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Alternator and battery changed, still low voltage
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MattTheTall77
 


Member Since: 24 Oct 2013
Location: Lincs
Posts: 266

United Kingdom 2005 Discovery 3 TDV6 SE Auto Tonga GreenDiscovery 3
Alternator and battery changed, still low voltage

Hi All,

Just wondering what to check next.

Kept having issues with the battery not being charged, and the breakdown chap saying the alternator wasn’t creating enough charge for the car and battery.

So in January I changed both the alternator with a new Denos and the battery for an Exide, but I still keep getting the same problem. Checking the secret menu it showed the voltage as 11.9 while running (it was 11.6 this morning and had to jump it from a spare).

Using a multimeter across the battery terminals while running it was showing 11.96 - 12.01, but from what I’ve read it should be up in the 13/14v.

I’m now wondering if the old battery and alternator were fine!

What would be the next likely cause? Is there a way to check the alternator directly?

Cheers,

Matt
  
Post #197509818th Aug 2018 10:28 am
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Hardware
 


Member Since: 28 Jun 2016
Location: Hiding under the M60
Posts: 12676

United Kingdom 2011 Discovery 4 3.0 SDV6 XS Auto Sumatra BlackDiscovery 4

I'd start by checking earth straps from engine to body. simplest way is use a jump lead to create a new earth connection between the two … if it starts looking better then that's the issue.
 .


Dean
====================================

2011 D4 XS - OBD port protection, RLD spare wheel protector, All LED interiors lights, Timed Climate enabled, iiD tool paired.
2011 D4 Landmark - Stolen from same dealer before I paid for it
2011 D4 GS - Stolen whilst at dealer Sad ... All LED interiors lights, DRLs, Spare Wheel protector.
1996 300Tdi - Eaten by tin worms 
 
Post #197509918th Aug 2018 10:31 am
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garrycol
 


Member Since: 06 Dec 2010
Location: Canberra
Posts: 1114

Australia 

Sorry but around 12v seems all normal. After start the alternator will charge around 14v but only until it has pushed the charge into the battery used in the start - then it will throttle back on the charge - it will fluctuate around as the car demands just above 12v - rising and lowering as needed.

I can assure you that if your alternator is not charging and your battery is low then you dash will light up like a Christmas tree and you will have faults and issues everywhere.

You may have had issues back in January and replaced and the alternator but it is now August. If there was actually an issue you would have had lights and gongs soon after installing the new stuff.

If you have no demonstrated faults and problems now, I think you are looking for a problem that is not there. The car will tell you if you have an issue.

Garry
  
Post #197513318th Aug 2018 12:07 pm
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Narpy
 


Member Since: 18 Jul 2011
Location: Stockport
Posts: 7830

2005 Discovery 3 TDV6 S Manual Cairns BlueDiscovery 3

Using the inbuilt secret menu is not a reliable way to check.

Those multimeter readings are very low for both battery and alternator, I'd go as far as to say your alternator might well be fecked but check cables first.
It should still be warranted if you fitted a Denso.
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Post #197513518th Aug 2018 12:18 pm
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lynalldiscovery
 


Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274

United Kingdom 2006 Discovery 3 TDV6 Metropolis LE Auto Bonatti GreyDiscovery 3

Im sure I read a post a year or so back where someone maybe Disomikey? had issues with genuine LR alts?
Mine does mainly short commutes and I have a battery monitor in the cig lighter and it normally shows 14.4/15.0 volts pretty much all the time

If I do a really long run ie 50/100 miles thats when it may drop to under 14 volts, i glanced at it today halfway through a 12 mile run and the gauge said 14.7 volts

Isnt there an inline fuse at the battery and another one down by the gearbox?
  
Post #197514318th Aug 2018 1:05 pm
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MattTheTall77
 


Member Since: 24 Oct 2013
Location: Lincs
Posts: 266

United Kingdom 2005 Discovery 3 TDV6 SE Auto Tonga GreenDiscovery 3

Thanks all. Silly question, but to test the earth using the jump cables, where do you connect them?

Just out scouting round the underneath to see if I could do the starter motor next week.
  
Post #197514518th Aug 2018 1:09 pm
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MattTheTall77
 


Member Since: 24 Oct 2013
Location: Lincs
Posts: 266

United Kingdom 2005 Discovery 3 TDV6 SE Auto Tonga GreenDiscovery 3

Changed over the 5amp fuse for the alternator and started, now showing 13.9v on battery terminals. Stopped, changed fuse back and on starting it’s on 13.9 again, not sure why it wasn’t doing that earlier.
  
Post #197514918th Aug 2018 1:52 pm
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garrycol
 


Member Since: 06 Dec 2010
Location: Canberra
Posts: 1114

Australia 

Because you don't actually have an issue and all is working as it should.
  
Post #197515418th Aug 2018 2:04 pm
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MattTheTall77
 


Member Since: 24 Oct 2013
Location: Lincs
Posts: 266

United Kingdom 2005 Discovery 3 TDV6 SE Auto Tonga GreenDiscovery 3

Just put car back together, starter motor looks a horrible job.

Checked voltages again, 11.9v engine off, 12.6v running dropping to 12.1 within 3 minutes. I’d have thought it would be higher to charge the battery given it was 11.9v? Must be an issue somewhere for it to keep going flat, gets a 1hr30 round trip during the week so should always be ok for charge I’d have thought?
  
Post #197517218th Aug 2018 3:28 pm
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lynalldiscovery
 


Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274

United Kingdom 2006 Discovery 3 TDV6 Metropolis LE Auto Bonatti GreyDiscovery 3

Have you actually measured whats at the battery with a multimeter?

They are pretty cheap from toolstation/screwfix, people may might scoff and say they are no good, which is true for people doing the job for a living but for simple diy checks they are just fine.
  
Post #197519918th Aug 2018 5:16 pm
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MattTheTall77
 


Member Since: 24 Oct 2013
Location: Lincs
Posts: 266

United Kingdom 2005 Discovery 3 TDV6 SE Auto Tonga GreenDiscovery 3

Thanks Lynalldiscovery, the voltages were checked at the time with a multimeter. I will do some more tests tomorrow to see I there is any pttern.
  
Post #197521218th Aug 2018 5:58 pm
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MattTheTall77
 


Member Since: 24 Oct 2013
Location: Lincs
Posts: 266

United Kingdom 2005 Discovery 3 TDV6 SE Auto Tonga GreenDiscovery 3

Changed starter motor on Saturday, as anticipated a horrible job. Started ok first time then just three clicks on further attempts. Battery was low so had it on charge, and trying to start now I get constant clicking, vid below. Back under to check cables and they look ok.

Edit: swapped relays and no difference

  
Post #197800027th Aug 2018 9:29 am
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gstuart
 


Member Since: 21 Oct 2016
Location: kent
Posts: 13568

United Kingdom 2005 Discovery 3 TDV6 Base 7 Seat Auto Java BlackDiscovery 3

Hi

Nothing like tearing ur hair out when issues come us Whistle

As you’ve got a multimeter have u tested all ur earths to ensure there all ok

Apologises if you’ve already done that Thumbs Up

Failing that can u go to Halfords or local garage to get ur alternator tested

Hope u get on ok
   
Post #197801027th Aug 2018 9:49 am
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MattTheTall77
 


Member Since: 24 Oct 2013
Location: Lincs
Posts: 266

United Kingdom 2005 Discovery 3 TDV6 SE Auto Tonga GreenDiscovery 3

Thanks for the advice. I should read up on wheee the earths are and how to check them >.< Just pulling the car apart to check the wire from alternator round to battery for any grounding, read that it can above the diff but that looked fine.
  
Post #197802327th Aug 2018 10:12 am
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Pete K
 


Member Since: 15 Jan 2016
Location: GL
Posts: 10335

England 2005 Discovery 3 TDV6 HSE Auto Rimini RedDiscovery 3

the terminals on that 5A fuse could be dirty.

ensure the fuse terminals on the fuse are nice and clean and use the new fuse.

Put the fuse in and while reading the voltage with the engine running jiggle it about until you get a nice high voltage reading
  
Post #197802427th Aug 2018 10:15 am
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