BMW Battery Cable for Battery relocation - PeachParts Mercedes-Benz Forum

charmalu · #1 11-22-2009, 01:31 AM

There has been discussion about installing a Battery in the trunk as a back up for cold weather or what ever.

I was at PNP a couple months ago, and a guy I was BS`n with, told me about some model BMW`s having the battery in the trunk. the cable runs from the trunk, up the right side to the eng compartment.

So Last Wed I got to looking around, and the 320i and the 520i (think that is the model) have this set up. one was a 2 door, and one was a 4 door.

The cable mounts to the firewall on the right side, (same area the 123 battery lives). remove the black plastic cover, then the 3 10mm nuts/bolts to loosen the end of the cable.

Remove the passenger kick pannel, one phillips screw, snip off a black plastic zip tie. pop off the threshold kick plate and pull off the door seal off the pinch weld. lift up the carpet, the cable and a bunch of wires run along the edge.

pry off the white plastic clips 4 or 5. gently remove the "B" piller cover, or use a prybar and rip it off as I did. hey its a BMW, who cares

.
same on the rear door as the front. remove threshold etc...

lift up seat cushion, and remove 2 screws for seat back (Same as MB 123) and lift out seat. snipp off a couple zip ties. pry off the white clips. pull out some insulation in the corner. cable runs under the seat pipe frame and into trunk.

in trunk there is a plastic cover to pry off. I then pulled cable into rear seat area.

under hood, use a large flat screwdriver to push the rubber grommet into the pass compartment. then from under the dash pull it on through.
then I pulled it into the rear seat area and all done.

battery cables at PNP are $3.99 plus tax and environmet fee. so around $5.

I measured the cable, and 11 1/2 ft or so. couple of them might make a set of jumper cables.
Hope this help someone.

Charlie

iwrock · #2 11-22-2009, 01:42 AM

why not do a battery relocation with it?

We moved the battery in a friends 300SD to the trunk, and theres no noticeable difference in starting power.

mytmousemalibu · #3 11-22-2009, 01:49 AM

This is actually a real good idea! Alot all BMW's have a rear mounted battery. E32 and E34 have them under the rear seat so there a bit shorter. I may just see if our parts car can make a charitable donation!

Brian Carlton · #4 11-22-2009, 04:40 AM

Quote:

Originally Posted by iwrock

why not do a battery relocation with it?

We moved the battery in a friends 300SD to the trunk, and theres no noticeable difference in starting power.

Sure, just think of the fantastic handling characteristics that you've achieved after spending three hours of your time.............not to mention the huge loss of available trunk space.

compu_85 · #5 11-22-2009, 09:03 AM

Great suggestion to get some quality wire.

There's a reason I don't buy wire for my projects anymore... I just keep pilfering it out of the 2000 Jetta harness I have in a box. Better quality wire then what you'd get at autozoo I think.

-Jason

soothappens · #6 11-22-2009, 12:14 PM

Quote:

Originally Posted by compu_85

Great suggestion to get some quality wire.

There's a reason I don't buy wire for my projects anymore... I just keep pilfering it out of the 2000 Jetta harness I have in a box. Better quality wire then what you'd get at autozoo I think.

-Jason

X2 especially with the cost of #2 and #4 guage wire.

Thanks

t walgamuth · #7 11-22-2009, 01:04 PM

I relocated the battery to the trunk on my 280e autocrosser for better balance. I used an old set of jumper cables for the wire. The wire is expensive enough to get your attention!

On a diesel the better handling characteristics would be completely un noticed, probably.

charmalu · #8 11-22-2009, 02:00 PM

Quote:

Originally Posted by iwrock

why not do a battery relocation with it?

We moved the battery in a friends 300SD to the trunk, and theres no noticeable difference in starting power.

Was the battery moved to clear out the engine compartment, or to add one more battery to the system?

Adding a second battery to the system would give you guys in the frigid East a little more Oomph getting started on those cold mornings that don`t use a block heater.

Here on the west coast, usually don`t have problems starting in the cold.

This BMW cable is one huge cable in size. and for only about $5.

Charlie

Brad123D · #9 11-22-2009, 04:49 PM

Quote:

Originally Posted by Brian Carlton

Sure, just think of the fantastic handling characteristics that you've achieved after spending three hours of your time.............not to mention the huge loss of available trunk space.

I just did a battery relocation to my 84 300d. Takes way more than 3 hours to do it right. I did it so that almost any battery can be used and to be different. I put the battery in a battery box in the passenger side drop down and very little trunk space is lost.
The front end sits high now. It is a well established fact that the closer one can get to a 50/50 weight bias the better it usually is for handling, but I don't plan on doing any autocross or racing events with a diesel benz.

It is a lot of work. Passenger and rear seat removal. Passenger carpet removal. Holesaw through firewall and trunk partition and grommets. I put the cable in 1/2" flex elec. conduit. Figuring out how to run it so the carpet will go back in and look o.k. is one of the biggest problems.Connect ground cable at back. etc. Lot's of work but I like the results.

pawoSD · #10 11-22-2009, 04:54 PM

My battery stays nice and dry right where it is....it would be wet constantly if I had it in my trunk.

I think I'll keep it where it is.

iwrock · #11 11-22-2009, 07:08 PM

Quote:

Originally Posted by Brian Carlton

Sure, just think of the fantastic handling characteristics that you've achieved after spending three hours of your time.............not to mention the huge loss of available trunk space.

More like 4 hours....

It does not take up that much space. The battery fits perfectly into the well on the right side of the trunk. The top of the battery sits almost level with the false floor which the spare rides in.

Pretty much moved it to the trunk to open up space under the hood....

iwrock · #12 11-22-2009, 07:11 PM

Quote:

Originally Posted by charmalu

Was the battery moved to clear out the engine compartment, or to add one more battery to the system?

Adding a second battery to the system would give you guys in the frigid East a little more Oomph getting started on those cold mornings that don`t use a block heater.

Here on the west coast, usually don`t have problems starting in the cold.

This BMW cable is one huge cable in size. and for only about $5.

Charlie

It was done to move the battery out from under the hood... But you could probably add a second battery to the mix this way as well.

That would be cool to add the second battery for some extra starting power.

JHZR2 · #13 11-22-2009, 08:03 PM

My E30 has this, it is atleast 1/0 cable. Running that stuff is a major hassle.