Gregors Posted January 16, 2016 Share Posted January 16, 2016 Hi All My motor home is blowing the inline fuse on the domestic battery circuit when I turn the engine off. Any ideas I addition to this my fridge igniter on the gas side does not now work and my inverter has also now broken. I am assuming some sort of power surge. Any help would be greatly appreciated. Thanks Chris Link to comment Share on other sites More sharing options...
Keithl Posted January 16, 2016 Share Posted January 16, 2016 Hi Chris and welcome to the forum, I would suspect your leisure battery has failed, what voltage does it read with no load or charge on it? Perhaps better if you could disconnect its negative and then measure with a voltmeter if you have one. Keith. Link to comment Share on other sites More sharing options...
Gregors Posted January 16, 2016 Author Share Posted January 16, 2016 Hi Keith Thanks for your reply I shall go and check them. There are two connected. If one was bad and one good would this still cause the fault Thanks Chris Link to comment Share on other sites More sharing options...
Keithl Posted January 16, 2016 Share Posted January 16, 2016 Quite possibly, the bad one would take the good one down. Disconnect them from each other to test them individually. If one has failed you will have to replace the pair as they need to be close to each other in terms of capacity and age. If you only replace one you will likely see another failure very shortly after. Keith. Link to comment Share on other sites More sharing options...
Gregors Posted January 16, 2016 Author Share Posted January 16, 2016 Hi thanks Keith. If there is an issue would this also result in some sort of surge to kill the inverter do you know Thanks Chris Link to comment Share on other sites More sharing options...
Keithl Posted January 16, 2016 Share Posted January 16, 2016 Not sure, but if the voltage is too low then the inverter will not work. Measure what the voltages of each individual battery are at rest and we'll take it from there. Keith. Link to comment Share on other sites More sharing options...
Gregors Posted January 16, 2016 Author Share Posted January 16, 2016 Hi Keith. Both batteries were at 14:95 so I think they Are both fine. Any other ideas Thanks Chris Link to comment Share on other sites More sharing options...
Gregors Posted January 16, 2016 Author Share Posted January 16, 2016 Hi Keith. Both batteries were at 14:95 so I think they Are both fine. Any other ideas Thanks Chris Link to comment Share on other sites More sharing options...
Keithl Posted January 16, 2016 Share Posted January 16, 2016 Sorry Chris but 14.95 says anything but that they are fine! At that voltage they must be on charge and at far too high a voltage! Is your MH plugged in to an EHU at the moment? If so either unplug it or turn off the charger then wait at least 3 or 4 hours and measure the voltage again. The 'Normal' voltage for a fully charged battery 'at rest' should be around 12.8 volts. Any higher and it must be on charge. Do you always leave your MH plugged in when not in use? If so it is possible that it has always been on charge and this may have damaged the batteries. PS What make, model and year of MH are we talking about here? Keith. Edit. if you want to try and understand batteries and chargers have a read of the very informative pages on A and N Caravans website... http://www.aandncaravanservices.co.uk/battery-technology.php Alan posts on here regularly and is a very knowledgeable person with regards to MH electrics. Link to comment Share on other sites More sharing options...
Gregors Posted January 17, 2016 Author Share Posted January 17, 2016 Hi Keith. The MH has solar panels to charge the domestic batteries. Also mains. However the mains have not been plugged in for a week or so. I also took the reading after unplugging all so just pos and neg on the batteries. I shall po over now and see what the reading are this morning The motor home itself is a Elnagh year 2001 Thanks for your help Chris Link to comment Share on other sites More sharing options...
Gregors Posted January 17, 2016 Author Share Posted January 17, 2016 Hi Keith. The voltage on both batteries this morning is 13.v. The inline fuse always blows when I turn the engine off. Could it be a problem with the alternator ??? Link to comment Share on other sites More sharing options...
alanedwin Posted January 17, 2016 Share Posted January 17, 2016 Mine was blowing the charging circuit fuse last year. I thought it was the battery going but turned out to be my alternator. I am not sure why but it has not happened since. Link to comment Share on other sites More sharing options...
Keithl Posted January 17, 2016 Share Posted January 17, 2016 Hi Chris, OK I'm afraid I'm going to ask a few more questions to try and understand your problem... How long have you owned the MH and has it always exhibited this problem? Are there any other loads connected to the leisure battery when you have the engine running? eg the Inverter you mentioned? What are the voltages at both leisure and starter batteries with engine running? At idle and also at approx 1,500 rpm. And again with headlamps turned on. What rating is the 'in line' fuse and exactly where is it located? Are you absolutely certain it is blowing when you turn the engine off and not when you start the engine? If I think of anything else I will post again. Oh and by the way, I still think your 13 volt reading is too high for batteries at rest and must question if the solar panels where charging at the time. Keith. PS Please can you try and post a photo of your leisure battery set up showing how they are wired together and where they are earthed. Thanks. Link to comment Share on other sites More sharing options...
bolero boy Posted January 17, 2016 Share Posted January 17, 2016 Gregors - 2016-01-17 11:01 AM Hi Keith. The MH has solar panels to charge the domestic batteries. Also mains. However the mains have not been plugged in for a week or so. I also took the reading after unplugging all so just pos and neg on the batteries. I shall po over now and see what the reading are this morning The motor home itself is a Elnagh year 2001 Thanks for your help Chris wont these readings be from the solar panel, if the batteries are not completely disconnected? Link to comment Share on other sites More sharing options...
aandncaravan Posted January 17, 2016 Share Posted January 17, 2016 That suggests a high current draw by something/several things from the Habitation battery? I am guessing that the reason it doesn't blow when the engine is running is because the Engine Alternator charge into the battery is most likely on the 'Appliance' side of the fuse (not the battery side) so this Alternator charge is helping to meet the current being drawn? If all the 12v has failed then a power surge may be the possible cause, but if some bits are working and some not, it is unlikely to be a power surge as surges are not selective. If you get a big power surge in the van all your electrics will be complaining. If you have used an unsuitable Generator, it is possible sensitive electronics are likely to suffer more than a Fridge Element? So you might get a mix of some work and some not. I would suggest that as the Invertor has failed, you start there, disconnect the Invertor and then retest? If that makes no difference, photograph all the fuse positions in the Power distribution unit. Then remove all the fuses and replace the main habitation one. Hopefully it won't blow. Then insert each fuse one by one until the main fuse goes, that should tell you which circuit is taking the power? If that makes no difference, another possibility (not very likely) is a short in the Charger unit? If the main fuse still pops, with all the fuses for the Appliances removed and the charger out of circuit, then we would suggest an Auto Sparky be summoned. Not just to find out the fault, but also to identify why an item is wired without a fuse? Obviously if you remove all the fuses and something is still able to draw power, it isn't wired safely. Link to comment Share on other sites More sharing options...
Gregors Posted January 18, 2016 Author Share Posted January 18, 2016 Hi All Thanks for all your help. I have since removed the inverter and the inline fuse is still blowing when you turn the engine off. In addition to the inverter going wrong, the ignitor to light to gas also went wrong as well. I have since replaced the ignitor box but this has had no effect. I think the initial problem has knocked out the inverter and also the fridge but finding it is difficult. I basically have an inline 25amp fuse and also all of the individual fuse going into the charger. Non of these have blown. I have never used a generator on the motorhome and before the fault has only plugged it in for a short period at camp site on the mains. Most of the charging of the domestic batteries is done on the solar power or though the generator. I cant help thinking that if I solve this issue all three are connected and the fridge and inverter issue will be resolved or I will find the cause. The inverter luckly was covered still by warranty. Thanks Chris Link to comment Share on other sites More sharing options...
Gregors Posted January 18, 2016 Author Share Posted January 18, 2016 Hi All Thanks for all your help. I have since removed the inverter and the inline fuse is still blowing when you turn the engine off. In addition to the inverter going wrong, the ignitor to light to gas also went wrong as well. I have since replaced the ignitor box but this has had no effect. I think the initial problem has knocked out the inverter and also the fridge but finding it is difficult. I basically have an inline 25amp fuse and also all of the individual fuse going into the charger. Non of these have blown. I have never used a generator on the motorhome and before the fault has only plugged it in for a short period at camp site on the mains. Most of the charging of the domestic batteries is done on the solar power or though the generator. I cant help thinking that if I solve this issue all three are connected and the fridge and inverter issue will be resolved or I will find the cause. The inverter luckly was covered still by warranty. Thanks Chris Link to comment Share on other sites More sharing options...
Keithl Posted January 18, 2016 Share Posted January 18, 2016 Hi Chris, Two questions have been asked which you haven't answered with any absolute certainty.. First, that the in-line fuse blows when you turn the engine off AND NOT when you start it. Or are you saying that you only notice it has blown after you have stopped the engine? Second, which is more something you need to do to answer... You said you have 2 leisure batteries, please can you disconnect the negative terminal of ONE battery (being careful not to short anything) then leave the battery to stand for 2 or 3 hours before measuring the voltage across its terminals. After doing the first battery reconnect its negative and then do the same for the second. Please tell us the voltages of each battery. Thanks. Keith. Link to comment Share on other sites More sharing options...
Gregors Posted January 18, 2016 Author Share Posted January 18, 2016 Hi Keith, Yes I can confirm everytime I turn my engine off the inline fuse blows. When I replace it turn the MH engine on its fine, then when I turn it off it blows the 25amp fuse again ! Also I did the check on the batteries as you said after 3-4 hours and repeated. These were showing 13.36 each ! Also when + & - were plugged back in they were then showing simular however the solar panels would also be kicking in then as well I am guessing ! Its strange, As Its been fine for 2 years no problems nothing then all of this ! Thanks Chris Link to comment Share on other sites More sharing options...
Keithl Posted January 18, 2016 Share Posted January 18, 2016 Chris, You MUST disconnect the negative terminal from one battery to check its voltage, all you are telling us is the output voltage of the solar panel and not the state of charge of the battery. Also please could you measure the voltage with the engine running. Thanks again, Keith. Link to comment Share on other sites More sharing options...
Gregors Posted January 18, 2016 Author Share Posted January 18, 2016 O.K No problem, I shall try again later tonight. However that voltage reading was taken with no leeds connected.Just taken from the +&- of each battery I shall come back to you Thanks Keith. Link to comment Share on other sites More sharing options...
Brian Kirby Posted January 18, 2016 Share Posted January 18, 2016 As the fuse keeps blowing, you must be replacing it each time this happens. So, when do you replace the fuse? Do you do this as soon as one blows, some time later, or only when the engine is running? If you replace the fuse when the engine is not running, and it doesn't blow, and survives the engine being started and running, but then blows when the ignition key is turned off, that would seem to me to suggest that the fault is related to the act of turning the ignition key. Something suddenly draws more then 2A when the ignition is cut, but only at that point in time. Just a thought, but how is the inverter is wired in? Link to comment Share on other sites More sharing options...
Gregors Posted January 19, 2016 Author Share Posted January 19, 2016 Hi Brian, I have been replacing the fuse after each time it blows when the engine is off. Its fine when you start it however when you turn the engine off it blows the 25amp fuse. With regards to the inverter, this is not currently mounted, however It was attached to the 2nd domestic battery. Thanks Link to comment Share on other sites More sharing options...
Keithl Posted January 19, 2016 Share Posted January 19, 2016 Chris, What is the voltage at both leisure and starter batteries with the engine running please? Keith. Link to comment Share on other sites More sharing options...
Brian Kirby Posted January 19, 2016 Share Posted January 19, 2016 Gregors - 2016-01-19 11:01 AM Hi Brian, I have been replacing the fuse after each time it blows when the engine is off. Its fine when you start it however when you turn the engine off it blows the 25amp fuse. With regards to the inverter, this is not currently mounted, however It was attached to the 2nd domestic battery. Thanks I realise there was a typo in my post above. I said "something suddenly draws more than 2A", which of course should have read "25A". Hope it was obvious, but apologies if it caused confusion. 25A is quite a chunky load, and it would take more than that to blow the fuse. Is it possible something momentarily shorts as the engine stops? Electricity is not my field, but I can't see how a surge from the alternator could blow that fuse without damaging a range of other equipment as well. I also don't think a surge alone could blow the fuse: surely there would also have to be a leakage path or high demand appliance to account for so high a current flow? The fault would, logically, have to be between the battery and the main distribution fuse board, because a problem downstream from the fuse board would first take out one of the lower amperage fuses. However, if there is something wired to the battery that is not fused, it could cause a high load if a fault has developed. However, none of the above seem to me to chime with failure when the engine is stopped, because under the above circumstances the 25A fuse should then blow as soon as you insert it, and it doesn't. The split charge relay (or similar) should disconnect the habitation batteries and the 12V fridge circuit from the alternator/starter battery when the engine is cut. Could a fault in that relay cause a short or momentary surge current when the circuit opens? Alternatively, how are the two batteries wired in? You said the inverter is wired to one battery only. I think it should probably have been wired across both (+ on one, - on the other). Is the second battery wired to the first so that the + terminal (the one with the 25A fuse) gets the feed and the - terminal of the other is the earth, with a double fused wired link + to + and an un-fused link - to - between the two batteries? Same with the solar controller, and are all connections to the same + terminal? I'm just wondering if the second battery is wired + to + and - to -, but all feeds and supplies are connected only to the original battery, leaving the second battery with only the two links connecting to it. Then, if it has failed and shorted internally, I think you may get a sudden surge current that might be enough to blow that 25A fuse when the charge from the alternator is cut. However, If things are not wired as above I would not alter anything at this stage, but proceed as follows. I think you should first make the sloar safe, and then disconnect it. Then do as Keith suggests and disconnect the batteries from each other, leave for 3 - 4 hours, and test the voltages of both. They should both read around 12.7V, or a bit over, if fully charged. Your present voltage readings are rather high (but may simply reflect the solar output). Do you have a second meter to check your readings? Then, if the original battery shows full charge, connect it alone (i.e. leaving the second battery disconnected). Next, as Ken suggests, pull all the fuses, except the 25A fuse, start the engine, let it run a few minutes, then stop it and see if the 25A fuse blows. If it doesn't, replace the lower amperage fuses one by one, starting and stopping the engine as above between each fuse to see if any blow. If anything blows then, you will know which circuit is affected. You should now have the van electrics back to their basic state with no solar involved, no inverter involved, and no second battery connected and, if nothing has blown, in normal working order. In that state, but with the 25A fuse pulled, re-connect the second battery and then re-insert the 25A fuse. If it holds, start the engine and then stop it again. If the fuse blows, the fault is in the second battery, or the wiring to it. If it doesn't blow, I would suspect that the solar connection is in some way involved. In short, it is just a matter of first removing all potential sources of trouble, and then reinstating them logically one by one, until the cause can be identified. Boring and time consuming but, apart from the cost of the fuses, not expensive. I'm more than happy to be corrected as to which/what to take out, in what sequence, and when/how to re-connect it/them, in what sequence: as I said above, electrics are not my field. But, logically, unless what you've described are typical symptoms of a particular fault that someone can immediately identify, I don't see what else you can do. Take notes as you go, and don't be tempted to cut corners. You will have to go one step at a time to get to the truth. Link to comment Share on other sites More sharing options...
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