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BATTERY CUT OFF SWITCH

Posted: Sat Nov 28, 2020 9:07 pm
by Shifted
   

Re: Battery Cut Off Switch

Posted: Thu Dec 03, 2020 3:58 am
by Sazerac
Well, there's an idea.

I used some of those switches that are mounted directly on the terminals and they kept corroding and causing electrical problems. On all my cars, I just pull the cable now. The switch you have looks robust. Do you have a link to it?

Re: Battery Cut Off Switch

Posted: Thu Dec 03, 2020 4:17 am
by Shifted
   

Re: Battery Cut Off Switch

Posted: Thu Dec 03, 2020 10:12 pm
by linderpat
Shifted wrote: Sat Nov 28, 2020 9:07 pm Here's mine:

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I like that. I may do this. :rockon:

Re: Battery Cut Off Switch

Posted: Fri Dec 04, 2020 7:39 am
by Geza-aka-Zombo
Nice installation! I used this one - made a small right angle bracket to mount it. After reading that post about the 928 that went up in flames at ~2:00 am in a shop, mine get's shut off every time.

https://www.amazon.com/Fastronix-Curren ... 469&sr=8-5

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Re: Battery Cut Off Switch

Posted: Fri Dec 04, 2020 7:48 am
by Shifted
   

Re: Battery Cut Off Switch

Posted: Fri Dec 04, 2020 11:54 am
by Hey_Allen
Shifted wrote: Fri Dec 04, 2020 7:48 am With a remote cut off switch, it would be really easy to wire in a whole car fuse.

... not anything inherently wrong with the 928's design, vehicle age included.
After the picture thread about the fire, I found a large fuse holder with intent to install it on my car.

That said, I have found degraded wiring on my car, with insulation just dissolving or cracked and crumbling off, so I'm not going to totaly lay the blame on the shop.

Re: Battery Cut Off Switch

Posted: Fri Dec 04, 2020 12:04 pm
by Shifted
   

Re: Battery Cut Off Switch

Posted: Fri Dec 04, 2020 10:47 pm
by worf
Shifted wrote: Fri Dec 04, 2020 7:48 am I remember reading that thread thoroughly, and looking at all of the photos. To be honest, I don't think the cause was as innocent and universally applicable as the business owner made it out to be. My personal opinion is that it was due to negligence of the shop, not anything inherently wrong with the 928's design, vehicle age included.
I posted to that thread with some observations of how the front main harness is often misrouted.

Also, 'round the same time I had just installed a brand-new-out-of-the-Porsche-bag engine bay (light) harness. The NOS is remarkably cheap for what it is. Reminds me that I need to pickup a spare for my '91 while they're available.

In any case, with everything correctly routed, in my opinion, a car fire caused by the light harness or front-main harness is effectively impossible.

My bet is that that car, earlier in it's life suffered collision damage in/around that area and the harness was either damaged and not replaced, or damage wasn't noticed, or was improperly routed/installed during the work.

I have seen with my own eyes, too many times, how body shops 'skip' things or just plan fuck things up.
Hey_Allen wrote: Fri Dec 04, 2020 11:54 am That said, I have found degraded wiring on my car, with insulation just dissolving or cracked and crumbling off, so I'm not going to totaly lay the blame on the shop.
This too. I have noticed over the last 5-ish years that all of the wiring harness on 928s brought to me are very brittle. I take extreme care to perturb them only as much as needed and every single time I see cracked insulation on a power lead I deal with it.

Now, as far as insulation just 'disintegrating' on 12v leads, this I have yet to see except for the front main harness. That harness gets the most 'abuse.'

The jump post area and ABS terminal area always get an inspection on a new-to-me 928.
Shifted wrote: Fri Dec 04, 2020 7:48 am How many others like this have you heard of vis-a-vis failed fuel line fires?
I am of the opinion that the majority of fuel fires are the result of poor work(*) just prior to the fire. Or, in other words, 100% of fuel fires after fuel system related work are the result of poor work. I believe that there have been fuel fires due to three-decade old fuel lines releasing fuel however, I do not recall a credible story being posted to the other site.

I, once, a long time ago, received an S4 on a flat bed. Long story short, after some repair work, not fuel related, I took it on a test drive for evaluation. One result of that evaluation was an intake refresh. When I went to remove the intake as I was wiggling it up, I started smelling fresh fuel. After investigating I discovered that the return line from the regulator had a crack in it such that every time the motor rocked side-to-side a drop of fuel would escape.

A couple of things I learned from this:
- check your fuel lines often once they are 10 years old
- a drip of fuel isn't an instant engine fire
- when you do motor mounts be damned sure your supply and return fuel lines are in really good shape
- if for some reason you get a 'new' 928 into your possession, always inspect the fuel lines. And I mean the part of them you can't see. With an inspection mirror. And wiggle them.

(*) Poor work seems, IMO, to be lacking in one or both of these:

1) Always, always, always, do a long careful leak check by bypassing the FP relay as soon as you 'button up' the fuel system.

2) Fuel injectors go into the rails, then the rails go into the engine. Never, ever, ever the reverse.

Re: Battery Cut Off Switch

Posted: Sat Dec 05, 2020 10:02 am
by hessank
Shifted wrote: Fri Dec 04, 2020 12:04 pm .............. I pointed out that ANL fuses are the right type for this application and provided technical references to back it up, ......... Just something to consider before you commit to a fuse type.
Can you please expand what you mean without going too technical?
While my car is sleeping and the battery is removed I plan on installing one of these System Protection Fuse.
Also can you say what amperage and is it installed on the Positive or Negative cable?
Please and thanks
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Re: Battery Cut Off Switch

Posted: Sat Dec 05, 2020 10:26 am
by Crumpler
Shifted wrote: Fri Dec 04, 2020 7:48 am With a remote cut off switch, it would be really easy to wire in a whole car fuse.

I remember reading that thread thoroughly, and looking at all of the photos. To be honest, I don't think the cause was as innocent and universally applicable as the business owner made it out to be. My personal opinion is that it was due to negligence of the shop, not anything inherently wrong with the 928's design, vehicle age included.
Yep.
And yet with every tragedy there is a budding business opportunity!
When I followed that thread I was mouth agape to see that the shop owner then marketed a kit to not burn down a car in your shop....that took brass tacks.

Re: Battery Cut Off Switch

Posted: Sat Dec 05, 2020 2:03 pm
by Shifted
   

Re: Battery Cut Off Switch

Posted: Sun Dec 06, 2020 1:09 pm
by hessank
Thanks
:thumbup:

Re: Battery Cut Off Switch

Posted: Sun Dec 06, 2020 1:16 pm
by Shifted
   

Re: Battery Cut Off Switch

Posted: Tue Dec 08, 2020 4:35 pm
by Shifted
   

Re: Battery Cut Off Switch

Posted: Mon Dec 14, 2020 2:55 pm
by Erik N
How much?

Re: Battery Cut Off Switch

Posted: Mon Dec 14, 2020 5:17 pm
by Shifted
   

Re: Battery Cut Off Switch

Posted: Mon Dec 14, 2020 5:38 pm
by Fox_
I'm considering making one, if I can find the flat wire by the foot.

Re: Battery Cut Off Switch

Posted: Mon Dec 14, 2020 5:54 pm
by SeanR
I'll be odd man out here. I abhor those things and have removed a ton of them from cars. Got a battery drain? Fix it. Want to disconnect the battery? Take the 13mm bolt or wing nut off and put a rag/cardboard on the end of the neg cable.

My '88 can sit there for a couple of months and will still crank over fine.

Re: Battery Cut Off Switch

Posted: Mon Dec 14, 2020 7:15 pm
by Fox_
SeanR wrote: Mon Dec 14, 2020 5:54 pm I'll be odd man out here. I abhor those things and have removed a ton of them from cars. Got a battery drain? Fix it. Want to disconnect the battery? Take the 13mm bolt or wing nut off and put a rag/cardboard on the end of the neg cable.

My '88 can sit there for a couple of months and will still crank over fine.
Do they cause issues?

Would think a switch would be better than wearing out the threads in the ground post and/or accidentally arcing off the rear wiper motor housing. :hiding:

Re: Battery Cut Off Switch

Posted: Mon Dec 14, 2020 7:18 pm
by SeanR
In theory they shouldn't. But you are adding additional points to ground out your battery and a switch that can fail. Some of the mikey mouse stuff I have seen just makes me cringe when I see one. Seriously, if you want to store your car, undo a fucking bolt, not add a couple feet of wire and a switch that if you hit a bump is going to shut off going down the road.

Re: Battery Cut Off Switch

Posted: Mon Dec 14, 2020 7:30 pm
by Shifted
   

Re: Battery Cut Off Switch

Posted: Mon Dec 14, 2020 7:32 pm
by Shifted
   

Re: Battery Cut Off Switch

Posted: Mon Dec 14, 2020 8:18 pm
by SeanR
Shifted wrote: Mon Dec 14, 2020 7:32 pm Whoa...bad day? lol

It's not going to fail from bumps. It's not going to short or ground out. Nothing is exposed, and the wire quality far exceeds the OEM ground strap. The switch will eventually wear out. In a decade or three. And when/if it does, it's very easy to bypass or replace.

To each their own, but I wouldn't rag on someone else doing something that works for them.

Not a bad day at all. Unless you find some idiot put engine coolant in the windshield washer tank and had just fitted a new pump, which put that crap all over the car. Or had to fix someones idiot fix of a washer and a bunch of bolts to make a window roller work instead of doing the smart thing.

I was going to post exactly what I posted before but refrained because I figured it might hurt someone's feelings. Just decided to post my thoughts, of which I've had the same ones for years. You'll be fine and what you are doing looks great if someone were to want to go down that road. I still say one bolt and you are done.

Re: Battery Cut Off Switch

Posted: Mon Dec 14, 2020 11:22 pm
by linderpat
SeanR wrote: Mon Dec 14, 2020 5:54 pm I'll be odd man out here. I abhor those things and have removed a ton of them from cars. Got a battery drain? Fix it. Want to disconnect the battery? Take the 13mm bolt or wing nut off and put a rag/cardboard on the end of the neg cable.

My '88 can sit there for a couple of months and will still crank over fine.
I agree completely with this. I had a cut off on my Boxster because you cannot disconnect easily like the 928. I like the options here, but only for my 997, for the same reason as the Boxster.

Re: Battery Cut Off Switch

Posted: Tue Dec 15, 2020 6:57 am
by Shifted
   

Re: Battery Cut Off Switch

Posted: Tue Dec 22, 2020 7:24 pm
by Crumpler
Got mine today, apparently the package was in USPS geospatial orbit for a week!

Looks awesome, build quality looks industrial performance. Thank you Chris.
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Re: Battery Cut Off Switch

Posted: Wed Dec 23, 2020 1:02 pm
by Crumpler
Track car goodness ensues.
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Re: Battery Cut Off Switch

Posted: Wed Dec 23, 2020 1:05 pm
by Shifted