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TD5 - Red Battery Light Stays On, Despite New Battery Being Fitted and Running Well!

Discussion in 'Land Rover Discovery' started by rjsdavis, Feb 17, 2011.

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  1. rjsdavis

    rjsdavis Active Member

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    Hi Paul

    Thanks for the replies...

    I think we're 99% certain that the altenator is indeed kaput. The fuses have all been checked, and whilst one did happen to be blown, it wasn't for the alternator in any case, and after replacement, made no difference.

    The key problem is:

    LR Main Dealer - £400 for a Denso OEM part

    LR Breaker in Scotland - £35 (+postage of £10) - bought with the protection of Paypal in case its a duffer when it gets here.

    The warranty on the new part is only 1 year - I'd have to get through more than 11 used ones to break even! It's a no brainer for me....
     
  2. paul_c

    paul_c New Member

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    Don't you have any local auto electricians?
     
  3. rjsdavis

    rjsdavis Active Member

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    For the time / effort in taking the little monkey out (est 2 hours because of its location) - I don't want to spend time on fixing something that's likely to be broken. It makes more sense to just have the replacement fitted at the same time, and then think about refurbing the one that came out.... otherwise the mechanic bill just gets bigger and bigger, and my wife is car-less for longer.
     
  4. rjsdavis

    rjsdavis Active Member

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    Sadly - the alternator was kaput.

    Got a good used one on Ebay, and got it fitted - job done for about £50 all in, so can't grumble too much at that.

    Anyone looking for a cheap and very reliable local (mobile) mechanic in the Canterbury area - drop me a line, I've found a gem!
     
  5. DISCO2RS4

    DISCO2RS4 Active Member

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    What should the alternator output be?? I checked my one yesterday with a warm engine and 2k rpm and was getting 13.35v across the battery
     
  6. discool

    discool Well-Known Member

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    Something like this : 12v then 14v with the engine running. SAM_2705 - Copy.JPG
     

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  7. DISCO2RS4

    DISCO2RS4 Active Member

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    I may have an alternator or regulator on its way out?
     
  8. discool

    discool Well-Known Member

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    Not necessarily, even my £220 Fluke meter which I have certified every year is out by + 2% so don't worry, unless you are having electrical issues. I use my Anolog meter on vehicle batteries and wiring normally, much more stable/accurate. Digital is for electronic products.

    Does the 13v stay when all your electrical items are on at once. ? If so the alternator is coping.
     
    Last edited: Nov 23, 2015
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  9. DISCO2RS4

    DISCO2RS4 Active Member

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    Perfect, sounds good to me. :cool:
     
  10. sierrafery

    sierrafery Well-Known Member

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    IMO nothing is good below 13.5 with loads on, especially at 2000rpm, it's possible that a diode to be shot within the diode pack then beside the low voltage/power there is an ''unhealthy'' sine wave component too in the supply and a parasitic drain.... unfortunately that's verifiable only with oscilloscope
     
  11. DISCO2RS4

    DISCO2RS4 Active Member

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    Thanks sierrafery, are these diode packs changeable? that test I mentioned above was with no load at all :/
     
  12. sierrafery

    sierrafery Well-Known Member

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  13. DISCO2RS4

    DISCO2RS4 Active Member

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    Thanks sierrafery, what test do you recommend next? warm it up and put all lights, radio etc on and see what the alternator pushes out? I also have the chain tensioner seal/washer leaking right onto the alternator, would this have an affect on it?
     
  14. The Mad Hat Man

    The Mad Hat Man Well-Known Member LZIR Despatch Agent

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    Just take the car to Halfrauds - they will test it for £0 :)

    You could, of course read the "alternator testing" thread in the CFAQ section :eek:
     
  15. sierrafery

    sierrafery Well-Known Member

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    no fluid ingress into an alternator would be a good thing ever... you dont have to warm up anything, from cold start at idle the voltage should grow to 14+ in max 30 seconds then if you switch on all the heavy loads it can drop below 13 but must start to rise to above 13.5 on it's own and if you rev it above 2000 it must get close to 14 again... that's how a ''healthy'' alternator should behave... the gist is that it should not stay below 13.5 what ever you do
     
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