E46 325ti Battery or alternator problem ?

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  1. 2002 E46 325ti compact - Battery or alternator problem ? NEW screen shots added 
    #1
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    Been having some battery drain issues resulting in a beeping low power sound when getting in to car
    checking with pa soft its giving a Vehicle power < 9 Volt and then after a while it will flatten battery eventually.
    Live results in PA soft showed a 11v rating

    Ive fully charged it up externally and now im getting 11.7v the following at position 1


    with engine running and nothing on this goes to 13.6v


    with 2100 rpm its showing 13.8v


    and 2500 rpm with full aircon, lights and wipers its at 13.4v


    i gathered its meant to be approx 14.2-14.8v with engine running if all working well
    given there is an increase from engine off to engine on, im "guessing" the altenator is working so would this be a battery issue not taking a higher voltage and not retaining it :?

    or am i barking up the wrong tree

    all help appreciated
    Last edited by mrwhite; 09-03-2012 at 19:19. Reason: added screenshots
     
     

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    Check the battery with an actual multimeter.

    If I plug up INPA to my car, it says my battery is about 11v, and I was worried my battery was faulty too, so I checked it with a multimeter and it was actually 12.2v.
     
     

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    Im planning on picking one up today (they are on 1/2 price offer at maplin £7.99) but if the battery is fine (checked its not original - its a Lion (eurocarparts brand) then what is causing the battery drain...
     
     

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    This is what i'm trying to say, I don't think you have a battery drain, I think it's the way the voltage is reported to your laptop.
    I think you'll find when you test the battery directly with your multimeter, you'll see a true voltage reading and it'll be what you expect it to be.

    If it is still 11v, then we'll take it from there !
     
     

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    Ok Im confused now.

    I used a multimeter and after an hours driving, it gave a voltage of 12.06 when standing and 14.02 when engine running at idle
    PAsoft was showing 11 and 13.8 at these times
    so that ties in with what you were saying

    but the reason I initially looked at the voltage is that I was getting battery drain resulting in total power failure on 3 times over past 2 months. Once when I was stranded away from home after not driving for 2 days I was able to get a jump start from my breakdown company, the other two times I was unable to get a jump started from my dads car, which i was parked next to while visiting, but was able to leave it charging for a few hours to get power to start it.
    Ill take reading again in the morning, and monitor it again but I think its an old battery
    Im happy the alternator seems to be working and think it may be a faulty battery or something else suddenly causing a drain
    im also getting conflicitng issues over what battery i need
    ECP isnt listing a high enough rating battery according to halfords and my manual which says I need an 12v 80AH battery - any assistance on that front appreciated too
     
     

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    When I originally read your first post, I missed that part where you said that you've had battery drain issues... I just thought your problem was you were seeing low voltage on your laptop.

    Anyway, here's a link on how to test for a parasitic drain: How to Find a Parasitic Battery Drain: 9 steps - wikiHow There may be better guides about, but this gives you a basic idea.
    You've now got the multimeter to do it.

    Also, as for your battery size, I wouldn't be too concerned about that - My last 2 E36 328's have had 70AH batterys, and my current 330 has a 72AH... The rating you want to look at is the CCA rating, but with your battery being 80AH, I would suspect you'd have quite a high CCA rating anyway.
     
     

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    thanks

    Ill give that a run through tomorrow after checking the voltage in the morning.

    ECP suggest batteries with :
    Amp Hours (Ah): 71 Ah Cold Cracking Amp (CCA): 680
    to
    Amp Hours (Ah): 70Ah Cold Cracking Amp (CCA): 420/720
    to
    Amp Hours (Ah): 77Ah Cold Cracking Amp (CCA): 780CCA
    Halfords suggest:
    AH: 80 CCA: 720

    manual just states 12v 80ah

    so is the 77ah 780CCA a better around choice if not parasitic drain is found.

    ps isnt taking just the negative off going to cause an open circuit error and cause the alarm to sound repeatedly ? (think ive had that happen before)
     
     

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    Quote Originally Posted by mrwhite View Post
    so is the 77ah 780CCA a better around choice if not parasitic drain is found.
    I'm not familiar with what the 325 battery CCA rating 'should' be, maybe someone else can help with that - But I would think that battery you've chosen would be more than sufficient.

    ps isnt taking just the negative off going to cause an open circuit error and cause the alarm to sound repeatedly ? (think ive had that happen before)
    Possibly, i'm not sure - I know it doesn't sound the standard alarm on my car, doesn't mean to say yours won't go off.
    Best way to find out, is whip the negative terminal off the battery - As soon as you connect your multimeter onto the battery and negative terminal, you'll have a closed circuit again anyway.

    Another thing to remember when doing the parasitic test, is it'll take about 15mins for the car to actually goto "sleep"... And I believe you want to be seeing less than 400mA when the cars asleep.
     
     

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