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View Full Version : How to - fit a battery cut off / kill switch?



stew
17-06-2006, 23:49
I want to get a battery cut off / kill switch fitted to the hybrid. Is this easy enough...what is involved?

I assume basically all i need is a switch, and a simple circuit with a relay to kill the power from the battery??? Only problem i can see with this idea is that when the circuit is killed, i would need to run the switch off a small battery otherwise i could never reactivate the relay!

How are they done on race cars? Any help from the clio cup car crew? :wink:

Does anywhere sell these as kits?

arj256
17-06-2006, 23:57
Im interested in this to
I know you can get a Fia one from Rally Design.
If your going to be mounting the battery in the boot? would be worth doing that first before wiring up the cut switches.

Justin..
18-06-2006, 04:14
whats wrong with the one in the ignition barrel ? :P

stew
18-06-2006, 10:37
whats wrong with the one in the ignition barrel ? :P

It doesnt kill the battery power! :roll:

It just turns off the ignition and dash lights etc etc.

Your stereo still works etc etc etc.

For a proper track car its advisable to have a kill switch!

:P

cliopete
18-06-2006, 11:47
Plenty of different types available, some bolt directly to batt. terminal, just disconnect battery and reconnect via switch. Best way would be to mount switch in car, on floor usually, and reroute leads. This is best way especially if battery is to be repositioned in boot. Don't forget though that you must not operate the switch with the engine running or the electrical surge will f**k up the alternator and possibly the ECU, but if you are upside down in a ditch or in the kitty litter with petrol pouring out everywhere this will be the last thing you will be worried about.

clowo16v
18-06-2006, 12:55
From my road car experience I always wire them inline into the negative side. This will completely cut the engine, as if wired into the positive side the alternator output can keep the engine running.

However if entering competition it must be wired into the positive side, to stop the switch earthing out in a collision.

With the cheaper type 2 terminal cut off switch its best to have it in the negative side. However you can get a slightly more expensive one that has terminals for the ignition circuit and a big resistor on top to stop the alternator powering on.

This is a pic of the expensive one as fitted to my mates hot rod. The resistor isn't fitted in the pic btw but you can see where it mounts:

http://www.hotrodphotos.co.uk/images.poppages/cut-off-switch-rear.jpg

Hope that answers your question OK.

Matt

stew
18-06-2006, 13:04
cheers matt! very helpful! :D

i want an in-car kill switch, with an aircraft style switch, so it wont get nocked accidently!

i was planning on wiring it in to the negative battery lead, but just wasnt sure about it!

i assume i need to buy a system from somewhere, as the switch alone will never cope with the current flowing thru it from the battery!

any recomendations on products to buy / where to get them?

cheers 8)

clowo16v
18-06-2006, 13:13
Just found this one:

http://www.merlinmotorsport.com/product_info.php?products_id=455

I wouldn't recommend one of the aircraft type switches they're not FIA approved so won't be legal if you want to race it.

I'd fit one on the outside of the car aswell while you're at it but if you're keeping the standard battery location it might be difficult.

Matt

stew
18-06-2006, 15:16
cheers matt, youve been most helpful!

8)

cliorod
18-06-2006, 15:21
http://i67.photobucket.com/albums/h305/Cliorod/Picture459.jpg
This is the one fitted in one of my Rally cars ~~ not the Maxi :wink:
It would be very difficult for anyone to accidental knock this of !!!.you insert the key,and turn it approx 1/4 turn to the right and it locks.I cannot recall in over 20 plus years competition of switching anything off :oops: :oops: .So much so,the cable to the left attached to it,is the master pull switch to the outside,it takes a hefty tug :twisted: to isolate it.
If in doubt,have a look at Rally cars in the service parks etc or race cars.hope this helps.
This the front side of the one shown with the terminals on.

stew
18-06-2006, 17:30
cheers rod!

only thing im not getting is the wiring.... :oops:

surely this cant be wired in series to the main battery loop? otherwise when the switch is closed then the wires will pull a fair few amps? no?

or is this for the negative battery lead - wired in series and is bassically like disconnecting the battery lead when the switch is opened?

ill draw a diagram in paint..... :wink:

stew
18-06-2006, 17:35
is this how it is wired in....

Lunner
18-06-2006, 18:50
Thats fine, just use a big cable, and stop worrying, you'll ahve a fire extinguisher fitted anyways lol

clowo16v
18-06-2006, 19:20
That looks right yeh. You should get instructions when you buy one.

Matt