2-way spring switch?

Question

After this hurricane I’m making a generator enclosure. When one of the generators turns on with the 12 V socket a switch opens and turns a linear actuator on that opens an exhaust port.

When the generator turns off. The switch closes with no power from the genny. I’ll have a battery activate the actuator in the opposite direction. Or close the port.

What would be the best way to tackle this? Is there a switch, relay, etc., that can get power when in the closed position?

Here is what I’m thinking?

Answer 1

The canonical reversing DPDT relay setup should work here, provided there are limit switches built into the actuator itself to automatically stop travel at each end (a common feature). D1 shunts the relay coil's voltage spike, Cs and Rs form a snubber that protects the relay's contacts; you could use a TVS as well. F1 should be a slow-blow fuse. I strongly recommend a secondary, redundant method of venting and/or an automatic shutdown of the generator if the vent should fail to open, not to mention designing the system so that exhaust gases can never enter or accumulate in a habitable location.

Rather than try to have the generator charge the battery (small sealed lead-acid gel cell is my vote), a solar charger is probably going to be the most effective.

^{simulate this circuit – Schematic created using CircuitLab}