bobmaddison Posted May 10, 2011 Share Posted May 10, 2011 Hi fellow motorhomers, I have a small problem requiring advice from those of experience and expertise. We bought a CI on a Fiat Ducato a couple of years ago. Being our first ever motorhome I do not know much about the electrics peculiar to campers although I am an electrician. Since the beginning it has occurred to me that the leisure batteries were not charging from the alternator and the fridge did not seem to work on 12v with engine running. In my naivety I was not sure how the system differentiated between the vehicle and leisure batteries. The other day I found a schematic diagram of the charging system and decided to investigate. I found there is a lead marked as D+ coming from the ignition switch, which needs to be energised to operate the relays for charging to take place while the engine is running. Following this lead from the charger I found that behind the dashboard it was connected to another lead that ran to the engine bay where there is a 1 amp in line fuse but then the lead has been terminated with a blank cable connector. I temporarily connected this lead to 12v and the fridge works and the batteries charge. Why should this lead have been blanked off and where should it be connected. Any ideas? Link to comment Share on other sites More sharing options...
Brambles Posted May 10, 2011 Share Posted May 10, 2011 The lead you refer to going to the engine bay should be connected to D+ on the alernator. Why on earth someone has siconnected it I have no idea. So 1st of all check if there is a connection to the D+ terminal on the alternator. The same circuity or 'signal' is used to control the Ignition lamp as well as the slave relays for the charger circuit and power to the fridge. I think before going any further you need to check what is connected to the D+ on the alternator and if your ignition light works and goes out when the engine starts. D+ is used to control the slave relays so power is only supplied to the leisure batteries and the fridge when the engine is actually generating power. You mention D+ coming from the ignition switch. This is baffling as it should not be connected to the ignition switch and someone may have altered the wiring in an attempt to fix a previous fault. In doing so they would have burned something out when trying to start the engine. All supposition of course at this stage. So instead of connecting your engine bay cable (and 1 Amp fuse) to 12 volts it should go to alternator D+ terminal. CI used to always connect, I believe, the slave relays to the D+ cable under the dashboard near side next to the fuse box. Hope this helps you in the right direction. Link to comment Share on other sites More sharing options...
bobmaddison Posted May 10, 2011 Author Share Posted May 10, 2011 AH, HA, Brilliant BRAMBLES, thank you very much. That explains a lot. Perhaps I should have said, the Diag for the charging box behind the drivers seat just shows a lead with D+ against it and the text says D+ comes from the ignition so I took that to mean the Ignition switch. Now I know why the lead goes to the front of the Engine Bay. I'm going to have to get under the wagon and see what is on the alternator because the ignition warning light and everything else appears to work OK. I think I'll wait until it stops raining though. As yet still a mystery why it has been disconnected. Once again thank you for your help. Bob Link to comment Share on other sites More sharing options...
Guest Tracker Posted May 10, 2011 Share Posted May 10, 2011 The biggest culprits for leisure batteries not charging via the alternator are broken, loose or dirty fuses / fuse holders at the under bonnet relays and dirty connections, fuses, holders, battery terminals, connecting cables etc at the battery end. Link to comment Share on other sites More sharing options...
Robinhood Posted May 10, 2011 Share Posted May 10, 2011 The wiring diagrams referenced in this post may be of some assistance: http://www.outandaboutlive.co.uk/forums/forums/thread-view.asp?tid=21765&posts=9 Link to comment Share on other sites More sharing options...
bobmaddison Posted May 12, 2011 Author Share Posted May 12, 2011 Thanks for all the advice. Further investigation has revealed there are two terminals on the alternator, a big one marked B+ (which I take to be the output) and another small terminal with no markings that I take to be D+. The small black lead connected to that terminal goes into some flexible conduit. However I found the conduit had some impact damage further up the front of the engine bay, no obvious reason for this unless someone had slipped with a tool. I also found that inside the damaged area the black lead was completely parted. 1/2 inch air gap. The ignition (battery symbol) was not extinguishing, in fact it was not coming on in the first place. I had not noticed "naive about campers". I have now repaired the lead and connected the charger lead to it and hey presto I'm getting more than 14v at both batteries, also the fridge works. Interestingly I was getting 13.5v from the alternator with the engine running when the lead was broken. The manual says that terminal provides the excitement to energise the alternator but there must be enough residual magnetism to provide the 13.5v. Again I thank you. Bob Link to comment Share on other sites More sharing options...
Brambles Posted May 12, 2011 Share Posted May 12, 2011 Well done. Pleased you have it all repaired now. Bet you are relieved. Jon. Link to comment Share on other sites More sharing options...
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