I fabricated a kill switch for my 928
 

Do you guys like my kill switch? Let me know your thoughts. This even conforms to the proper battery disconnection procedure. The only thing that doesn't completely satisfy me is that the secondary gound cable from the switch to the body is not copper. However, this system works great and has been 100% reliable for the past two three weeks. I thought I would share this.

http://forums.pelicanparts.com/uploa...1328127464.jpg
http://forums.pelicanparts.com/uploa...1328127527.jpg
http://forums.pelicanparts.com/uploa...1328127584.jpg
http://forums.pelicanparts.com/uploa...1328127621.jpg

Cant tell from the picture but is that wire sufficient ? Looks a little thin, but good idea..

but why?

I think because the ground cable should be a lot thicker (lower number Gauge). Your Ground cable looks about what I use on my Stereo amps.

A switch between the relay and the fuel pump is easier,smaller switch can be hidden anywhere close to the drivers seat. I use a gravity cut off switch from a bosch injection system , auto shut off if the car is in accident (or flips)
The reset button doubles as a security off switch.

ha ha, bought the switch yesterday, was gonna do the exact same thing tomorrow night. Funny. :)

I still think it's a "Great" idea, but I personally would go with a larger gauge cable. We all know the ground issues we have on our 928's so why skimp on the ground that comes "directly" off the battery? It's the Main Bad Boy ;)

Would it not be better to mount a kill switch where it can be reached by a seated driver? Unless you just want an easier way to disconnect the battery for when the car is sitting.

lol, my bad, why the kill switch?
but your right, the cable is (appears) too small. He'll know if it starts smoking.

I was thinking the kill switch needed to be on the outside?

It would be a quick convenient way to cut power during maintenance but other than that I'm not sure.

Great Anti-Theft Device :D

Who wants to steal a 928? Why would someone want to steal something that will cost them money? :)

It's not worth resetting the radio and clock to use as a theft device, it's out of reach of the driver for any safety benefit, and if it's for maintence, how much is being done? It's not that hard to just unscrew the ground to begin with. While it's kinda neat I don't see any real purpose for it.

I had the same switch in my car for a while between the battery ground and the chassis, since I wasn't driving the car much and didn't want to run down the battery between uses. I put the switch in around 2007 and loved it while it lasted. But.... the switch failed this fall. Since it is sealed, no way to clean it so I had to replace it. Ironic that the "newest" electrical part on the car failed. No telling how long it was making lousy contact before failing, either.

I replaced it with a knife switch by Wirthco. Much more "reliable" in my opinion. Quite handy now that I'm doing work on the electrical system. Once I'm done, I may retire it, but for now, it's pretty useful.

My current switch is similar to this one and was about $20-25

http://forums.pelicanparts.com/uploa...1328201917.jpg

When I am "doing stuff" I find it easier to loosen the neg clamp on the battery and take it on and off instead of messing with the wingnut.

Same here, my wingnut is tightened with channel locks and left alone.

these are the only type of Battery Disconnects I would trust since they are made by a company that makes proven race car stuff.

http://www.moroso.com/catalog/images/74100_part.jpg

http://www.moroso.com/catalog/images/74106_part.jpg

The boots to cover the connect part.

http://www.moroso.com/catalog/images/74110_part.jpg

Here's a quote of the cable gauge sizes:

Link to Morosso Battery Disconnects.

Moroso : Category Display

I replaced my negative cable wingnut with a washer and allen bolt. I leave the allen right there in the tool area. I have to secure a couple large amp cables as well as the battery cable to it works for me

Actually my car has draw thats dropping the battery. Big Surprise huh? Only, I've pulled tested the fuses and cannot isolate it. So this is what I did. I plan to get another stock ground strap and connect it to the body in a day or two. I agree that it's not a perfect set up yet.

Aren't those fun. I remember my Brother fixing my electrical short in my 79 Seville back in the day. I remember him using a $2 tester light and he fixed it in 5 minutes. I probably should have been paying attention when he fixed it too. Automotive Electrical Troubleshooting is a Talent, that's for sure :D

GTP
What wire gauge are you using? Any one know the wire equivalent of the flat cable? The round one is longer.

Sorry its NOT a kill switch. Though it could kill some of your electronics if you try to use it that way.

It is a battery isolation switch, but I would not do it that way, keep the wire big (1/0), short ~3" and non-movable (e.g. not on tool panel). This is suitable for maintenance use, battery charging & security.

If you want a real racing kill switch - you need to rewire the whole car, and really it needs to be on the outside, or accessible by wire pull from the outside.

Alan

I have a switch that cuts off the fuel pumps too - its on the Pod near my right hand - really easy to turn off - I use it just about every day.

Alan

I have a fuel pump cutoff switch as well. My car is actually setup on a different hot wire with a switch, relay, and fuse to the fuel pump. The PO said the original wiring to the fuel pump was burned. I checked it and he was right. This is probably the sourch of my draw. Hence the turn off switch. So far the wiring job is pretty solid though I did rewire some of it with wires from another 928. This rear switch is just a test idea. I wouldn't kill this switch while the car is running or anything. It's just to make it easier to turn off the battery for wrenching and battery preservation. That way I don't have to move covers, carpet, tool panel and all.

I suspect that everybody does...

So my point is - lets call it what is is in case anybody else gets the wrong idea about this - switching the battery out of circuit when the car is running is a VERY VERY BAD idea...

Alan

I also got the battery isolation switch for free. So that might help explain my idea. I would go back and change the original thread name to Battery Isolation Switch but I can't edit that part. So I'll just look stupid.

I guess I'm Old Skool as that's how I have always referenced this part as a Kill Switch. I do see your point Alan.

Here is an interesting description in a Hot Rod Mag:

The battery switch shown is quite actually adequate for normal duty, I have a similar one installed differently. However if you want the best battery switch money can buy - look for one from Blue Sea Systems: HD-Series Battery Switches - PN - Blue Sea Systems These also come in 2 way changeover and AFD options. Superb quality and sealed for marine use.

In the end how you install it is much more important than what it is. Don't add a new weak link to your cars higest power circuit.

Alan

Alan, I thought about this. The Blue Sea part is not copper. I would try to keep the parts copper at least for heat conductivity. Also think about this. If you ran a pull cable to this switch it could be used for racing. As a kill switch attached to the battery it would be useful as such if you were racing the car and rolled it. After all if you roll a 928, the body is going to be toast anyway. So why worry about the electronics? It would be better to kill the whole system than it would to burn to death in the car. The catch to it is that you cannot turn the system off while the car is running without fear of burning the alternator or the Jetronic.
I've done some positively bent things to a 928s electronics and they still work. I've hooked 50 amp chargers to the front jumper station to start a car over 100 times. The Jetronic still works flawlessly. The 928 is a pretty robust old dog. If anything I wouldn't make a habit of using it as a kill switch unless the car is upside down.
I'm working on a different ground strap setup. This is just the test for it. I have an original 911 ground strap. It's short and braided. I may use it.

The HD switch I showed is a simply superb switch - its current rating is 600A continuous, 2750A for 10 sec cranking. There is nothing to worry about with this switch - excepts its cost and size. I have 2 of these - I actually consider them works of art, I don't say that about much electric hardware.

The studs are heavily plated copper and sized for up to 4/0 cable.

If you reimplement your switch don't use any wiring on the ground point side - fabricate a copper/brass or aluminum bracket so the switch bolts to the GP directly.
Make the bracket sized to ~2/0 AWG.

This is not a racing kill switch and would not pass a sanctioning body check.

The point is if you are in the car, unconscious and someone needs to kill the car a kill switch should work to stop the car AND disconnect all power. Yours will not stop the car if the engine is running, so won't kill power => useless.

Alan

See pics for a good implementation strategy:

http://forums.rennlist.com/rennforum...h-dscn3468.jpg

http://forums.rennlist.com/rennforum...h-dscn3481.jpg

http://forums.rennlist.com/rennforum...nal-switch.jpg

$62.95 for that little switch on eBay

Blue Sea Systems #3000 Heavy Duty ON-OFF battery switch (632085030001) | eBay

Like I said - its the "Rolls Royce" of switches - you wouldn't expect that to come cheap right?

Alan