Where does a battery cut off switch go?

[Jayson Woodruff]

I know, sounds like a dumb question for an electrical engineer. But when I though about it, as a safety switch, interrupting the battery circuit doesn't seem to do much. It probably won't stop the engine, which keeps the alternator running, which will keep the full and ignition going. What to the various rule books say?

Seems to me a real safety switch would be to disable a main fuse or relay to kill the ignition and fuel pump. But this could actually be a pretty small switch compared to a battery kill.

Thoughts?

Jay W

[Adam Tarnoff]

The way I'm designing the circuit in my car is that that when amps exceed 160, a marine bus will be tripped and cut both the alternator and battery + to the starter.

[Bobby Beyer]

[Bobby Beyer]

A typical battery cutoff switch should also cut the lead to the alternator, there should 2 big posts for the battery and 2 smaller posts for the alternator.

The diagram I posted above is another way to wire a kill switch if your really paranoid about a battery fire.

[Bill Martin]

Gotta be a DPST. Isolate the battery and the other pole takes out either the alternator or the ignition. SCCA RR also wants it located in a specific location, but I assume you're not bound by that rule.

Buy TWO keys if they're the big red plastic removables. Hide one out on the car somewhere. You'll thank me later.