e46 battery keeps draining

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  1. e46 battery keeps draining 
    #1
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    jui2bad's Car Details
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    Hi guys,

    I recently purchased a 2005 330cd convertible, battery was fine when I received it, I had the BM54 upgraded, added a 12" sub and fitted an ipod cable to the sat nav. Now after 2 days of sitting there the battery on the car goes totally flat, and I mean totally. Any ideas on what could possibly be doing this? Have I cocked up on the wiring or something?

    Any help would be great.
     
     

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    #2
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    payno's Car Details
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    easy way to find out disconnect it and see if stops happening
     
     

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    #3
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    Joggy's Car Details
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    Hi. If you want to check if there is heavy drain on the battery, a quick test is to get a cheap multimeter and try to measure the voltage drop (not the current) across the earth strap (i.e. between the -ve battery post and the chassis end of the earth strap). If there is any appreciable current flowing from the battery when the engine is off, then you should see a very low voltage (say 300mV DC) which is typically just the drain of the clock, alarm or radio. Try turning on the headlights to get a comparison. Any more and you might try pulling fuses on various circuits to see what makes a difference.

    If you know the volt drop (in Volts) and the (very low) resistance of the earth strap in Ohms, you can work out the current in Amps from I=V/R eg 500mV / 0.9 Ohms = 0.5/0.9 = 0.55 Amps.

    Hope that helps.
     
     

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    #4
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    goldbcfc's Car Details
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    Sounds like a duff/cheap battery what wattage amp are u running? Mines got a 2000 watt amp with 1000 watt subwoofer running the same through the aux on the bm54 module to amp then to battery with no problems ive had other cars on cheap batteries and it will drain them if sat listening to music without the car ticking over. Buy a top brand battery and the right wiring kit to match amps power my wiring kit was £60 not those £10 ones u get this might have an effect the thicker the better

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    #5
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    gunslinger1's Car Details
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    if the car was fine befor fitting all the amps ect , take joggys advice , but you must let the cat go to sleep first , roll all door catches and roll the boot catch , as if you open and close the doors or boot the car wakes up , its being a while since i done a battery drain on one , so i would give it half an hour after removing the key befor testing for a battery drain .
     
     

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