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| falkster Member Since: 12 Nov 2023 Location: Sutton Coldfield Posts: 64   
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hi all,
tried to find something in the search but somehow not lucky... recently my voltage gauge shows a drop in voltage when i come to a stop at a traffic light for example. It did not do this before. you can even see a slight movement of the needle with every balast put onto it, be it lights, phone charger or whatever... sometimes the effect is stronger, sometimes less so. I have a USB socket fitted that also shows the voltage that. this used to show 14V+ when driving. Currently I am lucky when it goes up to 13.5V. On idle it falls to almost 11V, which used to be above 12.5V previously. I know the values are probably not accurate but they show a trend in the system. The strange thing is that this started after I had a nice long run back from our holiday in Cornwall, so I would have thought that during that long journey back the battery would have gotten enough charge. Also an interesting thing, sometimes my break warning light comes on and stays on when the voltage drop happens but brakes work fine. I have a leisure battery on board with a Victron charger but that does only charge very rarely, presumably because there isn't enough power provided to start charging as all appears to be needed to keep my starter battery under power. I am just not sure where to start the fault search. Anyone got any popinters? Alternator maybe? Thanks as always.   1988 Land Rover OneTen County SW, 3.9l Petrol V8 (serpentine), original "Santana" LT85 gearbox |
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1st Sep 2024 6:09pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8013  
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My.money is on a corroded ground cable, most likely the one from the battery -ve to the chassis, which is at a mid point on the cable as the cable continues to the transfer box to provide a transmission earth.
Remove that and clean up both surfaces with a grinder. Also.check.the earth strap on bulkhead outrigger behind drivers wheel for serviceability. It can also be beneficial to run an additional earth strap from chassis to engine. Cheers James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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2nd Sep 2024 7:05am |
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| lohr500 Member Since: 14 Sep 2014 Location: Skipton Posts: 1315  
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Could the corroded earth theory be tested by running a quality jump lead from the earth post on the battery directly to good earthing point on the engine?
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2nd Sep 2024 7:27am |
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| nosnibod Member Since: 15 Aug 2007 Location: West Midlands Posts: 370 
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I’d suggest popping down to Ian’s (IRB Developments) - he’s in Sutton Coldfield and he’s an electrical wizard. Dave
Green Goddess - 1998 Defender 110 300tdi |
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2nd Sep 2024 12:21pm |
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| falkster Member Since: 12 Nov 2023 Location: Sutton Coldfield Posts: 64
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Sounds like a plan, They are literally around the corner from where I work. I'll check tomorrow. Thanks everyone so far for the responses. gives me something to look at tonight. 1988 Land Rover OneTen County SW, 3.9l Petrol V8 (serpentine), original "Santana" LT85 gearbox |
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2nd Sep 2024 3:26pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20307
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Well worth looking into what JST suggested as well, that grounding point crimp is known for corrosion so you never know. It could even be behind it, on the mating surface between the chassis rail and the crimp hangar. ⭐️⭐️God Bless the USA 🇬🇧🇺🇸 ⭐️⭐️
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2nd Sep 2024 3:31pm |
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| falkster Member Since: 12 Nov 2023 Location: Sutton Coldfield Posts: 64
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and here the latest from this morning's way to work...
brake light on the dash comes on after starting the car and battery voltage drops almost completely to the left on the gauge. Feels like there is basically no charge(?). Thought I mentioned it as I would like to understand if in combination with the brake warning light this is a known symptom? brakes are totally fine by the way. 1988 Land Rover OneTen County SW, 3.9l Petrol V8 (serpentine), original "Santana" LT85 gearbox |
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3rd Sep 2024 1:24pm |
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| MadTom Member Since: 10 Sep 2013 Location: Olomouc Posts: 616  
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Not only corroded ground cables, but also check plus power cables. In Discovery 2 I had to replace cable between alternator and fusebox in engine compartment in several cars. Visualy all was nice, but there was 0,5V voltage drop just on the crimped cable eye. It was corroded inside of the crimp. New cable, new eye and the drop was less than 0,01V. Before replacemet the thick cable was really hot with isolation really soft and nearly melting. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo
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3rd Sep 2024 2:02pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8013
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Just check the earth's. Could done it in the time it takes to post updates. Cheers
James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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3rd Sep 2024 8:28pm |
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