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25th June 2021, 17:41 | #1 |
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Battery light
Hi all. Having issues with battery waring light it keeps flikering and stays on ive gone over the earths fitted a new battery and alternator with no success i am out of ideas now and hope someone could think of anything to look at thanks. 1.8 petrol
Last edited by rover_ed; 25th June 2021 at 17:57.. |
25th June 2021, 17:49 | #2 | |
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25th June 2021, 17:53 | #3 |
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I did have bumper off a not so long back and couldn't see any problems with any wires but could of missed somthing
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27th June 2021, 10:49 | #4 | |
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A poor connection from either the ignition switch or the alternator to the warning light. Last edited by COLVERT; 27th June 2021 at 21:23.. |
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27th June 2021, 11:32 | #5 |
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How does a battery warning light work, very simply.
It serves two functions, the main one being to allow a small current to the alt to start charging at low revs, the second is that it acts as a charge warning light. Engine stationary, ignition on, the battery + current say 12v flows through the bulb and to bat - 0v through the alt, via the brushes and slip rings, a difference of 12v from one side of the bulb filament to the other, so it lights up. Start the engine and the alt starts to charge at say 14v, this voltage is now present at both the battery + , ignition switch and ignition switch side of the bulb and also at the alternator side of the bulb, 14v at one side of the filament and 14v at the other side of the filament, the bulb won't light. So what can cause the bulb to come on and, or flicker ? Dead simple in theory, anything in any circuit from battery +, to ing. switch, to bulb, to wiring, to multi-plugs to alternator internals, to bat -, where there is is a poor resistive or loose connection and causes a volt drop across that connection of say 1v or more. We than have a difference in voltage between either side of the filament and depending on what the difference or cause is, it will cause the filament to glow, flicker or stay on even though the alt is charging perfectly. So in theory, somewhere, there is simply something causing a volt drop on one side of the bulb or the other, the practical side, finding the fault isn't that simple though. There will be many an alt. replaced unnecessarily due to the above.
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Common sense isn't a gift, it's a punishment because you have to deal with everyone who doesn't have it. Last edited by Ducati750cc; 27th June 2021 at 11:36.. |
28th June 2021, 19:20 | #6 |
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28th June 2021, 19:26 | #7 |
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Thanks for the replies i will be having a look during the week after work have a good look over the loom battery wires and from the alternator if im sat at idle very rarely come on mainly as the revs are raised
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28th June 2021, 19:31 | #8 |
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My reply could be better but 2 kids running round and playing a banana game keeps throwing me of took me half hour to write that
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29th June 2021, 09:22 | #9 | |
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How's the alternator drivebelt tension? Do you hear any squealing? Have you activated the instrument pack diagnostics to monitor the charging voltage? It would be helpful to know what this is as the revs are raised. Simon
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30th June 2021, 16:11 | #10 |
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The volts on the instrument panel is 12.4 idle and reved or driving is 14.2
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