a closer look. Open the fridge door just a fraction and check if the light is on or off. If it is indeed on all the time (except when the selector switch is in the OFF position), then I think you've got a fridge fault. Link to comment Share on other sites More sharing options...
Brambles Posted August 23, 2010 Share Posted August 23, 2010 You have not said what model of fridge you have. SO check if you have a low ambient switch, I think it is inside somewhere and only applies to certain models. Switch it to normal if so. What happens is for low ambient it switches the light on permanently which is enough to fool the fridge into opertating at low ambients. Summit like that anyway!! Link to comment Share on other sites More sharing options...
Derek Uzzell Posted August 23, 2010 Share Posted August 23, 2010 Brambles - 2010-08-23 11:29 AM You have not said what model of fridge you have. SO check if you have a low ambient switch, I think it is inside somewhere and only applies to certain models. Switch it to normal if so. What happens is for low ambient it switches the light on permanently which is enough to fool the fridge into opertating at low ambients. Summit like that anyway!! A new one on me, but perfectly correct. GOOGLE-ing on "Dometic refrigerators low ambient temperature switch" will retrieve more about this feature. It sounds like the switch may only be fitted to Dometic fridges with ice-making capability. My fridge/freezer hasn't got a LAT switch, though it does have an anti-condensation switch for heating the frame around the freezer door and this switch remains 'live' even when the fridge's energy selector switch is turned to the OFF position (which seems strange to me). If a fridge has a LAT switch, then it ought to be mentioned in the relevant manual. Link to comment Share on other sites More sharing options...
Clive Posted August 23, 2010 Share Posted August 23, 2010 Sounds like the door switch is shorted (magnetic switch). Take the bulb out until its sorted properly. C. Link to comment Share on other sites More sharing options...
hallii Posted August 23, 2010 Share Posted August 23, 2010 To check that the light goes off connect the leads of a multimeter to the bulb connectors, if it shows 12v with the door closed it is staying on. Or train your cat to meow once for on twice for off and shut it in the fridge. Hallii Link to comment Share on other sites More sharing options...
Brian Kirby Posted August 23, 2010 Share Posted August 23, 2010 What intrigues me is how Tony knows the fridge light is on when the door is closed. Tony? Link to comment Share on other sites More sharing options...
Brambles Posted August 23, 2010 Share Posted August 23, 2010 Brian Kirby - 2010-08-23 9:45 PM What intrigues me is how Tony knows the fridge light is on when the door is closed. Tony? Thats easy Brian, he opens the door and takes a look. :-S Link to comment Share on other sites More sharing options...
andy mccord Posted August 24, 2010 Share Posted August 24, 2010 The bulb will still be warm brian even after an hour? Andy Link to comment Share on other sites More sharing options...
tonyg3nwl Posted August 25, 2010 Author Share Posted August 25, 2010 Hi Again, Thanks for the comments. I will have to investigate further, but this all started when a freind came round seeking assistance to find why his leisure battery failed down to less than 9 volts while out on a Rally (no hookup). We spent the afternoon comparing current drain, voltages / charging currents etc and took extensive measurements on both vehicles trying to see if he had excessive drain compared to me. Results were inconclusive, as the vans are not identical (Stargazer mine, his is stardream?) both autocruise, both same vintage, both have same control boxes and control panels. However it did show that with everything apparently switched off there was an unaccountable leisure battery drain. Then I realised my Fridge was not switched fully off but was set to Gas and the gas was turned off so was attempting to get going but failing. thereby accounting for some drain. Opening and closing door didnt alter the drain but the light was on with door open. If closing the door turns light off, I would expect current drain to reduce but there was no difference, hence conclusion that light is on all the time. Turning control to OFF on the fridge, reduced current drain and turned light off (door open to see it) Of course it also stopped attempting to light the gas as well. so current drain dropped .(Fridge is Dometic 'power fridge', cant see a type number anywhere) We still havent reached any conclusion regarding my friend's battery failure but think that it might have been a lack of charge before the rally, aggravated by the incandescent bulbs he has in the reading lights, whereas I have fitted LED lights saving loads of current drain. Also I have a 40 watt solar panel, where he doesnt. I have now removed the light bulb in the fridge until I can discover how to switch it, and have just confirmed that my friend doesnt have a light in his fridge anyway, so that doesnt add any answers to his battery problem.. His next step is to seriously consider second leisure battery or solar panel (or maybe both) tonyg3nwl Link to comment Share on other sites More sharing options...
Brambles Posted August 25, 2010 Share Posted August 25, 2010 1st of all if you post your fridge model number then someone can check it out and advise where the switch is - makes it all the more interesting for us prepared to help rather than guessing. As to your friends battery, i suggest in 99% of cases where someone mentions battery problems a new battery is required. Jon p.s. How much did the curent fall when you switch fridge to off as the control module/spark generator may also have some drain. Is the fridge light an led light or filiment? Link to comment Share on other sites More sharing options...
tonyg3nwl Posted August 26, 2010 Author Share Posted August 26, 2010 Hi Again. I can now confirm that the Fridge is RM7391L, and I am now convinced that the wiring is correct having ploughed through the handbook wiring diagrams. It makes sense that there will be a small drain on leisure battery whenever the Fridge power source is selected to any position other than OFF, because the fridge has its electronics powered to control temperature whether power is 12volts,gas, or mains. The small light is 12 volt powered and is 2watt rating, so load is quite small, but the point is that if the van is to be laid up for any length of time it is essential to ensure fridge is selected to OFF and not any other position, or possibly have a Solar panel attached to sustain the small load of the quiescent electroncs Thanks for all the suggestions. tonyg3nwl Link to comment Share on other sites More sharing options...
Brambles Posted August 26, 2010 Share Posted August 26, 2010 Hi again, As far as I can make out your fridge has an optical sensor to detect the door is closed and is an IR (infrared sensor). It probbaly works by reflection of the IR light beam being reflected back off the door surround. It is mounted centre top of the fridge unit. Check it is clean and the door is clean as well. You could try holding a piece of white shiny paper or some other reflective material against it, even a bit of tin foil or a mirror to check it works. Move reflective paper towards and away from sensor. Of course it is also possible it has failed completely. Having not seen one in practice I cannot say exactly what would be involved in investigating this further or how easy to replace. Link to comment Share on other sites More sharing options...
BGD Posted August 26, 2010 Share Posted August 26, 2010 Brambles - 2010-08-23 10:19 PM Brian Kirby - 2010-08-23 9:45 PM What intrigues me is how Tony knows the fridge light is on when the door is closed. Tony? Thats easy Brian, he opens the door and takes a look. :-S Very very quickly........ :D Link to comment Share on other sites More sharing options...
oldlowie Posted August 26, 2010 Share Posted August 26, 2010 Brambles - 2010-08-23 10:19 PM Brian Kirby - 2010-08-23 9:45 PM What intrigues me is how Tony knows the fridge light is on when the door is closed. Tony? Thats easy Brian, he opens the door and takes a look. :-S I'm beginning to like this forum very much indeed. :-D Link to comment Share on other sites More sharing options...
Brambles Posted August 26, 2010 Share Posted August 26, 2010 Look on the bright side, at least Tony knows its faulty. Link to comment Share on other sites More sharing options...
tonyg3nwl Posted August 30, 2010 Author Share Posted August 30, 2010 Hi Again. We have just returned from the Wessex CC Rally. Now I am wondering why our Leisure battery dropped to below 9 volts last evening and sent us scurrying for the torch. I confess we were watching tv for an hour and had used my amateur radio in the morning on receive for half hour, but I cant really beleive that 120 amp hour battery would run out of oomph in 3 days.. Has my battery decided to head for the great battery dump as well, or is there something sinister going on (2 year old battery timing out??) The Autocruise handbook says that a second battery can be fitted if required, and the control panel can be used to "select "relevant battery. The wiring diagram doesnt give any clue as to how a second battery could be wired, other than in parallel with number one battery, but I cant see how I could then "select it " as working one. Also, I originally thought that the control system enabled us to change over to use the engine battery in an emergency (ie as second battery), but this is not so. The panel only enables the charger to be routed to the engine battery or the habitation battery, but doesnt permit the habitation load to operate from the engine battery. unlike in our previous caravan / car set up. If Clive sees this I wonder if he cares to comment. , in his capacity as electrics guru Now we are back home, the hookup is attached to give a thorough charge before our next outing in a couple of weeks. tonyg3nwl Link to comment Share on other sites More sharing options...
Brambles Posted August 30, 2010 Share Posted August 30, 2010 tony, As you mentioned in yoru 1st post leaving fridge selector in gas or electric position meant your light was on in fridge. Could you have drained your battery a few times because of this and hence taken it below the safe 12.4 v where sulphation starts. A battery must have its voltage maintained or the battery will degrade as a result. Also if you are away a lot and deep discharging batteries each time then depending on battrey you may be lucky to get 150 cycles. With other factors could well be less than 75 full cycles...you do not get a lot with some batteries, and if they need toppin up with water it does not help either. So! check they are topped up with water, and give then a full charge. Something which is very bad for batteries is to be without hook up and discharge deeply and then just drive home. Once home they really need to be on hook up for 24 or 48 hours to fully charge before letting sit idle. What make and model is your battery? Link to comment Share on other sites More sharing options...
Brambles Posted August 30, 2010 Share Posted August 30, 2010 On the topic of a second battery, it is normal to wire in parallel so both are in service together. It is recommended they are of similar capacity although you can have one as low as 25% of the other but I would stick to teh next size up/down or same, also must be of the same type/technology. They must also be of similar age, and recommendation is no more than 9 months between them. p.s. I jumped in and responded as I think Brian might be away just now. Link to comment Share on other sites More sharing options...
tonyg3nwl Posted August 31, 2010 Author Share Posted August 31, 2010 Hi. Thanks for latest comments. Yes the fridge was on for 3 days on gas, but I have already removed the light bulb so that wasnt adding to the load. The 40 watt solar panel was attached the whole time and the regulator was indicating charging during daylight hours The TV is avtek and a sky minibox both on 12 volts basically to catch the news and weather forecasts. This is unplugged when not in use so no standby load. The battery is 120 AH but make not obvious . However it is sealed so nowhere to top it up. With everything switched off there is a standing discharge of approx 100 mA due to the control panel, but this is more than offset by the solar panel givining a net charge of 1 amp plus in daylight hours. At home there is a hookup attached full time, with a timeswitch giving 1 hour on in 24 for the charger. And a 24 hour boost the day before we go away to cool the fridge I cant explain the problem, having checked out the loading using multimeter at the main fuse, and there is no unexpected drain, only the control panel approx 100mA so it seems that the battery itself must be suspect. Any other suggestions welcome. tonyg3nwl (?) Link to comment Share on other sites More sharing options...
Brambles Posted August 31, 2010 Share Posted August 31, 2010 What solar regulator/control to you have and what make/model of on board charger. Looks very much like you have probbaly overchrged teh battey too often and may be the one hour on every 24 hours. Basically your battey might be going a full chrage cycle every day. Much better just to maintain charge using solar panel, or hook up for one hour once a week. Ideally disconnevt battery when not in use, but that can upset some solar panel controllers especially ones which auto select 12 or 24 volts. Anyway, sounds like battery is needing replaced. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted August 31, 2010 Share Posted August 31, 2010 Brambles - 2010-08-26 10:55 AM Hi again, As far as I can make out your fridge has an optical sensor to detect the door is closed and is an IR (infrared sensor). It probbaly works by reflection of the IR light beam being reflected back off the door surround. It is mounted centre top of the fridge unit. Check it is clean and the door is clean as well. You could try holding a piece of white shiny paper or some other reflective material against it, even a bit of tin foil or a mirror to check it works. Move reflective paper towards and away from sensor. Of course it is also possible it has failed completely. Having not seen one in practice I cannot say exactly what would be involved in investigating this further or how easy to replace. Just for the record, I believe it's more likely that the sensor is a simple magnetic-field detector, as that's what is used on the fridge section of my own Dometic 7-Series fridge/freezer. In my appliance's case, the sensor is small, black and about 5mm in diameter, set (as Brambles says) at the centre-top front of the fridge's interior and directly facing you when the fridge door is open. In the door itself is a moulded plastic protrusion behind which is a permanent magnet. The position of the protrusion on the door matches that of the sensor inside the fridge. When you open or shut the door, the magnet moves away from or approaches close to the sensor, respectively switching the fridge's interior light on or off. It's easy to confirm the presence of the magnet in the door, as it is strong enough to hold a pin securely if the latter is placed against the inner vertical face of the plastic 'bump'. When the fridge light is on, if you move the 'attraction end' of a reasonably powerful magnet towards the sensor, the light should eventually switch off as the magnet approaches the sensor. The actual 'switching distance' between magnet and sensor will depend on the power of the magnet. If your magnet actually contacts the sensor but the light still stays on, then you either aren't using a powerful enough magnet or there are problems with the sensor and/or the electrical system to which it is connected. Link to comment Share on other sites More sharing options...
Brambles Posted August 31, 2010 Share Posted August 31, 2010 Hi Derek, I do not doubt what you are saying, but when I traced the Dometic part number for the sensor used in the RM7391L I found the supplier of the sensor and was listed as an IR proximity sensor. This is all I had to go on as I have not seen one of these models and accept data is often very wrong. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted September 1, 2010 Share Posted September 1, 2010 Brambles - 2010-08-31 5:03 PM Hi Derek, I do not doubt what you are saying, but when I traced the Dometic part number for the sensor used in the RM7391L I found the supplier of the sensor and was listed as an IR proximity sensor. This is all I had to go on as I have not seen one of these models and accept data is often very wrong. It could be that a RM7391L fridge has a different interior-light switching arrangement to mine (though I'd expect not as, if a 'mechanical' switch isn't used, a magnetic one is the most logical alternative in this instance). As I've described my switching set-up in some detail (shape/size/position of sensor, etc.) it should be straightforward enough for tony3nwl to confirm whether his is the same. If his fridge has a magenetic switching system, then the 'pin test' is an immediate give-away (assuming of course that a magnet was fitted in his fridge's door when Dometic manufactured the thing!!) Once that's been established, he can test whether or not the sensor is working by moving a strong magnet towards it when the the interior-light is on. I've no idea what the failure-rate is for Dometic interior-light switching systems, but I'd guess it's pretty low. My fridge's light comes on and goes off only when the door is nearly closed, when there's a gap of about 20mm between the flexible seal on the outer edge of the door and the face of the door-frame. If you look carefully through this gap and move the door in and out, you can see the light go off and on. As I said earlier, interior-light on/off operation depends on the strength of the magnet and its distance from the sensor. Thus, if tony3nwl's fridge had a slightly less powerful magnet than mine and/or its design were slightly different regarding the distance of the magnet from the sensor when his fridge's door is shut, then his fridge's 'switching distance' may be less than my fridge's and his light would consequently go off later and on earlier when his fridge's door was, respectively, closed or opened. If that were so, then the 20mm 'gap' I mentioned above could be significantly narrower for tony3nwl's fridge, making it more difficult to check whether or not the interior-light is going off when the door is closed. As there is absolutely no doubt that the interior-light of a Dometic 7-Series fridge SHOULD switch off when the fridge's door is closed, if I were in tony3nwl's shoes I'd put the light bulb back in and check really, realy carefully that the light isn't actually doing this. If this check proves that the light doesn't go out, then he can check whether his fridge has the same magnetic system as mine and, if so, carry out the tests I've referred to above. Link to comment Share on other sites More sharing options...
tonyg3nwl Posted September 1, 2010 Author Share Posted September 1, 2010 Hi Again. I spent yesterday rechecking for oddities, and thought I had discovered a faulty charger. The next 2 hours were spent trying to remove the charger from under front seat to run a bench test. This involved stripping some side trim, and then removing some floor trim so that the charger could be removed. Without stripping the trim, the charger was wedged very firmly under the seat. Eventually I also had to move the Mains box also so that I could get enough spare lead to be able to manouver the equipment to get at the connections. A bench test proved that there was absolutely nothing wrong with the charger !!! A faulty test meter lead ~#@"!!! Then an hour to replace the charger and replace the trim and eventually find the last remaining screw which decided to hide in the darkest and most difficult place to find !!!!!!!. The battery has a label name as ENERGY and there is a 5 and L in the number and is rated 120AH. I still have no definite conclusion about faulty battery, but beginning to think that is only thing left! Over £100 for a replacement ouch!!! tonyg3nwl Link to comment Share on other sites More sharing options...
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