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| JustFX Member Since: 10 Nov 2016 Location: Mendip Hills Posts: 190   
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Since I have owned the Defender (>1yr) its had a constant issue with the battery terminals being crusty and a tendency to run low on power quickly.
I have done a voltage drop test on the connector and found it to be ok. So I continued with it. Recently I noticed it was at times reluctant to start (clunk but not start) so I popped into a Halfords and got the chap there to do a load test on the battery and it turned out power from the alternator was good but the battery was failing under load so I bought a new battery. Well, last night I went to start the damned thing and it failed to start so I attached the new battery and tried to use it to jump start it. That failed, so I tried a local mechanics jump starter thing and that failed. So in the cold dark, I swapped the batteries over but it didn't go to plan as the old battery terminal was intermittent and it would still fail to start. But I managed to get home by using the jump leads to get an ok connection. So today I replaced and remade the connections and I oped for a different style of battery terminal and connector. All is well. The only problem was when looking at the brown wire in the ribbed sheath (goes towards the CDI etc) I noticed it was scorched but for only 5cm and goes around the wire following a few strands. Now the sheath is in OK and no signs of damage but do I need to worry about this? do I need to replace the wire?  Click image to enlarge |
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3rd Feb 2018 6:38pm |
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| ginjez Member Since: 18 Sep 2011 Location: huddersfield Posts: 1751 
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Has the wire got hot because of poor battery terminal connections. On a dumper I have similar issue where sheathing almost melts if the connections are poor
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3rd Feb 2018 7:34pm |
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| JustFX Member Since: 10 Nov 2016 Location: Mendip Hills Posts: 190
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Greenie, the wire is in that ribbed trunking so the wire damage is just from a melting session.
I think I may well look to replace. It looks like an old injury but might have been a incorrectly connected battery during jump starting I guess. |
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3rd Feb 2018 7:48pm |
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| GREENI Member Since: 22 Aug 2010 Location: staffs Posts: 10364
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Ah got ya:-)
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3rd Feb 2018 7:55pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 19618
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That melting is caused by high resistance, the higher the resistance. (Bad connection). The higher the current draw.
The higher the current draw the higher the excess heat, in this case that cable must be very near it's current capacity if not exceeded. The fuses should blow before too much cable melt has occurred. Has there been any fuses blown or replaced? I had at one time, a battery clamp that was loose, I believe it was earth. It shouldn't have been but it was, but in my case it failed to start and all you would get is a Relay click. There was no reason fo it being loose, but the factory clamps are not the best, so after carefully slightly flattening the battery post with a hammer. (Only a little, as they are soft lead). The battery clamp could go on, tighten up and then had no problem from that day to this. I don't know if fusing was blown in this case or not, but if you do get a fuse blow you have a significant short. And the answer is to trace the fault ASAP, not just fit another fuse. The fusing being there is a safety feature, without them you will get a fire in an event of a short. They are supposed to protect the cable and not specifically the device that is powered. Diesel$ Live$ Matter. ⛽️🛢️👨🔧🧰⚙️ RED, WHITE & BOOST! 🇬🇧 Last edited by custom90 on 3rd Feb 2018 9:30pm. Edited 1 time in total |
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3rd Feb 2018 8:41pm |
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| sako243 Member Since: 08 Jul 2014 Location: Wales Posts: 1190  
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@custom90steve, sorry but that's plain wrong. Go back to basic electrics and Kirchoff's voltage law (V=IR). If resistance goes up then assuming an ideal voltage source (which is what a battery is ideally) then current has to drop. In reality the voltage will also drop as nothing is ideal*.
Think, why do you normally refer to current limit resistors as limit... Because they limit the current. Admittedly if you have a parallel resistor network then a crappy connection can make one path higher resistance and therefore try to pull too much current through the other paths. Edit: * if the current draw is large and pushes the capability of the battery. Ed 82 Hotspur Sandringham 6x6 95 Defender 110 300Tdi |
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3rd Feb 2018 9:01pm |
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| Buz Member Since: 24 Jan 2014 Location: Forest of Dean Posts: 238 
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I had problems with my battery on my '87 200TDI. Cut a long story short, it was the cheap Chinese terminal connectors i got off ebay. I ended up changing those for some decent ones and 'that' electrical problem has now gone.
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3rd Feb 2018 9:39pm |
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| JustFX Member Since: 10 Nov 2016 Location: Mendip Hills Posts: 190
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This is a TD5 and was on standard connectors. I bought decent connectors of the right metal mix to go on there so hopefully no repeat.
I am guessing that is where the interior gets its power. and I haven't had a fuse go there so I doubt its draw from there. I know Discos had an issue if the engine earth was bed it would draw from the loom and kill it. I did once note the battery terminal was getting hot and that is when I did a volt drop test. But I guessed the heat may have been because the battery was rather low on power so was getting a real charging. I did clean all the contacts. Guess I need to find some more 16mm2 wire of the correct length to replace it as now I know of the burn mark I think its best to fix it. |
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3rd Feb 2018 10:17pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 16899 
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I think you'll find that one was down to Georg Simon Ohm and bears his name. Gustav Kirchoff was more into conservation of energy theory as it applies to circuit theory. |
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3rd Feb 2018 10:47pm |
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| sako243 Member Since: 08 Jul 2014 Location: Wales Posts: 1190
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I stand corrected. Been a long week...
 Ed
82 Hotspur Sandringham 6x6 95 Defender 110 300Tdi |
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3rd Feb 2018 10:49pm |
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