Switch/Relay advice needed.

[YBTURBO]

OK I'll try keep this as short as I can but with as much detail as i can. I'm basically looking for a button or switch that will only work when there is power available and that will turn off if its on when the power is off.

I have a ignition live space in my fuse box (for things not on my model rated 10A). I'm running out from that to a inline 10A fuse that is powering a double AUX port. in that port is a phone charger and a sat nav power lead. As it is now it all works fine but I'm looking for a way that when I turn on the ignition the charger and the cam will stay off until after I start the car then push the button/switch to turn it on. A normal switch would work but I know I would forget to turn it off most times when parking so it would be on as soon as i turn on the power to the ignition next time.

The main reason for wanting to do it is currently it will boot up the dash cam as i turn on the ignition but then power cycle it when i start the car and cause it to restart unless i let the cam fully boot then start up, then the power cycle just pops up as not on charge and back on charge.

 

thanks in advance for any advice on this one guys 😄

[unofix]

Any relay will do. You simply wire it as a 'No Volt Release' (NVR).

All machines in industry have to have a NVR on the supply. For example a machine lathe running and there is a power cut to the factory. You wouldn't want it to start back up when the power was restored as it could be dangerous.

See the sketch below:

[YBTURBO]

14 hours ago, unofix said:

Any relay will do. You simply wire it as a 'No Volt Release' (NVR).

 

i have a few relays around (4 pin) most are pinned 30, 85, 86, 87 love your diagram but not too sure what pin's are what if you could add the pin numbers to the image that be awesome and i'll get to trying to build it asap 😄

thanks for the help Unifix i would have been hunting for days if not weeks without your help on this haha.

 

[unofix]

With relay terminal numbers 👍

[YBTURBO]

6 hours ago, unofix said:

With relay terminal numbers 👍

thank you Unofix your a legend, saved me a lot of time and messing around 🙂 hopefully i'll get to return the favor some day 😄

[YBTURBO]

bit delayed due to work but time for a final update on this one.

All done and working perfect cant thank you enough Unofix, was a lot easier than i expected and went really smooth.

I was however limited to what I had to hand so I "made" it work will explain how now and you can tell me if I should worry about changing the way I done it any time soon. Basically I didn't have any connectors that would fit the larger legs on the relay so making do with what I had near me I drilled a small hole (enlarged a tiny hole already in them) and put ring end connectors on the cables, then I riveted them together so the only way that relay will be changed is cut the wires or drill the rivets. I did wrap each connection with loom tape (didn't have shrink tube big enough). Everything is tucked in nice behind the glove box inside the dash near the fuse box.

[unofix]

Well your solution is a first !!

Never had anyone pop-rivet ring crimps on to a relay before. There is a small problem with what you have done but I expect it will take 10 years before the problem starts to arise.

The legs/pins/blades of the relay will most likely be made of copper with a lead/tin coating, or if it's a lower quality relay the legs will be made out of mild steel with a coating of some sort. The pop-rivets are made out of an aluminum alloy and over time will react with the 'dis-similar metal' and eventually corrode leading to high resistance. I'd personally not worry about it, and just enjoy the fact it works 👍

[YBTURBO]

well i like the dont worry about it answer for now haha, i can confirm the rely is an older relay cant even remember where or when i acquired it but i can confirm it was copper with coating on the pins. i did think about corrosion being an issue but not for the same reason i was thinking if it got damp maybe now it was drilled it would rust where coating was worn but my best solution for that was wrap them well with loom tape (would have normally shrunk wrapped them but none big enough to hand).

what i'll do is not worry about it or even look into it unless there seems to be an issue starting then i'll check the relay first haha.