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ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

I'm planning to install my battery in the spare tire well on the 941. Here's what I have in mind:

Battery will be mounted in back in the spare tire well.
Battery Negative will be grounded directly to chassis with a LARGE gauge ground wire
A bulkhead connector will be installed in the spare tire well. This will be used to pass the main battery cable through the sheet metal, rather than simply passing the cable through a grommet.
A remote positive battery terminal will be installed in the stock battery tray location, in roughly the same position that the normal battery positive post would be.
A short large gauge positive battery cable will connect from the battery positive to the bulkhead connector discussed above.
A LONG large gauge positive batter cable will then run from outside side of the bulkhead connector on the spare tire well, and will be run to the front of the car, either along the passenger side frame rail, or through the torque tube tunnel. At the front of the car, this wire will connect to the remote battery terminal.
Everything else from there can use the stock wiring harness. In my case, I'm also planning to duplicate the stock harness for the starter/alternator circuit with higher quality stuff, but the nice thing about this approach is that it doesn't require any change whatsoever to the stock harness or layout.

So my main sanity check question is this:
Is it OK to have the main battery cable connected to the remote post up front, and then use the stock cable to attach from the post to the starter??? Or is there some reason that I need to have the battery connected directly to the starter?

For reference, here are images of the style of bulkhead connector and remote terminal I'm considering:

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erstwhile owner of just about every 924 variant ever made

Rich H · Posted: Sun Jan 17, 2010 3:01 am Post subject:

Seems OK to me, but I'd probably take the earth cable to the chassis rail off to one side of the wheel well.

What is wrong with the 944 location and offsetting the drivers weight a bit?
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
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1953 Landrover S1 - Pensioner Spec

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Mine was professionally done by a guy with loads of electrical and race experience. He ran both plus and minus cables along the torque tube directly to the starter. They are attached to the tube with stainless bands, and wrapped in "fire sleeve" to protect from heat.

I have the (über trick) tray he made removed from the car currently. . .I'll snap a photo of it this week.

As to your query about whether you should use a portion of the stock high current cabling, I guess the easy answer is to take the opportunity to get rid of old cable whenever you can, especially if it is being replaced with some sort of Ideo-ultimate stuff.

And Rich. . .the block does a fine job of offsetting weight to the right. My car will nearly balance on a single jackstand on the passenger side rail. . .
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WeiBe (1987 924S 2.5t) - 931 S3

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Rasta, would love to see your battery tray. Any chance he would make another? Can you put me in touch?

All of the cabling will be IceShark stuff, so it'll definitely be top shelf quality, including protective sleeve and all that. I am definitely going to replace the stock harness that connects the starter & alternator, with the same quality stuff as the IceShark kit currently available for the 2.5L platform. Unfortunately, our accessory cables that go to the fuse block are intertwined with the main engine / under dash harness, so there is no feasible way to pull them out. The only way to replace them is to disconnect them, and then run parallel cables. I may do that as a phase II, but the priority now is the rear battery kit + the starter/alt kit. Phase III will be a kit for upgraded headlamps.

I am developing the kits with Robby, who took over the IceShark operation, and they will be available later this winter / spring on my website. 931 will be available first, and then I'll work on the 924 NA application.

I've been under the car today. The torque tunnel is attractive for protective reasons, but I don't like that it is directly above the exhaust, and would also have to pass very close to things up front. The frame rail would be isolated much more from the heat, but would be more subject to underside damage. I'm leaning toward the torque tube because the material Robby uses has a very high heat tolerance rating.
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erstwhile owner of just about every 924 variant ever made

tuurbo · Posted: Sun Jan 17, 2010 8:21 am Post subject:

Dan the way you've mounted this is basically the same way I've done it and so far it's worked fine.

But I'm re-positioning it to the regular position in the spring - I want to restore the car to nearly stock form.
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1980 924 turbo, MSD, Meth. Inj, otherwise stock.

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Getting close to being ready to tackle this. Any opinions on where best to locate the main power cable? Along the passenger side frame rail, or in the torque tube tunnel? Note the pros & cons mentioned above.
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erstwhile owner of just about every 924 variant ever made

Joes924Racer

I used the lug in the first pic. went right thru the firewall.
Actually iused a piece of all thread a plastic plate some nuts and washers followed by some epoxy, sm screws.

Joes924Racer · Posted: Thu Feb 10, 2011 5:29 am Post subject:

Solid plan.. Dan man you gonna roll with a pic.. or is the schematic all we get.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

You know me, I take photos of everything.
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erstwhile owner of just about every 924 variant ever made

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

datatrain · Posted: Thu Feb 10, 2011 9:00 am Post subject:

What you propose is almost a standard BMW stock battery installation. The forward + post in the old battery box will give you a point to jump start or connect a charger in future. Just like BMW.

In regards the question. It doesn't matter. The current will flow to the correct location when required.
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jazz guy · Joined: 26 Nov 2002 Posts: 434 Location: Colorado

dpw928 · Joined: 02 Nov 2002 Posts: 1860 Location: owasso, ok 74055

The proposed schematic is very similar to the early 928's except that the positive cable runs to the positive feed on the starter solenoid and a short cable runs to the jump post on the drivers side fenderwell. With the long run an 0/2 gauge cable should be used.

I like the idea of running the negative cable to the front of the car where most of the electronics are located. IMHO the 928 has a lot more corrosion issues with the negative cable being mounted in the rear.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

TJC · Posted: Fri Feb 11, 2011 2:28 am Post subject:

First let me say that I don't know if you are planning on using the rear seat on this project, but you may consider locating the battery on the floor behind the passenger front seat, especially if you plan to use a conventional, i.e. heavy battery. This will lower the center of gravity and also help offset the driver's weight. You can run your positive cable alongside the inside of the passenger sill (under the carpet if you are installing it) and then run up under the dash to the firewall and through it. Your ground can go directly to the floor as long as you have the engine grounded properly to the chassis as well. You will have the added benefit of running shorter lengths of cable, and the cables will be protected from the elements.

As for running a "lug" from bat positive and then down to the starter with a seperate cable, this will pose no problem with starting. Race cars have a "Master" switch which is required to cut all power from the battery as a safety issue and this is how power is delivered to the starter. You may even consider using a master switch in the engine compartment instead of a lug as it may also serve as a theft deterrant when you leave the car unattended.
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dreamgts · Joined: 29 Dec 2009 Posts: 504 Location: malta

You could/might lose battery current if you place the battery at the rear. The long battery cable will be the cause of this since current will have to travel further. be sure to set up a good amp battery and good battery cables just to be safe and for good current flow.

dreamgts
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