Originally Posted by
Greg Amy
I believe so.
Hey, it's quite possible (probable!) that this is not a new issue. It's quite likely that someone has already seen this, questioned it, and gave it an okey dokey. Remember, this is all "but my opinion."
However, to make what I see as the best of both worlds - both safety and strict legality - here's how you, Chris, can mod your existing system:
- First, I'm assuming your solenoid is normally open, where when the switching circuit is NOT energized, the battery circuit is open.
- Next, move the fused circuit that powers the switching side of the solenoid from the battery terminal to the car side of the solenoid (in your drawing, move the fused wire currently attached over the "S" in the word solenoid to the terminal over the "d" in solenoid).
- Bisect that fused circuit, put an appropriate fuse in both wires at the solenoid, and run both wires into the cabin. Attach them to a normally closed momentary push button switch (S1).
- Take the ground side of the switching circuit - where you currently have the toggle switch wired - and connect it directly to ground.
- Add another wire between the "S" and "D" terminals, bisect it with a normally open momentary push button switch (S2), mounted right on top of the solenoid, as close as possible.
So, here's what happens: you just installed the battery, all circuits are dead. To energize the solenoid, pop the hood and push the momentary switch S2. This will energize the switching circuit of the solenoid and close the battery circuit. The solenoid is feeding both the car and its own switching circuit.
In the case of an emergency (or when you park the car in your garage), select S1. This will open the latched switching circuit, de-energizing the solenoid, and killing power to both the car and the switching circuit. Power is isolated to only the battery side of the solenoid (and the battery side of the close-by S2), and nowhere else.
To re-energize the circuit and re-latch the battery isolater, pop the hood and push S2. This will again close the switching circuit and energize the solenoid.
If at any time the switching circuit wiring is compromised by grounding (e.g., wires are crushed in a crash) the fuses in the S1 switching wires will open, causing the switching circuit to open, and de-energizing the solenoid and opening the battery circuit. Any failures in components of the switching circuit (wires, switches, fuses) and the system will fail "safe", de-energizing the solenoid and isolating the battery.
Last and final touch (and this is what I do to address that "hot wire into the cabin" problem): use an appropriate fusible link on the battery positive wire as close as practical to the battery. Any grounding of the battery wire (e.g., at firewall) will cause the fusible link to fail open, disconnecting the battery.
I'm terrible at Internet drawing, but I'd be glad to write it up on the back of a napkin next time we meet... - GA