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Any battery experts?

stu_m Dec 31, 2012

  1. stu_m

    stu_m Well-Known Member VCDS Map User

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    So over the past few months I have been getting the brake warning on start up and as we all know it suggests battery is on the way out so checked it and sure enough its only getting up to roughly 75% charged

    anyway I went and picked up a new bosch battery today from euro car parts got home and the first thing I did was check the charge state!

    to my horror its showing 10.6 volts!!!

    Am I right in thinking batteries should come already charged and must be kept charged and if the voltage drops below 12.3 then it needs to be charged otherwise permanent damage can be caused and the life expectancy reduced?

    I have searched online and found nothing about if they should be supplied fully charged etc

    Any advice welcome
     
  2. Inertiauk

    Inertiauk Active Member

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    I'm not an expert but I had one sat in my garage which was fully charged but ended up flat as can be reading 10v after about 6 months, my mate stuck it on charge overnight, put it in his car and it has been fine ever since.

    When I got this fault the same on my car I changed the battery (it was about 75% chargeable according to a garage who tested it) This never cured it, I needed a new fluid reservoir to cure it.
    This is the battery mentioned above, I kept my new one and sold the old one to a mate.
     
  3. AlexGSi2000

    AlexGSi2000 Well-Known Member VCDS Map User

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    Sounds like an alternator/drain issue to me.
    Batteries do come charged, I would expect a new battery to show above 12/13v even after 5 minutes charge.
     
  4. smiler2012

    smiler2012 Member

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    put a voltmeter across the battery to see if its chargeing whilst the engine is running? and check voltage when cracking see what it dropes down to? if not i would say you've got problem poss alternator or wireing fault check connection and earth points on loom to alternator
     
  5. smiler2012

    smiler2012 Member

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    meant cranking :yum:
     
  6. stu_m

    stu_m Well-Known Member VCDS Map User

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    Err think you need to re read!

    My old battery is only taking 75% charge so I have got a new one

    The new one has come straight from the shop with no charge and showing 10 volts! The new one has not been on the car

    The question I'm asking is can damage have been done with the new battery stored with only 10 volts?

    I don't want to mess about charging it if damage could have been already done because as far as I'm aware you have to keep battery's charged
     
  7. AlexGSi2000

    AlexGSi2000 Well-Known Member VCDS Map User

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    I wouldn't have said so. Batteries only really get damaged if overcharged/hot.
    If you charge it for 5 minutes or so it should jump straight to 13/14 volts. If charged for an hour or so it should hold 13/14 volts for a few days.
     
  8. Artimus

    Artimus Shortback

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    I don,t profess to be an expert, but from previous experience batteries only suffer permanent damage if they're left to run totally flat or the electrolyte is low! give it an 8 hour top-up charge, check the voltage again and if the alternator isn't the culprit, it should be fine. Once it's in the car with the engine running, it should how around 14 volts, if the Alts doing its job.
     
  9. stu_m

    stu_m Well-Known Member VCDS Map User

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    I've known batteries go bad and still show 12 volts

    I know your not suppose to discharge a battery as it can kill them I know as I have had it on a bike

    I don't want to start charging a battery that could already be shafted and a year down the line drop a cell and leave us stranded!

    Ok it has a 5 year warranty but that's not the point I don't pay 70 quid for something that could already be damaged
     
    Last edited: Jan 1, 2013
  10. marktdisport

    marktdisport Active Member

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    I wonder if someone as already fitted it who had a alternator fault, but then found the alternator fault afterwards and then taken battery back for a refund ?? Just an idea....
    The other thing is if the battery as been sat on a cold concrete floor that will probably zap the battery voltage a small amount..... But you would expect to buy a lively new battery that you fit in confidence..... Take it back and show them....
     
  11. stu_m

    stu_m Well-Known Member VCDS Map User

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    It's not been fitted before there is no marks at all on the terminals

    I can't work out where the date code is on it either so don't even know how old it is

    For a battery to lose that much charge it would take about 6 months maybe more

    I have found a bit of info which states if a battery has been discharged slowly to lower then 11.5 volts then permanent damage will be done so on that basis I shall be taking it back

    And just to point out for future reference if you discharge a battery fast then recharge it then no damage will be done
     

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