Technical electrical question...

[jimmothy86]

I work at an industrial electronics company in Franklin, IN as a former technician, current parts sourcer/buyer and would be more than happy to help you find parts if ever you need assistance with that, i don't get a commission, so i'll probably just give digikey/mouser links, but i can also tell you if we have it in stock (some of our parts are from the 80s, literally) if you need to pick it up somewhat locally!

 

[K_W]

I'm now making a SPDT automotive relay into a power selector (key switched on NC and constant on NO ) for my dash cam. This would allow the dash cam to turn on and off with the ignition using the NC pole, but then have a on/off switch to trigger the relay to the NO pole and supply it with constant power for parking in a public lot.

I picked up a couple different ones from a mechanic friend's junk drawer and then hooked them up for 20 minutes to simulate continuous usage and one got hot enough to almost burn me. Turns out even though it has 80 ohm resistance the spike suppression resistor inside was only a 20 ohm. Another relay has 180 ohm resistance and barely got warm, it has a 680 Ohm resistor inside... I decided to use that one unfortunately I broke it trying adapt it to fit in in the little box I am using.

 

[moosehead]

Something to think about adding, a low voltage cutoff. You don’t want to the camera to run the battery so low the car won’t start.
some people add a battery that charges on a switched circuit, so it’s disconnected from the battery with the ignition off.
then you have something like the Blackvue power magic pro which is hooked up to a non switched circuit, but cuts the link after a certain time, or when the battery voltage reaches a certain level.