Engine Battery Discharge Advice Please

Discussion in 'The Beginner' started by oldflemo, Oct 10, 2015.

  1. oldflemo

    oldflemo Funster

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    Our battery charges to 13V + after running the engine for 30 minutes approx.
    The battery is a YUASA 95 amph.
    After 3 days of inactivity the voltage drops to 11.5 or less and after 4 days it has dropped to 11V and the MH requires a jump start.
    Can I ask is the voltage drop irrefutable evidence that the battery is knackered?
    I ask this question because I'm taking it back to the dealer who wants to run a 24 hour test on the battery before agreeing (hopefully) to renew it and I don't want to be fobbed off by some inappropriate statement!
    Thanks again in anticipation
    Ian
     
  2. berni109

    berni109 Funster

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    Take the battery out of the vehicle and charge it with a 4 stage charger for 24 hrs.
    Measure the voltage when fully charged (totally disconnected) and then every 2 hrs.
    If the voltage continues to fall over 24 hrs then its fubar‘ed.
     
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  3. Don Quixote

    Don Quixote Funster

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    As you have run it / charged it via your engine and then left it for 3 days and it has dropped to 11.5 the battery is U/S period. It needs replaced now. I would also recommend a battery master which Jim sells here on the forum, which will therefore give you no further problems with the battery after it's replaced.
     
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  4. PhilandMena

    PhilandMena Funster

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    The 13V reading confirms your alternator is working as it should and charging your battery. The battery voltage drop over 3 days is an indication of A, a drain being placed on the battery which would need to be investigated further. (just replacing the battery with a new one would soon result in the same problem. B, Make sure your habitation 12V services are being fed from your leisure batteries and not your cab battery. C, The battery no longer capable of holding it's charge. This could be for a number of reasons, a sulfated battery etc.
    Let the dealer do his stuff and wait till he responds before doing anything else. It may be as simple as need a replacement battery due to age. They don't last forever.
     
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  5. oldflemo

    oldflemo Funster

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    Thanks I should have said I already have one of Jim's battery master fitted along with 2 solar panels which maintain my leisure batteries upwards of 13.7 V
     
  6. pappajohn

    pappajohn Funster Life Member

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    If in doubt just replace it.
    If, as you say, it has a BM fitted and solar your battery is cabbaged.

    An engine battery will cost around £60 at a guess.
     
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  7. oldflemo

    oldflemo Funster

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    Thanks Pappajohn but I do hope to get Marquis to replace it for me as I don't think you can say it's fit for purpose if you have a MH which can't motor without a jump start every 4 days or so
     
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  8. tonyidle

    tonyidle Funster

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    With engine running the voltage at the starter battery terminals should be over 14 volts (around 14.2 to 14.5). Any less than 14v and the battery is not being charged. Have the alternator checked and the battery fully charged off the vehicle then try again.
     
  9. oldflemo

    oldflemo Funster

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    Thanks for that advice -I've never actually checked the voltage with the engine running. I've checked it within minutes of stopping and get results in the upper 13 Vs
    Ian
     
  10. Charlie

    Charlie Funster

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    Have you done a drain test ? Often called a parasitic draw ?

    If you have a simple voltage meter it's not hard to do.

    If it's of interest I will find a YouTube link to a video which will explain it better than I can .

    If your battery is over 13 after a drive I would say your alternator is working fine. If it drops after that it's likely you have a draw on it.
     
    Last edited: Oct 11, 2015
  11. Charlie

    Charlie Funster

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    Look at the video below. It's long but for those with vehicles like ours it could be of much benefit .

     
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  12. The Silvers

    The Silvers Funster

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    Not sure if you have solved your problem yet but I had a similar problem, I suspected the battery would not hold it's charge and took it back to the dealer. They checked the vehicle and found the fault was a drain from an incorrectly wired reversing camera. They rewired it and it has been fine since. My advice is to take it back to your dealer and have the system checked.
     
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