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Thread: E34 battery move (engine to rear seat)

  1. #1
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    Default E34 battery move (engine to rear seat)

    olks, my car is a 520i 24v manual. the battery is in the engine bay.

    i would like to move it to be under the rear seats - cooler etc.

    do you know if bmw has pre-wired it so that i can make the move without changing the wiring harness or routing a long power cable etc??

    if anyone has any experience here to help me, i look fwd to your advice.

  2. #2
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    There's a main bus clamp position under the rear seat, you should be able to undo your batteries + lead from its clamp position under the bonnet/hood and transplant it under the rear seats.

  3. #3
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    On second thoughts, you'll also need the battery tray out of an under seat installed vehicle, and dont forget the vent tubes.

  4. #4
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    Quote Originally Posted by Ferret
    On second thoughts, you'll also need the battery tray out of an under seat installed vehicle, and dont forget the vent tubes.
    i made this operation :d you will need the batery cable( from a BMW that have the battery behind the rear seats ) and aprox 3 hours
    The procedure is easy .... all you need is to put the cable behind the carpet and behind the heating sistem , and to connect him to the electric motor and the accessory s cables
    525 i , e34 , m50 engine

  5. #5
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    Quote Originally Posted by vadim_braia
    i made this operation :d you will need the batery cable( from a BMW that have the battery behind the rear seats ) and aprox 3 hours
    The procedure is easy .... all you need is to put the cable behind the carpet and behind the heating sistem , and to connect him to the electric motor and the accessory s cables
    Just to satisfy my curiosity - which route does the new 'heavy' B+ cable take to get to the starter? Does it stay under the carpet and out through the bulkhead somewhere? Any chance of a pic?

    Cheers,

    Shaun M

  6. #6
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    some questions:

    1. if i used maintenance-free batteries, do i still need the vent tubes?

    2. what cables do i need to source for? i guess from an electrical perspective, i need two one for +ve and another for the -ve ground. is there anyway i can salvage the existing cable used in the current (engine bay) position?

    3. if no for (2), what is the part number for the correct cables and could i replace that with just any heavy duty electrical cable (what gauge would that be anyway)



    Quote Originally Posted by Ferret
    On second thoughts, you'll also need the battery tray out of an under seat installed vehicle, and dont forget the vent tubes.

  7. #7
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    Quote Originally Posted by E34-520iSE
    Just to satisfy my curiosity - which route does the new 'heavy' B+ cable take to get to the starter? Does it stay under the carpet and out through the bulkhead somewhere? Any chance of a pic?

    Cheers,

    Shaun M
    some pictures....
    Attached Images Attached Images   
    Last edited by vadim_braia; 03-15-2007 at 01:31 AM.
    525 i , e34 , m50 engine

  8. #8
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    Quote Originally Posted by ktteoh
    some questions:

    1. if i used maintenance-free batteries, do i still need the vent tubes?

    2. what cables do i need to source for? i guess from an electrical perspective, i need two one for +ve and another for the -ve ground. is there anyway i can salvage the existing cable used in the current (engine bay) position?

    3. if no for (2), what is the part number for the correct cables and could i replace that with just any heavy duty electrical cable (what gauge would that be anyway)
    You can't save the old + cable , because it's to short and to thin

    you will need the + cable ( a BMW original cable ) , you can use the old - cable(ground) . I connect the - cable to the right seat screw( the left one)
    the cable part number : http://www.realoem.com/bmw/showparts...14&hg=12&fg=29
    525 i , e34 , m50 engine

  9. #9
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    Hurr,

    That's interesting I wonder if it's year dependant whether the +B cable runs into the rear seats?

    My '91 525i had the main bus (IE starter motor capable) cable run straight under the rear seats with a mounting point for the battery lead...

    Snap us a photo of under your rear seats and lets have a look see if yours has the point.

    I'd have guessed that your original battery cable from under the bonnet/hood would bolt to this mounting point... but vadim_braia seems to have experience otherwise.

    Also : Categorically YES you have to use a vent tube on any battery under the rear seat... unless you want explosive hydrogen inside your car. (The chances of an actual explosion are small, but not unheard of.)

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