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L319
Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2080
  
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November last year new alternator( Land Rover) and Exide battery fitted. Recently I have found after starting especially if vehicle has been stood a few days, the dash display, navigation screen and interior light are pulsing ( voltage changes) .When idling, engine speed also pulses as though load changing. If driving the display is still pulsing but engine speed constant due to drive train engaged.
This morning put digital voltmeter across battery terminals before starting. Vehicle last run on Sunday for about an hour. prior to that it had run all week with no problem. Temperature -10C. Battery before starting 12.2V, ignition on 12.03V, dropped to 10V with starter engaged . Engine fired up instantly with no problem. Voltage climbed in a few secs. to 14.8V , put on heated seats and lights climbed to 15.4V. Then the pulsing started ( about 1 per sec.) and volts cycling between 14 and 15.4. ( A bit difficult to read exactly as meter changing too fast) After a couple of mins. volts steadied at 15.4, still with lights on. I had the battery checked last week at local Auto electrical shop and advised it was good, just slight drop in capacity.
Is this an indication of the alternator failing and are there any tests I can run to confirm? I could take it back to Listers who fitted the alternator but fear no fault will be found after running down to the workshop.
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 12th Dec 2017 11:09 am |
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Globetrotter448
Member Since: 21 Mar 2017
Location: Londonderry NSW
Posts: 1783
 
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Symptoms could be battery or alternator. I would check the ground at the alternator and battery and whether the alternator connector (red) is good and tight. Because of fluctuations it may be the alternator regulator has a faulty diode. Maybe a load test of the battery to prove its ok as a drop to 10v possibly indicates a cell failure.
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| 17th Dec 2017 8:25 am |
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Hot Tub
Member Since: 15 Aug 2017
Location: Milton Keynes
Posts: 1071
 
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I seem to remember if alternator faulty or playing up can kill battery so best to get it sorted sooner. Possibly somebody who knows more will confirm my suspicions.
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| 17th Dec 2017 8:31 am |
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L319
Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2080
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I had a load test done on the Battery on Friday and it proved OK, so will now check all the connections.
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| 17th Dec 2017 9:34 am |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10364
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I would almost say that's normal ?
The thing is idling as some low RPM?
And you are putting on loads like heated windscreens.
If you rev it slightly to 1000rpm, does it improve?
If you leave it stood for a few days, get yourself a CTEK charger to keep the battery topped up and in good condition.
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| 17th Dec 2017 10:44 am |
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L319
Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2080
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LR at Listers for MoT today, passed with advisories on bushes. While it was there I asked them to check alternator and was advised it was showing abnormal voltage variations. I was short of time so booked in later for a more in depth diagnosis.
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| 20th Dec 2017 6:13 pm |
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M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8103
 
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Sounds like the auxhilary drive belt is slipping under load to me  It can when others can't,
It will when others won't,
It goes where others don't.
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| 20th Dec 2017 6:35 pm |
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L319
Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2080
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Possible, although it had a new tensioner and belt when alternator changed. Not that that precludes anything
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| 20th Dec 2017 7:03 pm |
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hugeviking
Member Since: 08 Jun 2010
Location: cotswolds
Posts: 1482
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Robbie did a guide ref checking for AC from the alternator that proves faulty diodes.
Normaly 12.2 volts is pretty flat but -10 may have an affect on that.??
Andi.
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| 20th Dec 2017 10:26 pm |
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MG
D3 Decade
Member Since: 08 Nov 2005
Location: Surrey
Posts: 217
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Almost certainly it's the alternator. Make sure you ask for a new one rather than a re-manufactured one. Had experience recently where dealer fitted 3 re-manufactured before they realised they were from a duff batch! MG
HSE V6 Diesel
Buckingham Blue
Ebony Leather
Side Steps
Mini Fridge
Rosen A7 Roof-mount DVD player
Parrot 3100 Bluetooth
Removable Towbar and Elecs
Pure Highway DAB
Portable Fridge
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| 22nd Dec 2017 12:43 am |
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L319
Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2080
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Thanks, will keep that in mind.
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| 22nd Dec 2017 11:32 am |
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L319
Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2080
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To bring things up to date. As predicted it was a faulty alternator but as it was still under LR Warranty was replaced FOC.
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| 5th Jan 2018 5:54 pm |
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