Manually activate auto shut off switch.

Nerdrage88 · Mar 27, 2016

I can't find any automotive switches that, when it has power going to it, you turn it on and it will stay on but as soon as you turn your car off the switch turns off and in order for x load to be turned on the switch must have power (key turned to run position) and manually flip the switch to the on position.

I'm trying to come up with various kill switches and to force myself to not be lazy or forget to turn off when I leave my vehicle.

To you search snobs. Yes I looked on many search engines.

All I'm looking for is a lead as to what the specific term for said switch to aid in my search.

Spott · Mar 27, 2016

This can be done reliably and cheaply, but not with a specific switch; you need a little circuit to make it work.

They call it a self-latching relay circuit.

You need a momentary switch (normally open type), and a dual-pole relay or two single-pole (common in most automotive applications) relays. Optionally, if you want to be able to also turn off the load without having to turn off the vehicle, you can add another momentary switch (normally closed type).

See if searching that will provide you enough information; if not, inquire further and I'll explain how to connect them and how it works.

Nerdrage88 · Mar 27, 2016

So like this?

Spott · Mar 27, 2016

Sure, although that circuit is best suited for small loads that can run off switched ignition power.

If you have a large load, it would be best to daisy-chain the input coil of a second relay to the output of the first, that switches power straight from the battery.

Nerdrage88 · Mar 27, 2016

I'll keep that in mind.

If I were to do this on the ignition (shut off the coil, unless it's more complicated then that) I shouldn't need a ton on capacity since the coil gets power from the ignition switch (I can't imagine that the switch is passing a bunch of power to begin with) in the steering column and of course from the fuse box which comes from the battery.

Unless I'm wrong.

Spott · Mar 27, 2016

Yes, that should work. Cut the wire between the key switch and the ignition coil at a good spot to mount the relay, hook the "Hot" point on your circuit to the wire from the key switch, "Com" to ground, and "Load" to the wire that goes to the ignition coil. For vehicle wiring, I really suggest soldering the splices and connectors and covering them with heat-shrink tubing. Crimp connectors work also, but they don't seem to last nearly as long.

When you get into the vehicle, you will have to turn the key to run, push the latching button (which just might be concealed somewhere sneaky, depending on your intentions), and crank the engine until it starts. Once you turn the engine off, the latching circuit will reset, and until you turn the key to run and then push the button again, it will never fire a single spark.

If this is a vehicle you use much, and if you install this as a disable circuit in the ignition coil, make sure you put the button somewhere very convenient to reach, or you're going to get really tired of having to reach for it before the engine will start.

Manually activate auto shut off switch.

Nerdrage88

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