Battery Relocation

e30strube

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I am interested in relocating the battery to the trunk, while using an E30 style "power block" in the engine bay. For those that have done this, where did you run the ground? Did you connect to something in the trunk or run another wire back to the engine bay? Would 2ga be sufficient for the power and ground?
 

Mike Goble

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I used a stock E30 battery cable and ground my battery to the rear frame using a regular battery ground cable from a Chevrolet. I have three grounds coming off the engine block to the frame.
 

Mike Goble

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You can buy battery cable kits from Summit, you can use welding cable, or you can go to Pick-n-Pull and get one from a BMW.
 

Jellobmw

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I used welding wire, not sure of the gage but it was bigger than the std ground cable, when I ran the + from the trunk to the engine bay.
 

decoupe

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I used 4ga welding cable from the battery (under the rear seat in this case) through disconnect switch to a power distribution block in the driver footwell and then 8ga to the alternator and starter. Removing the switch "key" is my low tech immobilizer.

Grounds from the battery to chassis (used rear seatbelt anchor - seats deleted) and engine to three locations using the 4ga.

Doug
 

daicos35

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put an odyssey pc680 under your back seat,,,, smaller and more powerful than a regular battery,,,
 

Nicad

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decoupe

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Still have all the parts but no intention of undeleting the deleted rear seats. Vague notions of using the rear seats as furniture in my studio - BMW meets Ames chair. Just about as bizarre as your hollowed out battery battery. Do it.
 

daicos35

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pc 680 -mjt (the one with the metal case), fits neatly under a rear seat... i removed the battery tray all together....
 

bfeng

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BMW furniture

We have a guy here at work that built a desk using body panels from a 2002.
The desk has a glass top that is 2" above a 2002 trunk lid. The trimmed trunk lid covers the top of the actual desk 'case'. IIRC, he used part of the 2002 nose to clad the front of the desk (the privacy panel). I could see cutting an old door pair and using them to clad the desk sides or as doors for a cabinet. Us E9'ers would put fender side grills on the sides of the desk. Where would you put your spare C-pillar badges? I'd be tempted to mount the grills and a functional set of headlamps on the privacy panel.

Anyway, I thought it looked really great and was a nice way to customize a bland office. Now I know what I'm going to do with my left over 2002 body panels, grills and roundels.
 

Stevehose

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Out of curiosity, what makes Odyssey batteries better than others? It weighs more than an Optima and apparently lesser stats and more expensive:

Odyssey:
Specifications Pulse (5-second) Hot Cranking Amps (PHCA) 1200
Cold Cranking Amps (CCA) 540
20Hr Nominal Capacity (Ah) 42
Reserve Capacity Minutes 78
Dimensions L x W x H (in) 7.87x6.66x6.80
Weight (lbs) 38.2

Optima:
Cold Cranking Amps: 720
Cranking Amps: 910
Nominal Voltage: 12 volts Open Circuit Voltage (fully charged): 12.8 volts
Internal Resistance (fully charged): 0.0030 ohms
Capacity: 44 Ah (C/20)
Reserve Capacity: BCI: 100 minutes (25 amp discharge, 80°F (26.7°C), to 10.5 volts cut-off)
Weight: 31.7 lb
 

jmackro

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Out of curiosity, what makes Odyssey batteries better than others? It weighs more than an Optima and apparently lesser stats and more expensive:
Steve:

The Odyssey PC680 in my Alfa doesn't match the specifications that you posted at all:

Weight: The Odyssey model PC680 weighs 15.4 pounds; not the 38.2 that you show. This compares with your figure of 31.7 pounds for the Optima.

Size: The Odyssey PC680 is much smaller than a 12V Optima. Your specs show dimensions of 7.87x6.66x6.80, or about 360 cu in, but the Odyssey PC680 only measures 7.15 x 3.00 x 6.65 or about 142 cu in. An Optima red top measures 10.06 x 6.94 x 7.88 or about 545 cu in.

Price: An Odyssey PC680 costs $129 on Amazon, while they charge $225 for an Optima 8002-002 34 Red Top.

I'll give you that an Optima has more cranking amps than the Odyssey.
 
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teahead

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Odyssey PC680:

Pulse (5-second) Hot Cranking Amps (PHCA) 520
Cold Cranking Amps (CCA) 170
20Hr Nominal Capacity (Ah) 16
Reserve Capacity Minutes 24
Dimensions L x W x H (in) 7.15 x 3.00 x 6.65
Metric Dimensions L x W x H (mm) 181.5 x 76.3 x 167.8
Weight (lbs) 15.4
Weight (kg) 7

https://shop.odysseybattery.com/p/pc680


Seems small enough to run two in parallel under the rear seat.
 
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