Battery disconnect wiring

[Sandy]

Tell your drivers to keep on the track and off the bump strips and right side up

I think that TransAm and some other sanctioned bodies now required them, but I like the idea. When playing with the switch it seems in 2 states, on or triggered to off.

The one I have looks to be made by ford UK, not sure if the same one your guys have run.

Electric Fuel Pump Inertia Shutoff Switch

But I do like the comment, "Mount near driver for reset"...

 

[Ross Nicol]

Ok now it is known you should never disconnect the battery while the engine is running.The reason is simply that the battery acts as a load for the alternator. If you disconnect the battery while the engine is running you unload the alternator and the voltages generated can damage the rectifier diodes that convert the alternator output from AC to DC or damage the Engine Management,ABS computer etc. I don't go along with the capacitor/spike explanation.
When I fitted a Cut Off Switch to the 240z I used to race, it continued to run when the switch was turned off.I put this down to 2 things.The ignition was still on and the alternator was able to maintain an output which fed back to the field circuit/regulator. Also the electrical demand on the alternator to run the car was very low.I fixed the problem by connecting the alternator output to the battery side of the cut off switch.As has been discussed this left a permanently hot wire on the alternator output.
Moving onto the GT40. I have the Battery cut off switch in the +ve lead and alternator output through a fuse to the battery. Again switching the switch off stops the motor ok but leaves the hot wire on the alternator.
Scrutineers have only insisted the cut off switch stops the motor which it does.

Ross

 

[Russ Noble]

Russ, there is no requirement to run the leads & switch to that area- simply install a pull cable from that area to the switch- a sturdy hood release or manual choke cable usually does the trick, Mark it with the appropriate info ( pull/twist etc ) & decal. This also keeps the switch away from the elements- the contacts usually need a clean up on these if they are subject to moisture & then left sitting between meetings.

Hmmm.... Good thinking Jac Mac. I'll see how I can implement that one.

Cheers

 

[Jac Mac]

One other thing- Im sure we used a diode in the field wire to prevent the alternator from self energising when the master is turned off.

Jac Mac

 

[Brian]

Hoping that I am not diverting this thread, has anyone experience with this item?

CDOC.com | Electronic Kill Switch (2509-400S02)

Considering how many feet of heavy cable I'll have to run to put a dash and an external cut-off switch in, this may be a good trade-off.

I know some folks could stitch together some latching solenoids, etc, to do this, but I can't , just like some of the builders on the forum could not shoot their own paint or bend metal, I'm just not good with electrons.

Many thanks in advance for any observations.

Brian