Majikthyse Posted October 3, 2016 Share Posted October 3, 2016 This is a great mystery. We have had our Murvi Pimento since new and it's just coming up to 3 years old. The 12v sockets in the habitation area have worked fine up to a few months ago. I usually use a little USB charger for my phone that plugs into one of these 3 sockets. They are the usual fag lighter type, one in the kitchen area and two on the cab door pillars. Recently the 30A fuse started blowing - we have got through over 10 so far. Throughout I have used the same USB charger. I have done a lot of tests and found the following: 1. Only the two sockets on the door pillars are affected. The kitchen one is fine. 2. Both these sockets sometimes spark when plugging in the charger, even before connecting the USB cable. The charger has a metal case and this has burn marks. 3. The problem is worse with lights turned on. 4. I bought a new Belkin USB charger (with plastic case) and this also blows the fuse, although not as often. 5. No other device blows the fuse. I have tried an inverter and a wander light. I used the USB charger for 2.5 years in this van without problems, so I am baffled as to what is going on. Any ideas? Link to comment Share on other sites More sharing options...
Mike P Posted October 3, 2016 Share Posted October 3, 2016 Sounds as if it could be a loose connection shorting out or possibly since you see burn marks a bit of conducting material (foil or something similar floating around in the socket). Mike P Link to comment Share on other sites More sharing options...
Majikthyse Posted October 3, 2016 Author Share Posted October 3, 2016 There is nothing in either socket, and if it's a loose connection it's too much of a coincidence for two sockets to do this suddenly. Link to comment Share on other sites More sharing options...
sshortcircuit Posted October 3, 2016 Share Posted October 3, 2016 You need to look at the adapters etc you are plugging in as a socket on its own, unliess wiring problems, will no blow fuses. I had problems with a router I plugged in which was a fault in the plug creating a dead short. Link to comment Share on other sites More sharing options...
Majikthyse Posted October 3, 2016 Author Share Posted October 3, 2016 The new USB adapter has the same problem, and it's a different type. Why does turning on the lights trigger the fuse blowing, but only when I plug in the adapter? Link to comment Share on other sites More sharing options...
flicka Posted October 3, 2016 Share Posted October 3, 2016 As the van should still be under warranty, my first port of call, would be for the Dealer to check it out. Link to comment Share on other sites More sharing options...
Majikthyse Posted October 4, 2016 Author Share Posted October 4, 2016 flicka - 2016-10-03 10:52 PM As the van should still be under warranty, my first port of call, would be for the Dealer to check it out. Not really, it's only the habitation area sockets that are affected and the Murvi conversion only has a 2-year warranty. The vehicle fuses are not affected. I have asked Murvi for advice though. I forgot to mention that both USB chargers are fine in my car, it's just the Ducato that has the problem. Link to comment Share on other sites More sharing options...
StuartO Posted October 4, 2016 Share Posted October 4, 2016 Majikthyse - 2016-10-03 4:33 PMThis is a great mystery. We have had our Murvi Pimento since new and it's just coming up to 3 years old. The 12v sockets in the habitation area have worked fine up to a few months ago. I usually use a little USB charger for my phone that plugs into one of these 3 sockets. They are the usual fag lighter type, one in the kitchen area and two on the cab door pillars. Recently the 30A fuse started blowing - we have got through over 10 so far. Throughout I have used the same USB charger. I have done a lot of tests and found the following:1. Only the two sockets on the door pillars are affected. The kitchen one is fine.2. Both these sockets sometimes spark when plugging in the charger, even before connecting the USB cable. The charger has a metal case and this has burn marks.3. The problem is worse with lights turned on.4. I bought a new Belkin USB charger (with plastic case) and this also blows the fuse, although not as often.5. No other device blows the fuse. I have tried an inverter and a wander light.I used the USB charger for 2.5 years in this van without problems, so I am baffled as to what is going on. Any ideas? Blowing a 30 amp fuse is a big electrical event and the burn marks give you a strong clue about where the short is occurring. Cigar-type 12 volt sockets are a poor connection because the "plug" is often a sloppy fit and the central (positive) connector in the socket can also be loose. The USB charger plug you are using which has burn marks is clearly causing a short (hence the burn marks) but maybe because the socket is faulty. The fact that your second USB charger plug has also caused a short suggest that the socket is faulty. The body of the socket might be cracked but the crack not apparent looking down the hole. Remove the socket assembly from the door post and check it carefully. If you can get a replacement socket then replace it anyway, even if you cannot see a fault. Link to comment Share on other sites More sharing options...
AlanS Posted October 4, 2016 Share Posted October 4, 2016 We had a similar problem in my wife's Hyundai car when we were using a USB charger and even had to pull the fuse as, even without the cigarette lighter inserted, it was 'blowing a fuse'. Our dealer replaced it under warranty and no problem since. Alan Link to comment Share on other sites More sharing options...
Majikthyse Posted October 5, 2016 Author Share Posted October 5, 2016 Thanks guys, without any other explanation I have to resort to replacing two sockets. Very odd that other plugs don't do this. Link to comment Share on other sites More sharing options...
Alanb Posted October 5, 2016 Share Posted October 5, 2016 Hi Majikthyse, Would I be correct in thinking that the 12V sockets in your Murvi are of CBE manufacture, and that you have only recently started using the phone charger? I had a similar problem about 3 years ago. I had bought a 12V to USB charger which and tested it out OK, but on plugging in on a subsequent occasion blew the 15A supply fuse. I have followed a career as a professionally qualified electrical engineer, with many years of experience in fault finding in complex systems. However as in your case, on initial investigation, the cause was a mystery. A second incident eventually led to the cause of the fault. It was due to an incompatibility between the plug in USB charger, and the CBE socket. The CBE "auto" socket has the 12v positive connection entering about half way along the barrel of the socket and it runs uninsulated to the positive contact at the bottom of the socket. The negative contacts on my 12V to 5V USB charger were further forward on the plug than on some other plugs. One of the negative contacts was shorting between the negative ring inside the front of the socket and the previously mentioned positive connecting strip. The short circuit only occurs when the plug is inserted in either of two angular positions. My cure was to remove and dismantle the CBE socket, with some judicious bending, the positive connection of the socket was sleeved with suitable heat shrink sleeving. All will now be OK until the sleeving wears through!! I hope that this helps, but in any case the forum does appreciate feedback. Link to comment Share on other sites More sharing options...
Majikthyse Posted October 6, 2016 Author Share Posted October 6, 2016 Thanks Alanb. I have used the same USB charger from when we first bought the Murvi. This problem only arose a few months ago, when the van was about 2.5 years old. The O/S door pillar socket is worse than the N/S one, and the kitchen one seems OK. Much worse with lights on so there seems to be a surge when the plug goes in. Link to comment Share on other sites More sharing options...
Majikthyse Posted October 7, 2016 Author Share Posted October 7, 2016 I may have found the problem. I removed the socket and found that the negative terminal inside was sliding very close to the positive one. Very bad design as they are only 2mm apart! I may be able to fix this - will let you know if it works. Link to comment Share on other sites More sharing options...
Majikthyse Posted October 8, 2016 Author Share Posted October 8, 2016 My solution seems to work. The design of the socket is even worse than I thought. The positive contact is brought up the inside before exiting to the terminal, purely so that the terminals are at the same level on the outside. This is stupid as this brings it within 2mm of the negative contact. The latter is a ring which becomes loose and slides inwards when the plug goes in, eventually hitting the positive contact, with obvious results. I have fixed the negative contact in place using metallic resin - it was originally just pressed in and retained by the other half of the plastic body, which wasn't very accurately moulded. These are the usual CBE sockets. Link to comment Share on other sites More sharing options...
Alanb Posted October 11, 2016 Share Posted October 11, 2016 This does seem to be a similar experience to my own, described earlier in this thread. In my case it was the negative contacts of a USB charger which were shorting the socket negative ring to positive strip. Very puzzling at the time as other plugs were OK due to the negative contacts being further back on the plug. Link to comment Share on other sites More sharing options...
fairlawn2284 Posted November 5, 2016 Share Posted November 5, 2016 really unable to help you but, perhaps you my be able to help me. I am looking for maxi fuse in the wardrobe area ( so handbook says ) Found 2 near Aux battery One near vehicle battery There is a fuse box in wardrobe However, in book it says 'in the same area ( wardrobe ) there are TWO fuses one 50amp, one 100 amp Maxi fuses I can not see them anywhere can anyone help john Link to comment Share on other sites More sharing options...
Derek Uzzell Posted November 6, 2016 Share Posted November 6, 2016 I notice you asked about this separately http://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Fuses-location-murvi-pimento/45748/ but the logical first point of contact for advice about the invisible ‘maxi fuse’ is Murvi itself. http://www.murvi.co.uk/contact/ Motorhome handbooks are often generic (so the fuse in the wardrobe area may be present on some Murvi models but not on others) or the motorhome converter has changed the installation methodology but the handbook has not been updated to match, or the information in the handbook is just plain wrong (more common in my experience than one might hope). There’s a Murvi Lovers chat-group that might be of interest https://groups.google.com/forum/#!forum/murviloverschat Link to comment Share on other sites More sharing options...
QFour Posted November 6, 2016 Share Posted November 6, 2016 Majikthyse - 2016-10-07 11:29 AM I may have found the problem. I removed the socket and found that the negative terminal inside was sliding very close to the positive one. Very bad design as they are only 2mm apart! I may be able to fix this - will let you know if it works. Down to cost saving. Why pay £10 for a socket when you can get one that looks the same for a £1. Some of these sockets are only rated at low watts so everything is fine until you plug something in that needs some juice. First thing that happens is it gets warm. The plastic then deforms and things can only get worse. The Laika Motorhome we have uses Hella Plugs / Sockets. Same principle but a far better socket. They have also fitted separate USB Sockets. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.