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Do batteries need changing?

Discussion in 'A3/S3 Forum (8L Chassis)' started by Defratos, Apr 30, 2006.

  1. Defratos
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    Defratos You’re Dethpicable!!

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    [Apr 30, 2006]
    Hey guys, I left my interior light on the whole of yesterday and today my battery is dead. Now I was just wondering would a simple jump start do? or do I have to replace the whole battery? cheers for any help
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  3. madvw
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    madvw Active Member

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    [Apr 30, 2006]
    if you can, disconnect and charge it for a while, it's much kinder on the car.

    Otherwise, a jump will do.
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  4. Defratos
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    Defratos You’re Dethpicable!!

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    [Apr 30, 2006]
    how exactly do u charge it? Do u just disconnect it from the car and plug the leads from another battery and leave it for a while? then connect it up again?
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  5. RichA3Turbo
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    RichA3Turbo ...Watching you! Staff Member Moderator

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    [Apr 30, 2006]
    you need a battery charger! Or a set of jump leads, and start it off another car and then take yours for a drive to charge it.

    Rich
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  6. Rev-head
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    Rev-head Active Member

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    [Apr 30, 2006]
    [ QUOTE ]
    how exactly do u charge it? Do u just disconnect it from the car and plug the leads from another battery and leave it for a while? then connect it up again?

    [/ QUOTE ]


    Thought this was a wind up at first............lol

    Do as Rich says........if you get a jump start and take for a good run down the road and let it sit and tick over for 15-20min that should charge the battery up

    Wouldnt worry about taken the battery out unless you have really drained it and with the jump off other car is not making it turn over

    Battery charger from halfords or even better get one of those power pack things that you leave charged up in the house
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  7. imported_Stewart
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    imported_Stewart Guest

    [Apr 30, 2006]
    Do as Rich says........if you get a jump start and take for a good run down the road and let it sit and tick over for 15-20min that should charge the battery up



    [/ QUOTE ]

    Alternators have, in effect, a 'kick in' speed of around 1800rpm (obviously varies) so leaving the car on tickover wont charge the battery.

    Usually something more than a 20 minute drive will put enough charge back in to start confidently.
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  8. Rev-head
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    Rev-head Active Member

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    [Apr 30, 2006]
    [ QUOTE ]
    Do as Rich says........if you get a jump start and take for a good run down the road and let it sit and tick over for 15-20min that should charge the battery up



    [/ QUOTE ]

    Alternators have, in effect, a 'kick in' speed of around 1800rpm (obviously varies) so leaving the car on tickover wont charge the battery.

    Usually something more than a 20 minute drive will put enough charge back in to start confidently.

    [/ QUOTE ]

    Good point
    most Alternators give out 13.8v so would not do any harm in leaving the car running but as you say 20 minute run should rectify the problem
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  9. Rev-head
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    Rev-head Active Member

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    [Apr 30, 2006]
    [ QUOTE ]
    how exactly do u charge it? Do u just disconnect it from the car and plug the leads from another battery and leave it for a while? then connect it up again?

    [/ QUOTE ]

    This is for you

    http://www.carbuyingtips.com/jumpstart.htm
    #8
  10. neil.c
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    neil.c Senior

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    [Apr 30, 2006]
    If a modern low maintenance battery is discharged it will benefit from being charged up to its full capacity. My recommendation would be to disconnnect the negative terminal and charge the battery for at least 24 hours.
    I have a 1.2A trickle charger and just connecting this to the batteries on our cars every month or so it takes on average 36 hours to get the batteries to the fully charged state /ubbthreads/images/graemlins/smile.gif
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  11. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    [Apr 30, 2006]
    why the hell are you recharging your battery every month?
    I've had my car for 7 years and never once recharged the battery
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  12. neil.c
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    neil.c Senior

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    [Apr 30, 2006]
    Too many cars and not enough time to drive them all /ubbthreads/images/graemlins/frown.gif
    I don't bother with the cars we drive every day but the others only get driven at the weekends, the S3 starter sounds sluggish when it wants charging(but I have just put a new battery on it so it may not be such a problem now ) The wifes Porsche seems to discharge the battery when I clean it if I am not careful and as it is not locked up in the garage it does not seem shut down the electrics

    It was just an observation that even if you think your battery is charged it may well only be 70 or 80% charged
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  13. Defratos
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    Defratos You’re Dethpicable!!

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    [Apr 30, 2006]
    wow didn't expect to see so many replies, but thanks guys /ubbthreads/images/graemlins/beerchug.gif. I jump started my car earlier on today with my mom's Bmer and surprisingly enough her battery was in the boot, oh well, it started up first time and I took it out for a 15min drive. I'll try it tomorrow but it seems good. Once again thanks for the help
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  14. neil.c
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    neil.c Senior

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    [May 1, 2006]
    Your average car battery is 70AH capacity(so you would have to put 70A into it for 1 hour to recharge it). the resistance is lower if it is discharged so you may be able to pump 20AH into it but as it charges up its resistance increases, so the amount of current it will draw goes down. It takes an exponential amount of time to charge it up fully.
    Automatic battery chargers work by monitoring the current that the battery is drawing to asses the charge of the battery
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  15. HTC
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    HTC Active Member

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    [May 1, 2006]
    [ QUOTE ]

    Alternators have, in effect, a 'kick in' speed of around 1800rpm (obviously varies) so leaving the car on tickover wont charge the battery.

    [/ QUOTE ]

    It would be a very bad design if this was the case.

    For example if you had to sit in traffic for a few hours, with the stereo on etc, your engine might stop running due to lack of electricity for the spark.

    If your alternator warning light is out then it is charging the battery.
    #14

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