Hello, and thanks in advance for giving this a read. I have done my research and I'm seeking help on a best option before committing to learning how to implement the best one.

Project -

Two dashcams and one Powerpack Battery.

Goal - key on - switch dashcams power source from Powerpack Battery to car 12v (5v inverted). Begin charging Powerpack Battery. Isolate battery supply side from cams.

Key off - Switch cams power supply back to Powerpack Battery. Isolate car fuse box.

I first considered using transistors as switches but because Powerpack Battery supply needs to come on when12v goes off, I thought maybe a normally closed relay would be best. A quick search showed a lot of these but all are 40 amp or more (switch currents too high). Each cam only draws about 0.6 amps. It seems that a single relay and a diode to isolate the battery leg of the circuit is a possible solution but not sure where to find correct part.

I started thinking about Arduino Uno. I know that device is overkill but it's also cheap and simple. I'll hold these questions for the Arduino section if this turns out to be the better option.

Q- Is there a simpler way to achieve this goal?

Q - Can I find a NC relay in the 1 amp range?

Q - Arduino Uno?

 

Something simple like this could work.
But there is no battery discharge protection.

 

hi 22,
Use a single pole change over relay, SPCO, look thru this PDF for a 12V SPCO relay, use the normally closed pair of contacts, N/C
E

 

Use Schottky diodes for the circuit dendad proposed, to minimize diode forward voltage drop.